READILY BIODEGRADABLE COD AS AN INDICATIVE PARAMETER
IN ESTIMATING THE EFFICACY OF A SEWAGE FOR
BIOLOGICAL EXCESS PHOSPHORUS REMOVAL
by
RAMANATHAN MANOHARAN
B . S c . ( C i v i l E n g . ) , U n i v e r s i t y o f P e r a d e n i y a , 1977
. E n g . ( C i v i l E n g . ) , U n i v e r s i t y o f B r i t i s h C o l u m b i a , 1982
A THESIS SUBMITTED IN PARTIAL FULFILLMENT OF
THE REQUIREMENTS FOR THE DEGREE OF
DOCTOR OF PHILOSOPHY
in
THE FACULTY OF GRADUATE STUDIES
(Department of C i v i l
We a c c e p t
Engineering)
t h i s t h e s i s as
to the required
conforming
standard
THE UNIVERSITY OF BRITISH COLUMBIA
December
w
1988
Ramanathan M a n o h a r a n , 1988
In
presenting this thesis
in partial fulfilment of the requirements for an advanced
degree at the University of British Columbia, I agree that the Library shall make it
freely available for reference and study. I further agree that permission for extensive
copying of this thesis for scholarly purposes may be granted by the head of my
department
or
by his or
her
representatives.
It
is
understood
that
copying or
publication of this thesis for financial gain shall not be allowed without my written
permission.
Department of
C i v i l Engineering
The University of British Columbia
Vancouver, Canada
D a t e
DE-6 (2/88)
D e c . U , 1988
-i i-
ABSTRACT
The o b j e c t i v e s of t h i s r e s e a r c h were to develop a r e l i a b l e
measurement
technique
s u b s t r a t e s present
to
in a
quantify
the
given
s u b s t r a t e added,
sewage
with
respect
to
experimental
work
l a b o r a t o r y s c a l e systems i n
readily
used
biodegradable
as
readily
a
biodegradable
i t s natural
butyrate
and
specific
substrates
phosphorus
glucose.
removal
release, aerobic
anaerobic carbon
this
which one
content
dosages of sodium
the
efficacy
i n the
process.
during
excess
different
on
the c h a r a c t e r i z a t i o n of a
study
was used
i n v o l v e d two
t o q u a n t i f y the
s u b s t r a t e s i n the feed while the other was
biological
substrates)
role in
under a c c l i m a t e d c o n d i t i o n s
leading to
b i o l o g i c a l excess phosphorus removal
The
biodegradable
sewage and t o i n v e s t i g a t e t h e i r
b i o l o g i c a l excess phosphorus removal,
f o r each
readily
of
the
acetate,
The
and
phosphorus
feed
sodium
system. The
was changed using
p r o p i o n a t e , sodium
e f f e c t s of these compounds
as
general
various
elements
mechanism
(such
phosphorus uptake,
storage
removal
and
readily
biodegradable
of the b i o l o g i c a l
as
anaerobic
carbon
excess
phosphorus
o v e r a l l phosphorus
aerobic
(both as
removal,
consumption) were
investigated.
R e s u l t s of t h i s study showed that almost a l l the d i f f e r e n t
elements
of
the
biological
compared very well among the
excess
phosphorus
different
removal
process
s u b s t r a t e s used when the
—i i i—
readily
biodegradable
biodegradable
overall
COD)
was
phosphorus
substrates
direct
release in
as
readily
used as the u n i t of measurement. A l s o , the
removal
efficiency
amounts of r e a d i l y biodegradable
A
(quantified
relationship
the anaerobic
improved with i n c r e a s i n g
s u b s t r a t e s e n t e r i n g the
existed
zone and
between
the
system.
phosphorus
the phosphorus uptake i n the
a e r o b i c zone, a c c o r d i n g to
P uptake (mg/L) = 1.21
+ 1.701
x P r e l e a s e (mg/L)
w i t h the constant of c o r r e l a t i o n being 0.985.
The
carbon
r e s u l t s of t h i s
storage.
storage
(as
anaerobic
A
PHB
study a l s o
definite
or
PHV)
conditions,
link
and
and
addition
(glycogen) was
consumed
found to
under
relationship
trial,
existed
consumption, with
the
amount
approximately
of
0.41,
In terms
COD,
had
the
phosphorus
release
under
second
be s t o r e d
between
per
carbon
the
PHB
unit
of
and
the
compound
c o n d i t i o n s and
excellent
synthesis
mean value
the
during
storage
An
carbon
consumption
under a e r o b i c
conditions.
the estimated
PHB
between
c o n d i t i o n s . However,
a
anaerobic
importance of
existed
between the carbon
phosphorus uptake under a e r o b i c
glucose
showed the
and
linear
glycogen
f o r the i n c r e a s e i n
glycogen
consumed
being
on a weight b a s i s .
of s p e c i f i c
substrates, for
the same dosage as
t h e i r e f f e c t i v e n e s s i n b i o l o g i c a l excess
phosphorus removal
the f o l l o w i n g d e c r e a s i n g
order:
- i v-
acetate > propionate
I t was
n o t i c e d d u r i n g the study
r e d u c t i o n i n the dosage
the s t e a d y - s t a t e
to
of the
biological
f o r a p e r i o d of upto 5
decreasing
> b u t y r a t e > glucose
the
new
days
added simple
excess
at
lower
that whenever there was a
carbon s u b s t r a t e s ,
phosphorus removal
the
level,
same
higher
reflecting
s u b s t r a t e dosage. But, as a c o r o l l a r y , when the
was
increased,
immediately without
the
excess
phosphorus
continued
level
the
before
reduced
s u b s t r a t e dosage
removal
the presence of any s i g n i f i c a n t
increased
lag period.
-v-
TABLE OF CONTENTS
Page
ABSTRACT
i i
TABLE OF CONTENTS
v
LIST OF TABLES
viii
LIST OF FIGURES
ix
ACKNOWLEDGEMENT
xii
1.
INTRODUCTION
1
2.
LITERATURE REVIEW
8
2.1.
B i o l o g i c a l Excess Phosphorus Removal
8
2.2.
Concept
2.3.
The Role of R e a d i l y Biodegradable S u b s t r a t e s
on B i o l o g i c a l Excess Phosphorus Removal
3.
EXPERIMENTAL
of R e a d i l y Biodegradable S u b s t r a t e s
METHODS
15
23
32
3.1.
Experimental Design
32
3.2.
Quantification
33
3.3.
of R e a d i l y Biodegradable S u b s t r a t e s
3.2.1.
Experimental Set-up
33
3.2.2.
Measurement Procedure
38
3.2.3.
C a l c u l a t i o n Procedure
39
3.2.4.
Example C a l c u l a t i o n
39
L a b o r a t o r y Scale Operation of Phosphorus Removal
System
40
3.3.1.
Wastewater Source
40
3.3.2.
Chemical A d d i t i o n
43
3.3.3.
Anaerobic Reactor
44
3.3.4.
Anoxic Reactor
44
-vi-
Page
3.4.
3.3.5.
Aerobic Reactor
45
3.3.6.
Clarifier
45
3.3.7.
Operation
46
Analytical
Methods
3.4.1.
Chemical
3.4.2.
D i s s o l v e d Oxygen
48
3.4.3.
Glycogen
48
3.4.4.
Nitrogen
48
3.4.5.
O x i d a t i o n Reduction
3.4.6.
pH
Oxygen Demand
46
3.4.7.
Poly-B-hydroxybutyrate
hydroxyvalerate
Potential
49
50
and
Poly-B50
3.4.8.
Phosphorus
52
3.4.9.
Solids
54
3.4.10. V o l a t i l e
4.
46
3.5.
Cold Storage
3.6.
Statistics
RESULTS AND
Fatty Acids
Testings
54
,
55
56
DISCUSSION
57
4.1.
Acetate Addition
58
4.2.
Propionate Addition
60
4.3.
Butyrate Addition
63
4.4.
Glucose Addition
65
4.5.
Readily Biodegradable
4.6.
Phosphorus Release
4.6.1.
Anaerobic
COD
and Uptake
Zone
68
72
79
Page
4.7.
5.
4.6.2.
A e r o b i c Zone
4.6.3.
Anoxic
4.6.4.
Phosphorus Accumulation
86
Zone
..
90
i n Sludge
94
Carbon Storage and Consumption
Zone
95
4.7.1.
Anaerobic
4.7.2.
A e r o b i c Zone
106
4.7.3.
Anoxic
107
4.7.4.
Carbon Storge and Consumption as Glycogen
Zone
100
110
4.8.
O v e r a l l Phosphorus Removal
117
4.9.
O v e r a l l N i t r o g e n Removal
125
4.10.
Experimental Run with Combined A c e t a t e and
Propionate
130
4.11.
Lag Response d u r i n g Dosage T r a n s i t i o n s
133
CONCLUSIONS AND RECOMMENDATIONS
141
5.1.
141
Conclusions
5.2.
5.1.1.
C o n c l u s i o n s D i r e c t l y R e l a t e d t o O b j e c t i v e s 141
5.1.2.
Other C o n c l u s i o n s R e l a t e d t o R e a d i l y
Biodegradable Compounds i n General
143
5.1.3.
Other C o n c l u s i o n s R e l a t e d t o S p e c i f i c
R e a d i l y Biodegradable Compounds
145
Recommendations
148
BIBILIOGRAPHY
150
APPENDICES
157
Al.
Development of the Method Used f o r the
Determination of the R e a d i l y Biodegradable COD ... 157
A2.
Raw Data
from the V a r i o u s E x p e r i m e n t a l Runs
169
A3.
Raw Data
from the C o l d Storage T e s t i n g s
192
—v i i i -
LIST OF TABLES
Page
3.1.
Summary of O p e r a t i n g Parameters f o r the Laboratory
Excess
Phosphorus Removal System
47
4.1.
R e s u l t s of A c e t a t e A d d i t i o n Experiments
59
4.2.
R e s u l t s of Propionate A d d i t i o n Experiments
62
4.3.
R e s u l t s of B u t y r a t e A d d i t i o n Experiments
64
4.4.
R e s u l t s of Glucose A d d i t i o n Experiments
66
4.5.
Phosphorus Uptake f o r Acetate Run
75
4.6.
Phosphorus Uptake f o r Propionate Run
76
4.7.
Phosphorus Uptake f o r Butyrate Run
77
4.8.
Phosphorus Uptake f o r Glucose Run
78
4.9.
Average Phosphorus Uptake f o r A l l Runs
80
4.10. Carbon Consumption
f o r Propionate Run
99
4.11. Carbon Consumption
f o r Butyrate Run
99
4.12. Carbon Consumption f o r Glucose Run
101
4.13. O v e r a l l N i t r o g e n Removal f o r A l l Runs
4.14. Phosphorus Uptake, Carbon Consumption and N i t r o g e n
Removal d u r i n g the Run with Combined Acetate and
Propionate
129
131
4.15. Phosphorus and Carbon Balances f o r the Butyrate
Run d u r i n g the Dosage T r a n s i t i o n s
138
- ix-
LIST OF FIGURES
Page
2.1.
P r o f i l e of oxygen uptake
wastewater as feed
rate with
domestic
17
2.2.
P r o f i l e s of oxygen uptake
feeding c o n d i t i o n s
r a t e s under two
2.3.
P r o f i l e s of oxygen uptake
types of feed
r a t e s with two
different
17
different
19
2.4.
P r o f i l e of oxygen uptake
substrate
2.5.
Process c o n f i g u r a t i o n used f o r the d e t e r m i n a t i o n of
the r e a d i l y biodegradable COD of feed
22
D e n i t r i f i c a t i o n r a t e s used
d e n i t r i f i c a t i o n method
22
2.6.
r a t e w i t h g l u c o s e as
19
i n the b a t c h
2.7.
Oxygen uptake
method
2.8.
The m o d i f i e d L u d z a c k - E t t i n g e r p r o c e s s f o r b i o l o g i c a l
n i t r o g e n removal
24
2.9.
The m o d i f i e d UCT process f o r b i o l o g i c a l n i t r o g e n and
phosphorus removal
24
3.1.
Schematic l a y o u t of the process c o n f i g u r a t i o n f o r the
d e t e r m i n a t i o n of the r e a d i l y b i o d e g r a d a b l e COD of the
feed
34
Schematic l a y o u t of the l a b o r a t o r y s c a l e experimental
set-up of the b i o l o g i c a l excess phosphorus removal
system
41
4.1.
T o t a l r e a d i l y biodegradable COD i n f e e d v s . chemical
a d d i t i o n to feed, expressed as COD
71
4.2.
T o t a l r e a d i l y biodegradable COD i n f e e d v s . chemical
a d d i t i o n to feed, expressed as mg/L
71
4.3.
Mass of phosphorus e n t e r i n g and l e a v i n g each
i n d i v i d u a l r e a c t o r per u n i t i n f l u e n t flow
73
4.4.
The anaerobic phosphorus r e l e a s e with chemical
dosage, expressed as COD e n t e r i n g the a n a e r o b i c zone
85
The anaerobic phosphorus r e l e a s e w i t h r e a d i l y
biodegradable COD a v a i l a b l e i n the a n a e r o b i c zone ...
85
3.2.
4.5.
r a t e p r o f i l e used
i n the batch a e r o b i c
22
-x-
Page
4.6.
The a e r o b i c phosphorus uptake
expressed as COD i n the feed
4.7.
The a e r o b i c phosphorus uptake with r e a d i l y
b i o d e g r a d a b l e COD i n the feed ( i n c l u d i n g the chemical
addition)
87
R e l a t i o n s h i p between the a e r o b i c phosphorus
and the anaerobic phosphorus r e l e a s e
92
4.8.
4.9.
with chemical dosage,
87
uptake
The anoxic phosphorus uptake with chemical dosage,
expressed as COD i n feed
92
4.10. R e l a t i o n s h i p between the a e r o b i c sludge percent
phosphorus and the chemical dosage, expressed as COD
i n feed
96
4.11. R e l a t i o n s h i p between the a e r o b i c sludge percent
phosphorus and the r e a d i l y biodegradable COD i n feed
( i n c l u d i n g the chemical a d d i t i o n )
96
4.12. Mass of carbon storage compounds e n t e r i n g and l e a v i n g
each i n d i v i d u a l r e a c t o r per u n i t i n f l u e n t flow
98
4.13. A s i m p l i f i e d model f o r anaerobic metabolism
bacteria
of bio-P
101
4.14. R e l a t i o n s h i p between carbon storage and phosphorus
r e l e a s e i n the anaerobic zone f o r the p r o p i o n a t e run
104
4.15. R e l a t i o n s h i p between carbon storage and phosphorus
r e l e a s e i n the anaerobic zone
104
4.16. Anaerobic carbon storage v s . chemical dosage, as COD
e n t e r i n g the anaerobic zone
105
4.17. Anaerobic carbon storage vs r e a d i l y biodegradable COD
(from the feed and the chemical a d d i t i o n ) e n t e r i n g
the a n a e r o b i c zone
105
4.18. A s i m p l i f i e d model f o r a e r o b i c metabolism
bacteria
108
of bio-P
4.19. R e l a t i o n s h i p between carbon consumption and
phosphorus uptake i n the a e r o b i c zone
108
4.20. R e l a t i o n s h i p between carbon
uptake i n the anoxic zone
112
storage and phosphorus
4.21. R e l a t i o n s h i p between the phosphorus uptake and
glycogen consumption i n v a r i o u s zones f o r glucose run
112
-xiPage
4.22.
4.23
R e l a t i o n s h i p between the i n t r a c e l l u l a r PHB
glycogen f o r glucose run
and
118
The o v e r a l l phosphorus removal of the system v s . the
chemical a d d i t i o n , expressed as COD i n feed
118
The o v e r a l l phosphorus removal of the system v s . the
r e a d i l y biodegradable COD i n feed ( i n c l u d i n g the
chemical a d d i t i o n )
122
4.25. The o v e r a l l phosphorus removal of the system vs. the
chemical dosage, expressed as mg/L i n feed
122
4.24.
4.26.
4.27.
R e l a t i o n s h i p between the o v e r a l l phosphorus removal
of the system and the anaerobic phosphorus r e l e a s e ...
124
R e l a t i o n s h i p between the o v e r a l l phosphorus removal
of the system and the a n a e r o b i c carbon storage
124
4.28. O v e r a l l n i t r o g e n removal e f f i c i e n c y of the system v s .
the chemical dosage, expressed as COD i n feed
127
4.29. O v e r a l l n i t r o g e n removal e f f i c i e n c y of the system v s .
the r e a d i l y biodegradable COD i n feed ( i n c l u d i n g the
chemical a d d i t i o n )
127
4.30
P r o f i l e of the e f f l u e n t
a c e t a t e run
ortho phosphorus
f o r the
135
4.31.
P r o f i l e of the e f f l u e n t ortho phosphorus
p r o p i o n a t e run
f o r the
4.32.
P r o f i l e of the e f f l u e n t o r t h o phosphorus
b u t y r a t e run
f o r the
4.33.
P r o f i l e of s t o r e d PHB i n the v a r i o u s zones of the
system f o r the b u t y r a t e run
135
136
136
-xi i -
ACKNOWLEDGEMENT
I wish
t o express
Head o f t h e C i v i l
B r i t i s h Columbia,
my s i n c e r e
Engineering
thanks
Department
at
thesis.
I
their
for their assistance
t h a n k Susan
invaluable
i n the
L i p t a k , Paula
assistance
Oldham,
U n i v e r s i t y of
and a d v i c e
given
research.
I a l s o w i s h t o t h a n k D r . D.S. M a v i n i c ,
Beatty
the
for h i s e n t h u s i a s t i c support
during the e n t i r e p e r i o d of t h i s
Dr. T.
t o D r . W.K.
in
D r . K . J . H a l l and
p r e p a r a t i o n of t h i s
P a r k i n s o n and
the
laboratory
Romy So f o r
a n a l y s i s , Guy
K i r s c h f o r h i s a s s i s t a n c e i n the
c o n s t r u c t i o n of
experimental
Mukunthan f o r h i s a s s i s t a n c e i n
system,
Kannappar
collecting
sewage
Engineering
f o r the f i n a n c i a l
Dr. W.K. Oldham a n d
support.
f o r the
study,
the
support
Yogeswary Manoharan
the laboratory
Department
from
of
Civil
t h e NSERC g r a n t s o f
f o r her
constant
moral
-1 -
CHAPTER
ONE
INTRODUCTION
The
impact of i n c r e a s e d
bodies has
f a s t become an
of u r b a n i z a t i o n
water
bodies
and
land e x p l o i t a t i o n , causing
with
algal
disruption
of
of
on n a t u r a l
also
cause
foul
recreational
dissolved
water
levels
eutrophication
blooms y i e l d i n g numerous p h y s i c a l
treatment c o s t s . Furthermore, f i s h
depletion
loadings
important concern with i n c r e a s e d
a e s t h e t i c problems. They
water,
nutrient
oxygen
taste
activities
k i l l s could
and
and
of
and
odour of
high
r e s u l t due
water
to
the
r e s u l t i n g from the decay of
the
a l g a l blooms.
The
growth
three
are
major
carbon,
nitrogen
unwanted growth, the
and
subsequently
Khettry,
aquatic
1980).
It
compounds
The
longer
due
system.
curtail
any
usually
to an
to
or the
assimilable
should be
from
Thus,
unwanted
the
To
curtail
first
not
any
identified
possible
extent that
b i c a r b o n a t e ion
forms
to
i t will
of
(Black
nitrogen
and
f o r most
ammonia. However, when these forms
(e.g. blue-green algae)
atmosphere
controlling
algal
any b i o l o g i c a l
i t s n a t u r a l abundance from
a v a i l a b l e , some s p e c i e s
f i x the n i t r o g e n
aquatic
is
of carbon
growth are n i t r a t e and
become no
can
input
for
phosphorus.
limiting nutrient
limiting nutrient
e i t h e r the organic
required
and
controlled.
c o n t r o l the aquatic
become the
nutrients
growth
the
in a
and
input
water
add
of
it
to
nitrogen
body
the
to
becomes
-2-
i r r a t i o n a l . T h i s l e a v e s the c o n t r o l
p r a c t i c a l means
of c u r t a i l i n g
of
phosphorus
as
the most
the e u t r o p h i c a t i o n of the n a t u r a l
water b o d i e s .
Phosphorus has been recognized as the l i m i t i n g n u t r i e n t i n
most
of
the
eutrophication
situations
(Porter,
1975).
The
phosphorus a v a i l a b l e to the organisms i n a given ecosystem e n t e r s
the
system p r i m a r i l y v i a anthropogenic point and d i f f u s e
s i n c e the n a t u r a l source of phosphorus
earth's crust
sources are d i f f i c u l t
wider
to
the
such
monumental e f f o r t .
as
the
proper
a p p l i c a t i o n to the a g r i c u l t u r a l
in
ecosystem
terms
of
lands
a
on
the
other
hand,
i d e n t i f i a b l e and c o n t r o l l e d , based on s i t e - s p e c i f i c
water
O f t e n , the
major point
bodies
the
primary
is
sources
of
chemicals
corrosion
used
to
discharge
laundry
protect
of man's
prove t o be
are e a s i l y
needs.
source of phosphorus t o r e c e i v i n g
phosphorus
human waste, s y n t h e t i c
fertilizer
control
e x t e n s i v e u r b a n i z a t i o n may
more e f f e c t i v e . P o i n t sources,
their
In these s i t u a t i o n s
management of
and
The
through non-point
to d i s t i n g u i s h and f o r the most p a r t ,
require a
controls,
activities
m i n e r a l s of the
i s u s u a l l y scarce due to t h e i r low s o l u b i l i t y .
c o n t r i b u t i o n of phosphorus
c o n t r o l would
from the
sources,
of
in
domestic
wastewaters. The
the domestic wastewater are
detergents
and
water treatment
the water d i s t r i b u t i o n systems from
(U.S.EPA, 1976).
Municipal
wastewaters
are most o f t e n
treated
u s i n g the
-3-
a c t i v a t e d sludge p r o c e s s . In a t y p i c a l a c t i v a t e d sludge
process,
1.0-1.5
mg/L
of
phosphorus i s removed ( f o r the b a s i c
m e t a b o l i c purposes) f o r every 200 mg/L
1976)
and
weight
the phosphorus
treatment
of COD
removal (U.S.EPA,
makes up approximately
of
biomass
(Hoffmann
and
phosphorus
removal
obtained
by
process i s
o f t e n inadequate
Marais,
this
1.5%
of the dry
1977).
Since
conventional
to protect
the
treatment
the environment, b e t t e r
phosphorus removal i s being r e q u i r e d by many government agencies.
Two
major
strategies
(excess) phosphorus
Chemical
are
available;
removal i s
phosphates with c e r t a i n c h e m i c a l s ,
s e d i m e n t a t i o n . The
necessary
for
achieved by
Although
most commonly used chemicals
f o r t h i s purpose
chloride,
which
provide
extremely
or as
a final
stage or d i r e c t l y
stage of
low e f f l u e n t phosphorus l e v e l s may
treatment.
be obtained
p r o c e s s , i t s u f f e r s from a number of drawbacks such
r e q u i r e s subsequent
method
the c a t i o n s
the p r e c i p i t a t i o n of phosphates i n the wastewater.
as the p r o d u c t i o n of
this
precipitating
c o a g u l a t i o n and
b i o l o g i c a l process
through t h i s
biological
by
ferric
followed
These chemicals are added e i t h e r at the i n i t i a l
i n t o the
or
removal.
phosphorus
are l i m e , alum and
chemical
of
a
large
amount
of
chemical
sludge that
d i s p o s a l . High chemical c o s t s a l s o have made
phosphorus
removal
prohibitive
for
many
communities.
Another
method
which
does
not
require
any
chemical
a d d i t i o n or produce i n c r e a s e d volumes of sludge to dispose o f , i s
-4-
b a s e d on t h e b i o l o g i c a l
bio-P
process,
metabolic
believed
of
phosphorus
requirements
t o be s t o r e d
inorganic
Shapiro,
normal
phase and
upon
phosphorus
as
properly
phosphorus
It
of the normal
is
granules
entering
well
release,
to
with
(Barnard,
However,
phosphorus
generally
chains
( L e v i n and
aerobic
biomass,
sludge into
zone,
consequence
of
being
is
in
for this
upstream
conditions,
the l i q u i d
a l l the released
phosphorus
resulting
activated
zone
anaerobic
The r e a s o n
release
further
micro-organisms
t a k e n up by a
excess
phosphorus
b e h a v i o u r was
the anaerobic
the r e s u l t
the anaerobic
stress
propionate etc.)
by b e t t e r
has
the carbon-based
in
that
research
was more c l o s e l y
the nature of
demonstrated
standard
first
phosphorus
of the anaerobic
1976).
release
anaerobic
a
the
the return
influent
be t h e
that
Under
the
as
in
by a d d i n g an a n a e r o b i c
from
the system.
hypothesized
followed
earlier.
removal
zone.
released
acclimated
r e m o v a l by
of
i n excess
by t h e o r g a n i s m s i n t h e f o r m o f l o n g
aerobic
is
and
described
i s stimulated
phosphorus
stress
t a k e n up
1965).
sludge process
the
is
p o l y p h o s p h a t e , known a s v o l u t i n
The e x c e s s
of
( b i o - P ) r e m o v a l . In t h e
excess phosphorus
(Siebritz
simpler
produce
excess
shown
related
zone, r a t h e r
carbon
available
t o the
than t o the degree
1982). I t
substrates
anaerobic
the anaerobic
t o the c o n c e n t r a t i o n
substrates
et a l . ,
better
that
has a l s o
been
(such as acetate,
phosphorus
release,
phosphorus uptake i n the a e r o b i c
zone.
-5-
It
is
now
a
substrates
standard
to
the
practice
anaerobic
to supply these simple
zone
either
through
a d d i t i o n s or by p r o d u c i n g these simple carbon
T h i s can be done i n a
of a
primary
b i o l o g i c a l excess
with low COD
strong
carbon
(such
as
zone
r e t e n t i o n times
of
the
main
(2-3 hours
It
is
clear
a
system
that
desired
generated
process
the
degree
with
the
should be
noted t h a t
to the presence
necessary
f o r any
The
composed
of
f r a c t i o n that
two
time)
carbon
necessary to
the raw
feed
i t varies directly
provided by the c o l l e c t i o n
of
fermentative
deposits
and
zero
with
system,
conditions. It
the low v e l o c i t y of flow i s a l s o
sludge
itself.
i n the feed sewage depends on the
presence
important
d i s s o l v e d oxygen
fermentation a c t i v i t y .
biodegradable
of
hydraulic
of phosphorus removal depends on the
r e t e n t i o n time
possible
longer
i n the
through f e r m e n t a t i o n .
c h a r a c t e r i s t i c s of the c o l l e c t i o n system:
due t o
either
of the fermentation
s u b s t r a t e s present
the h y d r a u l i c
simple
hydraulic retention
a v a i l a b i l i t y of these simple s u b s t r a t e s i n
The simple
However, with
amount of e x t e r n a l simple
s u b s t r a t e s needed or the degree
produce
be
of nominal
or i n the sewage c o l l e c t i o n
1985).
i n South A f r i c a ) , these
substrates could apparently
anaerobic
substrates in s i t u .
process, f o r sewages
(Rabinowitz,
those
external
fermenter p l a c e d up-stream
phosphorus removal
concentrations
sewages
sludge
carbon
portion
fractions:
i s used by the
a
of
a m u n i c i p a l wastewater i s
readily
biodegradable
microorganisms
soluble
at a r a p i d r a t e ;
and
-6-
a slowly biodegradable
and
particulate fraction
enzymatic breakdown p r i o r to t r a n s f e r
that requires
through the
storage
cell
wall
(Dold e t a l . , 1980).
Although many r e s e a r c h e r s have i n v e s t i g a t e d the e f f e c t s of
specific
simple
substrates
in
the
volatile
f a t t y a c i d s ) on b i o l o g i c a l excess phosphorus removal, no
s i g n i f i c a n t attempt has been made
these
preferred
substrates
feed
to
on
(such
quantify
as
short chain
the
presence of
a more g e n e r a l i z e d b a s i s . There
were many i n s t a n c e s where the phosphorus removal e f f i c i e n c y
biological
excess
good, although
was found
phosphorus
i n the
converted
feed (Koch,
to
zone of the process
p r a c t i c a l to
in
a
sewage,
estimate
the
process
was found to be
no s i g n i f i c a n t amount of any v o l a t i l e
p r e f e r r e d s u b s t r a t e s or
easily
removal
compounds
were present
more
that
lend
i n the
fatty acids
i n d i c a t e s that
the p r e f e r r e d s u b s t r a t e s
i d e n t i f y every
a
1984). T h i s
themselves
f e e d . Since
parameter
other
to be
i n the anaerobic
i t i s not
possible preferred substrate
generalized
of a
present
i s necessary t o
a v a i l a b i l i t y of the t o t a l p r e f e r r e d s u b s t r a t e s
in a
given sewage.
T h i s research
i n v e s t i g a t e s the p o s s i b i l i t y
parameter " r e a d i l y biodegradable
simple
p r e f e r r e d carbon
of
u s i n g the
COD" t o q u a n t i f y the presence of
substrates
in a
sewage,
in
order t o
assess t h e s u i t a b i l i t y of a given sewage f o r i t s n a t u r a l e f f i c a c y
in the b i o l o g i c a l excess phosphorus removal
process.
-7-
The
objectives
of
this
research
may
be
summarized
as
follows:
(i)
Development
of
a
quantification
(as
(ii)
readily
of
removal
(such
as
the
the
entering
system
on
readily
uptake,
overall
storage
and
a
biodegradable
COD
characterization
excess
of
phosphorus
carbon
the
of
the
a
in a
for
substrates
sewage.
phosphorus
elements
of
the
release, aerobic
anaerobic
process
phosphorus
carbon
consumption).
of
using
parameter
sewage
phosphorus
with
readily
for a
respect
removal
the
biodegradable
excess
removal,
efficacy
as
present
biological
various
technique
biodegradable
readily
phosphorus
aerobic
I n v e s t i g a t i o n of
role
the
anaerobic
biological
measurement
biodegradable.COD)
I n v e s t i g a t i o n of
substrates
(iii)
reliable
general
to
process.
the
-8-
CHAPTER TWO
LITERATURE REVIEW
The
r e a l i z a t i o n of the importance of having
concentrations
in
sewage
treatment
the e u t r o p h i c a t i o n
of n a t u r a l
research
this
work
in
(bio-P) removal
methods
plant discharges
waterbodies has
l e d to extensive
i s considered
for
removing
to
be one
phosphorus
wastewater d i s c h a r g e s , as d i s c u s s e d i n the p r e v i o u s
T h i s chapter
been used
provides a
i n developing
to c o n t r o l
f i e l d . The b i o l o g i c a l excess
technique
available
low phosphorus
review
of
phosphorus
of the best
from
domestic
chapter.
p r e v i o u s work
that has
the o b j e c t i v e s and methods used i n t h i s
research.
2.1
BIOLOGICAL EXCESS PHOSPHORUS REMOVAL
Comprehensive l i t e r a t u r e reviews
phosphorus removal have been presented
Comeau
the
subject
matter,
plus
excess
by S i e b r i t z et a l . (1983),
provide
some of
an update on the more
research.
Biological
Srinath
the b i o l o g i c a l
(1984) and o t h e r s . T h i s s e c t i o n w i l l b r i e f l y cover
same
recent
on
et
excess
a l . (1959),
phosphorus removal was f i r s t
followed
by
Alarcon
reported by
(1961).
However,
-9-
neither Srinath
et a l .
nor A l a r c o n
o f f e r e d any e x p l a n a t i o n f o r
the o c c u r r e n c e of t h i s phenomenon or why i t was observed
certain
treatment
The
facilities.
first
attempt
phosphorus removal
s e r i e s of
removal
to
explain
phenomenon was made
batch t e s t s .
a process
a p p r o p r i a t e food
any excess
Levin
propose
and
by
factor
of
microorganisms
of
inorganic
p r o s p e c t s of
using a
that the excess phosphorus
temperature
of
about
25°C,
although
i n treatment processes
that do
with
the
aeration later
were the f i r s t
process.
researchers to
e x p l a n a t i o n f o r excess phosphorus
role
of
phosphorus
They
the a b i l i t y
to
polyphosphates
achieving a
inadequate
i n the phosphorus removal
carbohydrates.
have
(1962)
ratio,
(1965)
Shapiro
relating
utilization
chains
occur
a b i o c h e m i c a l l y based
removal
Feng
excess
phosphorus removal. H i s f i n d i n g that the
phosphorus r e l e a s e c o u l d
emerged as an important
biological
t o micro-organism
these c o n d i t i o n s a r e o f t e n found
not e x h i b i t
this
by
He concluded
was s t i m u l a t e d by
a e r a t i o n and
only i n
also
noted
store
and
to
the a e r o b i c
that
certain
phosphorus i n long
concluded
that
the
r e d u c t i o n i n the d i s s o l v e d phosphorus
content of a sewage, using a
modified activated
sludge p r o c e s s ,
were p r o m i s i n g .
As
a
result
of
these p a r t i a l e x p l a n a t i o n s , a number of
r e s e a r c h e r s , such as Shapiro e t a l . ( 1 9 6 7 ) , Vacker
Wells
(1969),
Bargman et a l . (1970) and
Milbury
et a l . (1967),
et a l . (1970,
-10-
1971)
began
investigating
the
biological
excess
phosphorus
removal phenomenon. Although many
invaluable findings
during
the
these
studies,
such
as
anaerobic c o n d i t i o n s , phosphorus
and
the minor
role
phosphorus
uptake
r e l e a s e under
under a e r o b i c
indisputable explanations
f o r that
removal p r o c e s s ,
g e n e r a l l y accepted to be b i o l o g i c a l
a
modified
"Bardenpho"
employed.
activated
process)
process
i n which
removal was
i n nature.
r e p o r t e d about 97% phosphorus
sludge
no exact
removal were g i v e n . However,
at t h i s stage, the mechanism of the excess phosphorus
(1974)
conditions
that i n o r g a n i c p r e c i p i t a t i o n of phosphates
p l a y s i n the o v e r a l l excess phosphorus
Barnard
were made
(referred
removal from
to
as the
an a n a e r o b i c - a e r o b i c sequence was
Although the author
refers to
the unaerated
zones of
the process as the anaerobic zones, they a r e i n f a c t anoxic zones
due t o the presence of r e c y c l e d n i t r a t e s i n them.
Fuhs
specifically
and
Chen
(1975)
investigate
the
were
the
role
of
sequence on the excess phosphorus
anaerobic/aerobic
sequence
the
anaerobic
this
researchers
to
anaerobic-aerobic
removal. They reported that the
allowed
capable of s t o r i n g excess phosphorus)
since
first
conditions
f a c u l t a t i v e anaerobic p o p u l a t i o n of
Acinetobacter
(which a r e
t o f l o u r i s h i n the p r o c e s s ,
promoted
the growth
of
a
microorganisms that produced
carbon sources (such as e t h a n o l , a c e t a t e and s u c c i n a t e ) necessary
f o r the slow growing A c i n e t o b a c t e r . Although t h i s theory
first
attempt t o
explain
the
excess
phosphorus
was the
removal i n a
-11-
p r o c e s s having an a n a e r o b i c - a e r o b i c sequence
basis,
on a m i c r o b i o l o g i c a l
i t d i d not e x p l a i n e i t h e r the anaerobic phosphorus
or i t s r o l e i n the b i o l o g i c a l excess phosphorus
According
to
Davelaar
(1979), the micro-organisms
phosphorus
et
release
removal.
a l . (1978) and T o e r i e n e t a l .
r e s p o n s i b l e f o r the b i o l o g i c a l
excess
removal a r e u b i q u i t o u s and t h e i r p r o l i f e r a t i o n depends
p r i m a r i l y on the a p p r o p r i a t e environmental c o n d i t i o n s .
The
r e l e a s e as
first
researcher
anaerobic
phosphorus
an i n t r i n s i c p a r t of the b i o l o g i c a l excess
phosphorus
removal mechanism was Barnard
excess
phosphorus
release i s
indicated
removal
induced
by
the
researchers
stress,
and
and
anaerobic
the
Wood,
a l s o confirmed
stress
potential
characteristics
of
removal
polyphosphate
Comeau
that
(bio-P
aerobically
can be
(ORP). He a l s o
e n t e r i n g the a n a e r o b i c
increase
1976;
of
in
the
ORP.
1978), w h i l e
nitrates
e n t e r i n g the
a l . (1985),
responsible
bacteria)
and
the
are
Other
Nicholls,
the importance
et
bacteria
t h a t the
phosphorus
of the a n a e r o b i c
r e l e a s e i n the b i o l o g i c a l excess phosphorus
According to
phosphorus
out
removal, through the r e d u c t i o n of
i n v e s t i g a t i n g the d e t r i m e n t a l e f f e c t s
phosphorus
pointed
of n i t r a t e s
phosphorus
(McLaren
a n a e r o b i c zone,
He
oxidation-reduction
the excess
anaerobic
the
(1976).
an
r e p o r t e d the adverse e f f e c t s
zone on
link
occurs when the anaerobic
through
the
to
the
removal.
two e s s e n t i a l
for biological
the
ability
ability
to
store
excess
to store
carbon
-12-
anaerobically,
When simple
i n such
preferred
a form as poly-B-hydroxybutyrate
carbon
substrates
(such
as
(PHB).
a c e t a t e or
propionate) a r e present i n the anaerobic zone, t h e b i o - P b a c t e r i a
store
these
substrates
h y d r o x y v a l e r a t e ) by
motive
carbon
reserves
c l e a v i n g polyphosphates
f o r c e ) and r e l e a s i n g phosphorus i n t o
The c o n c e n t r a t i o n
is
as
generally
low
or
i n the a e r o b i c
bio-P b a c t e r i a
solution.
zone
substrates
of a c o m p l e t e l y mixed
of P r a c t i c e
with t h e i r
poly-B-
(to m a i n t a i n proton
of the e x t e r n a l carbonaceous
a c t i v a t e d sludge process (Manual
T h e r e f o r e , the
(PHB
No.8, WPCF, 1977).
internal
r e s e r v e s w i l l be a b l e t o compete b e t t e r with other
s t o r e d carbon
microorganisms
upon e n t e r i n g the a e r o b i c zone. Under these c o n d i t i o n s , the bio-P
bacteria
degrade
polyphosphates
their
by
stored
removing
sequence
reserves
and
store
phosphorus from s o l u t i o n . Thus, the
presence of p r e f e r r e d s u b s t r a t e s
anaerobic-aerobic
carbon
i n the anaerobic zone
(with
recycle)
are
and the
important
to
e s t a b l i s h a s u f f i c i e n t p r o p o r t i o n of bio-P b a c t e r i a .
I t may
take 6
to 8
weeks t o
develop t h e microorganisms
r e s p o n s i b l e f o r the b i o l o g i c a l excess phosphorus removal
and Stevens,
organisms
1984; Manning and I r v i n e ,
are
established,
a
short
1985). However, once these
period
c o n d i t i o n s would not wipe them out. In f a c t ,
by
Manning
reestablish
and
Irvine
(1985)
good phosphorus
p e r i o d of upset.
that
(Oldham
of
unfavourable
i t has been r e p o r t e d
i t took
removal e f f i c i e n c y
only
2 days t o
after a
13 day
-13-
Since q u a n t i f i c a t i o n
the
phosphorus
removal
release
using
of the anaerobic s t r e s s r e q u i r e d f o r
and
the
subsequent
excess phosphorus
oxidation-reduction potential
(ORP) measurements
are d i f f i c u l t and u n r e l i a b l e , an a l t e r n a t e parameter was
by Rabinowitz and Marais
The parameter,
potential",
(1980) t o q u a n t i f y the anaerobic
known as
was
proposed
the "anaerobic
defined
as
stress.
c a p a c i t y " or "anaerobic
the
difference
between
the
d e n i t r i f i c a t i o n c a p a c i t y of the anaerobic r e a c t o r and the mass of
nitrates entering
of
f e e d ) . The
anaerobic
the r e a c t o r
authors
capacity
(both expressed i n mg N per l i t r e
concluded
is
that
necessary
to
phosphorus r e l e a s e and the subsequent
S i e b r i t z et a l .
(1982,
at
least
achieve
9
mg
the
anaerobic
a e r o b i c phosphorus
1983),
while
N/L of
uptake.
investigating
this
concept of anaerobic c a p a c i t y , r e p o r t e d that an a n a e r o b i c - a e r o b i c
p r o c e s s d i d not produce
an
anaerobic
any phosphorus
capacity
of
35
mg
release, although
N/L. They concluded that the
anaerobic phosphorus r e l e a s e and the subsequent
uptake
i t had
excess phosphorus
are c l o s e l y l i n k e d to the r e a d i l y biodegradable s u b s t r a t e s
a v a i l a b l e i n the anaerobic zone r a t h e r than any
This w i l l
At
biological
other
parameter.
be d i s c u s s e d i n d e t a i l i n s e c t i o n 2.3.
this
excess
emerge.A good
stage,
biochemical
phosphorus
removal
l i t e r a t u r e review
b i o c h e m i c a l models f o r the
has been presented by Simm
with a
models
phenomenon
explain
started
the
to
s p e c i a l emphasis on the
b i o l o g i c a l excess
(1988).
to
phosphorus
removal
-14-
A
significant
phosphorus
Nicholls
removal
and
biochemical
was
Osborn
explanation
presented
by
Hall
(1979), i n d i c a t i n g
f o r the a e r o b i c organisms
et
for
al
excess
(1978) and
two s u r v i v a l mechanisms
under anaerobic c o n d i t i o n s , as o u t l i n e d
below.
(i)
the breaking-up of the i n t r a c e l l u l a r polyphosphate c h a i n
to p r o v i d e the energy needed, and
(ii)
formation of PHB,
the
a common carbon r e s e r v e compound, f o r
accumulation of the hydrogen
ions and e l e c t r o n s i n
order to p r o c e s s more s u b s t r a t e s .
These
ideas
were f u r t h e r
extended by Rensink
suggested that the lower f a t t y a c i d s present i n
under
anaerobic
necessary
cleavage,
for
thus
conditions
this
are
storage
creating
results
in
the
better
biological
the l i q u i d phase
as
PHB.
from
conditions
A c i n e t o b a c t e r to s u r v i v e and to
micro-organisms
stored
the
for
compete
excess
(1981). He
The
energy
polyphosphate
the
slow-growing
with
the other
phosphorus
removal
systems.
A c c o r d i n g t o Comeau et a l . (1987),
the
form
(e.g.
storage i n
of p o l y - B - h y d r o x y v a l e r a t e (PHV) would exceed the carbon
storage i n the form of PHB
(or t h e i r
the carbon
s a l t forms)
when short c h a i n v o l a t i l e
c o n t a i n i n g an
fatty
acids
odd number of carbon atoms
p r o p i o n a t e ) are added t o the system.
C o n v e r s e l y , PHB
would
-15-
become the dominant form of carbon
acids
(or
their
salt
storage, i f
short chain
fatty
forms) c o n t a i n i n g an even number of carbon
atoms (e.g. a c e t a t e , butyrate) a r e added.
Comeau (1984) i n
phosphorus removal,
h i s biochemical
proposed
t o maintain
for
that the polyphosphate
a d d i t i o n t o t h e i r r o l e i n the
supply energy
model
storage
of
the proton
the excess
reserves ( i n
carbon)
are
used to
motive f o r c e of the bio-P
bacteria.
However,
Wentzel
mechanism proposed
imbalances
a l . (1986)
by Comeau
motive f o r c e i n the
proton
et
pointed
out
t h a t the
(1984) f o r m a i n t a i n i n g the proton
anaerobic
zone
a c r o s s the
gives
rise
to
c y t o p l a s m i c membrane
They presented a m o d i f i e d biochemical model based
charge and
of the c e l l .
on
the e f f e c t s
of anaerobic and a e r o b i c phases on the i n t r a c e l l u l a r NADH/NAD and
ATP/ADP r a t i o s and t h e i r i n f l u e n c e on
of
carbon
maintained
and
both
phosphorus
the
the b i o c h e m i c a l
metabolic
proton
motive
pathways.
force
and
regulation
This
model
the
charge
neutrality.
2.2
CONCEPT OF READILY BIODEGRADABLE
Ekama and Marais
(1978), while t r y i n g t o d e v e l o p a general
model f o r the dynamic behaviour
observed a p r e c i p i t o u s
SUBSTRATES
drop
of the a c t i v a t e d
(or a step
change)
sludge p r o c e s s ,
i n the
oxygen
-16-
uptake
rate
(OUR) a t the t e r m i n a t i o n of the feed ( F i g . 2.1). The
system used was
a
sludge
with
process
single
a
reactor,
12
hour
completely
cyclic
mixed a c t i v a t e d
loading
of m u n i c i p a l
wastewater a t 20°C, pH of 7 and a s h o r t process sludge age of 2.5
days.
At f i r s t ,
t h i s p r e c i p i t o u s drop i n the oxygen uptake
rate
was b e l i e v e d t o be a b e h a v i o u r a l c h a r a c t e r i s t i c of n i t r i f i c a t i o n .
In
order
to
verify
similar laboratory
unit
this
h y p o t h e s i s , the authors operated two
scale activated
sludge u n i t s
(unit C) being operated under c y c l i c
wastewater, while the second
unit
steady
of
continuous
with a c y c l i c
loading
(unit
with the f i r s t
l o a d i n g of low n i t r o g e n
N)
was
operated under
the same low n i t r o g e n wastewater
l o a d i n g of s a l i n e ammonia superimposed.
c o n d i t i o n s , the
p r e c i p i t o u s drop
i n the
Under these
oxygen uptake
r a t e was
observed o n l y i n u n i t C ( F i g . 2.2).
The
same experiments
operated under
nitrogen
cyclic
wastewater
wastewater.
oxygen uptake
Both
repeated with
loadings,
and
units
rate
were
under
unit
but with u n i t C r e c e i v i n g a low
N
receiving
exhibited
these
both u n i t s being
the
a
high
nitrogen
p r e c i p i t o u s drop i n the
conditions
of
operation ( F i g .
2.3).
From the
r e s u l t s of these two s e t s of experiments,
concluded that the s t e p change observed
was i n response
t o the energy
i t was
i n the oxygen uptake
requirement
f o r the
rate
a d s o r p t i o n of
-17-
°
o
START
FEED
STOP
FEED
START
FEED
is
o
H-O
£°
zo
oo
o
z •
32
>X
oo
o
^.00
F i g . 2.1.
4.00
8
,
0
0
nriE * (VR S)
2
0
6
00
2
°'°°
2 4
'°°
2 8
-
0 0
P r o f i l e o f oxygen uptake r a t e w i t h domestic wastewater as
feed ( a f t e r Ekama and Marais,
1978).
UNIT C
UNIT N A
8
^
*>
U n i t C: C y c l i c l o a d i n g of
o
e
low N wastewater
o
UJ M
H
U n i t N: Continuous l o a d i n g
<
of low N wastewater
V
I0.
HI
to
+ c y c l i c l o a d i n g of
s a l i n e ammonia
I,
z
UJ
CD
>-
x
Om
-4 -2
F i g . 2.2.
0 2 4
6
TIME (hours)
P r o f i l e s o f oxygen uptake r a t e s under two d i f f e r e n t
conditions
( a f t e r Ekama-and Marais,
1978).
feeding
-18-
the
carbonaceous
characteristic
material
of
feeding ceased,
and
not
nitrification.
there was
due
to
Therefore,
a step-wise
a
as
behavioural
soon
decrease i n
as the
the r a t e at
which oxygen was u t i l i z e d .
Dold e t a l . (1980)
led to
the c o n c l u s i o n
c o n t r a s t t o the b a s i c
the adsorbed
criticized
this
that a d s o r p t i o n
explanation,
since i t
was energy demanding, i n
thermodynamic p r i n c i p l e
which s t a t e s
that
s t a t e i s a s s o c i a t e d w i t h a lower energy l e v e l
than
the unadsorbed s t a t e . T h i s doubt was r e i n f o r c e d when a r e l a t i v e l y
large
precipitous
drop
biodegradable s u b s t r a t e
was
observed when a s o l u b l e and e a s i l y
(glucose)
was
used
as
the
feed ( F i g .
2.4).
From
these
pure
substrate
hypothesized that the municipal
experiments,
wastewater
the
i s composed
authors
of two
f r a c t i o n s , namely
(i)
a readily assimilable soluble
f r a c t i o n that
(ii)
( r e a d i l y biodegradable)
i s used r a p i d l y , and
a slowly biodegradable p a r t i c u l a t e f r a c t i o n r e q u i r i n g
storage
and enzymatic breakdown p r i o r t o being
transferred
through the c e l l membrane.
Under
this
hypothesis,
the
step
uptake r a t e was a t t r i b u t e d t o the c e s s a t i o n
change
i n the oxygen
of oxygen
utilization
-19-
UNIT C
UNIT N
A
•
^o
o
£
U n i t C: C y c l i c l o a d i n g o f
low N wastewater
U n i t N: C y c l i c l o a d i n g o f
high N wastewater
o
-4
-2
0
2
4
6
T I M E (hours)
F i g . 2.3- P r o f i l e s o f oxygen uptake r a t e s w i t h two d i f f e r e n t types o f
feed
( a f t e r Ekama and Marais,
1978).
STOP
FEED
8.00
F i g . 2.4.
1 2 . 0 0 16.06
TIME
(HOURS)
20.00
24.00
P r o f i l e o f oxygen uptake r a t e w i t h glucose
( a f t e r Dold e t a l . , 1980).
as s u b s t r a t e
-20-
f o r the metabolism of the r e a d i l y biodegradable
f e e d . Subsequent to t h i s step change
the oxygen
uptake behaviour
biodegradable
the
in the
oxygen uptake r a t e ,
remains a consequence of the
slowly
s u b s t r a t e s made a v a i l a b l e before the t e r m i n a t i o n
of
feed.
At
least
literature
substrates
The
three
for
the
(as COD)
different
measurement
of
by
system ( F i g . 2.5). The
biodegradable
Ekama
and
reported
readily
Marais
b a s i s of
biodegradable
and
is
a l . (1985),
substrates
i n the
discussed
in contrast
i n v o l v e s the
of determining
in
a
the
sewage
oxygen uptake r a t e
in
detail
Large s c a t t e r i n the r e s u l t s by t h i s method was
N i c h o l l s et
i n the
mixed a c t i v a t e d sludge
t h i s method
carbonaceous
feed t e r m i n a t i o n
(1984),
completely
c o n s i s t s of measuring the step change
at the
the
are
a e r o b i c method, developed at the U n i v e r s i t y
o p e r a t i o n of a s h o r t sludge age
readily
methods
i n a sewage. They are b r i e f l y o u t l i n e d below.
continuous
of Cape Town (UCT)
3.2.
s u b s t r a t e s in the
in section
reported
by
to the r e s u l t s achieved
by
the r e s e a r c h e r s at the U n i v e r s i t y of Cape Town.
The
second
method, operates
distinct
method,
known
as
the
batch
on the b a s i s t h a t there are three d i f f e r e n t
denitrification
rates in
the a c t i v a t e d
as r e p o r t e d by S t e r n and Marais (1974). The
denitrification
biodegradable
denitrification
i s r e l a t e d to
the
initial
availability
carbonaceous s u b s t r a t e s and
sludge
of
and
process,
r a p i d rate of
the
readily
the measurement of
this
-21-
denitrification
biodegradable
rate
is
substrate
used
to
content
of
N i c h o l l s et a l . (1985), the second
extrapolated
determined.
back
The
to
the
mg
mg
of
Y-axis
nitrate
1981). Recovery
this
method,
gave
(as N)
(Fig.
et a l . ,
the
COD
=
2.6)
is
8.6
According
rate
and
the
AN0
then c a l c u l a t e d
a
s u b s t r a t e (as
recovery
x
of
COD)
(van
10.4
mg/L
from
ratio is
uptake
with
such
obtained.
time
r e a d i l y biodegradable COD
is
8.6
Haandel et
the added
1985).
batch a e r o b i c method
investigation
microorganism
rate
by
with sodium a c e t a t e , u s i n g
( N i c h o l l s et a l . ,
r e c e n t l y developed
under
3
ANO^
(Nicholls
1985), a batch sample of a c t i v a t e d sludge i s d i l u t e d
sewage
to
line is
r e s u l t s i n the o x i d a t i o n of
s t u d i e s conducted
c o n c e n t r a t i o n of 10.5 mg/L
In the
feed.
readily
formula:
of r e a d i l y biodegradable
al.,
the
denitrification
R e a d i l y biodegradable COD
s i n c e each
the
r e a d i l y biodegradable
u s i n g the f o l l o w i n g
estimate
The
that
a
variation
plotted,
high
of
food
to
the oxygen
as shown i n F i g . 2.7.
The
be p r o p o r t i o n a l
to the
shaded area with i t s c o n c e n t r a t i o n g i v e n by the f o l l o w i n g
formula
( N i c h o l l s et a l . ,
i s r e p o r t e d to
with
1985):
R e a d i l y biodegradable COD
where
0.33
i s the general
=
Area
0.33
conversion
f a c t o r f o r COD
to oxygen
- 2 2 -
AERATION
SETTLING
REACTOR
TANK
EFFLUENT
SLUDGE
RECYCLE
Process c o n f i g u r a t i o n used f o r the d e t e r m i n a t i o n o f the
F i g . 2.5.
r e a d i l y biodegradable COD of f e e d
( a f t e r Ekama and Marais,
1984).
A NO,
\ 1st
Rate
NO,
^ v ^ ^
2nd Rate
3rd
T
F i g . 2.6.
Rate
imt
D e n i t r i f i c a t i o n r a t e s used i n the batch d e n i t r i f i c a t i o n
method ( a f t e r N i c h o l l s e t a l . , 1985).
Ox/gen
Utilisation
Rate
T i•e
F i g . 2.7.
Oxygen uptake
r a t e p r o f i l e used i n the batch a e r o b i c
method ( a f t e r N i c h o l l s e t a l . , 1985).
-23-
(Ekama and Marais,
However,
1984).
preliminary
investigations
with
using sodium a c e t a t e as s u b s t r a t e , showed poor
2.3
THE
this
method,
recoveries.
ROLE OF READILY BIODEGRADABLE SUBSTRATES IN BIOLOGICAL
EXCESS PHOPHORUS REMOVAL
The
excess
defining
phosphorus
of
the
removal
prerequisites
by
for
the
biological
S i e b r i t z et a l . (1982, 1983), i n
terms of the r e a d i l y b i o d e g r a d a b l e s u b s t r a t e s a v a i l a b i l i t y
anaerobic zone,
was
a very s i g n i f i c a n t
of
of
the
the
nature
mechanism. I t
biological
a l s o produced
the p r e v i o u s l y h y p o t h e s i z e d
importance
of
the nature
step i n the
excess
a major s h i f t
anaerobic
of the
i n the
understanding
phosphorus
removal
i n emphasis away from
stress
to
a v a i l a b l e carbon
recognize the
substrates in
the anaerobic zone.
This significant
investigating
the
f i n d i n g was
applicability
made
of
by
the
the
authors while
anaerobic
h y p o t h e s i s (proposed by Rabinowitz
and Marais,
m o d i f i e d Ludzack
- Ettinger
(MLE)
and the m o d i f i e d U n i v e r s i t y of
Cape Town
processes,
with
(UCT)
phosphorus removal.
The
schematic
shown i n F i g u r e s 2.8
and
2.9.
UCT
process were set up
and
regard
to
1980)
to
capacity
both the
biological
excess
l a y o u t s of these processes are
Three MLE
processes and
a modified
f e d from the same wastewater source.
-24-
ANOXIC
REACTOR
F i g . 2.8.
AEROBIC
REACTOR
The modified Ludzack - E t t i n g e r process
n i t r o g e n removal ( a f t e r S i e b r i t z
ANAEROBIC ANOXIC
REACTOR REACTORS
F i g . 2.9.
for biological
et a l . , 1982).
AER03IC
REACTOR
The modified UCT process
f o r b i o l o g i c a l n i t r o g e n and
phosphorus removal ( a f t e r S i e b r i t z e t a l . , 1982).
-25-
The
three MLE
40,
55 and 70
set to
N/L
u n i t s were given unaerated
percent
achieve the
respectively
sludge mass f r a c t i o n s of
and the
r e c y c l e r a t i o s were
anaerobic c a p a c i t i e s ranging from 6 to 35
mg
i n the anoxic r e a c t o r s .
Over two months of
nor
excess
phosphorus
operation, neither
removal
was
u n i t s . In c o n t r a s t , the m o d i f i e d UCT
sludge
mass
fraction
anaerobic
phosphorus
observed
i n any of the
process with a 10%
capacity
clearly
hypothesis
indicating
and
for
the
biological
UCT
processes
substrates
biodegradable
COD)
were
(quantified
surrounding
the
in
to
nitrates
unaerated
anaerobic
of
r e a c t o r i n the
(since
no
nitrates
terms
of
organisms i n the
r e a c t o r i n the MLE
presence
the m o d i f i e d
e x p l a i n e d i n terms of the r e a d i l y
r e a c t o r . The unaerated
first
excess
removal.
biodegradable
the
anaerobic
a breakdown i n
The d i f f e r e n t phosphorus r e l e a s e p a t t e r n s i n
MLE
MLE
c o n s i s t e n t l y gave good phosphorus r e l e a s e
and excess phosphorus removal,
the
phosphorus r e l e a s e
process was
readily
unaerated
anoxic
(due
through the r e c y c l e ) whereas the
modified
enter
UCT
this
process
was
truly
r e a c t o r through
the
recycle).
In the
the
anoxic
MLE
process,
reactor
biodegradable COD,
o x i d a t i o n of 8.6
mg
to
sufficient nitrates
utilize
s i n c e each mg
of r e a d i l y
all
the
of n i t r a t e
available
(as N)
biodegradable
are r e c y c l e d to
readily
r e s u l t s i n the
substrate,
as
COD
-26-
(van
Haandel
et
al.,
1981).
In c o n t r a s t , i n the m o d i f i e d
UCT
p r o c e s s , the c o n c e n t r a t i o n of the r e a d i l y b i o d e g r a d a b l e s u b s t r a t e
available
organisms
for
anaerobic
i s maximized, s i n c e no
anaerobic r e a c t o r .
t h e m o d i f i e d UCT
to
the
c o n d i t i o n i n g of the p h o s p h o r u s - s t o r i n g
nitrates
t o the
process, which can ensure zero n i t r a t e d i s c h a r g e
zone,
are
at
a
s i g n i f i c a n t advantage with
r e s p e c t to b i o l o g i c a l excess phosphorus
From these o b s e r v a t i o n s , the
the
removal.
authors
concentration
of
microorganisms
i n the anaerobic r e a c t o r i s
whether
phosphorus uptake
a l s o showed
recycled
T h e r e f o r e , the process c o n f i g u r a t i o n s such as
anaerobic
determining
are
concluded
r e a d i l y biodegradable COD
or
not
the
takes p l a c e .
that the
from
c o n c e n t r a t i o n of the r e a d i l y
the organisms
exceed
25
approximately
the key
results
r e l e a s e and subsequent
mg/L
excess
i n the
as COD
the
s u r r o u n d i n g the
parameter i n
phosphorus r e l e a s e and
The
s u b s t r a t e surrounding
that
excess
their studies
biodegradable
a n a e r o b i c zone must
to ensure good phosphorus
phosphorus
uptake.
It
was
also
concluded that the b i o l o g i c a l excess phosphorus removal i n c r e a s e d
w i t h i n c r e a s i n g r e a d i l y biodegradable
anaerobic zone beyond 25
Marais
excess
et
phosphorus
s u b s t r a t e , as
al.
COD
concentration
i n the
mg/L.
(1983)
removal
in
further
terms
summed up the
of
readily
biological
biodegradable
follows:
"Poly-P accumulation
serves as an energy
r e s e r v o i r , to
s u s t a i n the organism d u r i n g the anaerobic s t r e s s e d
state,
-27-
but p r i n c i p a l l y
accumulating
t o gain a p o s i t i v e advantage over non-P
organisms
b i o d e g r a d a b l e COD
by p a r t i t i o n i n g o f f r e a d i l y
( i n the lower
f a t t y a c i d form) i n the
anaerobic s t a t e f o r i t s e x c l u s i v e use subsequently
aerobic
state".
The
readily
substrates)
removal,
necessary
through
microorganisms,
This
can
be
simple carbon
produced
thickener
biodegradable
in
f o r the
the
biological
proliferation
(or
excess
of
preferred
phosphorus
the
appropriate
a r e u s u a l l y made a v a i l a b l e t o the anaerobic zone.
accomplished
e i t h e r through e x t e r n a l a d d i t i o n s of
s u b s t r a t e s (such
situ
ahead
by
of
Oldham (1985),
the
a
process
propionate e t c . ) or
primary sludge fermenter or
(Oldham
and
Stevens,
1984;
1985).
while working
excess phosphorus removal
reported
as a c e t a t e ,
employing
Oldham, 1985; R a b i n o w i t z ,
Columbia,
substrates
i n the
with a f u l l
treatment
t h a t the
plant
in
a v a i l a b i l i t y of
scale
biological
Kelowna, B r i t i s h
the primary
sludge
t h i c k e n e r supernatant
t o the fermentation zone of the process had
a
on
marked
influence
the
phosphorus removal
system. The o v e r a l l phosphorus removal
to l e v e l s
found
dropped
flow was removed. Conversely,
the a d d i t i o n
supernatant t o a u n i t that was m a r g i n a l l y a c h i e v i n g good
phosphorus removal,
removal.
efficiency quickly
i n c o n v e n t i o n a l a c t i v a t e d sludge p l a n t s when the
t h i c k e n e r supernatant
of t h i s
c a p a c i t y of the
He a l s o
quickly
reported
restored
the
e x c e l l e n t phosphorus
that when the t h i c k e n e r
supernatant
-28-
flow was
changed from one p a r a l l e l module of the treatment
to the o t h e r , phosphorus
i n the f i r s t
Once
removal c a p a b i l i t i e s
were q u i c k l y
lost
module, and even more q u i c k l y r e s t o r e d i n the o t h e r .
the b a s i c
hypothesis
s u b s t r a t e s i n the b i o l o g i c a l
was
plant
developed,
many
excess
research
a t t e n t i o n on the e f f e c t s
f o r the
of
role
phosphorus
workers
these
specific
removal process
started
specific
of
t o focus
substrates
their
on the
v a r i o u s a s p e c t s of the phosphorus removal mechanism.
Fukase
et
a l . (1982),
while
conducting
a
series
of
l a b o r a t o r y s c a l e batch experiments
using a c c l i m a t e d
synthetic
a c e t a t e or g l u c o s e as the BOD
feed
source, found
the
made up
of e i t h e r
that the phosphorus r e l e a s e
disappearance
of
the
substrates
biomass and
was concomitant
from
the
with
s o l u t i o n . The
r e l a t i o n s h i p observed between the r e d u c t i o n i n o r g a n i c matter and
the
being
increase
in
soluble
phosphate
was g i v e n as ^ a c e t a t e : A P 0
1:1 and aglucose:APO^ being 2:1, i n terms
They a l s o
of molar
4
ratios.
found that the carbon was s t o r e d by the microorganisms
under anaerobic c o n d i t i o n s as PHB d u r i n g t h e a d d i t i o n of a c e t a t e ,
and as glycogen during the a d d i t i o n of g l u c o s e .
However,
the o p p o s i t e
(1987) where glycogen was
finding
found t o
was
made by Mino e t a l .
be consumed
under anaerobic
c o n d i t i o n s . During t h e i r study of two l a b o r a t o r y s c a l e anaerobica e r o b i c prosesses using s y n t h e t i c
acid,
sodium
propionate,
sewage
glucose and
(consisting
peptone),
of a c e t i c
they found two
-29-
carbon s t o r a g e
other
compounds - PHB and glycogen.
r e s e a r c h e r s , PHB was found
conditions
(associated
under a e r o b i c
However,
conditions
glycogen
f o r the
conditions,
the
stored
phosphorus
the
with
They
synthesis
under
release)
opposite
storage.
PHB
be
(associated
showed
consumption and a e r o b i c
required
with
to
As r e p o r t e d by many
anaerobic
and consumed
phosphorus
trend
uptake).
with
concluded
anaerobic
that
the NADH
from a c e t a t e , under
anaerobic
i s s u p p l i e d from the consumption of glycogen,
Embden-Meyerhof-Parnas
(EMP)
pathway.
through
They a l s o i n d i c a t e d
that the a n a e r o b i c / a e r o b i c
a c c l i m a t i z e d sludge was c o n v e r t i n g the
stored
during
PHB
maintain
to
the
glycogen
required
d u r i n g the a n a e r o b i c
As d i s c u s s e d
level
the
of
aerobic
glycogen
phase,
so as to
f o r the consumption
phase.
by Mino
et a l .
(1987), the decrease of the
intracellular
carbohydrate
concentration
c o n d i t i o n s was
a l s o reported by Tsuno e t a l . (1986) and could be
a t t r i b u t e d t o t h e consumption of glycogen
under
anaerobic
s t o r e d i n the m i c r o b i a l
cells.
Somiya e t
phosphorus
a l . (1988), i n t h e i r study of b i o l o g i c a l
removal,
r e l a t i o n s h i p between
reported
the
value
e x t r a c e l l u l a r glucose
f o r the i n c r e a s e
carbohydrate
of
a
linear
the i n c r e a s e i n the amount of i n t r a c e l l u l a r
PHB and the decrease i n the amount of
when the
existence
excess
i n the
intracellular
i s depleted.
amount of
carbohydate,
The estimated
PHB per
u t i l i z e d was reported t o be approximately
mean
u n i t mass of
0.2, on a
-30-
weight b a s i s
or approximately
0.3, on TOC ( t o t a l organic carbon)
basis.
P o t g i e t e r and Evans (1983),
unacclimated
biomass,
u s i n g batch
investigated
s u b s t r a t e s on phosphorus
release,
substrates
non-aerated
as
following
COD,
to
decreasing
order
of
the
by
experiments
effects
adding
of
equal
with
various
amounts of
r e a c t o r s . They reported the
effect,
with
the
first
named
s u b s t r a t e being accompanied by the g r e a t e s t phosphorus r e l e a s e .
acetate >
p r o p i o n a t e > formate
> b u t y r a t e > hydroxybutyrate >
glucose.
Oldham and Koch (1982) i n a s i m i l a r batch
unacclimated biomass,
observed
experiment
with
the f o l l o w i n g d e c r e a s i n g order of
phosphorus r e l e a s e among the v a r i o u s s u b s t r a t e s t e s t e d .
sodium a c e t a t e > p r o p i o n i c a c i d > a c e t i c a c i d > glucose > i s o butyric
acid.
Jones
et
a l . (1985), working w i t h continuous l a b o r a t o r y
s c a l e excess phosphorus removal systems w i t h
reported
that
the
degree
of
a c c l i m a t e d biomass,
phosphorus r e l e a s e was s u b s t r a t e
s p e c i f i c and the phosphorus r e l e a s e and the subsequent phosphorus
uptake had the f o l l o w i n g d e c r e a s i n g order of e f f e c t .
butyric acid
>
ethanol
>
methanol
> acetic acid
> sodium
-31-
acetate
They a l s o
r e p o r t e d that
phosphorus
release
although s i g n i f i c a n t d i f f e r e n c e s i n the
were
apparent,
the
difference
phosphorus uptake or removal d i d not appear to be
in
the
significant.
While s t u d y i n g the e f f e c t s of s h o r t - c h a i n carbon compounds
on the k i n e t i c s of the b i o l o g i c a l n u t r i e n t removal, Gerber et a l .
(1986) r e p o r t e d
from s o l u t i o n
propionate
that the
is
and
most favourable
obtained
lactate.
by
the
Formate
use
was
net phosphate removal
of
acetate, butyrate,
found
to s t i m u l a t e good
phosphorus r e l e a s e under anaerobic c o n d i t i o n s , but was worst with
respect
to
the
c o n c l u d e d t h a t the
from
sludges
overall
net
phenomenon
accomplishing
p r i m a r i l y dependent
on the
w i t h the b a c t e r i a l mass.
phosphorus
of
anaerobic
enhanced
nature of
removal.
They
phosphorus
phosphorus
the s u b s t r a t e
also
release
removal
was
interacting
-32-
CHAPTER THREE
EXPERIMENTAL METHODS
This
chapter
details
the
t h i s study. S e c t i o n 3.1 d e a l s with
measurement of
experimental methods used i n
the experimental
d e s i g n . The
r e a d i l y biodegradable COD of feed, the l a b o r a t o r y
o p e r a t i o n of the b i o l o g i c a l excess phosphorus removal
sampling and
a n a l y s i s techniques
study the e f f e c t of c o l d
storage
system, the
used and the procedure
used t o
(at
are a l l
4°C)
on
sewage
o u t l i n e d i n s e c t i o n s 3.2, 3.3, 3.4 and 3.5 r e s p e c t i v e l y .
3.1
EXPERIMENTAL DESIGN
The
systems
experiments
in
which
biodegradable
one
was
substrates
development of t h i s
appendix
involved
A1
in
system
to
the
feed
while
r e a d i l y biodegradable
u s i n g d i f f e r e n t dosages
of
quantify
the
(the elements
described
the
b i o l o g i c a l excess phosphorus removal
3.3). The
p a r a l l e l laboratory scale
used
are
respectively)
two
in
other
system
section
was
used
readily
and the
3.2 and
as
a
(described i n section
content of the feed was changed
sodium
acetate,
sodium p r o p i o n a t e ,
sodium b u t y r a t e and g l u c o s e . The e f f e c t s of these compounds (both
as
specific
substrates)
phosphorus
substrates
on
the
removal
and
various
mechanism
as
general
elements
(such
readily
biodegradable
of the b i o l o g i c a l
as
anaerobic
excess
phosphorus
-33-
release, aerobic
phosphorus uptake,
anaerobic carbon
storage
and
o v e r a l l phosphorus
aerobic
carbon
removal,
consumption) were
investigated.
3.2
QUANTIFICATION OF READILY BIODEGRADABLE SUBSTRATE
The
technique
used
to
s u b s t r a t e of feed d u r i n g t h i s
procedure
used
by Ekama
filamentous
The
basis
biodegradable
and
growth.
are o u t l i n e d i n d e t a i l
of
substrate
the
adaptation
of the
(1984). The a d a p t a t i o n s were
nitrification
A1.
method
for
determining
the
readily
c o n s i s t s of measuring the step change i n
completely
activated
3.2.1
an
suppress unwanted
i n Appendix
rate
s h o r t sludge
to
was
biodegradable
The development of these m o d i f i c a t i o n s
the oxygen uptake
mixed
study
and Marais
made both f o r convenience
and
q u a n t i f y the r e a d i l y
(OUR)
at
sludge
the
feed
process
termination,
in a
operated at a very
age.
EXPERIMENTAL SET-UP
A schematic
l a y o u t of the process i s shown i n F i g . 3 . 1 .
elements of t h i s e x p e r i m e n t a l
set-up are o u t l i n e d below.
The
Chemical A d d i t i o n
Air
Supply
Chemical
Container
Scraper
Effluent
Clarifier
Return Sludge
Feed Tank
Fig. 3.1.
Schematic l a y o u t o f the process c o n f i g u r a t i o n f o r the d e t e r m i n a t i o n of the r e a d i l y
biodegradable COD
of the f e e d .
-35-
(a)
FEED
The
feed,
concentration
system a t
plastic
the
i s to
a rate
in
which
the
readily
biodegradable
be
found,
was
continuously
COD
added
t o the
of 12 l i t r e s per day from a c o n s t a n t l y
stirred
tank with a l i d . The s t i r r i n g was slow and g e n t l e t o keep
particulate
matter
from
entrainment i n t o the f e e d .
settling,
The
feed
to
but
to
a v o i d any a i r
the
biological
excess
phosphorus removal system used i n t h i s study was a l s o pumped from
the same c o n t a i n e r .
(b)
CHEMICAL ADDITION
The
chemical
concentrations
as
in
system) were done using
actual
concentrations
according
to the
a d d i t i o n where
the feed
chemical
(c)
flow
substrate
the
a
additions
(at
the
same
b i o l o g i c a l excess phosphorus removal
separate
in
rates
the
Masterflex
chemical
(except
in
pump,
with the
container
adjusted
the
case
of a c e t a t e
the sodium a c e t a t e s o l u t i o n was d i r e c t l y added t o
tank, a t
approximately
8
feed c o n t a i n e r was f i l l e d
hour i n t e r v a l s ) .
The 500 ml
on a d a i l y b a s i s .
AEROBIC REACTOR
The
reactor consisted
of
a
c y l i n d r i c a l p l e x i - g l a s s tank
-36-
with a l i q u i d volume
constant
mixing.
of 2
The
l i t r e s , complete
mixed
liquor
with a
i n the r e a c t o r was a e r a t e d
u s i n g a f i n e bubble p u r g i n g stone a t t a c h e d to
dissolved
oxygen
concentration
1.5 and 2.5 mg/L. A l l l i q u i d
entered
below
the
entrainment. Mixed
from
this
liquid
on
s o l i d s r e t e n t i o n time
a
a glass
tube. The
was manually c o n t r o l l e d between
streams
to
surface
l i q u o r suspended
reactor
stirrer for
and
from
i n order
the r e a c t o r
t o a v o i d any a i r
s o l i d s were
wasted d i r e c t l y
twice d a i l y b a s i s t o achieve a syste:
(SRT)
of
3
days,
giving
an approximate
a e r o b i c SRT of 1.5 days. The l o s s of s o l i d s through the e f f l u e n t ,
due
to
the
concentrations,
aerobic
(d)
relatively
was
taken
high
into
effluent
suspended
solids
account while wasting from the
reactor.
RETENTION TANK FOR RETURN SLUDGE
could
A c y l i n d r i c a l p l e x i - g l a s s tank,
where
be
litres,
varied
between
0.5
to
r e t e n t i o n tank f o r t h e r e t u r n s l u d g e .
2
the
l i q u i d volume
was
The l i q u i d
used as the
volume of t h i s
r e a c t o r d u r i n g t h i s study was 1 l i t r e f o r the a c e t a t e , propionate
and b u t y r a t e runs and
surface
of
this
0.5
reactor
minimize any entrainment
primary purpose
litre
of t h i s
was
of
during
the
glucose
run. The
covered with a f l o a t i n g cover t o
a i r into
the r e a c t o r
c o n t e n t s . The
h o l d i n g tank was t o c o n t r o l filamentous
growth i n t h i s s h o r t sludge age system, as d i s c u s s e d i n d e t a i l i n
Appendix A1.
The
c o n t e n t s of t h i s
r e a c t o r were
s t i r r e d at a l l
-37-
times, u s i n g a magnetic
(e)
stirrer.
CLARIFIER
Mixed l i q u o r from the a e r o b i c r e a c t o r was
into a
cylindrical
having a
liquid
continuously
settling
volume
recycled
of
back
sludge r e t e n t i o n tank, with a
scraper
mechanism
was
tank
1
to
to flow
a centre b a f f l i n g
litre.
was
the a e r o b i c r e a c t o r through
the
installed
to
The
settled
tube)
sludge
recycle
adhering to the s i d e w a l l s of the
(f)
(with
allowed
ratio
of
prevent
1:1.
the
A
1 rpm
sludge
from
clarifier.
OPERATION
For every run d u r i n g the study, t h i s system was
to be
i n steady
s t a t e when the d a i l y oxygen uptake
considered
r a t e and
a e r o b i c mixed l i q u o r suspended s o l i d s showed a p p r o x i m a t e l y
values
(less
ammonia was
than
10
percent
keeping the same oxygen requirement
a f t e r the t e r m i n a t i o n
selection
of
discussed
in
an
feed.
This
appropriate
short
liquid
under
the
the system
for n i t r i f i c a t i o n ,
the
detail
of
steady
v a r i a t i o n ) . More than 5 mg/L
always present i n the e f f l u e n t of
section
development of t h i s method (Appendix A l ) .
was
the
of
thereby
b e f o r e and
ensured
by the
r e t e n t i o n time, as
dealing
with
the
-38-
3.2.2
MEASUREMENT PROCEDURE
The
following
procedure
was
carried
measurement o f t h e r e a d i l y b i o d e g r a d a b l e
(i)
was
concentration
switching
decrease
measured
of
the aerobic
the dissolved
OmniScribe c h a r t
plot
(ii)
raising
mixed
o f f the a i r supply,
of
expressed
by
was
recorder
then
feeding
the dissolved
oxygen
oxygen
to
and
the r e s u l t a n t
concentration
(by Houston I n s t r u m e n t ) .
the
oxygen
6 mg/L,
using
an
The s l o p e o f
uptake
rate
a s mg/L/h.
The a b o v e
the p r o c e d u r e
p r o c e d u r e was
repeated,
except
oxygen was
that the feed
i n the middle of
(when t h e d i s s o l v e d o x y g e n c o n c e n t r a t i o n was a b o u t
3 mg/L) a n d t h e d e c r e a s e i n
the concentration
monitored continuously
t e r m i n a t i o n of the
slope of
about
monitoring
( i n c l u d i n g t h e s u b s t r a t e a d d i t i o n ) was s t o p p e d
The
each
substrate
liquor
and
calculated
during
COD o f t h e f e e d .
The o x y g e n u p t a k e r a t e u n d e r c o n t i n u o u s
conditions
this
out
the dissolved
feed would
oxygen v s
until
of t h e d i s s o l v e d
i t was l e s s t h a n
have c a u s e d
a change
1 mg/L.
i n the
t i m e p l o t and t h e new r e d u c e d
oxygen u p t a k e r a t e was c a l c u l a t e d .
The
above
reproducibility,
procedures
and
average
u p t a k e r a t e w i t h and w i t h o u t
were
values
feed
repeated
used
termination.
to
ensure
t o c a l c u l a t e oxygen
-39-
3.2.3
CALCULATION PROCEDURE
T h i s p r o c e d u r e was a d a p t e d
Marais
the
from
the
( 1 9 8 4 ) . The f o l l o w i n g i n f o r m a t i o n
concentration
influent
of
the
readily
work
of
i s required
biodegradable
Ekama and
to calculate
COD
in
the
feed.
Q = Flow r a t e of t h e f e e d (L/h)
V = Volume o f t h e a e r o b i c
OUR^
= A v e r a g e OUR
before
OUR
= A v e r a g e OUR
after
a
Then, the
given
readily
r e a c t o r (L)
the feed
the feed
biodegradable
termination
termination
(mg/L/h)
(mg/L/h)
COD c o n c e n t r a t i o n
of the feed i s
by,
(OUR.
Readily
biodegradable
COD
=
- OUR
) x V
*
0.334 x Q
where 0.334 = G e n e r a l
and
Ekama,
3.2.4
factor
f o r COD
t o oxygen
(Marais
1984).
EXAMPLE
The
conversion
CALCULATION
f o l l o w i n g data
mg COD/L a c e t a t e r u n .
Q = 0.49 L / h
was o b t a i n e d
on t h e f i r s t
d a y o f t h e 30
-40-
V = 2 L
OUR
b
OUR
= 39.5
mg/L/h
= 32.4
mg/L/h
T h e r e f o r e , r e a d i l y biodegradable COD
= (39.5 - 32.4) x 2
0.334 x 0.49
= 87
3.3
mg/L
LABORATORY SCALE OPERATION OF PHOSPHORUS REMOVAL SYSTEM
A bench top, l a b o r a t o r y s c a l e b i o l o g i c a l
removal
system
was
operated
during
excess phosphorus
t h i s study. The
schematic
diagram
of t h i s e x p e r i m e n t a l set-up i s shown i n F i g . 3.2,
details
of the v a r i o u s components are o u t l i n e d below.
3.3.1
and
the
WASTEWATER SOURCE
The
wastewater
used
during
most
o b t a i n e d from the wastewater
storage tanks
treatment
the U n i v e r s i t y
plant
s i t u a t e d on
campus i n Vancouver, B r i t i s h Columbia.
t h i s treatment
p l a n t was
The
of
this
of the
study
was
p i l o t sewage
of B r i t i s h
Columbia
wastewater source f o r
a main sewer l i n e s e r v i c i n g the student
r e s i d e n c e s , on-campus housing and
the u n i v e r s i t y
The
pumped d a i l y , commencing at 10
a.m.
raw
sewage from t h i s l i n e was
using
a submersible
mixed p l a s t i c
s t o r a g e tanks
macerator
pump,
sports centre.
i n t o two m e c h a n i c a l l y
(each with a c a p a c i t y of 9000 l i t r e s )
F i g . 3.2.
Schematic l a y o u t of the l a b o r a t o r y s c a l e e x p e r i m e n t a l set-up of the b i o l o g i c a l excess
removal system.
phosphorus
-42-
u n t i l the tanks were f u l l . Due
sewage
(80-120
approximately
form
sodium
collected
every
in
as
3
stored
weeks
i n the
the l a b s c a l e experiments
low
was added to
From
in
alkalinity
additional
3
bicarbonate.
two
the
CaC0 ),
100 mg/L as CaC0
of
subsequently
mg/L
to
alkalinity
these tanks
from
B r i t i s h Columbia
the
pilot
25
of t h i s
litre
carboys.
propionate
runs
and
due
the
p l a n t a t the U n i v e r s i t y of
s c a l e sewage
the
25
treatment
closure
of
and
20
the
upgrading, and d u r i n g the 30 and 75 mg COD/L of
to
source was
plant
T h i s was done d u r i n g the 15 and 10
during
to
I t was
study.
treatment
campus t o the f u l l
acetate
i n the
l a b o r a t o r y c o l d room at 4°C, f o r use
i n Richmond, B r i t i s h Columbia.
mg COD/L of
of
these tanks, the sewage was
During a p o r t i o n of t h i s study, the wastewater
switched
of t h i s
mg
COD/L of
p i l o t plant for
glucose runs due
the low COD s t r e n g t h of the p i l o t p l a n t wastewater.
The
strength
of the c o l l e c t e d wastewater was a d j u s t e d ( i f
necessary) by d i l u t i n g w i t h
e n t e r i n g the system
t a p water,
such that
( i n c l u d i n g t h e chemical a d d i t i o n ) l i e s w i t h i n
the range of 250-275 mg/L. However, d u r i n g the
COD of
the raw
the t o t a l COD
sewage was kept around
the glucose dosage) t o
m a i n t a i n the
glucose runs, the
200 mg/L ( i r r e s p e c t i v e of
composition of
the feed as
mostly sewage,
s i n c e h i g h e r g l u c o s e dosages (up t o 150 mg COD/L)
were
to
required
effect
good
excess
phosphorus
removals.
O c c a s i o n a l l y , the phosphorus c o n t e n t of the feed was i n c r e a s e d by
adding
tribasic
sodium
phosphate
(Na-PO-.12H,0) t o maintain a
-43-
t o t a l phosphorus c o n c e n t r a t i o n of about 4 mg/L.
The
sewage
was
added
to
the
removal system a t a r a t e of 12 l i t r e s
stirred plastic
tank. To
experimental
per day
a v o i d changing
from a c o n s t a n t l y
the c h a r a c t e r i s t i c s of
the wastewater due to excess a e r a t i o n , the tank
a plastic
l i d and the s t i r r e r
while s t i l l
keeping
The
for
feed
system
used
the feed
to
biodegradable COD of the feed was pumped
storage tank.
4°C,
was
The d a i l y
allowed
(approximately
3.3.2
of
acclimate
i n suspension.
determine
the
readily
from the same l a b o r a t o r y
feed, having been s t o r e d at
to
ambient
temperature
20°C) before being added t o the system.
chemicals added d u r i n g t h i s study were sodium a c e t a t e ,
sodium p r o p i o n a t e ,
during
sodium
the
a c e t a t e ; 25,
butyrate
various
e n t e r i n g the anaerobic
10 f o r
with
CHEMICAL ADDITION
The
dosages
aliquot
to
was covered
speed was kept as low as p o s s i b l e ,
the p a r t i c u l a t e s of
the
phosphorus
and
glucose.
experimental
runs
The chemical
(as
mg
COD/L
r e a c t o r ) were 30, 25, 20, 15, 10 and 5 f o r
20, 15, 10 and 5 f o r p r o p i o n a t e ; 30, 25, 20, 15 and
b u t y r a t e ; and 75, 60, 45 and 30 f o r g l u c o s e .
During the
acetate
run,
appropriate
amounts
of sodium
a c e t a t e s o l u t i o n were mixed with raw sewage and added t o the feed
tank,
a t approximately
8 hour i n t e r v a l s .
However, t h i s p r a c t i c e
-44-
was
changed
during
the
other runs and the chemical s u b s t r a t e s
were pumped s e p a r a t e l y from the feed,
using a
pump. The a c t u a l c o n c e n t r a t i o n i n the chemical
adjusted, according to
achieve
the
anaerobic
desired
the
dosage
of
and
the
chemical
feed c o n t a i n e r was
feed
flow
rates, to
chemical s u b s t r a t e i n the
r e a c t o r . The chemical c o n t a i n e r had
ml and was f i l l e d on a d a i l y
3.3.3
chemical
separate
a capacity
of 500
basis.
ANAEROBIC REACTOR
This
reactor
l i q u i d volume
of
1.5
c o n d i t i o n s necessary
mixed u s i n g a s t i r r e r
minimize
any
was
a
cylindrical
litres,
f o r the
and
p l e x i - g l a s s tank with a
i t provided
excess phosphorus
and was
a i r entrainment
f i t t e d with
due
the anaerobic
removal.
a floating
I t was
cover t o
to surface turbulence. This
r e a c t o r was f e d c o n t i n u o u s l y with the v a r i o u s chemical s u b s t r a t e s
t o g e t h e r with the sewage f e e d .
3.3.4
ANOXIC REACTOR
A
2.25
cylindrical
plexi-glass
tank
l i t r e s was used as the anoxic r e a c t o r . The contents
reactor
were
constantly
mixed
with
s u r f a c e was covered u s i n g a f l o a t i n g
of
with a l i q u i d volume of
this
anoxic
a
s t i r r e r and the l i q u i d
cover. The
r e a c t o r was t o d e n i t r i f y
of t h i s
primary
the r e t u r n
purpose
sludge
from
-45-
the
clarifier,
anaerobic
thus
reactor
preventing
through
any
the
NO
bleeding
anoxic-anaerobic
n e c e s s i t y and the advantage of p r e v e n t i n g
the NO
the anaerobic zone, are d i s c u s s e d i n d e t a i l
3.3.5
x
into
the
recycle.
The
from e n t e r i n g
i n Chapter
4.
AEROBIC REACTOR
T h i s r e a c t o r c o n s i s t e d of a p l e x i - g l a s s tank with a l i q u i d
volume of
fine
4 litres.
bubble
The
sparger
reactor
stone
attached
d i s s o l v e d oxygen c o n c e n t r a t i o n
1.5 and
2.5
mg/L.
The
was
contents
mixed at a l l times with a
3.3.6
c o n t e n t s were
to
a
manually
g l a s s tube and
the
c o n t r o l l e d between
of t h i s r e a c t o r were completely
stirrer.
CLARIFIER
Mixed l i q u o r from the a e r o b i c r e a c t o r was
into a
having a
cylindrical plexi-glass
liquid
r e c y c l e d back
A 1
a e r a t e d using a
rpm
volume
of
1
clarifier
litre.
allowed
to flow
(with c e n t r e b a f f l i n g )
The
settled
sludge
to the anoxic r e a c t o r with a r e c y c l e r a t i o of
scraper
mechanism was
installed
from adhering to the s i d e w a l l s of the
to
prevent
clarifier.
the
was
1:1.
sludge
-46-
3.3.7
OPERATION
The
(SRT)
system
was
of 18 days,
liquor
which
suspended
daily basis.
operated at a system sludge
was
maintained
solids directly
Since
the
wasting
the mixed
from the a e r o b i c r e a c t o r , on a
effluent
of
this
system
contained a
relatively
high
wastage was
a d j u s t e d to compensate f o r the l o s s of s o l i d s
the e f f l u e n t .
1:1.
The
A l l recycle
system
d u r i n g each
effluent
concentration
by
r e t e n t i o n time
was
v a l u e s . Table 3.1
3.4
r a t i o s during
considered
run when
phosphorus
the mixed
to
t h i s study was
have
reached
through
kept at
steady s t a t e
l i q u o r suspended s o l i d s and
concentrations
showed
relatively
the
steady
p r e s e n t s a summary of o p e r a t i n g parameters.
ANALYTICAL METHODS
All
f i l t r a t i o n s of the samples d u r i n g t h i s study were done
u s i n g Whatman No.4
which
Whatman
filters,
934-AH
the study are now
3.4.1
fibre
during
solids
filters
the d e t e r m i n a t i o n
analysis in
were
used.
The
of each parameter
described.
CHEMICAL OXYGEN DEMAND
The
except
glass
a n a l y t i c a l methods used f o r
in
of suspended s o l i d s , the a e r o b i c
(COD)
samples were preserved with concentrated
sulfuric
acid
-47-
Table 3.1
Summary of Operating Parameters f o r the Laboratory
B i o l o g i c a l Excess Phosphorus Removal System
Parameter
Values
A c t u a l H y d r a u l i c Retention Time (h)
Anaerobic
1 .5
Anoxic
1 .5
Aerobic
4.0
Sludge Retention Time (d)
System
18
Aerobic
approx.10
Feed Flow (L/d)
12
Recycle R a t i o
Return
sludge
Anoxic t o anaerobic
Aerobic D i s s o l v e d Oxygen (mg/L)
1:1
1:1
1.5-2.5
-48-
(pH < 2.0)
and analysed i n
(A.P.H.A. et a l . ,
3.4.2
accordance with
1980).
DISSOLVED OXYGEN
D i s s o l v e d oxygen
concentrations in
measured u s i n g Model 54A d i s s o l v e d oxygen
Instrument
Co.). The membranes and the e l e c t r o l y t e s
the
Winkler
(A.P.H.A. et a l . ,
3.4.3
method,
probes
probes were c a l i b r a t e d
as o u t l i n e d
i n the Standard Methods
1980).
determination
hydrolysis
in
30%
of
glycogen
(wt./vol.)
p r e c i p i t a t i o n with ethanol and
as
outlined
Microbiology
3.4.4
i n the
GLYCOGEN
The
method,
the b i o - r e a c t o r s were
meters (Yellow S p r i
were r e p l a c e d once a week on average. The
using
the Standard Methods
in
in
(A.S.M. et a l . ,
in
the
sludge
was
by
potassium hydroxide, f o l l o w e d by
using
the
the
Manual
anthrone
colorimetric
of Methods i n General
1981).
NITROGEN
Two
types of n i t r o g e n
r e s e a r c h , namely NOx
measurements were
made d u r i n g t h i s
(which i n c l u d e s both n i t r a t e s and
nitrites)
-49-
and T o t a l K j e l d a h l N i t r o g e n
mg/L
N.
(a)
N0
X
analysis
was
which n i t r a t e s a r e reduced
measurements on
the Technicon
done
to n i t r i t e s ,
a Technicon
analysed
3.4.5
Autoanalyser
I I , i n accordance
according
with
(1973).
(TKN)
a Technicon
to Technicon
block d i g e s t o r 40
Block D i g e s t e r I n s t r u c t i o n
(1974).
OXIDATION REDUCTION POTENTIAL
ORP
measurements
Corporation's
combined
were
ORP
u s i n g Ag/AgCl as r e f e r e n c e
digital
as
f o l l o w e d by c o l o r i m e t r i c
I n d u s t r i a l Method No.100-70W
TOTAL KJELDAHL NITROGEN
Manual
presented
using a copper-cadmium column i n
Samples were d i g e s t e d i n
and
v a l u e s are
- NITROGEN
The
(b)
(TKN). A l l
panel
meters
with
(ORP)
made
probes,
using
with
crystal
to high impedance
displays.
maintenance of these e l e c t r o d e s i n v o l v e d a thorough
a paper towel.
A minimum of three
hours was
James
peripheral junctions
c o u p l e s , connected
liquid
Broadley
Regular
c l e a n i n g with
allowed a f t e r each
-50-
cleaning
of the probes
f o r them
to e q u i l i b r a t e
with
the reactor
c o n t e n t s b e f o r e t a k i n g any r e a d i n g .
3.4.6
pH
The
Accumet
pH
Model
of
the
320
b i o - r e a c t o r s , was m e a s u r e d w i t h a F i s h e r
expanded
scale
reference electrodes
combined
standardized against
Fisher
outlined
3.4.7
i n the Standard
(PHB)
pH
chemical
AND
procedure
of
Braunegg
et
of
liquor
were c e n t r i f u g e d
and
pellets
a l . (1978).
a Virtis
s o l u t i o n s as
The
method
acid,
adapted
involved
conversion
into
methanol and e x t r a c t i o n i n
from
the
to give approximately
frozen
were a c c u m u l a t e d ,
buffer
on a gas c h r o m o t o g r a p h .
samples
the sludge p e l l e t s
The meter was
(PHV) were done u s i n g an
esters with a c i d i f i e d
Mixed
and
poly-B-hydroxybutyrate
volatile
for injection
glass
POLY-B-HYDROXYVALERATE
o f PHB a n d PHV by s u l f u r i c
chloroform
probe.
pH 7
depolymerization
methyl
with
(A.P.H.A. e t a l . , 1 9 8 0 ) .
quantification
and p o l y - B - h y d r o x y v a l e r a t e
meter
a single
4 and
Methods
POLY-B-HYDROXYBUTYRATE
The
in
pH
for
sludge
30 mg o f s u s p e n d e d
storage.
t h e y were t h e n
10-234 o r a M u l t i - D r y
activated
Once
lyophilized
(by FTS S y s t e m s
process
solids
enough
sludge
using
either
Inc.) l y o p h i l i z e r .
-51-
Two ml
as
of a c i d i f i e d
methanol
(3% H2S0^) c o n t a i n i n g benzoic a c i d
the i n t e r n a l standard and 2 ml of
measured amount
of l y o p h i l i z e d
c h l o r o f o r m were
added to a
sludge i n 15 ml Pyrex t e s t tubes
with T e f l o n - l i n e d caps.
The samples and
hydroxybutyric
acid
the
standards
dissolved
(sodium
salt
of
D-L
3-
i n a c i d i f i e d methanol) were then
heated a t 100°C f o r approxmately 3.5 hours and allowed to c o o l to
room
temperature.
Two
ml
of the denser chloroform phases were
then t r a n s f e r r e d t o 10 ml Pyrex t e s t tubes
d i s t i l l e d water
phases
containing
minutes
the
PHB
at
and
1500
PHV
transformed t o gas chromatograph v i a l s f o r 1 ml
into a
Hewlett-Packard 5880A
and
chromotograph
to
avoid
the
mm
to
achieve
premature
and the
methyl e s t e r s
split
injections
reliability
degradation
of
of the
the
gas
column.
The gas chromatograph
auto sampler
g
gas chromotograph. T h i s a d d i t i o n a l
p u r i f i c a t i o n s t e p was necessary
method
ml of
and v i g o r o u s l y shaken f o r about 5 minutes. These
were then c e n t r i f u g e d f o r about 10
chloroform
c o n t a i n i n g 0.5
(7672A) and
was
equipped
a c a p i l l a r y column
i n t e r n a l diameter) coated
with
1
um of
with
a programmable
(15 m long and
DB-Wax. Experimental
c o n d i t i o n s f o r the chromatograph were as f o l l o w s :
Temperature of the i n j e c t i o n
port
Temperature of the d e t e c t o r port
0.52
= 210°C
= 220°C
L i n e a r v e l o c i t y of the c a r r i e r gas (helium) = 20
cm/s
-52-
The f o l l o w i n g
oven temperature p r o f i l e was used:
I n i t i a l temperature =- 50°C
Initial
time
== 1 min
Program
rate
== 8°C/min
F i n a l temperature
•= 160°C
F i n a l time
=- 5 min
A f i n a l p e r i o d of 4 minutes with an oven temperature of 200°C was
a l s o employed
t o c l e a r any sample
the a n a l y s i s of each
r e s i d u e from
the column
after
sample.
A r a t i o of HV to HB of 1.211 was used t o c a l i b r a t e the gas
chromatograph's
for
HV response, s i n c e
i t s direct calibration.
no
standards
The f o l l o w i n g
were a v a i l a b l e
correction
factors i n
terms of l y o p h i l i z e d mass of the samples were a l s o a p p l i e d
PHB and
PHV c a l c u l a t i o n s ,
s i n c e the r e c o v e r i e s
method were found to be i n v e r s e l y p r o p o r t i o n a l
t o the
o b t a i n e d by t h i s
t o the l y o p h i l i z e d
mass (Comeau e t a l . , 1 9 8 8 ) .
PHB c o r r e c t i o n
f a c t o r = 1.000 + 0.00361 x l y o p h i l i z e d mass
PHV c o r r e c t i o n
f a c t o r = 1.000 + 0.00780 x l y o p h i l i z e d mass
3.4.8
PHOSPHORUS
Three
types of phosphorus
measurements
were made d u r i n g
-53-
t h i s study, namely ortho-phosphorus,
phosphorus
(a)
ORTHO-PHOSPHORUS
stannuous
(A.P.H.A.
reduction
analysis
c h l o r i d e technique
et
al.,
by
done
e i t h e r by using the
i n the Standard Methods
the automated
Technicon Auto-analyser
I n d u s t r i a l Method
produced comparable
was
outlined
1980) or
method on a
w i t h Technicon
ascorbic
acid
I I , i n accordance
NO.94-70W (1973). Both methods
results.
TOTAL PHOSPHORUS
The
samples
Technicon b l o c k
by
and percent
content i n sludge.
Ortho-phosphorus
(b)
t o t a l phosphorus
Technicon
were f i r s t
digestor
subjected to a c i d digestion using a
40 and s u l f u r i c a c i d , p r i o r t o a n a l y s i s
Auto-analyser
I I , according
to
the Technicon
I n d u s t r i a l Method No.327-73W (1974).
(c)
PERCENT PHOSPHORUS CONTENT IN SLUDGE
The
subjecting
phosphorus
content
a measured amount
104°C) sludge
to acid
of
digestion
i n the sludge was determined by
finely
ground
(as d e s c r i b e d
oven
d r i e d (at
i n the Technicon
-54-
Block D i g e s t e r
I n s t r u c t i o n Manual,
1974) and
a n a l y s i n g f o r the
t o t a l phosphorus, as d e s c r i b e d above i n s e c t i o n 3.4.8 ( b ) .
3.4.9
SOLIDS
(a) TOTAL SUSPENDED SOLIDS (TSS)
T h i s was done by vacuum
through a pre-washed and
filter
and
oven
drying
f i l t e r i n g a known volume of sample
oven d r i e d
for
a
Whatman 934-AH
glass
fibre
minimum of 1 hour at 104°C, as
o u t l i n e d i n the Standard Methods (A.P.H.A. et a l . , 1985).
(b)
VOLATILE SUSPENDED SOLIDS
T h i s was determined by
obtained
in
3.4.9
(a)
at
(VSS)
igniting
550°C,
the
nonfiltrable
as o u t l i n e d
solids
i n the Sta;.
Methods (A.P.H.A. et a l . , 1985).
3.4.10
VOLATILE FATTY ACIDS (VFA)
The v o l a t i l e f a t t y a c i d
computer-controlled
measurements
Hewlett-Packard
5880A
equipped with a flame i o n i z a t i o n d e t e c t o r
as the
c a r r i e r gas.
The g l a s s column
were
done
using a
gas chromatograph,
(FID) and
(0.91 m long
using helium
with a 6 mm
-55-
e x t e r n a l diameter and 2 mm
0.3%
Carbowax/0.1 %
Supelco
Inc.).
P 0
4
°
column
be
f i l t e r s and 1.0 u l
aliquots
701N, 10
acid
Supelco
was
analysed
was
Carbopak
conditioned
packed
with
C ( s u p p l i e d by
according
to
were
were
filtered
t o the
injected
u s i n g Whatman 4
using microsyringes
u l ) and a Hewlett-Packard
(Model 7672A). Samples were
phosphoric
n
diameter)
i n the Supelco B u l l e t i n 751E (1982).
to
(Hamilton Model
3
The
procedure o u t l i n e d
Samples
H
internal
acidified
bring
the
pH
using
below
a
auto-sampler
1%
3.0,
s o l u t i o n of
before
their
i n j e c t i o n s . Experimental c o n d i t i o n s f o r the chromatograph were as
follows:
I n j e c t i o n port
D e t e c t o r port
temperature
150°C
temperature
Isothermal oven
200°C
temperature
120°C
Flow r a t e of c a r r i e r gas (helium) = 20 ml/min
Volatile
and
butyric
fatty
acids
a c i d s analysed
with
included a c e t i c ,
quantification
done
by
propionic
the e x t e r n a l
s t a n d a r d methods, u s i n g reagent grade standards.
3.5
COLD STORAGE TESTINGS
Since
kept a t 4°C
the
sewage
collected
d u r i n g t h i s study was t o be
f o r approximately 2 weeks,
i t was decided t o study
-56-
the
effects
beginning
look
at
over
a
of
two
bottles
was
(i)
in
every
sewage
Two
pilot
and
a
and
undertaken
their
different
plant
500
ml
analysed
batches
mixed
two
for
of
large
plastic
weeks,
the
to
storage
in
air tight
p e r i o d of
the
variation
wastewater
completely
Over
day
was
at
one
following
duplicate.
oxygen
oxygen
(iii)
Nitrates
and
demand
demand
nitrites
(NO )
x
Total
Kjeldahl nitrogen
(v)
Total
phosphorus
Ortho-phosphorus
Volatile
fatty
(BOD)
(COD)
(iv)
(vii)
the
separate
4°C.
characteristics
study
3.3.1,
other
Chemical
(TKN)
(TP)
(P0 ~P)
4
acids
(VFA)
STATISTICS
The
Texas
with
of
i n seven
(ii)
3.6
brief
the
section
at
sewage
storage.
from
room
Biochemical
(vi)
a
cold
taken
parameters
in
stored
i n the
A
in cold
collected
and
on
parameters
period
described
containers
bottle
week
storage
experiments.
various
were
as
cold
the
the
sewage
tanks,
of
the
linear
regression analysis
Instrument
TI-66
TI-66
Sourcebook
of
programmable
(Texas
the
data
was
calculator,
Instruments,
1977).
in
done,
using
accordance
-57-
CHAPTER
R E S U L T S AND
The
this
results
study
initial
are
of the
discussion
relevant
to
sections
the
activated
from
the i n d i v i d u a l
(Section
noticed
were
analysis
fraction
different
butyrate
no
significant
during
comparable
dosages
of
glucose.
these
particular
runs.
under
removal
cold
the
broader
technology
the results
in
obtained
study.
storage
of
a p e r i o d o f two w e e k s .
The
variations
those
expected
errors.
i n Appendix
during
sodium
3,
i n any
4°C)
(at
parameters
i n Chapter
of the i n f l u e n t
runs
of t h i s
variation
The
individual
combining
on
chapter.
four
phosphorus
runs
in
the
to
are given
this
conducted
of
experimental
described
and
study
in
discussion
process,by
experimental
3.4)
study
the
excess
of the
through
this
As
sludge
results
tested
during
present
of the b i o l o g i c a l
showed
discussed
the
Subsequent
sewage
experiments
describe
with
The
and
scale
sections
separately,
aspects
DISCUSSION
bench
detailed
four
FOUR
during
The
data
chemical
obtained
A3.
the r e a d i l y
the experiments
acetate,
raw
the
sodium
biodegradable
was
varied
propionate,
COD
using
sodium
-58-
4.1
ACETATE ADDITION
Sodium a c e t a t e was added
dosages of
continuously
to
the
system at
30, 25, 20, 15, 10 and 5 mg/L as COD i n the anaerobic
r e a c t o r . The raw data
f o r these
experimental
runs
are given i n
Appendix A2.
The
results
shown
in
Table
4.1 i n d i c a t e d that a t 5 mg
COD/L of a c e t a t e a d d i t i o n , the phosphorus removal was only
1.0 mg
of P/L
sludge
of feed
was 1.5%. T h i s
and the percent phosphorus i n the a e r o b i c
value
corresponds
to
the
expected
dry weight
percent phosphorus content of organisms not e x h i b i t i n g any excess
b i o l o g i c a l phosphorus removal (Hoffmann
than
100
percent
improvement
and Marais,
i n phosphorus removal, from 1.0 to
2.2 mg of P/L of feed was o b t a i n e d when the
10 mg
COD/L. The
a l s o higher a t
percent phosphorus
2.2
excess phosphorus
%,
1977). More
indicating
a c e t a t e a d d i t i o n was
i n the
the
removing organisms.
a e r o b i c sludge was
presence
of b i o l o g i c a l
T h i s t r e n d continued
with
increasing loadings.
However,
significant
improvement
in
biological
excess
phosphorus removal was not achieved by i n c r e a s i n g a c e t a t e l o a d i n g
beyond 20 mg
conditions
COD/L.
of
significant
obtained
by
the
This
i s due
influent.
advantage
increasing
in
r e a c t o r beyond 20 mg COD/L.
Thus,
excess
the
to
the
in
phosphorus l i m i t i n g
this
phosphorus
acetate
loading
circumstance, no
removal
c o u l d be
i n the anaerobic
-59-
Table 4.1
R e s u l t s of Acetate A d d i t i o n Experiments
Acetate Dosage in mg COD/L
Parameter
30
25
20
15
10
5
TOTAL P :
(mg/L)
Influent
Effluent
4.5
<0.2
4.2
<0.2
4.1
0.4
4.4
0.8
4. 1
1.9
4.4
3.4
ORTHO-P :
(mg/L)
Influent
Anaerobic
Anoxic
Aerobic
Effluent
3.2
18.1
15.6
<0.1
<0.1
3.2
16.0
13.5
<0.1
<0.1
3.2
10.5
8.2
0.3
0.3
3.2
5.2
4.4
0.6
0.8
3.0
3.6
3.3
1.7
1.8
3.3
3.4
3.5
3.1
3.4
Aerobic sludge % P
5.7
5.5
4.8
4.6
3.0
1 .5
AP (mg/L)
4.3
4.0
3.7
3.6
2.2
1 .0
Influent
Added
Effluent
219
60
35
224
50
40
230
40
32
234
30
29
240
20
32
246
10
36
Readily biodegradable COD (mg/L)
84
77
71
63
55
48
COD:
Tmg/L)
-60-
The
ortho-P
concentrations
in
both anaerobic
and aerobic
r e a c t o r s showed that the phosphorus was r e l e a s e d i n the anaerobic
zone and subsequently
phosphorus
release
taken
and
up
the
in
the
uptake
aerobic
zone.
increased
Both the
with i n c r e a s i n g
a c e t a t e dosages.
4.2
PROPIONATE ADDITION
A f t e r the l a s t
run with a c e t a t e
( i . e . the 5 mg COD/L r u n ) ,
the same system was spiked c o n t i n u o u s l y with sodium propionate a t
dosages of 25, 20, 15,
reactor.
These
dosages
limiting conditions
higher
10
and
were
5
mg
COD/L,
selected
experienced
in
the anaerobic
to a v o i d the phosphorus
during
the a c e t a t e
runs with
dosages.
S t a b l e steady
state conditions
days. No s i g n i f i c a n t changes
suspended s o l i d s
were achieved
were n o t i c e d
i n about 20
and the mixed l i q u o r
c o n c e n t r a t i o n remained v i r t u a l l y unchanged over
the whole t r a n s i t i o n p e r i o d .
The
experimental
run with
10 mg
COD/L was
the sewage used d u r i n g t h i s run was found
level
of
14.7
experimental
runs
mg/L
as
COD.
However,
throughout t h i s
repeated
since
t o c o n t a i n a c e t a t e at a
during
a l l the other
study, the raw sewage d i d not
c o n t a i n any measurable short c h a i n v o l a t i l e f a t t y
acid.
-61-
Starting
from
the
propionate
consumption) i n
individual reactors
understand
biological
the
S i g n i f i c a n t amounts
hydroxybutyrate
d u r i n g the
(PHB) were found
p r o p i o n a t e run.
carbon
dosages
of
storage
and
are l i s t e d
The
results
phosphorus
removal process.
(PHV) and poly-B-
i n mixed l i q u o r suspended s o l i d s
PHV was
s t o r e d d u r i n g the anaerobic
phase. The
q u a n t i t i e s of
consumption i n c r e a s e d with
The
raw
data
for
increasing
this
series
of
indicated
that
the
i n Appendix A2.
shown
in
Table
phosphorus removal i n c r e a s e d with
showing the
storage (or
was a l s o measured to b e t t e r
the a e r o b i c
propionate.
experiments
carbon
of p o l y - B - h y d r o x y v a l e r a t e
phase and consumed d u r i n g
this
excess
run,
same t r e n d
observed
4.2
i n c r e a s i n g p r o p i o n a t e dosages,
d u r i n g the a c e t a t e run. At 5 mg
COD/L dosage, no s i g n i f i c a n t b i o l o g i c a l excess phosphorus removal
was t a k i n g p l a c e , s i n c e the percent phosphorus i n the dry a e r o b i c
sludge was only 1.4%
biological
excess
(Hoffmann and
phosphorus
Marais,
removal
"bio-P" mode
be
due to
c o n c e n t r a t i o n of the p r e f e r r e d s u b s t r a t e (propionate, i n
t h i s case)
The
the
Although the
organisms c o u l d s t i l l
p r e s e n t , they might not be o p e r a t i n g i n the
the low
1977).
i n the anaerobic
ortho-P c o n c e n t r a t i o n s i n
phosphorus
phosphorus
zone.
uptake
release
in
in
the
i n c r e a s i n g propionate l o a d i n g .
the
aerobic
various
anaerobic
reactor
zones
showed that
reactor
and
increased
the
with
- 6 2 -
Table 4.2
Results of Propionate
A d d i t i o n Experiments
Propionate
Parameter
25
20
Dosage i n mg COD/L
15
10
5
1 0*
TOTAL P :
(mg/L)
Influent
Effluent
4.3
0.3
4. 1
0.9
4.2
1 .6
4.0
2.6
4. 1
3. 1
3.9
<0.2
ORTHO-P :
(mg/L)
Influent
Anaerobic
Anoxic
Aerobic
Effluent
3.2
13.7
11.5
0.3
0.3
3.0
10.3
8.7
0.9
0.8
3.3
5.3
4.2
1 .5
1 .5
3.1
4. 1
3.6
2.5
2.4
3.2
3.3
3.0
3.0
3. 1
2.9
15.5
11.2
<0. 1
<0.1
% P
5.5
4.4
3.7
2.2
1 .4
5.2
(mg/L)
4.0
3.2
2.6
1 .4
1 .0
3.7
Influent
Added
Effluent
226
50
25
227
40
25
234
30
21
241
20
25
244
10
24
239
20
28
66
59
51
46
71
Aerobic
sludge
AP
COD:
(mg/L)
Readily biodegradable COD (mg/L)
71
* The raw sewage during
this
c o n c e n t r a t i o n of 14.7 mg/L as COD.
run
had
an
acetate
-63-
4.3
BUTYRATE ADDITION
Once the
propionate
c o n t i n u o u s l y with
sodium b u t y r a t e at a
as COD
i n the anaerobic
25,
15 and
20,
When
butyrate,
10 mg
the
the
runs were over,
substrate
mixed
was
liquor
i n the
shift
aerobic and
in
another 2
for
a
further
system s t a r t e d removing
Oct.9,1986)
t h e r e a f t e r , although
data
anoxic
solids
of
the
to
system
2300 mg/L
to
r e a c t o r s ) w i t h i n a p e r i o d of
weeks. T h i s
normal
concentration
indicated a significant
5
not e x h i b i t
weeks p e r i o d
phosphorus
from
continued
to
and
fact
organisms,
and
( u n t i l Oct.6,1986).
the
6th
perform
The
week onwards
satisfactorily
The
that the excess phosphorus removal mechanism
was
with no apparent change i n any
7
excess phosphorus
changed.
i n Appendix
e s t a b l i s h e d i n a very short p e r i o d
almost
any
no o p e r a t i o n a l c o n d i t i o n s were
f o r t h i s run are g i v e n
The
took
mg/L
i n the p o p u l a t i o n of organisms i n the system.
removal
raw
propionate
(from approximately
However, the system d i d
(from
from
g r a d u a l l y i n c r e a s e d back to the
mg/L
30
f o l l o w e d by dosages of
changed
suspended
250
of 2300
of
spiked
COD/L.
as much as ten times
11 days and
concentration
r e a c t o r . T h i s was
decreased
mg/L
the system was
weeks
to
of only
A2.
3 days
a f t e r Oct.6,
other parameter, suggested t h a t i t
establish
then only 3 days
the
correct
culture
of
f o r t h a t c u l t u r e to m u l t i p l y to
-64-
Table 4.3
R e s u l t s of Butyrate A d d i t i o n Experiments
Butyrate Dosage i n mg COD/L
Parameter
30
25
20
15
10
4. 1
0.5
4.2
0.9
3.9
1.8
4.2
2.3
4.0
3.1
3.3
12.9
9.8
0.5
0.5
3.2
10.1
7.7
0.9
1 .0
3.0
7.4
5.9
1.7
1.7
3.2
4.7
4. 1
2.3
2.4
3.0
3.4
3.1
3.0
2.9
4.6
4.3
2.7
2.1
1 .6
3.6
3.3
2.1
1.9
0.9
Influent
Added
Effluent
220
60
34
223
50
38
230
40
40
234
30
39
241
20
34
Readily biodegrada b l e COD (mg/L)
69
66
62
59
50
TOTAL P :
(mg/L)
Influent
Effluent
ORTHO-P :
(mg/L)
Influent
Anaerobic
Anoxic
Aerobic
Effluent
Aerobic sludge % P
AP
COD:
Tmg/L)
(mg/L)
-65-
significant
levels.
Once
this
population
was
significantly
e s t a b l i s h e d , the system s t a r t e d t o perform s u c c e s s f u l l y .
From the day the b u t y r a t e
days f o r
the system
r e t e n t i o n time
t o reach
(SRT)
of
a d d i t i o n was s t a r t e d , i t took 76
the steady s t a t e . Since the s o l i d s
the
the usual
(54
days)
was
i n t h i s case. T h i s r a i s e d an important
conclusion
required
issue
before
well
regarding
making
the
that a system would not work (or v i c e v e r s a ) .
As observed
phosphorus removal
anaerobic
time
SRT's
days,
surpassed
adjustment
3
18
adjustment
operational
of
was
accepted
the
period
system
in earlier
a c e t a t e and
increased with
phosphorus r e l e a s e and
propionate
i n c r e a s i n g butyrate
a e r o b i c phosphorus
f o l l o w e d the same t r e n d . The carbon storage
runs, the
dosage.The
uptake a l s o
during these runs was
p r i m a r i l y as PHB.
4.4
GLUCOSE ADDITION
The
COD
in
glucose
the
anaerobic
over from butyrate
(MLSS) of
aerobic
of
shift
r e a c t o r . When the s u b s t r a t e was
to g l u c o s e ,
the system
MLSS
population
run was s t a r t e d with the dosage of 60
thinned
around
in
approximately 5 weeks.
the
2500
the mixed l i q u o r
out
and was
mg/L,
system.
switched
suspended
solids
r e - e s t a b l i s h e d at an
indicating
This
mg/L as
a significant
adjustment
p e r i o d was
-66-
T a b l e 4.4
R e s u l t s of Glucose A d d i t i o n Experiments
Glucose Dosage i n mg COD/L
Parameter
TOTAL P:
(mg/L)
Influent
Effluent
ORTHO-P:
(mg/L)
Influent
Anaerobic
Anoxic
Aerobic
Effluent
A e r o b i c sludge % P
AP
COD:
(mg/L)
(mg/L)
Influent
Added
Effluent
R e a d i l y biodegrada b l e COD (mg/L)
75
60
45
30
3.9
0.2
3.6
0.7
3.7
1.7
3.7
2.4
3.3
13.3
6.9
0.1
0.1
2.7
1 1.2
6.8
0.7
0.6
2.8
6.8
6.0
1.6
1 .6
2.7
4.1
3.1
2.4
2.3
4.1
3.4
2.7
1 .7
3.7
2.9
2.0
1 .3
1 92
1 50
37
189
120
31
199
90
33
214
60
27
83
70
62
54
-67-
Although
phosphorus
appeared
those
the
removal
solids
was
taking
associated
with
kind
of
the
fermentative
anoxic r e a c t o r was
anaerobic
poor
6
place.
reactor.
weeks.
formation
during
state,
nitrates
However,
Once
the
r e a c t o r was s i g n i f i c a n t l y
no
excess
The anoxic mixed l i q u o r
of
(much
more than
n i t r o g e n gas, d u r i n g
the other
condition.
and
the anoxic r e a c t o r improved
about
steady
very gluey w i t h s i g n i f i c a n t gas bubbles
d e n i t r i f i c a t i o n , as observed
some
reached
runs), indicating
Denitrification
were
bleeding
i n the
i n t o the
the d e n i t r i f i c a t i o n performance of
g r a d u a l l y over
nitrate
reduced,
a further
p e r i o d of
b l e e d i n g i n t o the anaerobic
the
system
s t a r t e d removing
phosphorus s u c c e s s f u l l y .
Other dosages
used
i n t h i s run were 45, 30 and 75 mg/L as
COD. U n l i k e the other runs, the f i n a l
the i n i t i a l
estimated loading
loading
was higher
due t o
not y i e l d i n g the maximum p o s s i b l e
excess phosphorus removal f o r the given c o n d i t i o n s . The
raw data
f o r these are g i v e n i n Appendix A2.
As observed
i n a l l the p r e v i o u s runs, anaerobic phosphorus
r e l e a s e , a e r o b i c phosphorus
uptake
and
the
o v e r a l l phosphorus
removal i n c r e a s e d with i n c r e a s i n g glucose dosages. Carbon storage
and consumption i n v o l v e d two compounds, PHB and glycogen.
-68-
4.5
READILY BIODEGRADABLE COD
The
readily
significance
in
biodegradable
b i o l o g i c a l excess
COD
in
a
sewage, i t s
phosphorus removal
p r o c e s s and
t h e methods f o r i t s d e t e r m i n a t i o n were a l l e x p l a i n e d i n d e t a i l i n
the
previous
chapters.
biodegradability
different
This
section
( i n terms o f
chemical
readily
substrates
d u r i n g t h i s s t u d y . The e f f e c t s
on
the
biological
excess
discusses
biodegradable
COD) o f t h e
added t o t h e e x p e r i m e n t a l
of
the r e a d i l y
phosphorus
d i s c u s s e d under t h e d i f f e r e n t
the degree of
system
biodegradable
removal
process w i l l
COD
be
a s p e c t s of t h e p r o c e s s , i n s e c t i o n s
4.6 t o 4.9.
The
technique
d e t e r m i n a t i o n of
measuring
the
the r e a d i l y
and
readily
study represent
biodegradable
the t o t a l
t h i s study, f o r the
was c a p a b l e o f
b i o d e g r a d a b l e COD, w h i c h i n c l u d e
b i o d e g r a d a b l e COD a l r e a d y p r e s e n t
chemical substrates. Therefore,
readily
used i n
b i o d e g r a d a b l e COD,
only the t o t a l r e a d i l y
the r e a d i l y
and
developed
COD
the
readily
i n the
introduced
results
by
raw sewage
the
presented
added
in this
b i o d e g r a d a b l e COD a n d n o t t h e
b i o d e g r a d a b l e COD i n t r o d u c e d
by t h e
added s i m p l e
carbon
substrates alone.
The
dosages
s e c t i o n s 4.1 t o
r e a c t o r . To
of
4.4,
various
were
a c h i e v e these
t w i c e as h i g h t o account
in
experimental
mg/L
as
runs
described i n
in
the anaerobic
COD
d o s a g e s , t h e f e e d c o n c e n t r a t i o n s were
f o r the d i l u t i o n e f f e c t
taking
place i n
-69-
the anaerobic
r e a c t o r due
recycle r a t i o
of 1:1).
t o the
anoxic-anaerobic
The d i s c u s s i o n presented
d e s c r i b e the c h e m i c a l dosages with r e s p e c t
to the a n a e r o b i c
The
showed that
of
readily
f o r the
f o r the
biodegradable
in this
t o the
(with
section
feed (and not
reactor contents).
plot
dosages (as COD)
recycle
biodegradable
various
experimental
same dosage
s u b s t r a t e s had the
COD vs the chemical
( i n mg/L
following
runs
( F i g . 4.1)
as COD), the r e a d i l y
decreasing
order of
effect.
a c e t a t e > p r o p i o n a t e > b u t y r a t e > glucose
As
expected,
it
biodegradability
is
seems
to
suggest
some i n v e r s e
that
f u n c t i o n of
the
degree
of
the complexity of
the added compound.
It was
plot
a l s o noted
(between t h e dosages
that in
of
the more l i n e a r ranges of the
20-40
mg/L
as
COD
for acetate,
propionate, b u t y r a t e and between 60-120 mg/L as COD f o r g l u c o s e ) ,
an i n c r e a s e of
1
mg
COD/L
readily biodegradable
0.27
mg/L
for
respectively.
in
COD i n
acetate,
However,
chemical
the feed
propionate,
these
values
dosage
by 0.80,
i n c r e a s e d the
0.75, 0.45 and
butyrate
and
can
be
only
glucose
used
as
approximate e s t i m a t e s , s i n c e the d i f f e r e n t batches of sewage used
d u r i n g each run might not have had the same r e a d i l y
substrate
content.
This
might a l s o
be a
reason
biodegradable
(besides any
-70-
l i m i t a t i o n of the method
COD) f o r
of measuring
not o b t a i n i n g
compound,
(as observed
et a l . , 1 9 8 5 ) .
carbon/L
degree
by N i c h o l l s
chemical
d i d not
of
acetate,
dosages
show
any
corresponding
and b u t y r i c
and
volatile
terms
correlation
Surprisingly,
fatty
biodegradable
of e i t h e r mM/L
significant
butyrate
expressed
acid
to be a rough guide i n
these
group
of
COD
or mM of
with t h e i r
the same dosages of
as
mg/L
of
the
(acetic acid, propionic acid
a c i d r e s p e c t i v e l y ) , gave r e l a t i v e l y
biodegradable COD content
of
as r e a d i l y
in
biodegradability.
propionate
biodegradable
complete recovery of the added a c e t a t e , a
simple e a s i l y degradable
The
the r e a d i l y
the same r e a d i l y
( F i g . 4.2). T h e r e f o r e , t h i s i s observed
e s t i m a t i n g the
chemicals,
b i o l o g i c a l excess phosphorus
r e a d i l y biodegradable
commonly
removal
encountered
process.
COD
i n the
However, glucose
d i d not f o l l o w t h i s t r e n d .
E x t r a p o l a t i o n of
the p l o t
around 40 mg/L of r e a d i l y
addition,
indicating
in F i g .
biodegradable
that
the
4.2, gave
COD
approximate
average
readily
t h i s study
was 40
raw sewage
mg/L. Since
t o t a l COD of the raw sewage used during
the p e r i o d
of
these
percentage
basis,
experiments
18%
of
the
was
in
zero chemical
biodegradable COD of the
the average
used
for
a value of
around
t o the biodegradable COD
COD) o b t a i n e d by
mg/L,
on a
t o t a l COD i n the raw sewage was
r e a d i l y biodegradable. T h i s compares w e l l w i t h
with r e s p e c t
225
the v a l u e
of 24%
( i e about 20% of the t o t a l
Dold e t a l . (1980) f o r
South
African
sewage.
-71-
90
0
20
40
60
80
100
120
140
160
Dosoge in m g / L a s COD In feed
Fig.
T o t a l r e a d i l y b i o d e g r a d a b l e COD i n f e e d v s .
a d d i t i o n t o f e e d , e x p r e s s e d a s COD.
4..1.
0
20
40
60
80
100
chemical
120
140
Dosoge in m g / L in feed
Fig.4..2.
T o t a l r e a d i l y b i o d e g r a d a b l e COD i n f e e d v s . c h e m i c a l a d d i t i o n
to f e e d , e x p r e s s e d as mg/L. Dosages of a c e t a t e , p r o p i o n a t e and
b u t y r a t e are expressed as t h e i r c o r r e s p o n d i n g a c i d s .
-72-
The percentage
treatment
facility
collection
is
system
systems p r o v i d i n g
conditions,
of
biodegradable
significantly
(Paepcke,
1983;
long r e t e n t i o n
resulting
molecules to
readily
in
the
Barnard,
1984). C o l l e c t i o n
times can p r o v i d e fermentative
breakdown
of
complex
simple compounds c a u s i n g h i g h r e a d i l y
system
f o r the treatment
sewage
study
was
used
in
time
this
and
thus
fermentative c o n d i t i o n s
was
of
the sewage
slightly
low
acid
obtained,
unlikely
of any
biodegradable
p l a n t , where the
had
to
a
very short
provide
enough
measurable s h o r t c h a i n
i n the raw sewage. In a d d i t i o n t o the nature
itself,
this
percentage
might
of
also
readily
content obtained f o r the sewage used
4.6
organic
t o breakdown the complex compounds. T h i s
was a l s o confirmed by the absence
v o l a t i l e fatty
entering a
i n f l u e n c e d by the type of
c o n t e n t . The c o l l e c t i o n
detention
COD
be
a
reason
biodegradable
in this
f o r the
substrate
study.
PHOSPHORUS RELEASE AND UPTAKE
The p r e r e q u i s i t e f o r b i o l o g i c a l
i n the
a c t i v a t e d sludge
zone upstream of the
released in
removal
process i s the presence of an anaerobic
aerobic
zone.
In
general,
phosphorus i s
the anaerobic zone and taken up i n the a e r o b i c zone.
The q u a n t i t a t i v e amounts of
be found
excess phosphorus
by mass
phosphorus r e l e a s e
and uptake c o u l d
balance, using c o n c e n t r a t i o n s of phosphorus i n
v a r i o u s zones of the p r o c e s s .
-73-
During t h i s study, phosphorus
sewage
and
the
effluent
were
measured
phosphorus and ortho phosphorus.
was measured
i n the
was a v a i l a b l e
f o r measuring
including
the
phosphorus
both
in terms of t o t a l
However, only
ortho phosphorus
unfiltered total
present
in
mixed
exact phosphorus
be c a l c u l a t e d
the b i o r e a c t o r
d i f f e r e n c e between
feed) to
the raw
technique
phosphorus without
liquor
suspended
mass balances
i n the
r e a c t o r s could not be done. However, the extreme range
values could
zone of
in
v a r i o u s r e a c t o r s , s i n c e no simple
s o l i d s . For t h i s reason,
individual
concentrations
caused
assumption was
made on which
the complex phosphorus
t o t a l phosphorus
be transformed
to 4 . 8 present the
i f an
and ortho
( i . e . , the
phosphorus i n the
to simpler ortho phosphorus. Tables
values f o r
the phosphorus
4.5
uptake i n v a r i o u s
r e a c t o r s under d i f f e r e n t assumptions.
The values
of phosphorus
i n d i c a t i n g phosphorus r e l e a s e ) ,
presented
uptake (with
per
unit
the negative s i g n
volume
of
the feed,
i n t h i s s e c t i o n were d e r i v e d i n the f o l l o w i n g way
mass balance
using
(Fig.4.3).
i
anox
Fig.4.3.
Mass of phosphorus e n t e r i n g and l e a v i n g each i n d i v i d u a l r e a c t o r
per u n i t i n f l u e n t flow. P i n d i c a t e s the ortho-P c o n c e n t r a t i o n .
-74-
P uptake = Mass of P e n t e r i n g - Mass of P l e a v i n g
Phosphorus uptake
(per u n i t i n f l u e n t
flow) i n the anaerobic
r e a c t o r i s given by
( i n f l u e n t ortho-P) + (anoxic ortho-P) - 2x(anaerobic ortho-P)
Phosphorus uptake
(per u n i t
influent
flow) i n the anoxic r e a c t o r
i s given by
2x(anaerobic ortho-P) + ( a e r o b i c ortho-P) - 3x(anoxic ortho-P)
Phosphorus uptake (per u n i t i n f l u e n t
flow) i n the a e r o b i c
r e a c t o r i s g i v e n by
2x(anoxic ortho-P) - 2 x ( a e r o b i c
Depending on the zone
transformed
into
ortho
ortho-P)
i n which the complex
phosphorus,
phosphorus i s
the d i f f e r e n c e between the
t o t a l phosphorus and the o r t h o phosphorus of the feed i s added to
the formula
that the
of the
daily
c o r r e s p o n d i n g zone.
wastage
phosphorus balance,
was
not
I t should a l s o be noted
included
in
s i n c e i t s c o n t r i b u t i o n was
to the wastage volume being
very
small
c a l c u l a t i n g the
insignificant
compared
to
due
the d a i l y
flows.
The r e s u l t s
presented i n T a b l e s 4.5
to 4.8
indicated
the d i f f e r e n c e s between the phosphorus uptake v a l u e s i n
zone under
the
the d i f f e r e n t
averages of these
that
the same
assumptions were not l a r g e . T h e r e f o r e ,
extreme
v a l u e s a r e used i n the f o l l o w i n g
-75-
T a b l e 4.5
Phosphorus Uptake f o r Acetate Run
Chemical Dosage i n
Anaerobic Reactor
(mg COD/L)
Phosphorus Uptake
(mg of phosphorus/L of feed)
Anaerobic
Anoxic
Aerobic
(a) when the complex phosphorus i n the i n f l u e n t i s transformed
c o m p l e t e l y t o ortho phosphorus i n the anaerobic zone
30
25
20
15
10
5
-16.1
-14.3
-8.7
-1.6
0.2
1.1
-10.5
-8.4
-3.3
-2.2
-1.0
-0.6
31.0
26.8
15.8
7.6
3.2
0.8
(b) when the complex phosphorus i n the i n f l u e n t i s transformed
c o m p l e t e l y t o ortho phosphorus i n the anoxic zone
30
25
20
15
10
5
-17.4
-15.4
-9.6
-2.8
-0.9
0
-9.2
-7.4
-2.4
-1.0
0.1
0.5
31.0
26.8
15.8
7.6
3.2
0.8
(c) when the complex phosphorus i n the i n f l u e n t i s transformed
c o m p l e t e l y t o ortho phosphorus i n the a e r o b i c zone
30
25
20
15
10
5
-10.5
-8.4
-3.3
-2.2
-1.0
-0.6
32.3
27.8
16.7
8.8
4.3
1.9
(d) when the complex phosphorus i n the i n f l u e n t
and ends up i n the sludge
i s unchanged
30
25
20
15
10
5
-17.4
-15.3
-9.6
-2.8
-0.9
0
-17.4
-15.3
-9.6
-2.8
-0.9
0
-10.5
-8.4
-3.3
-2.2
-1.0
-0.6
31.0
26.8
15.8
7.6
3.2
0.8
-76-
T a b l e 4.6
Phosphorus Uptake
C h e m i c a l Dosage i n
Anaerobic Reactor
(mg COD/L)
f o r P r o p i o n a t e Run
Phosphorus Uptake
(mg o f p h o s p h o r u s / L o f f e e d )
Anaerobic
Anoxic
Aerobic
(a) when t h e c o m p l e x p h o s p h o r u s i n t h e i n f l u e n t i s t r a n s f o r m e d
c o m p l e t e l y t o o r t h o p h o s p h o r u s i n t h e a n a e r o b i c zone
25
20
15
10
5
•11.6
-7.8
-2.2
-0.6
0.5
•6.8
•4.6
•0.5
•0.1
0.6
22.4
15.6
5.4
2.2
0
(b) when t h e c o m p l e x p h o s p h o r u s i n t h e i n f l u e n t i s t r a n s f o r m e d
c o m p l e t e l y t o o r t h o p h o s p h o r u s i n t h e a n o x i c zone
25
2015
10
5
•12.7
-8.9
-3. 1
-1.5
-0.4
•5.7
•3.5
0.4
0.8
1 .5
22.4
15.6
5.4
2.2
0
(c) when t h e c o m p l e x p h o s p h o r u s i n t h e i n f l u e n t i s t r a n s f o r m e d
c o m p l e t e l y t o o r t h o p h o s p h o r u s i n t h e a e r o b i c zone
25
20
15
10
5
•12,
-8,
-3,
-1 ,
-0,
•6.8
-4.6
•0.5
•0.1
0.6
(d) when t h e c o m p l e x p h o s p h o r u s i n t h e i n f l u e n t
and ends up i n t h e s l u d g e
25
20
1 5
10
5
•12.7
-8.9
-3. 1
-1.5
-0.4
•6.8
•4.6
•0.5
•0.1
0.6
23.5
16.7
6.3
3. 1
0.9
i s unchanged
22.4
15.6
5.4
2.2
0
-77-
T a b l e 4.7
Phosphorus Uptake f o r Butyrate Run
Chemical Dosage i n
Anaerobic Reactor
(mg COD/L)
Phosphorus Uptake
(mg of phosphorus/L of feed)
Anaerobic
Anoxic
Aerobic
(a) when the complex phosphorus i n the i n f l u e n t i s transformed
c o m p l e t e l y t o ortho phosphorus i n the anaerobic zone
30
25
20
15
10
•12.7
-9.3
-5.9
-2.1
-0.7
•3.1
•2.0
•1 .2
•0.6
0.5
18.6
13.6
8.4
3.6
0.2
(b) when the complex phosphorus i n the i n f l u e n t i s transformed
c o m p l e t e l y t o ortho phosphorus i n the anoxic zone
30
25
20
15
10
•1 1.9
-8.3
-5.0
-1.1
0.3
•2.3
•1 .0
0.3
0.4
1 .5
18,
13,
8,
3,
0,
(c) when the complex phosphorus i n the i n f l u e n t i s transformed
c o m p l e t e l y t o ortho phosphorus i n the a e r o b i c zone
30
25
20
15
10
•1 1.9
-8.3
-5.0
-1.1
0.3
•3.1
•2.0
•1 .2
•0.6
0.5
19,
14,
9,
4,
1 ,
(d) when the complex phosphorus i n the i n f l u e n t
and ends up i n the sludge
i s unchanged
30
25
20
15
10
•1 1.9
-8.3
-5.0
-1.1
0.3
•3.1
•2.0
•1 .2
•0.6
0.5
18.6
13.6
8.4
3.6
0.2
-78-
Table 4.8
Phosphorus Uptake f o r Glucose Run
Chemical Dosage i n
Anaerobic Reactor
(mg COD/L)
Phosphorus Uptake
(mg of phosphorus/L of feed)
Anaerobic
Anoxic
Aerobic
(a) when the complex phosphorus i n the i n f l u e n t i s transformed
c o m p l e t e l y to ortho phosphorus i n the anaerobic zone
75
60
45
30
•15.8
•12.0
-3.9
-1 .4
6.0
2.7
•2.8
1 .3
13.6
12.2
8.8
1.4
(b) when the complex phosphorus i n the i n f l u e n t i s transformed
c o m p l e t e l y t o ortho phosphorus i n the anoxic zone
75
60
45
30
-16.4
-12.9
-4.8
-2.4
6.6
3.6
-1 .9
2.3
13.6
12.2
8.8
1 .4
(c) when the complex phosphorus i n the i n f l u e n t i s transformed
c o m p l e t e l y to ortho phosphorus i n the a e r o b i c zone
75
60
45
30
•16.4
•12.9
-4.8
-2.4
6.0
2.7
-2.8
1 .3
(d) when the complex phosphorus i n the i n f l u e n t
and ends up i n the sludge
75
60
45
30
-16.4
-12.9
-4.8
-2.4
6.0
2.7
•2.8
1 .3
14.2
13.1
9.7
2.4
i s unchanged
13.6
12.2
8.8
1.4
-79-
discussion.
The
negative) i n
average
phosphorus
v a r i o u s zones
f o r the
uptake
(or
different
release, i f
experimental
runs
are given i n Table 4.9.
4.6.1
ANAEROBIC ZONE
The anaerobic
neither dissolved
zone
i s considered
oxygen nor n i t r a t e
n i t r o g e n ) i s p r e s e n t . The
denitrification)
( i n c l u d e s both
anaerobic
in
this
nitrates
reactor
presence
study
and
through
most of the study, except at
be
one
i n which
(or other forms of o x i d i z e d
of
was
an anoxic
to
nitrites)
the
to
zone (used f o r
ensure
was
that
introduced
no
N0
X
t o the
r e c y c l e . T h i s was a c h i e v e d d u r i n g
the higher
dosages of
the glucose
run.
Phosphorus
release
in
the anaerobic
chemical s u b s t r a t e a d d i t i o n s , i n
shown
in
Fig.4.4.
terms of
The
reactor for various
COD i n
the anaerobic
reactor,
is
phosphorus r e l e a s e i n the
anaerobic
r e a c t o r , f o r the same COD dosage, appeared
t o have the
f o l l o w i n g d e c r e a s i n g order of e f f e c t .
a c e t a t e , propionate > butyrate > g l u c o s e
This perfectly
agreed with the f i n d i n g s of Gerber
e t a l . (1986),
although they used a c e t i c , p r o p i o n i c and b u t y r i c a c i d s i n s t e a d of
t h e i r sodium s a l t s .
I t i s a l s o i n general
agreement w i t h
other
-80-
T a b l e 4.9
Average Phosphorus Uptake f o r A l l Runs
Chemical Dosage i n
Anaerobic Reactor
(mg COD/L)
RUN 1
ACETATE
30
25
20
15
10
5
RUN 2
•16.75
-14.80
-9.15
-2.20
-0.35
0.55
-9.85
-7.90
-2.85
-1 .60
-0.45
-0.05
31 .65
27.30
16.25
8.20
3.75
1 .35
-12.15
-8.35
-2.65
-1 .05
0.05
-6.25
•4.05
•0.05
0.35
1 .05
22.95
16.15
5.85
2.65
0.45
-12.30
-8.80
-5.45
-1 .60
-0.20
-2.70
-1 .50
-0.75
-0.10
1 .00
1 9.00
14.10
8.85
4.10
0.65
-16.10
-12.45
-4.35
-1 .90
-6.30
•3.15
•2.35
1 .80
1 3.90
12.65
9.30
1 .90
PROPIONATE
25
20
15
10
5
RUN 3
Phosphorus Uptake
(mg of phosphorus/L of feed)
Anaerobic
Anoxic
Aerobic
BUTYRATE
30
25
20
15
10
RUN 3 : GLUCOSE
75
60
45
30
-81-
s t u d i e s by P o t g i e t e r and Evans (1983) and Oldham and Koch (1982),
although
these s t u d i e s were conducted u s i n g
mass
in
batch
experiments.
It
acid,
i n s t e a d of sodium propionate, was
non-acclimatized
should be noted
bio
that p r o p i o n i c
used d u r i n g
the study
by
Oldham and Koch (1982).
Although
the
results
reported
(1983) showed the same general
this
current
a c e t a t e and
butyrate
propionate
and
propionate,
as COD,
study,
anaerobic
The
those
very low
their studies
higher phosphorus
current
importance
those o b t a i n e d
using
r e l e a s e s observed
study
of
using
under i n v e s t i g a t i o n ,
(using
that
8.2
acetate,
110
mg/L
5.0
mg/L
with b u t y r a t e
and
to the usage of
The much
with b u t y r a t e and glucose i n
sludge)
acclimatized
studying
and
experiments.
acclimatized
organisms
in
54.5,
c o u l d be p r i m a r i l y due
batch
during
with
r e l e a s e s observed
their
Evans
releases
reported
gave phosphorus r e l e a s e s of 58.6,
in
observed
phosphorus
authors
and
butyrate and g l u c o s e , at a c o n c e n t r a t i o n of
n o n - a c c l i m a t i z e d biomass i n
this
as
Potgieter
were much higher than
glucose.
r e s p e c t i v e l y . The
glucose
the
trend
by
the
i n d i c a t e the
to the
effects
of
substrates
the v a r i o u s
s u b s t r a t e s on the b i o l o g i c a l excess phosphorus removal.
However, a c c o r d i n g
r e l e a s e due
r e l e a s e due
to Jones
to b u t y r i c a c i d was
to a c e t i c
acid
et a l . (1985), the phosphorus
much g r e a t e r
(for
c o n t r a d i c t i n g the o b s e r v a t i o n s made
than the phosphorus
the same COD
in this
a c c l i m a t i z a t i o n p e r i o d of two weeks allowed
dosage), somewhat
study.
Insufficient
between the
different
-82-
substrate a d d i t i o n s , during
might
be
a
reason
the
for this
study
by
Jones
discrepancy,
et al.(l985),
especially
i f the
a d d i t i o n o f a c e t a t e had f o l l o w e d t h e
butyrate a d d i t i o n .
a l m o s t f o u r weeks t o c o m p l e t e a s h i f t
i n o r g a n i s m p o p u l a t i o n when
the c h e m i c a l
s u b s t r a t e was
during t h i s current
the
amount
phosphorus
deviation
of
of
30
mg
on t h e s e
released
f o r every
anaerobic
reactor.
was
reactor v a r i e d almost
propionate
taking
place
or butyrate
of
(Fig.4.4).
The
a c e t a t e r u n 'from t h i s t r e n d i s
phosphorus l i m i t i n g
linear
mg
acetate,
COD/L
b e l i e v e d t o be due t o t h e
feed. Based
to butyrate
15 mg COD/L i n w h i c h a c t i v e b i o l o g i
removal
the
propionate
i n the anaerobic
a d d e d , f o r d o s a g e s above
excess
from
study.
Phosphorus release
linearly with
switched
I t took
conditions i n the
ranges,
1.26 mg
acetate
available
This represented
o f p h o s p h o r u s was
as
COD
i n the
a m o l a r r a t i o o f 2.60 m o l e s
of p h o s p h o r u s p e r mole o f a c e t i c a c i d . The m o l a r r a t i o v a l u e s f o r
propionate
and
b u t y r a t e were
per mole o f t h e
that butyrate
corresponding
mole o f
acid,
compared t o t h e v a l u e
0.9:1,
r e s p e c t i v e l y . This indicated
ratios.
m o l a r r a t i o o f 2.60 m o l e s
acetic
Fukase e t
acid
3.69 moles o f p h o s p h o r u s
r e l e a s e d p h o s p h o r u s t h e most and a c e t a t e t h e l e a s t
i n terms o f molar
The
3.44 a n d
of phosphorus
d u r i n g the a c e t a t e run i s r e l a t i v e l y
of
1.76
obtained
by
Rabinowitz
a l . (1982) r e p o r t e d a p h o s p h a t e : a c e t a t e
while
released per
A r v i n (1985)
and
high
(1985).
molar r a t i o of
Comeau e t a l . (1987) o b s e r v e d
a
-83-
ratio
of
1.4:1.
experiments
However,
where
they
these
were
values
were
calculated
by
based
on batch
adding
different
c o n c e n t r a t i o n s of a c e t a t e at the b e g i n n i n g of the experiments
monitoring
the
corresponding
phosphorus
releases.
c o n t r o l l e d c o n d i t i o n s are u s u a l l y not present
experiments
The
and
These
i n continuous
flow
where a c e t a t e i s added t o g e t h e r with the sewage feed.
higher molar r a t i o obtained i n t h i s c u r r e n t study under these
continuous
flow c o n d i t i o n s might be due t o the presence
than the added
fermentation
concentrations
of
the
raw
of
acetate,
sewage
in
of higher
resulting
from the
the anaerobic r e a c t o r . I t
should a l s o be noted that the above r e p o r t e d r a t i o s were based on
substrate
utilization
rather
S i e b r i t z et a l . (1983)
than
reported a
substrate
availability.
phosphate:acetate
molar
ratio
of 2:1 based on s u b s t r a t e a v a i l a b i l i t y .
Glucose
did
phosphorus r e l e a s e i n
expressed as
not
exhibit
the
anaerobic
section
linear
reactor,
anaerobic r e a c t o r .
probably due
with
the dosage
than
to n i t r a t e
of
expected
entrainment
T h i s w i l l be d i s c u s s e d i n d e t a i l i n
4.6.3.
The anaerobic phosphorus r e l e a s e
an
relationship
COD. The phosphorus r e l e a s e was lower
d u r i n g the 75 mg COD/L run,
i n t o the
a
intrinsic
part
mechanism
by
anaerobic
phosphorus
of
Barnard
was f i r s t
recognized as
the b i o l o g i c a l excess phosphorus removal
(1976).
release
He
is
also
induced
hypothesized
that the
through an anaerobic
s t r e s s t h a t can be i n d i c a t e d by the o x i d a t i o n r e d u c t i o n p o t e n t i a l
-84-
(ORP)
of
that zone.
i n v a l i d i t y of
during
the
The data
this
from t h i s c u r r e n t study shows the
anaerobic
experimental
stress
runs
hypothesis.
with
p r o p i o n a t e and b u t y r a t e , and 30 mg
25
mg
COD/L of
For example,
COD/L
of a c e t a t e ,
g l u c o s e , the average
o x i d a t i o n - r e d u c t i o n p o t e n t i a l s of the anaerobic zone were
-353,
-364
and -353
mV
respectively.
This
degree of the anaerobic s t r e s s that was
would
be
relatively
hypothesis
be
true,
s h o u l d have been
releases
were
indicates
-338,
that the
present d u r i n g these runs
the
same.
the
phosphorus r e l e a s e s d u r i n g these runs
approximately
significantly
d e c r e a s i n g order (with the
Should
equal.
the
anaerobic
However,
different,
the phosphorus
with
average phosphorus
stress
the
following
r e l e a s e s given i n
b r a c k e t s , i n mg/L).
acetate
(14.80) > p r o p i o n a t e (12.15) > b u t y r a t e (8.80) >
glucose
(1.90)
For
all
experimental
phosphorus i n the anaerobic
r e a d i l y biodegradable
COD
runs,
reactor
i n i t was
there
when
was
the
COD
of
(1983) who
readily
reactor
was
suggested
biodegradable
necessary
t h a t the phosphorus
with
25
mg/L.
increasing
present i n the same r e a c t o r ( F i g . 4 . 5 ) .
T h i s i s i n good agreement with the o b s e r v a t i o n s
et a l .
c o n c e n t r a t i o n of
above approximately
A l s o , the anaerobic phosphorus r e l e a s e i n c r e a s e d
r e a d i l y biodegradable
a net r e l e a s e of
release
Siebritz
that a minimum of about 25 mg COD/L
COD
to
made by
concentration
in
the anaerobic
s t i m u l a t e the phosphorus r e l e a s e and
increased
with i n c r e a s i n g
readily
-85-
RBD COD in anaerobic zone (mg/L)
Fig.4.5.
The anaerobic phosphorus, r e l e a s e with r e a d i l y biodegradable
a v a i l a b l e i n the anaerobic zone.
COD
-86-
b i o d e g r a d a b l e COD present
i n the anaerobic r e a c t o r .
The c l o s e agreement
of the phosphorus
release f o r various
s u b s t r a t e a d d i t i o n s , with respect to r e a d i l y biodegradable COD i n
the anaerobic zone, emphasizes the importance of the a v a i l a b i l i t y
of r e a d i l y biodegradable
is a
major s h i f t
that
a
minimum
precondition
s u b s t r a t e i n the anaerobic r e a c t o r . T h i s
i n emphasis
degree
f o r the
of
away from
anaerobic
anaerobic
the i n i t i a l
stress
phosphorus
hypothesis
i s the necessary
release
and
the
subsequent o v e r a l l excess phosphorus removal (as a l s o r e p o r t e d by
S i e b r i t z et a l . , 1983).
4.6.2
AEROBIC ZONE
Under a e r o b i c c o n d i t i o n s , the
c o n d i t i o n e d biomass removes
phosphorus from s o l u t i o n . The uptake of phosphorus i n the a e r o b i c
zone f o r v a r i o u s experimental
The r e s u l t s
i n d i c a t e that
reactor increased
same COD
runs are shown i n Figs.4.6 and 4.7.
the phosphorus
with the
uptake i n the a e r o b i c
i n c r e a s i n g chemical
dosage. For the
dosage, the a e r o b i c phosphorus uptake had the f o l l o w i n g
d e c r e a s i n g order of e f f e c t .
a c e t a t e > propionate > b u t y r a t e > glucose
An apparent
mass of phosphorus
direct
relationship
r e l e a s e d under
was observed
between the
anaerobic c o n d i t i o n s
and the
-87-
46
56
65
76
86
RBD COD in feed (mg/L)
Fig.I.7.
The a e r o b i c phosphorus uptake w i t h r e a d i l y biodegradable COD i n
the feed ( i n c l u d i n g the chemical a d d i t i o n ) .
-88-
mass of
phosphorus taken
up under subsequent a e r o b i c c o n d i t i o n s
f o r most p o r t i o n s of the study, except
glucose
dosages.
for
the runs
with higher
Less
than expected phosphorus uptake
d u r i n g the experimental
runs with higher glucose dosages
addressed
in
the
uptake was
observed
all
study,
Increased
a e r o b i c phosphorus
with
i n c r e a s e d anaerobic
phosphorus r e l e a s e
the
the
be
section.
nearly l i n e a r (Fig.4.8).
data
phosphorus uptake and
this
will
next
and the r e l a t i o n s h i p was
For
observed
the
linear
points
obtained
anaerobic
for
phosphorus
the
aerobic
release during
r e g r e s s i o n a n a l y s i s gave the f o l l o w i n g
2
r e l a t i o n s h i p between them, with
correlation
R
being
0.830 (where
R i s the
coefficient).
P uptake (mg/L) = 1.94
+ 1.402
x P r e l e a s e (mg/L)
The data p o i n t s o b t a i n e d during the higher dosages of g l u c o s e
and 60 mg
COD/L r u n s ) , however,
s i n c e these
4.6.3.
runs had
Neglecting
improvement i n
zone,
with
other problems
these
two
the c o r r e l a t i o n
the a e r o b i c zone and
2
R
c o e f f i c i e n t ) . The
should hot
the
being
data
points
gave
a
significant
between the phosphorus uptake i n
(where
release
R
r e l a t i o n s h i p obtained was
P uptake (mg/L) = 1.21
importance,
to be d i s c u s s e d i n s e c t i o n
phosphorus
0.970
be g i v e n
(75
+ 1.701
is
in
the
the
anaerobic
correlation
as f o l l o w s :
x P r e l e a s e (mg/L)
-89-
However, Wentzell et a l .
r e l a t i o n s h i p between
(1984) developed
the phosphorus
uptake and
study of the b i o l o g i c a l excess phosphorus
P uptake (mg/L) = 3.14
+ 1.145
In the equations d i s c u s s e d
the f o l l o w i n g
release in their
removal.
x P r e l e a s e (mg/L)
above,
the
phosphorus uptake
f o r zero phosphorus r e l e a s e g i v e s the b a s i c metabolic
of the t o t a l
metabolic
organism
mass
phosphorus
In a
system.
of
compared to
The
3.14
1.21
mg/L
mg/L
mg/L
typical activated
of
COD
mg/L)
would
metabolic
the study
c o n c e n t r a t i o n of
be
2.50-3.75
mg/L
( f e e d COD
and
of
the c e l l s , f o r
requirements
et a l .
was
mg/L
1976). Using t h i s as a
phosphorus
by W e n t z e l l
and t h i s c u r r e n t study
of higher
sludge p r o c e s s , 1-1.5
removed (U.S. EPA,
by
obtained i n t h i s
r e s u l t i n g from the higher COD
g u i d e l i n e , the b a s i c
systems d u r i n g
higher b a s i c
obtained
phosphorus i s removed f o r the b a s i c metabolism of
every 200
requirement
i s p r i m a r i l y a t t r i b u t e d to the presence
mass of organisms,
the f e e d .
the
requirement
W e n t z e l l et a l . (1984),
c u r r e n t study,
in
as the
(feed COD
225 mg/L,
1.13-1.69 mg/L
of the
was
500
on average)
respectively.
The
c o r r e s p o n d i n g v a l u e s o b t a i n e d from the equations d i s c u s s e d above,
fall
within
associated
W e n t z e l l et
these ranges.
with
the
a l . (1984),
since
lower c o e f f i c i e n t
phosphorus
study, seems to suggest
limiting,
The
release
in
term
the
(of 1.145)
equation
by
compared to that (1.701) of the c u r r e n t
that their
their
feed
r e l a t i v e l y high a t 15-20
mg/L.
system was
phosphorus
p r e f e r r e d substrate
concentrations
were
-90-
4.6.3
ANOXIC ZONE
A n o x i c zone i s one
available
in
i n t h e f o r m o f NO
which
the
electron
acceptor i s
and not as d i s s o l v e d oxygen.
Since a
A
subpopulation
of
bacteria
capable
are
take place
(McLaren
the
i n the
et
biological
of d e n i t r i f i c a t i o n ,
presence of
a l . 1976,
w i t h NO
f a c i l i t a t e d by t h e
production
is
oxygen. O t h e r
cannot
use
NO
removal
uptake can
of d i s s o l v e d
oxygen
as the
of
electron
of the
terminal electron acceptor i s
the
inhibited
The r e p l a c e m e n t
enzyme,
by t h e
b i o l o g i c a l excess phosphorus
as
phosphorus
instead
a l . 1985).
formation
generally
NO
phosphorus
O s b o r n e t a l . 1978, S i m p k i n s e t a l . 1978,
Iwema e t a l . 1984, Comeau e t
d i s s o l v e d oxygen
excess
nitratase,
whose
presence of d i s s o l v e d
removing
bacteria
that
acceptor, are expected t o release
A
phosphorus,
provided
readily
biodegradable
s u s t r a t e s a r e a v a i l a b l e . The " b i o - P " d e n i t r i f i e r s ,
i n the absence
o f NO , behave
like
that
those
sufficient
not
capable
of
using
NO
as the
X
A
electron acceptor.
The
is,
observed
phosphorus
concentration
t h e r e f o r e , the net r e s u l t of the opposing
and u p t a k e
t h e s e two
r e a c t i o n s , and
reactions.
simultaneously
in
These
phosphorus
release
depends on t h e r e l a t i v e m a g n i t u d e s
two
the presence
(such as a c e t a t e o r
i n t h e a n o x i c zone
opposing
of
reactions
can occur
of both the p r e f e r r e d
substrates
p r o p i o n a t e ) and
electron acceptors
(NO
or
- 9 1 -
Studies
by Gerber et a l . (1987) showed that the phosphorus
r e l e a s e r e a c t i o n predominates when a p r e f e r r e d s u b s t r a t e ,
acetate
in
or p r o p i o n a t e ,
significant
until
the
concentration.
preferred
phosphorus
release
i s present
uptake
in
the
commences.
presence
the
cell
transported
across
e s t a b l i s h e d due
facilitate
its
across
degradation
is
The
of
be
release
reaction
consumed,
For
in
terms
example,
membrane,
across
neutral
continues
of
the
phosphorus
a p r e f e r r e d s u b s t r a t e , even under
membrane.
transport
zone
whereupon
observation
explained
the c e l l
(or a e r o b i c )
a
of
pH
when
pH
form
the
gradient
(HAc)
cell
gradient
acetate
to a proton accompanying each acetate
electrochemically
gradient
The
substrate
a e r o b i c c o n d i t i o n s , may
across
i n the anoxic
such as
shift
1984).
as
an
The
pH
the c e l l membrane i s q u i c k l y r e e s t a b l i s h e d by
of
the
stored
polyphosphate and
is
molecule to
membrane
(Comeau,
is
the
thereby r e l e a s i n g
phosphorus i n t o s o l u t i o n .
At low
substrates
get
or none enter
reaction
causing
c h e m i c a l dosages, most of the
utilized
the a n o x i c
becomes
readily
i n the anaerobic r e a c t o r and
reactor.
dominant
Thus,
the
higher
carbon s u b s t r a t e s
phosphorus r e l e a s e
very
dosages,
some b l e e d i n g
i n t o the anoxic r e a c t o r may
r e a c t i o n to
little
phosphorus uptake
over the phosphorus r e l e a s e
net a n o x i c phosphorus uptake (provided
p r e s e n t ) . At
biodegradable
reaction
s u f f i c i e n t N0
x
is
of the added simple
occur,
become dominant,
causing
as reported
the
by
Gerber et a l . (1987). T h i s r e s u l t s i n a net phosphorus r e l e a s e i n
the anoxic
r e a c t o r under these
conditions.
Fig.4.9
shows that
-92-
-1
1
3
6
7
9
11
13
16
17
Phosphorus Rdoase (mg of P/ L of f««d)
Fig.4.8.
0
Relationship between the aerobic phosphorus uptake and the
anaerobic phosphorus release.
20
40
60
80
100
120
140
160
Dosage in feed (mg C O D / L )
Fig.U.9.
The anoxic phosphorus uptake with chemical dosage, expressed as
COD i n feed.
-93-
this
behaviour
was
observed
d u r i n g most of t h i s study,
except
with the h i g h e r dosages of g l u c o s e .
During
75 and 60 mg COD/L glucose runs
COD/L with
respect to
conditions
in
oxidation
the
and 120 mg
the f e e d ) , the occurrence of fermentative
anoxic
reduction
(or 150
reactor
potentials,
was
suspected
due
to low
s t i c k y appearance of the mixed
l i q u o r and the f o r m a t i o n of s u b s t a n t i a l gas bubbles. According t o
Wilderer et
a l . (1987),
f e r m e n t a t i v e c o n d i t i o n s i n such a system
would e n r i c h t h e biocommunity
for bacteria
which reduce
only t o n i t r i t e , and such a p o p u l a t i o n s h i f t
anaerobes) o c c u r s
o b s e r v a t i o n was
glucose as
treatment
at
the
expense
facultative
denitrifiers.
A similar
a l s o made by Manoharan e t a l . ( 1 9 8 8 ) , while u s i n g
the carbon
source
for d e n i t r i f i c a t i o n
in biological
of l a n d f i l l l e a c h a t e s .
Although
no
d i f f e r e n t i a t i o n between n i t r i t e s and n i t r a t e s
were made d u r i n g t h i s
the anoxic
c u r r e n t study,
the NO
concentrations in
x
r e a c t o r were higher than normal f o r the 75, 60 and 30
mg COD/L dosages of
the expense
g l u c o s e . Since
the p o p u l a t i o n
of the normal d e n i t r i f i e r s ,
might have been a c t i v e i n
the
anoxic
c a u s i n g anoxic phosphorus uptake,
It
of
(towards
nitrate
should
a l s o be
s h i f t was a t
the "bio-P" d e n i t r i f i e r s
zone
during
these
runs,
as shown i n Fig.4.9.
noted that
even i f some glucose b l e d
i n t o the anoxic zone a t the higher dosages, the s t u d i e s by Gerber
et a l . (1987) showed
that
glucose
does
not
give
r i s e to any
-94-
phosphorus
reason
release
unless
strict
anaerobiosis
f o r t h i s may be that unless s t r i c t
glucose
cannot
be
fermented
to
prevails.
The
anaerobiosis prevails,
form the p r e f e r r e d s u b s t r a t e s
(such as a c e t a t e or propionate) t o e f f e c t any phosphorus r e l e a s e ,
as d i s c u s s e d e a r l i e r .
4.6.4
PHOSPHORUS ACCUMULATION IN SLUDGE
As
discussed
in
the
r e l e a s e d i n the anaerobic
The
phosphorus
taken
phase i s s t o r e d i n
system
through
preceding
s e c t i o n s , phosphorus i s
zone and taken
up
from
a e r o b i c zone.
the s o l u t i o n d u r i n g the a e r o b i c
the sludge
wasting.
up i n the
and p h y s i c a l l y
Therefore,
the
phosphorus content of the a e r o b i c sludge
removed from t h e
dry
isa
weight
percent
good i n d i c a t i o n of
the extent of b i o l o g i c a l excess phosphorus removal.
Since
the
dry
organisms i n a t y p i c a l
weight
percent phosphorus content of the
a c t i v a t e d sludge
system, not e x h i b i t i n g
b i o l o g i c a l excess phosphorus removal, i s about
Marais,
direct
1.5% (Hoffmann and
1977), any i n c r e a s e d phosphorus content
above 1.5%
isa
i n d i c a t i o n of the degree of excess phosphorus removal. The
r e s u l t s from t h i s study showed t h a t the percent phosphorus i n the
aerobic
chemical
dosages
( F i g . 4 . 1 0 ) . The percent phosphorus i n the a e r o b i c sludge
had the
following
sludge
increased
decreasing
order
with
of
increasing
e f f e c t , among the v a r i o u s added
compounds, f o r the same dosage expressed
as COD.
-95-
a c e t a t e > propionate > b u t y r a t e > glucose
T h i s was expected,
the a e r o b i c
s i n c e f o r the
phosphorus uptake
same dosage,
had the
expressed as COD,
same d e c r e a s i n g order of
e f f e c t , as d i s c u s s e d i n s e c t i o n 4.6.2.
The percent phosphorus i n
1.5%
f o r a l l the
b i o d e g r a d a b l e COD i n
(corresponds t o
added
the
aerobic
sludge
was above
chemical s u b s t r a t e s , when the r e a d i l y
the
feed
the anaerobic
exceeded
approximately
54 mg/L
zone value of 27 mg/L, due to the
1:1 r e c y c l e ) . T h i s confirms the f i n d i n g s of S i e b r i t z et a l . ( l 9 8 2 )
that
at
least
25
mg/L
of
readily
a n a e r o b i c zone i s necessary f o r any
removal
to
occur.
The
percent
comparable among the
various
expressed
of
in
terms
biodegradable
b i o l o g i c a l excess phosphorus
phosphorus
chemicals
readily
COD i n the
values
when
the
biodegradable
were
more
dosages were
COD ( F i g . 4 . 1 1 ) ,
r a t h e r than as t o t a l COD.
4.7
CARBON STORAGE AND
CONSUMPTION
B a c t e r i a r e s p o n s i b l e f o r the
removal
(hereafter
referred
c a p a b l e of s t o r i n g both
and carbon
under anaerobic
t o s t o r e carbon
as
polyphosphate
key t o the p r o l i f e r a t i o n of
ability
to
b i o l o g i c a l excess phosphorus
bio-P
under
b a c t e r i a ) are those
aerobic conditions
c o n d i t i o n s (Comeau et al.,1985). The
the
bio-P
bacteria
i n a s t r e s s e d environment,
is
l i k e l y the
where a e r o b i c
-96-
c
a
5 -
•a
D
a
o
0
z
a.
ti
0
a.
c
3 -
2
-
a
+
O
A
CL
1
-r
20
I
60
-
40
—I—
100
I
60
—I—
120
Acetate
Propionate
Butyrate
Glucose
140
160
Dosage in mg/L as COD in feed
Fig.4-10
Relationship
between
the
the
dosage,
expressed
chemical
aerobic
as
sludge
COD i n
percent
phosphorus
and
feed.
6
o
o
3
ao
i.
o
o
4
-
2
-
o
c
a.
D
0
JC
a.
c
e
u
i.
o
a
a
+
O
A
—r-
40
Fig.4.11
60
I
60
70
I
80
/"cetate
Propionate
Butyrate
Glucooo
90
RBD COD in feed (mg/L)
R e l a t i o n s h i p between the a e r o b i c s l u d g e p e r c e n t phosphorus and
t h e r e a d i l y b i o d e g r a d a b l e COD i n f e e d ( i n c l u d i n g t h e c h e m i c a l
addition).
-97metabolism
occur
is
not p o s s i b l e .
i n the a e r o b i c zone of a completely
process.
Therefore
the
organisms,
t h a t have i n t r a c e l l u l a r l y
over
Substrate l i m i t i n g c o n d i t i o n s o f t e n
mixed a c t i v a t e d
sludge
such as the bio-P b a c t e r i a ,
s t o r e d carbon have a d e f i n i t e
advantage
those t h a t r e l y on the membrane t r a n s p o r t of the s u b s t r a t e s .
It
i s f o r t h i s reason t h a t an anaerobic, a e r o b i c zone sequence i s
a
prerequiste
for
the
biological
p r o c e s s , as d e s c r i b e d i n S e c t i o n
No carbon
runs. Carbon
storage a n a l y s i s
propionate
(PHV)
runs.
was
PHB
and
done
PHB
was
the
most
(PHB)
during
significant
although
i n v o l v e d two
the a c e t a t e
some
carbon
PHV
storage
was
also
storage compounds,
glycogen.
negative
quantitative
sign
values
indicating
carbon
of
carbon
calculation
consumption
storage)
s e c t i o n were d e r i v e d i n the f o l l o w i n g
way,
presented
using
carbon
storage
compounds ( C ^ ^
n
s i n c e i t s c o n t r i b u t i o n was
= 0)
this
assumed t o
upon e n t e r i n g the
not taken
i n s i g n i f i c a n t as
in
(with
a mass b a l a n c e
( F i g . 4 . 1 2 ) . Feed, with i t s low s o l i d s , was
system. D a i l y wastage from the system was
4.6.
removal
made up of both p o l y -
poly-B-hydroxybutyrate
glucose runs
The
have no
during
and
compound d u r i n g the b u t y r a t e runs,
found. The
phosphorus
4.6.
storage (and consumption) was
B-hydroxyvalerate
the
excess
into
account,
discussed in Section
-98-
<
k
Fig.4-.12.
anox
Mass of carbon storage compounds entering and leaving each
individual reactor per unit influent flow. C indicates the
concentration of the carbon storage compounds. *It should
be noted that the return sludge has twice the aerobic carbon
concentration.
C consumption = Mass of C e n t e r i n g - Mass of C leaving
Carbon consumption
(per u n i t
i n f l u e n t flow) i n the anaerobic
r e a c t o r i s given by
(anoxic carbon) - 2x(anaerobic carbon)
Carbon consumption
reactor
(per u n i t
i n f l u e n t flow) i n the anoxic
i s given by
2x(anaerobic carbon) + 2x(aerobic carbon) - 3x(anoxic carbon)
Carbon consumption (per u n i t
reactor
i n f l u e n t flow) i n the aerobic
i s given by
2x(anoxic carbon) - 2x(aerobic carbon)
The v a r i o u s carbon balances f o r the d i f f e r e n t
runs are presented i n Tables 4.10 to 4.12.
experimental
-99-
T'able 4.10
Carbon Consumption
P r o p i o n a t e Dosage i n
Anaerobic Reactor
(mg COD/L)
Anaerobic
. PHB
PHV
25
20
15
10
.5
T a b l e 4.11
-15.5
-10.5
-8.5
-6.2
-3.4
Carbon Consumption
B u t y r a t e Dosage i n
Anaerobic Reactor
(mg COD/L)
30
25
20
15
10
-11.7
-4.5
-8.6
-9.8
-9.8
f o r P r o p i o n a t e Run
Carbon Consumption
(mg /L o f f e e d )
Anoxic
PHB
PHV
-9.7
-2.7
0.9
3.2
2.8
-3.1
-10.5
12.4
5.2
9.2
-7.0
-4.0
-1.8
-1.4
-1.6
25.2
13.2
7.6
3.0
0.6
14.8
15.0
-3.8
4.6
0.6
f o r B u t y r a t e Run
Carbon Consumption
( m g / L of feed)
Anaerobic
Anoxic
PHB
PHV
PHB
PHV
-27.7
-19.3
-11.3
-6.0
-4.5
Aerobic
PHB
PHV
-7.1
-4.7
-2.5
-0.2
0.5
4.6
1 .6
-0.8
-0.4
0.8
Aerobic
PHB
PHV
34.8
24.0
13.8
6.2
4.0
2.4
2.4
2.6
1 .8
0.8
-1 00-
4.7.1
ANAEROBIC
ZONE
In the a n a e r o b i c zone of the
removal process, polyphosphate
postulated
to
be
broken
f a c i l i t a t e transport
simple carbonaceous
acetate
and
membrane of
(as
down
and
have
acid
to
and
thereby
facilitating
an energy
Mino et a l . , 1 9 8 4 ) .
breakdown i s r e l e a s e d
be
transported
pH
acid),
illustrated
more
through the
across
ot
the c e l l
carbon storage (Comeau et
the polyphosphate breakdown
i n t o the s o l u t i o n
in
to
such as
degradation
gradient
resulting
4.6.1) s i n c e i t i s unusable by
These are
these s u b s t r a t e s ,
source f o r the carbon storage
Phosphate
order
storage of the a v a i l a b l e
propionic
a l . , 1 9 8 5 ) . I t i s a l s o suggested that
serves as
in
electrochemically neutral f o r -
i n an
polyphosphates r e - e s t a b l i s h e s the
membrane,
hydrolyzed
s u b s t r a t e s . Since
the organisms
phosphorus
r e s e r v e s of the bio-P b a c t e r i a are
and i n t r a c e l l u l a r
propionate,
acetic
b i o l o g i c a l excess
from
(Kulaev,1975;
the polyphosphate
(as d i s c u s s e d i n s e c t i o n
the c e l l
under
such c o n d i t i o n s .
terms of a simple b i o c h e m i c a l model i n
Fig.4.13.
A c c o r d i n g t o Comeau et a l . ( 1 9 8 7 ) , the p r o p o r t i o n of carbon
storage as
PHV would
exceed the storage as PHB when short c h a i n
f a t t y a c i d s c o n t a i n i n g an odd number of carbons
are
added
accumulated
containing
to
the
with
an
system,
the
even
whereas
addition
number
of
of
(e.g. propionate)
more PHB than PHV would be
short
carbon
chain
atoms
fatty
acids
(e.g. a c e t a t e ,
b u t y r a t e ) . The authors used batch experiments with pure s u b s t r a t e
-101-
T a b l e 4.12
Carbon Consumption
Glucose dosage i n
Anaerobic Reactor
(mg COD/L)
75
60
45
30
Fig.4.13.
f o r G l u c o s e Run
Carbon Consumption
(mg /L o f f e e d )
Anaerobic
.
Anoxic
PHB
Glyc.
PHB
Glyc.
-43.0
-31.9
-12.2
-7.6
108
68
29
13
12.8
5.5
-3.2
3.0
-24
-10
5
1
A s i m p l i f i e d model f o r anaerobic metabolism of bio-P
Adapted from Comeau e t a l . ( 1 9 8 5 ) .
Aerobic
PHB
Glyc
30.2
26. 4
15.4
4.6
-84
-58
-34
-14
bacteria.
-1 02-
additions
in
reaching
these
conclusions.
This
c u r r e n t study
confirmed these f i n d i n g s , except at lower propionate dosages.
To s t o r e 1 mole of PHV,
a c e t a t e should
1 mole of propionate and
be p r e s e n t . The a c e t a t e component can be obtained
e i t h e r by b r e a k i n g down some of the propionate
the
fermentation
of
the
raw
sewage.
propionate dosages, i t i s p o s s i b l e
molecules may
result
outnumber those
i n the f o r m a t i o n
thereby
experimental
runs w i t h lower
storage
very
good
at
number
lower
of a c e t a t e
in
can
a c e t a t e molecules among
more PHB
than PHV
propionate dosages,
followed
phosphorus
PHB,
storage
the
the
not
run, with carbon
was
was
d u r i n g the
as observed i n
follow
non-bio-P b a c t e r i a
the
due
as
PHV
during
and glucose
the
runs are
above d e s c r i b e d b i o c h e m i c a l
to the
a d d i t i o n of propionate
t r e n d of i n c r e a s i n g with
assumed
to
represent
increasing
the
carbon
the bio-P b a c t e r i a , f o r the propionate
carbon
storage
release (Fig.4.14).
bacteria)
with
respect to
as
addition, did
it
consumption
i n both b u t y r a t e
standard
release,
storage, with
and
agreement
model. Since PHV
run.
the
by some
resulting
propionate run and as PHB
and
Therefore,
from
study.
Carbon
in
that
molecules or
of p r o p i o n a t e . T h i s s i t u a t i o n
of PHB
themselves,
this
1 mole of
storage
compound
the expected
decreasing
The presence
t r e n d during most of the
with
of PHB
during propionate
i n c r e a s i n g phosphorus
c o u l d have been due
to
( s i n c e i t i s a common storage compound i n many
and c o u l d have r e s u l t e d from a c e t a t e
d e r i v e d from the
-103-
fermentation of
importance
as d i s c u s s e d
e a r l i e r . However, great
should not be g i v e n to these v a l u e s ,
analysis during
each
the feed,
steady
the propionate
state
run,
b u t y r a t e and glucose
As
a d d i t i o n was
compared
to
(if
COD)
the a c e t a t e
in
Section
4.6.1,
is
runs
least
during
addition,
are
glucose
for
the
d u r i n g the
f o r the same amount of
not
considered).
addition
same
chemical s u b s t r a t e
f o r p r o p i o n a t e and most f o r glucose
o b s e r v a t i o n that the anaerobic carbon
most
times
runs.
discussed
(as
carbon
done o n l y once f o r
three
anaerobic phosphorus r e l e a s e , the a d d i t i o n of
necessary
s i n c e the
and
This
s t o r a g e was
least
e x p l a i n s the
found to be the
during
propionate
amount of anaerobic phosphorus r e l e a s e
(Fig.4.15).
From the e a r l i e r d i s c u s s i o n s , i t may
role
of
the
anaerobic
zone
i n a b i o l o g i c a l excess
removal process emerges as the one
the bio-P
b a c t e r i a should
i n which the carbon
be maximized.
that t h i s c o u l d be ensured by the presence
s u b s t r a t e s i n the anaerobic
The
of simple
the
comparison
phosphorus
storage by
c l e a r l y shows
carbonaceous
storage values during
shows the importance
feed
that the
zone.
r e a d i l y biodegradable COD
i n c l u d i n g both
meaningful
Fig.4.16
c l o s e agreement among the carbon
v a r i o u s runs i n Fig.4.17
amount of
be concluded
and
the
purposes.
of
q u a n t i f y i n g the
e n t e r i n g the anaerobic zone,
chemical
( I t should
addition,
be
noted
f o r any
that the
-104-
Phosphorus Release (mg of P / L of feed)
.4..14..
R e l a t i o n s h i p between carbon storage and phosphorus r e l e a s e
the a n a e r o b i c zone f o r the p r o p i o n a t e r u n .
45
AO -
~
35
-
30
-
25
-
20
-
15
-
10
+
O
-1
T
3
-r5
-T
-
9
11
Propionate
Butyrate
Glucose
I
I
13
15
17
Phosphor L B release (mg of P / L of feed)
Fig.4-15.
R e l a t i o n s h i p between carbon storage and phosphorus r e l e a s e i n
the a n a e r o b i c zone. Carbon storage i s as PHV f o r propionate
a d d i t i o n and as PHB f o r b u t y r a t e and glucose a d d i t i o n s .
-10545
40
-
35
-
30
25
-
20
-
15
10
-
5
+
O
-
I
20
Propionate
Butyrate
Glucose
I
60
I
40
80
Dosage in anaerobic zone (mg COD/L)
4.16.
45
Anaerobic carbon storage v s . chemical dosage, as COD e n t e r i n g
the anaerobic zone. Carbon storage i s as PHV f o r propionate
a d d i t i o n and as PHB f o r b u t y r a t e and g l u c o s e a d d i t i o n s .
40
35
-
30
25
-
20
15
-
10
+
O
A
22
—T—
24
I
26
I
28
30
—T—
32
-r
34
-
-T
36
-
—I
38
-
Propionate
Butyrate
Glucose
I
40
I
42
RBD COO In anaerobic reactor (mg/L)
4.17.
Anaerobic carbon storage v s . r e a d i l y biodegradable COD (from
the feed and the chemical a d d i t i o n ) e n t e r i n g the anaerobic
zone. Carbon storage i s as PHV f o r p r o p i o n a t e a d d i t i o n and
as PHB f o r butyrate and g l u c o s e a d d i t i o n s .
-106-
a d d i t i o n of
1 mg
of glucose as COD, c o n t r i b u t e s only 0.27 mg as
r e a d i l y biodegradable COD, as d i s c u s s e d i n s e c t i o n 4.5). In other
words, i t means that
a n a e r o b i c zone
the r e a d i l y biodegradable COD e n t e r i n g the
i s an
excellent
indicating
parameter
f o r the
a n a e r o b i c carbon storage c a p a c i t y of the system.
4.7.2
AEROBIC ZONE
In
bio-P
a
biological
bacteria
polyphosphate,
have
when
excess
phosphorus removal
significant
they
enter
carbon
the
common f o r the exogenous carbonaceous
concentration
reserves
aerobic
In f a c t ,
data
from
an examination
a
(W.P.C.F.
et a l . ,
a t a low
of 100
s e t s of annual
v a r i e t y of m u n i c i p a l a c t i v a t e d
quality,
in
sludge
terms of
t y p i c a l completely
low c o n c e n t r a t i o n
equal to
liquor
mixed a c t i v a t e d
of a v a i l a b l e
a e r o b i c zone.
10 mg/L
or l e s s
19% of the
1977). These values a r e approximately the
same f o r the f i l t e r e d mixed
i n the
t o be
be 50 mg/L or l e s s 95% of the time; equal to 20 mg/L or
l e s s 50% of the time; and
time
low
zone. I t i s very
substrates
wastewater p l a n t s showed that the e f f l u e n t
BODg, t o
and
i n the a e r o b i c zone of a completely mixed a c t i v a t e d
sludge p r o c e s s .
performance
process, the
of
the
aerobic
zone
in a
sludge p r o c e s s , i n d i c a t i n g a
e x t e r n a l carbonaceous
substrates
Under these c o n d i t i o n s , the bio-P b a c t e r i a
degrade t h e i r carbon r e s e r v e s and s t o r e polyphosphate
by removing
s o l u b l e phosphate from the s o l u t i o n . T h e r e f o r e , phosphorus
i n the a e r o b i c zone i s accompanied
by s t o r e d carbon
uptake
consumption
-107-
(as i l l u s t r a t e d
The
results
this
of t h i s
by a
s i m p l i f i e d biochemical model).
study, shown
i n Fig.4.19, agreed w e l l with
theory.
The
s t o r e d carbon
t h e i r growth
of
i n Fig.4.18
this
i n the
cells
can
be
used
either for
or t o take up phosphorus from s o l u t i o n . The r e s u l t s
study
showed
consumption, the
that
for
the
a s s o c i a t e d phosphorus
same
amount
of
carbon
uptake had the f o l l o w i n g
d e c r e a s i n g order of e f f e c t .
propionate > b u t y r a t e >
T h i s means t h a t d u r i n g
of the
s t o r e d carbon
propionate a d d i t i o n ,
was used
than f o r growth, i n d i c a t i n g
the
biological
glucose
excess
a higher p r o p o r t i o n
f o r the phosphorus uptake,
rather
the e f f e c t i v e n e s s of p r o p i o n a t e i n
phosphorus
removal
over
butyrate
and
glucose.
4.7.3
ANOXIC ZONE
As d e s c r i b e d i n
present
in
the
section
absence
of
4.6.3,
any
when
preferred
a c e t a t e or p r o p i o n a t e ) , the bio-P d e n i t r i f i e r s
the
electron
acceptor,
consume
i s believed
the
to
be
sufficient
NO
is
s u b s t r a t e (such as
c o u l d use
NO
x
as
s t o r e d carbon and take up
phosphorus.
This
the
case
during
the
experimental
runs with low p r o p i o n a t e and b u t y r a t e dosages, s i n c e
-108-
Fig.4-.18.
A s i m p l i f i e d model f o r aerobic metabolism of bio-P b a c t e r i a .
Adapted from Comeau et a l . ( l 9 8 5 ) .
40
Phosphorus uptake (mg of P / L of feed)
F i g . 4.19. Relationship between carbon consumption and phosphorus uptake
i n the aerobic zone. Carbon storage i s as PHV f o r propionate
addition and as PHB f o r butyrate and glucose additions.
-109-
the p o s s i b i l i t y
of t h e s e
substrates bleeding
i s remote. When a p r e f e r r e d s u b s t r a t e
into the anoxic
zone
i s present
under t h e a n o x i c
(or a e r o b i c ) c o n d i t i o n s , t h e p r e f e r r e d s u b s t r a t e
i s u t i l i z e d and
s t o r e d as
i s accomplished
carbon reserves
by b r e a k i n g
to
those
by t h e o r g a n i s m s ; t h i s
down p o l y p h o s p h a t e s a n d r e l e a s i n g p h o s p h o r u s ,
observed
in
the
opposing r e a c t i o n s can take
of b o t h
anaerobic
place
zone. Although
simultaneously
was
substrates
reported
disappear
case d u r i n g
the
runs
b u t y r a t e , as d i s c u s s e d
However,
to
predominate
(Gerber
et
with
higher
i n Section
the presence
( i n conjunction
anaerobiosis prevails
behaviour
(Gerber
dosages
of
glucose
not give
carbon
et
i n p l a c e o f t h e above
rise
storage)
a l . , 1987).
t o phosphorus
unless
s t o r e d c a r b o n was consumed
during
experimental
t h e 45 mg COD/L r u n . D u r i n g
this
complete
anaerobiosis
r e l e a s e and c a r b o n
in
the
was
clearly
associated
4.12) where
runs,
except
r u n , w i t h t h e a b s e n c e o f a n y NO
anoxic
existed,
zone,
thereby
x
t h e p o s s i b i l t y of
promoting
phosphorus
storage.
Whatever t h e c a s e m i g h t
study
a l l
strict
This explains the
a d d i t i o n (Table
l o w ORP (-176 mV)
preferred
p r o p i o n a t e and
the glucose
and
observed during
the
4.6.3.
of
with
until
the release
a l . , 1 9 8 7 ) . T h i s m i g h t be t h e
d i s c u s s e d p r e f e r r e d s u b s t r a t e s does
release
t h e s e two
i n the presence
p r e f e r r e d s u b s t r a t e s and e l e c t r o n a c c e p t o r s ,
reaction
similar
showed t h a t
with
be, the
i n the anoxic
carbon
storage
r e s u l t s of
this
current
zone, phosphorus
release
(similar
t o the anaerobic
-1 10-
zone) and the phosphorus
consumption
4.7.4
uptake was
a s s o c i a t e d with
the carbon
( s i m i l a r t o the a e r o b i c zone) ( F i g . 4 . 2 0 ) .
CARBON STORAGE AND CONSUMPTION AS GLYCOGEN
One
of
the
reasons
f o r s e l e c t i n g glucose as the added
c h e m i c a l s u b s t r a t e f o r the f i n a l run
was to
i n v e s t i g a t e whether
the glucose would be s t o r e d and consumed p r i m a r i l y as glycogen or
whether i t would f i r s t
be reduced
f o l l o w the pathway of
with e a r l i e r
to a c e t a t e
PHB storage
(or p r o p i o n a t e ) and
and consumption, as observed
runs.
Fukase et a l . ( l 9 8 2 ) , while u s i n g s y n t h e t i c wastewater w i t h
g l u c o s e and
was
peptone as the only BOD sources, found
s t o r e d under anaerobic
using
acclimated
biomass.
a c h i e v e d a t the time
the
solution.
conditions
The
when the
However,
soon
during
maximum
batch
glycogen
s o l u b l e glucose
glycogen
experiments
storage
was
disappeared
from
a f t e r the a e r o b i c c o n d i t i o n s were
i n i t i a t e d , the glycogen c o n c e n t r a t i o n s t a r t e d t o
but a t
that
increase again,
a slower r a t e than d u r i n g the anaerobic c o n d i t i o n s i n the
presence
of s o l u b l e g l u c o s e .
No e x p l a n a t i o n
was given
for this
behaviour.
Mino
experiments
et
a l . (1987),
with s y n t h e t i c feed
p r o p i o n a t e , glucose
and
in
studies
using
batch
(containing acetic
acid,
sodium
peptone),
their
found that the i n t r a c e l l u l a r
-111-
carbohydrates are
consumed under anaerobic c o n d i t i o n s and s t o r e d
under a e r o b i c c o n d i t i o n s . The
of
glycogen
to
the
authors a t t r i b u t e
decrease
the consumption
i n the i n t r a c e l l u l a r
carbohydrate
c o n c e n t r a t i o n under a n a e r o b i c c o n d i t i o n s .
The
contradictory
s t u d i e s may
be due
t o the
f e e d . The presence of
glucose i s
behaviour
compounds
two
(such
as
acetate)
other than
be
Since a c e t a t e c o u l d be formed i n the anaerobic zone due
to
later.
u s i n g sewage
by Mino et a l . (1987) appears
the c o n d i t i o n s
of t h i s
The
results
glycogen was
consumption
t o be more l o g i c a l
i t was
confirmed
study.
of the g l u c o s e runs i n t h i s
study showed that
s t o r e d i n the a e r o b i c zone w h i l e phosphorus
(Fig.4.21).
The
increased
with
Substantial
of
increasing
glycogen
glucose
PHB
were
s y n t h e s i z e d i n the a n a e r o b i c zone
and
consumed
PHB
amounts
amounts
of
The
to expect under
consumed i n the anaerobic zone w h i l e phosphorus
r e l e a s e d , and was
up
as feed, the behaviour r e p o r t e d
c u r r e n t study. In f a c t ,
by the glucose runs of t h i s
zone.
these
d i f f e r e n c e i n the composition of the
b e l i e v e d t o have p l a y e d an important
f e r m e n t a t i o n , when
4.12).
during
r o l e , as w i l l
discussed
taken
observed
followed
storage
was
was
and
dosages (Table
also
found
in
to
be
the a e r o b i c
the standard p a t t e r n observed with the
other runs, as d i s c u s s e d i n the p r e v i o u s s e c t i o n s .
-1 1 2 14
-
7
-
6
-
3
-
1
1
3
6
7
Phosphorus uptake (mg of P / L of feed)
Fig.
4-.20.
R e l a t i o n s h i p between c a r b o n s t o r a g e a n d p h o s p h o r u s u p t a k e
t h e a n o x i c z o n e . C a r b o n s t o r a g e i s a s PHV f o r p r o p i o n a t e
a d d i t i o n a n d a s PHB f o r b u t y r a t e a n d g l u c o s e a d d i t i o n s .
20
15
-20
-
H
-100
1
1
-60
1
1
1
-20
1
1
T
20
60
1
r—
100
Glycogen consumption (mg/L of feed)
Fig.4..21.
R e l a t i o n s h i p between
the
consumption i n v a r i o u s
phosphorus uptake and glycogen
zones
for
glucose
run.
in
-113-
An
of
almost
linear
intracellular
glycogen
depleted
increase
in
is
a
based
similar
on
glycogen
terms
the
total
of glycogen
that
sludge
microbial
Assuming
organisms
sewage
acetyl-CoA,
added
a s shown
is
then
would
zone,
glucose,
^
ATP r e q u i r e d f o r t h i s
of
consumed
very
well
e t a l . d 988),
rather
than the
t o about
total
the
0.48 i n
of Fukase e t
sugars
stored in
could
be
explained
using
be f o r m e d
by t h e f e r m e n t a t i v e
by
fermenting
i t
could
form)
either
be f i r s t
converted
to
below:
—
>
Acetyl-CoA
conversion
could
(+ ? )
±
be
polyphosphate,
supplied
NADH
^
NAD
—
+
_
from the
and t h e A c e t y l - C o A
t o PHB.
Acetyl-CoA
t h e raw
ADP
the accumulated
converted
Somiya
convert
of the
(in abbreviated
CH^COOH
hydrolysis
42%
acetate
ATP
The
by
compares
for
as follows:
that
the
This
on t h e f i n d i n g s
behaviour
in the anaerobic
or
based
value
glycogen.
discussed
pathways
would
intracellular
of glycogen
consumption
value
approximately
above
obtained
t h e amounts
of
mean
mass
basis.
carbohydrate
This
between
estimated
o f PHB p e r u n i t
consumption,
was a s
The
t h e amounts
and
o f 0.2,
consumption.
al.(1982)
stored
0.41 on a w e i g h t
value
the
existed
( F i g . 4 . 2 2 ) . The
t h e amount
approximately
with
PHB
relationship
(C H,0 )
-114-
According
required
of
for
(TCA)
cycle,
cannot
to
cycle.
in general,
succinate
maintain
Mino
does
n o t work
its activity
supplied
through
Glycogen
for
c a n be
pyruvic
acid,
(1987)
of
under
from
of the stored
to
since
i n t h e TCA c y c l e ,
conditions.
o f PHB
t h e TCA
conditions
t h e enzymes
Instead,
acetyl-CoA
i s
glycogen.
pyruvic
pathway.
i t i s converted
the tricarboxylic
indicated that
anaerobic
converted
t h e NADH
b y o x i d i z i n g some
anaerobic
the synthesis
(EMP)
(1984),
through
under
the consumption
Embden-Meyerhof-Parnas
of
et a l .
one
Comeau
i s produced
dioxide
But
necessary
and
o f PHB
carbon
dehydrogenase,
NADH
(1985)
the synthesis
the acetyl-CoA
acid
the
t o Matsuo
acid
Through
through the
further
to acetyl-CoA
oxidation
generating
carbon
dioxide.
ADP
(C H
6
1 0
0 )
5
NAD
These
proposed
storage
of
In
removal
the
PHB s t o r e d
source
not only
glycogen
under
NADH
explain
zone
the
phosphorus
observed
of the
consumed
t o Mino
in
release,
the anaerobic
anaerobic
under
biological
and
conditions
aerobic
excess
glycogen
e t a l . (1987),
f o r the metabolism
synthesis
( + CO,, )
PHB
zone
the glucose run.
PHB was
According
Acetyl-CoA
consumption
aerobic
process,
(Fig.4.22).
the
during
<
+
pathways
and glycogen
the system
ATP
>
n
was
this
was u s e d
of the c e l l s ,
conditions.
phosphorus
synthesized
indicated
that
as the carbon
but a l s o
They
also
for
the
argued
-115-
that " i t
sludge
is
to
essential
convert
for
the
the
anaerobic/aerobic a c c l i m a t i z e d
s t o r e d PHB
phase so as to maintain
the
to glycogen
required l e v e l
consumption d u r i n g the subsequent anaerobic
provide a sound
argument.,
since
a n t i c i p a t e the anaerobic/aerobic
it
d u r i n g the a e r o b i c
of glycogen
f o r the
phase". T h i s does not
implies
that
the biomass
sequence. A p o s s i b l e e x p l a n a t i o n
i s provided below.
The
conditions
PHB
consumption and
might
d i f f e r e n t groups
excellent
have
of
been
two
organisms.
correlation
storage during
glycogen
independent
However,
between
the e n t i r e
synthesis
the PHB
glucose run
the
under a e r o b i c
events
in
existence
consumption and
two
of an
glycogen
(Fig.4.22), suggests
p o s s i b i l i t y of a s i n g l e group of organisms being
the
involved.
Under a e r o b i c c o n d i t i o n s , energy i s produced by p r o c e s s i n g
the PHB
v i a the TCA
c y c l e , generating carbon d i o x i d e . Malate,
of the intermediate products
by
either
the
"malic
phosphoenol pyruvate,
y i e l d s glucose
of the TCA
enzyme"
or
c y c l e , can be
malate
finally
transformed
dehydrogenase
which on f u r t h e r biochemical
6-phosphate and
one
glycogen,
to
tranformation
as
shown ( i n
abbreviated form) below:
Acetyl-CoA
PHB
NADH,
—
Malate
Glycogen
Glucose
6-phosphate
Phosphoenol
pyruvate
C0
2
-116-
However,
i f
a
second
group
chemoautotrophs) a r e a l s o i n v o l v e d ,
using the carbon
first
dioxide
of
glycogen
(released during
group of o r g a n i s m s ) through
organisms
can
(such
as
be s y n t h e s i z e d
t h e TCA c y c l e o f t h e
the Calvin cycle,
as i n d i c a t e d
below:
PHB
(CALVIN
Glycogen -*
Glucose 6-phosphate
As o b s e r v e d
to
discussed
i n section
either
4.6.3.
No
uptake
storage
In
was
zone, as
zone, phosphorus
and glycogen
consumption
a s s o c i a t e d w i t h PHB c o n s u m p t i o n a n d
a n a l y s i s was
done
f o r acetate,propionate or
P r e l i m i n a r y i n v e s t i g a t i o n s by N i c h o l l s a n d O s b o r n
typical
waste
removal.
However, t h e p r e s e n c e
(such
b i o l o g i c a l excess
investigated.
the aerobic
the anoxic
PHB s t o r a g e
(1979) i n d i c a t e d t h a t no g l y c o g e n
compounds
or
( F i g s . 4 . 2 0 and 4.21).
glycogen
butyrate runs.
—
the anaerobic
r e l e a s e was a c c o m p a n i e d by
glycogen
^
w i t h t h e o t h e r r u n s , t h e a n o x i c zone b e h a v e d
similarly
while phosphorus
CYCLE)
treatment
as
accumulation
plants
achieving
of o t h e r
carbohydrates)
phosphorus removal
was p r e s e n t
excess
secondary
and
process
their
i n two
phosphorus
carbon
storage
role
i n the
should
be f u r t h e r
-1 17-
4.8
OVERALL PHOSPHORUS REMOVAL
Although
the phosphorus
uptake
( s e c t i o n 4.6.2) g i v e s an i n d i c a t i o n
phosphorus removal
this
section
biological
with
excess
by the
i n the a e r o b i c r e a c t o r
of
the degree
system, i t i s d i s c u s s e d s e p a r a t e l y i n
respect
to
phosphorus
the v a r i o u s
removal
and
i s c o n s i d e r e d as
expressed
as
mg
of
the phosphorus
phosphorus
aspects
process.
between the t o t a l phosphorus c o n c e n t r a t i o n s of
effluent
of expected
of the
The d i f f e r e n c e
the feed
and the
removal of the system
per
litre
of
feed. The
v a r i a t i o n of the t o t a l phosphorus i n the feed was between 3.9 and
4.5
mg/L d u r i n g the a c e t a t e , propionate
the
variation
during
the glucose
mg/L. The range of the t o t a l
f e e d a r e a l s o presented
and b u t y r a t e
run was between 3.6 and 3.9
phosphorus
concentrations
chemical
o v e r a l l phosphorus removal, with r e s p e c t
substrates
as COD
i n feed
o v e r a l l removal i n c r e a s e d with
s u b s t r a t e . For
the same
increasing
chemical
t o the added
dosage
of
the added
s u b s t r a t e dosage, expressed as
the f o l l o w i n g d e c r e a s i n g
o f e f f e c t among the v a r i o u s chemical
a c e t a t e > propionate
experienced.
(Fig.4.23), showed that the
COD, t h e o v e r a l l phosphorus removal had
order
of the
i n the v a r i o u s p l o t s i n order t o i d e n t i f y
the runs where phosphorus l i m i t i n g c o n d i t i o n s were
The
runs while
s u b s t r a t e s added.
> b u t y r a t e > glucose
However, a c c o r d i n g t o Jones e t a l . (1985), the d i f f e r e n c e s
-11840
Dosoge in mg/L as COD In feed
Fig.4.23-
The o v e r a l l phosphorus removal of the system v s . the chemical
a d d i t i o n , expressed as COD i n f e e d .
-119-
i n the o v e r a l l phosphorus removal with sodium a c e t a t e and b u t y r i c
a c i d was
not s i g n i f i c a n t ,
c o n t r a r y to
the o b s e r v a t i o n s made i n
t h i s c u r r e n t study with sodium acetate and sodium
difference
might
be
the
result
of
a c c l i m a t i z a t i o n p e r i o d of 2 weeks provided
s u b s t r a t e runs
acetate
d u r i n g the
was
(1986)
virtually
insufficient
between the d i f f e r e n t
by Jones et a l . , (1985), i f the
non-acclimated
reported
identical
b u t y r a t e . T h i s study was
biomass.
performance
of
that
conducted using
It
should
continuous
the
for acetate,
be
phosphorus removal i n t h i s study was
the
the
This
run had succeeded the butyrate run.
Gerber e t a l .
uptake
study
butyrate.
net phosphorus
propionate
batch experiments
noted
that
r e l a t i v e l y low
flow
systems
and
with
the net
compared t o
under comparable
conditions.
These r e s u l t s i n d i c a t e that
between
the
acclimated
of the
behaviours
of
biomasses. A more
e f f e c t i v e n e s s of
significant differences exist
sufficiently
acclimated
meaningful and
reliable
various substrates,
and
comparison
with regard t o the
b i o l o g i c a l excess phosphorus removal, can only be a r r i v e d
using a
s u f f i c i e n t l y acclimated
non-
a t , by
biomass f o r the s u b s t r a t e under
i n v e s t i g a t i o n , and f o r the o p e r a t i n g c o n d i t i o n s .
The
r e s u l t s from t h i s c u r r e n t study,
conditions
effectiveness
with
an
acclimated
of a s p e c i f i c
under continuous
biomass,
suggest
that
substrate on the b i o l o g i c a l
flow
the
excess
-120-
phosphorus removal
i s some d i r e c t
function
of the
s i m p l i c i t y of
that s u b s t r a t e molecule.
The
various
overall
chemical
biodegradable COD
phosphorus
substrate
removal
of
the
system
additions
in
terms
f o r the
of
readily
i n the feed (Fig.4.24) were i n c l o s e agreement,
i n d i c a t i n g the use of t h i s parameter to optimize the system. Once
the
requirement
of
the
readily
biodegradable COD
enter the anaerobic zone t o e f f e c t
phosphorus removal
carbon
COD
c a l c u l a t e d using
the
same
a d d i t i o n of
available
in
the r e s u l t s
readily
( t o supplement
the
raw
obtained in
biodegradable
short c h a i n
overall
volatile
fatty
normal
of COD
removal,
metabolic
a c t i v a t e d sludge
phosphorus
requirement
is
for
systems (U.S. EPA,
removal
biodegradable COD
was
r e a d i l y biodegradable
reactor,
taking
i n the
exceeded approximately
anaerobic
it
However,
content i n feed, the
acid salts
outperformed
be c l a s s i f i e d
mg/L
as excess
g e n e r a l l y accepted t o be the
the
cell
growth
in
1976). On t h i s b a s i s ,
place
whenever
the
such
excess
readily
f e e d ( i n c l u d i n g the chemical a d d i t i o n )
50
COD
due
i t s e l f ) can be
i n excess of 1.0-1.5
removed, can
since
feed
readily
removal.
phosphorus removal
f o r every 200 mg/L
phosphorus
of excess
the
S e c t i o n 4.5.
COD
glucose i n b i o l o g i c a l excess phosphorus
Any
degree
i s e s t a b l i s h e d , the amount of e x t e r n a l simple
s u b s t r a t e a d d i t i o n s necessary
biodegradable
for
the d e s i r e d
that should
to
mg/L
of
(Fig.4.24).
approximately
the
1:1
This
represents a
25 mg/L
e n t e r i n g the
anoxic/anaerobic
recycle.
-121-
Therefore,
takes
i t c o u l d be
place
i f the
anaerobic
zone
excellent
agreement
concluded
that
excess
readily biodegradable
exceeds
approximately
with
the
removal
COD a v a i l a b l e i n t h e
25
earlier
phosphorus
mg/L.
This
is in
f i n d i n g s of S i e b r i t z e t
al.(l982).
Although
various
phosphorus removal
mM/L,
of r e a d i l y
propionate
and
in
mg/L
as
butyrate
present
equal
in
dosages
t h e same
surprising
s u b s t r a t e s . But f o r
f o r the
the
same d o s a g e s
volatile
since
overall
fatty
biodegradable
COD
acids
t h e s e compounds, when
t h e same mg/L a s a c i d c o n c e n t r a t i o n s , p r o v i d e d
readily
earlier
forms (mg/L a s a c i d ,
additions,
their corresponding
( F i g . 4 . 2 5 ) . T h i s was n o t
overall
COD p r o v e d t o be t h e b e s t f o r
the d i f f e r e n t
p h o s p h o r u s r e m o v a l was r e l a t i v e l y
expressed
the
investigated, expressing
biodegradable
c o m p a r i s o n p u r p o s e s among
acetate,
between
and d o s a g e s i n d i f f e r e n t
mM o f c a r b o n / L e t c . ) were
i n terms
any
correlations
concentrations,
almost
as d e s c r i b e d
i n s e c t i o n 4.5 ( F i g . 4 . 2 ) .
The
overall
with increasing
supported
addition
an
phosphorus
anaerobic
earlier
to being
the
release to
the excess
degree
phosphorus
of
removal
phosphorus
observation
first
to
by
link
of the system
release
Barnard
the
phosphorus removal,
release
during
increased
(Fig.4.26).
(1976)
anaerobic
who, i n
phosphorus
also reported
the
This
that the
anaerobic
determined the o v e r a l l phosphorus removal of the system.
phase
-1225
40
60
Fig.4.24..
The o v e r a l l
60
70
80
90
RBD COD in feed (mg/L)
phosphorus
biodegradable
5
0.5
removal
COD i n f e e d
of
the
system
( i n c l u d i n g the
vs.
chemical
the
readily
addition).
1
-1
H
0
Fig.4.25.
1
1
20
1
1
40
1
1
60
1
1
80
|
1
100
1
1
120
1
1
140
Dosage in m g / L In feed
The o v e r a l l p h o s p h o r u s r e m o v a l o f t h e s y s t e m v s . t h e c h e m i c a l
d o s a g e , e x p r e s s e d a s mg/L i n f e e d . D o s a g e s o f a c e t a t e ,
propionate
and b u t y r a t e are expressed as t h e i r c o r r e s p o n d i n g a c i d s .
-123-
The
overall
phosphorus
removal
d i r e c t l y with the anaerobic carbon
the
recent
paramount
(Comeau
theory
that
importance
et
the
to
al.,1984;
the
system
varied
storage ( F i g . 4 . 2 7 ) , c o n f i r m i n g
anaerobic
biological
excess
storage
i s of
phosphorus removal
however the
anaerobic phosphorus r e l e a s e and the anaerobic carbon
storage are
the carbon
was done
and
carbon
Kristensen,1985);
closely linked
Arvin
of
( s e c t i o n 4.7.1).
The r e s u l t s a l s o i n d i c a t e d that
s t o r a g e was l e a s t with propionate
d u r i n g the
(no
carbon
a c e t a t e run) and most w i t h g l u c o s e , f o r the
same o v e r a l l phosphorus removal of the system. The
used
and
carbon
the
additional
storage
as
PHB,
might
be
the
4.7.4),
production
through
reasons
p r o p i o n a t e were
phosphorus removal.
the
higher
carbon
consumption
of b u t y r a t e ,
T h i s i s b e l i e v e d to be the
storages
compared t o
obtained
with
primary
cause f o r
b u t y r a t e than
significant differences
d u r i n g the
attempting
to compare the r e s u l t s from t h i s run with the o t h e r t h r e e
runs
with
with
removal.
the f o l l o w i n g should be c o n s i d e r e d while
During the i n i t i a l
storage
r e q u i r e d t o provide the same degree of
Since t h e r e were some
(i)
f o r the
(section
f o r t h i s h i g h e r carbon
propionate f o r the same degree of phosphorus
glucose run,
l a r g e dosages
of NADH n e c e s s a r y
glycogen
d u r i n g the g l u c o s e r u n . Higher dosages
those of
analysis
acetate,
runs.
p r o p i o n a t e and
b u t y r a t e , the t o t a l COD of the feed ( i n c l u d i n g the added chemical
s u b s t r a t e ) v a r i e d between 254 and
281
mg/L
whereas
d u r i n g the
glucose run, i t v a r i e d between 274 and 342 mg/L due t o the higher
-124-
4.5
-
0.5
-j
7
0
Fig.4.27.
1
1
10
1
1
20
1
1
30
1
1
40
1
50
Anoorobk: carbon storage (mg/L of feed)
R e l a t i o n s h i p between the o v e r a l l p h o s p h o r u s r e m o v a l o f t h e system
a n d t h e a n a e r o b i c c a r b o n s t o r a g e . C a r b o n s t o r a g e i s a s PHV f o r
p r o p i o n a t e a d d i t i o n a n d a s PHB f o r b u t y r a t e a n d g l u c o s e a d d i t i o n s .
-125-
glucose
dosages
necessary
removal. As
a result,
the glucose
run, c r e a t i n g
mixed
liquor
(ii)
The
total
compared
were
excess
removed by the system during
mass (as
i n d i c a t e d by the
s o l i d s c o n c e n t r a t i o n s data) and
for
the
normal
metabolic
Glucose
relatively
and 4.5
runs
suspected
to
purposes,
low
i n the feed during
( v a r i e d between
3.6
( e s p e c i a l l y the
have
and
3.9
butyrate
mg/L).
had
60 and
75 mg
COD/L runs)
a s i g n i f i c a n t l y d i f f e r e n t type of
as
dicussed in
compared to the a c e t a t e , p r o p i o n a t e and b u t y r a t e
s e c t i o n 4.6.3)
runs.
OVERALL NITROGEN REMOVAL
Although
not
thereby
runs.
organisms ( f a c u l t a t i v e anaerobes,
4.9
phosphorus
to the runs with a c e t a t e , p r o p i o n a t e and
( v a r i e d between 3.9
(iii)
good
phosphorus c o n c e n t r a t i o n
the glucose run was
mg/L)
was
more c e l l
phosphorus
compared to the other
induce
more COD
suspended
r e q u i r i n g more
to
the
specifically
o v e r a l l nitrogen
process c o n f i g u r a t i o n used
designed
to
optimize
i n t h i s study
nitrogen
removal,
removal of the system i n c r e a s e d with
was
the
increasing
dosages of chemical s u b s t r a t e s , with the e x c e p t i o n of the glucose
runs
(Fig.4.28).
Overall nitrogen
removal percentages
i n t h i s s e c t i o n were c a l c u l a t e d as f o l l o w s :
presented
-126-
% N i t r o g e n removal = ( f e e d T K N ) - ( e f f l u e n t T K N ) - ( e f f l u e n t NO jxlOO
(feed TKN)
x
The
feed
throughout
NO
was
x
not
considered
since
it
was
negligible
the study.
The
two
most
probable
reasons
f o r the i n c r e a s e i n the
n i t r o g e n removal e f f i c i e n c y with i n c r e a s i n g chemical
dosages are
as f o l l o w s :
(i)
The
simple
addition to
being
chemical
the
excess phosphorus
substrates
desired
used i n t h i s study, i n
substrates
f o r the b i o l o g i c a l
removal p r o c e s s , a r e a l s o p r e f e r r e d s u b s t r a t e s
f o r b i o l o g i c a l n i t r o g e n removal. The d e n i t r i f i c a t i o n
these s u b s t r a t e s
complex o r g a n i c
Gerber
et
a r e much
s u b s t r a t e s present
a l . (1986),
MLSS.h) f o r a c e t a t e ,
concentration
higher than
of
the
200
mg
those achieved with more
i n the
butyrate
COD/L)
level
pattern
in
of
the
440
mg/L).
overall
increasing readily
f u n c t i o n of the s i m p l i c i t y
feed, except
(ii)
The
incremental
Fig.4.29
nitrogen
biodegradable
of
rates
and
( i n mg N/g
glucose
(at a
a r e 2.51, 1.68, 2.13 and 0.92
r e s p e c t i v e l y , compared t o 0.64 f o r s e t t l e d
COD
sewage. A c c o r d i n g to
denitrification
propionate,
r a t e s using
sewage ( d i l u t e d
shows a g e n e r a l i n c r e a s i n g
removal
COD
the
to a
of
content
substrates
the
system with
(which
i s a direct
present)
i n the
f o r the g l u c o s e run.
decrease
in
the
influent
i n c r e a s e of the added chemical
TKN/COD
ratio
by the
s u b s t r a t e s might have
-127-
72
70
•
+
O
A
68
66
Acetate
Propionate
Butyrate
GIUCODO
64
62
60
o
>
o
58
C
56
E
c
s
o
0
z
54
52
50
48
46
I
20
40
60
—T—
80
—1—
100
r
I
120
- i
140
r
160
Dosage in m g / L as COD
Fig.
4.28.
O v e r a l l n i t r o g e n removal e f f i c i e n c y
d o s a g e , e x p r e s s e d a s COD i n f e e d .
72
of
the
system
vs.
the
chemical
70
•
+
6
68
Acetate
Propionate
Butyrate
66
64
62
60
o
>
o
58
£
56
o
54
E
c
«
L.
52
50
48
46
40
Fig.4-29.
I
50
I
60
—T—
70
—r80
RBD COD In feed (mg/L)
O v e r a l l n i t r o g e n removal e f f i c i e n c y of the system v s . t h e
r e a d i l y b i o d e g r a d a b l e COD i n f e e d ( i n c l u d i n g t h e c h e m i c a l
addition).
90
-128-
provided
improved
n i t r o g e n removal
valid
characteristics
(Table 4.13). Although
f o r most
completely
influent
parts
falls
of
apart
the
biological
t h i s e x p l a n a t i o n appears
acetate
f o r the
for
and
butyrate
propionate
runs, i t
run, due
v a r i a t i o n of the TKN c o n c e n t r a t i o n s i n the d i f f e r e n t
t o the
batches of
feed used.
The
relatively
lower o v e r a l l
a c e t a t e run, compared t o the
believed to
be due
n i t r o g e n removal d u r i n g the
propionate
and
butyrate
runs, i s
t o the r e l a t i v e l y high TKN/COD r a t i o s of t h e
feed d u r i n g t h a t run (Table 4.13).
The
run was
o v e r a l l n i t r o g e n removal
pattern
the glucose
unique among the v a r i o u s runs of t h i s study. The removal
was q u i t e low a t higher dosage runs (75
anaerobic
COD/L
during
in
zone),
and 60
mg COD/L
i n the
while the runs with lower dosages (45 and 30 mg
anaerobic
zone)
followed
the
standard
pattern
e s t a b l i s h e d by the other runs. T h i s was b e l i e v e d t o be due to the
higher glucose
concentrations,
population
facultative
to
denitrifiers,
accompanied by
as
described
symptoms of
favouring
anaerobes
in
at
section
a
shift
the
i n organism
expense
4.6.3.
The
of t r u e
s h i f t was
f e r m e n t a t i v e c o n d i t i o n s , such as low
ORP, f o r m a t i o n of s u b s t a n t i a l gas bubbles and gluey
appearance.
-129-
Table 4.13
O v e r a l l N i t r o g e n Removal f o r A l l Runs
Chemical Dosage i n
Anaerobic Reactor
(mg COD/L)
Percent N i t r o g e n Removal
of the System
(%)
Ratio
of
TKN/COD
RUN 1 : ACETATE
30
25
20
15
10
5
57.9
56.5
52.9
52.2
51.4
50.9
0.0971
0.1007
0.1015
0.1102
0.1131
0.1121
66.9
68.7
64.1
62.4
58.3
0.0942
0.0970
0.0928
0.0927
0.0898
66.9
66.7
65.7
64.3
61.5
0.0864
0.0802
0.0885
0.0837
0.0897
51.3
59.9
63.2
62.0
0.0564
0.0735
0.0761
0.0785
RUN 2 : PROPIONATE
25
20
15
10
5
RUN 3 : BUTYRATE
30
25
20
15
10
RUN 3 : GLUCOSE
75
60
45
30
-1 30-
4.10
EXPERIMENTAL RUN
WITH COMBINED ACETATE AND
T h i s p a r t i c u l a r c o m b i n e d run
accidental,
run w i t h
d o s a g e was
r e d u c e d t o 10 mg/L
a new
batch
of
concentration
steady
f e e d change
dropped
was
biodegradable
mg/L). The
and
less
1.4
this
various parameters
the
zone),
the
zone)
and
phosphorus
from t h e
two
days
previous
after
a decrease i n the
the
added
the e f f l u e n t phosphorus
an
increase
the
feed
for this
i n the
(up f r o m
readily
59
run are g i v e n
in
to
71
Tables
4.14.
results
All
the phosphorus r e l e a s e s ,
e t c . compared
study,
Although
it
the
well with
only
was
in
carbon
terms
known
excellent
later.
been b e l i e v a b l e
readily biodegradable
those
of
batch
excess
COD
storages,
the
readily
readily
of
phosphorus
t h i s was
not
feed.
removals
the o t h e r
runs
biodegradable
biodegradable
feed
i f not
i n the
overall
observed during
t h a t the
in this particular
the
w o u l d have
compound or compounds c a u s i n g
weeks
drop i n
by
mg/L
within
t h e r e was
c o n c e n t r a t i o n of
t h e measurement of
causing
mg/L,
sudden
for
content
t h a n 0.1
accompanied
None o f t h e s e
this
e f f l u e n t ortho
was
of
i n the anaerobic
s t a r t e d . The
to
termination
i n the a n a e r o b i c
(as COD,
made. A l t h o u g h
was
COD
( a s COD,
of a b o u t
dosage,
concentration
4.2
15 mg/L
f e e d was
state value
propionate
(acetate plus propionate)
r a t h e r than i n t e n t i o n a l . A f t e r the
propionate
PROPIONATE
was
identified
COD.
substrate
unusually
removal,
of
high,
the
until
exact
two
-131-
Table 4.14
Phosphorus Uptake, Carbon Consumption and N i t r o g e n
Removal d u r i n g the Run with
Combined A c e t a t e and
Propionate
Parameter
Values
Phosphorus Uptake
(mg of P/L of feed)
Anaerobic
Anoxic
Aerobic
-16.40
-3.00
22.70
Carbon Consumption
(mg/L of feed)
as
PHV:
Anaerobic
Anoxic
Aerobic
-9.1
3.9
5.2
as PHB:
Anaerobic
Anoxic
Aerobic
Percent n i t r o g e n removal
-12.2
-2.6
14.8
73.8
-1 32-
The raw
feed samples f o r v o l a t i l e f a t t y a c i d measurements
were u s u a l l y preserved and analysed approximately
during t h i s
study. The v o l a t i l e f a t t y a c i d r e s u l t s f o r the feed,
d u r i n g t h i s run, showed the presence
a c e t a t e . The
c o n c e n t r a t i o n of
Knowing
biodegradable
this
of u n u s u a l l y
the a c e t a t e
14.7 mg/L as COD compared to almost
study.
every two weeks
information,
i n the
raw feed was
none d u r i n g the
r e s t of t h i s
an
estimate
COD i n the feed was made as
r e s u l t s obtained
h i g h l e v e l s of
of the r e a d i l y
f o l l o w s , based
on the
i n s e c t i o n 4.5.
Since 1 mg COD/L of a c e t a t e p r o v i d e s 0.80 mg/L of
r e a d i l y biodegradable
the
COD, the c o n t r i b u t i o n from
14.7 mg COD/L of a c e t a t e present
i n the feed
=
14.7x0.80
= 11.8 mg/L
S i n c e 1 mg COD/L of propionate p r o v i d e s 0.75 mg/L
of r e a d i l y biodegradable
COD,the c o n t r i b u t i o n from
the 20 mg COD/L of propionate added t o the feed
= 20x0.75
= 15.0 mg/L
Since approximately
raw sewage
18% of the t o t a l COD i n the
(= 239 mg/L f o r t h i s batch of feed) i s
r e a d i l y b i o d e g r a d a b l e , c o n t r i b u t i o n from the feed
= 239x0.18
= 4 3.0 mg/L
Therefore, t o t a l
This
compared
r e a d i l y biodegradable
very
well
with
COD = 69.8 mg/L
the measured v a l u e of 71
mg/L, showing the v a l i d i t y of the r e s u l t s obtained
i n s e c t i o n 4.5
-133-
in e s t i m a t i n g the r e a d i l y biodegradable COD of the sewage used i n
t h i s study. T h i s method of e s t i m a t i o n i s p o s s i b l e only i f most of
the r e a d i l y
chain
b i o d e g r a d a b i l i t y of
volatile
fatty
acids,
the feed r e s u l t s from the short
a
common
occurrence
where
the
c o l l e c t i o n systems p r o v i d e long d e t e n t i o n times.
The
been found,
than
the
importance
source
of the e x t r a b i o d e g r a d a b i l i t y would have never
i f i t had r e s u l t e d
volatile
and
fatty
the
biodegradable COD
from any
acids.
This
necessity
of the
of
simple compound other
clearly
i l l u s t r a t e s the
measuring
the
readily
sewages to c h a r a c t e r i z e them, i n order
to optimize the b i o l o g i c a l excess phosphorus removal p r o c e s s .
4.11
LAG RESPONSE DURING DOSAGE
The experimental
TRANSITIONS
runs, with each chemical s u b s t r a t e d u r i n g
t h i s study, were s t a r t e d with the h i g h e s t dosage and
reduced
an
i n s t e p s , except
interesting
f o r the glucose run. With t h i s sequence,
phenomenon
was
observed
propionate and b u t y r a t e runs. Whenever there
the
dosage
of
the
subsequently
added
chemical
during
was a
the
acetate,
reduction i n
s u b s t r a t e , there was a l a g
p e r i o d f o r the e f f l u e n t phosphorus c o n c e n t r a t i o n t o i n c r e a s e to a
level
corresponding
words, the
occur f o r
the
higher
to
biological
a short
dosage
that
excess
p e r i o d of
before
of
the
reduced
phosphorus
dosage. In other
removal
continued t o
time a t the l e v e l corresponding t o
decreasing
to
a
lower
level,
-1 34-
corresponding
longer
(4
to the new
to 5
reduced
days) d u r i n g
dosage.
the smaller dosages (Figures.4.30,
order
to
lag
period
4.31
investigate
the t r a n s i t i o n s between
and 4.32).
and e x p l a i n t h i s l a g response,
carbon storage a n a l y s i s was done d u r i n g the t r a n s i t i o n
the
butyrate
S i m i l a r to
was
runs,
in
addition
the s i t u a t i o n
(as
PHB)
during
consumption was
the
anaerobic,
the steady
phases of
state periods.
s t a t e c o n d i t i o n s , carbon
zone and consumed i n the a e r o b i c
transition
periods.
This
storage
zone
and
accompanied by phosphorus r e l e a s e and phosphorus
uptake r e s p e c t i v e l y .
the
to
under steady
s t o r e d i n the anaerobic
was
the t r a n s i t i o n s between the h i g h e r
dosages and s h o r t e r (1 to 2 days) d u r i n g
In
This
The p r o f i l e s
anoxic
and
of the
aerobic
PHB c o n c e n t r a t i o n s i n
zones
during
the
entire
butyrate run are shown i n Fig.4.33.
As soon
concentrations
new
steady
until
the
low
in
the
chemical
a l l reactors
state concentrations.
aerobic
lower steady
same
as
PHB
was
s t a r t e d to
However,
concentrations
reduced,
decrease
it
was
phosphorus
concentration,
to
c o n c e n t r a t i o n s reached
resulting
the higher
the new
the PHB
towards the
noticed that
were reduced
s t a t e values, the e f f l u e n t c o n t i n u e d
phosphorus removal corresponding
a e r o b i c PHB
dosage
t o the new
to m a i n t a i n
i n higher
the
excess
dosage. Once the
steady
state values,
the e f f l u e n t phosphorus c o n c e n t r a t i o n s t a r t e d t o i n c r e a s e towards
the
new
higher
steady
d e t e r i o r a t i o n of the excess
state
values,
phosphorus removal
resulting
(Fig.4.30).
in
the
-1 3 5 4
Fig.4-.31.
Days
P r o f i l e of the e f f l u e n t o r t h o phosphorus f o r the p r o p i o n a t e r u n .
A r r o w s i n d i c a t e t h e d a y s on w h i c h t h e d o s a g e was c h a n g e d . * The
raw sewage d u r i n g t h i s r u n h a d a n a c e t a t e c o n c e n t r a t i o n o f 14-.7
mg/L a s COD.
-1363.5
E
£
a
«
3
-
2.5
-
2
-
1.5
-
£
a
0
£
0.5
120
Days
Fig.4.32.
P r o f i l e o f the e f f l u e n t ortho phosphorus f o r the b u t y r a t e
A r r o w s i n d i c a t e t h e d a y s on w h i c h t h e d o s a g e was c h a n g e d .
run.
Anaerobic sone
-i
\
at
£
5>
E
c
•
u
c
o
o
O
I
ft.
120
Days
Fig.4.33.
Profile
butyrate
changed.
of
stored
PHB i n t h e
r u n . Arrows i n d i c a t e
various
the
zones
days
of the
system
on w h i c h t h e
for
dosage
the
was
-137-
At
t h i s p o i n t , the reason f o r t h i s behaviour
was b e l i e v e d
to be as f o l l o w s :
Although
the
PHB
synthesis
during
the a n a e r o b i c phase
s t a r t e d to decrease immediately due t o the dosage
r e d u c t i o n , the
organisms had the l u x u r y of u s i n g the e x t r a PHB a l r e a d y s t o r e d i n
them. The a c c e s s i b i l i t y of
could
have
helped
to
these e x t r a
maintain
the
through h i g h e r carbon consumption,
the
higher
degree of
i n t e r n a l carbon r e s e r v e s
same uptake of phosphorus
l e a d i n g to the c o n t i n u a t i o n of
excess phosphorus
removal. Once t h i s
a v a i l a b l e PHB r e s e r v e i s d e p l e t e d , the carbon consumption
to decrease
towards
reduced phosphorus
the
extra
started
lower steady s t a t e v a l u e s , r e s u l t i n g i n
uptake and c a u s i n g the lower excess
phosphorus
removal by the system.
However,
the
phosphorus
transition
p e r i o d s d i d not
phosphorus
uptake
support
the
another
reduction
in
mechanism
must
organisms were a b l e t o maintain
the
lower phosphorus
carbon balances d u r i n g the
this
hypothesis.
and the carbon consumption
immediately a f t e r
Therefore,
and
the
exist
same
Both the
s t a r t e d to decrease
dosage
(Table 4.15).
through
removal,
uptake and carbon consumption.
which
the
d e s p i t e the
Further research
i s necessary t o f u l l y e x p l a i n and understand t h i s behaviour.
N e v e r t h e l e s s , one of the reasons f o r the absence
behaviour,
during
the
shadowing o f t h i s e f f e c t
glucose
of t h i s
run, might be due to the over-
by those of the p o p u l a t i o n
s h i f t of the
-1 38-
Table 4.15
Phosphorus and Carbon Balances f o r the Butyrate Run
d u r i n g the Dosage T r a n s i t i o n s
Number of Days
a f t e r the
Dosage Change
Phosphorus Uptake
(mg of P/L of feed)
Carbon Consumption
(mg of PHB/L of feed)
Anaero
Anox
Aero
Anaero
Anox
Aero
30 mg COD/L
steady s t a t e
-12.30
-2.70
19.00
-27.7
-7.1
34.8
1
3
5
-10.30
-8.90
-8.80
-2.70
-2.90
-2.10
17.00
15.80
14.60
-22.8
-20.5
-19.4
-7.2
-6.7
-5.8
30.0
27.2
25.2
25 mg COD/L
steady s t a t e
-8.80
-1.50
14.10
-19.3
-4.7
24.0
1
3
5
-7.20
-6.40
-5.80
-1.50
-1.10
-0.60
12.50
11.30
9.50
-16.1
-13.7
-11.4
-3.9
-3.7
-3.4
20.0
17.4
14.8
20 mg COD/L
steady s t a t e
-5.45
-0.75
8.85
-11.3
-2.5
13.8
1
3
5
-4.55
-3.35
-2.15
-0.25
-0.05
-0.25
7.45
5.85
4.65
-8.8
-6.8
-6.3
-2.2
-1.2
0.3
11.0
8.0
6.0
15 mg COD/L
steady s t a t e
-1.60
-0.10
4.10
-6.0
-0.2
6.2
1
3
-1.10
-0.70
0.70
1.40
2.50
1.10
-4.8
-4.6
-1.0
-0.2
5.8
4.8
10 mg COD/L
steady s t a t e
-0.20
1.00
0.65
-4.5
0.5
4.0
-139-
organisms, as d i s c u s s e d e a r l i e r
i n s e c t i o n 4.6.3.
On the c o n t r a r y , when the dosage of the
was
increased,
the
immediately without
T h i s was
the
excess
phosphorus
the presence
of any
simple
substrates
removal
increased
significant
observed d u r i n g the 10 mg COD/L propionate
sewage
discussed
used
in
had
unusually
s e c t i o n 4.9,
high
levels
of
lag period.
run i n which
acetate.
As
when the c o n c e n t r a t i o n of the simple
s u b s t r a t e s e n t e r i n g the system
increased
from
15
propionate
propionate
plus
14.7 mg COD/L of
acetate,
less
to
10 mg
COD/L of
the e f f l u e n t ortho phosphorus dropped
than
0.1
mg/L
within
two
mg
from 1.4
COD/L of
mg/L t o
days, i n d i c a t i n g an immediate
improvement i n the excess phosphorus removal.
The
b e n e f i t s of
removal f o r a short
simple
the
higher
excess phosphorus
duration a f t e r a reduction
carbon s u b s t r a t e s and
excess phosphorus
continued
the
immediate
i n dosage of the
improvement
of the
removal e f f i c i e n c y a f t e r an i n c r e a s e i n dosage
c o u l d be q u i t e s u b s t a n t i a l .
Some of
the p o s s i b l e
advantages of
t h i s behaviour a r e l i s t e d below:
(i)
The
considerable
and
(ii)
biological
short-term
excess phosphorus removal process
stability;
i.e.
phosphorus l o a d i n g s need not balance
The
addition
b i o l o g i c a l excess
of
extra
phosphorus
shows a
the p r e f e r r e d s u b s t r a t e
on a r e a l - t i m e b a s i s .
simple carbon s u b s t r a t e s i n the
removal
treatment
plants
may be
-1 40-
optimized
dosages
using
cyclic
resulting
further research
loading
i n reduced
i s necessary
chemical
However,
fashion
without any i l l - e f f e c t s
the p r o c e s s .
(iii)
There
i s an emerging
excess phosphorus
removal
t r e n d i n the d e s i g n of the b i o l o g i c a l
systems
t o i n c o r p o r a t e primary sludge
fermenters ahead of the anaerobic zones
design of the o v e r a l l
fermenter
process t r a i n
process may
set-up f o r two or
in
be accomplished
the f u l l - s c a l e
treatment p l a n t
by p r o v i d i n g
more p r o c e s s t r a i n s , with each
r e c e i v i n g the fermenter e f f l u e n t
The type of behaviour
observed
t o generate the necessary
s u b s t r a t e s (Rabinowitz and Oldham, 1985). A b e t t e r
simple carbon
one
consumption.
t o i n v e s t i g a t e as to how long the
system c o u l d be s t r e s s e d i n t h i s
to
p a t t e r n s with higher and lower
dicussed in
in turns.
t h i s section
was a l s o
b i o l o g i c a l excess phosphorus
i n Kelowna,
B r i t i s h Columbia.
removal
When the primary
sludge t h i c k e n e r
supernatant ( c o n t a i n i n g simple p r e f e r r e d carbon
s u b s t r a t e s ) flow
was
phosphorus removal
deterioration
in
i n the
from
one
to
a v a i l a b l e improved
which
almost
only 2
module
to
the o t h e r ,
f i r s t module d i d not show any s i g n of
f o r another 3 days, whereas
the module
reported that
changed
the
thickener
immediately
days were
the phosphorus
supernatant
removal
was made
(Oldham, 1985). I t was a l s o
r e q u i r e d t o r e - e s t a b l i s h a good
phosphorus removal, a f t e r
13 days of upset i n a b i o l o g i c a l
phosphorus removal
(Manning and I r v i n e ,
system
1985).
excess
-141-
CHAPTER FIVE
CONCLUSIONS AND
5.1
RECOMMENDATIONS
CONCLUSIONS
Significant
aspects
of
the
progress has been
biological
made i n
excess
phosphorus
d u r i n g the course of t h i s r e s e a r c h . The
study
have
contributed
mechanism of
helped
in
the
towards
excess
assessing
be summarized
removal
results
process
obtained in t h i s
b e t t e r u n d e r s t a n d i n g of the
removal
suitability
b i o l o g i c a l excess phosphorus
r e s e a r c h may
a
phosphorus
the
u n d e r s t a n d i n g many
removal.
of
The
under three
a
process
given
and have
sewage f o r
conclusions
different
of
this
c a t a g o r i e s as
follows:
5.1.1
CONCLUSIONS DIRECTLY RELATED TO OBJECTIVES
(1)
The
technique
quantification
sewage, was
proposed
of r e a d i l y
proved to
technique cannot
for
the
biodegradable s u b s t r a t e s a v a i l a b l e
in a
be e f f e c t i v e
be used
short
(in
Section
and
reliable.
3.2)
However, t h i s
as a f i e l d t e s t , s i n c e i t r e q u i r e s the
o p e r a t i o n of
a
sludge
age,
completely-mixed,
sludge system
under continuous flow c o n d i t i o n s .
activated
-1 42-
(2)
Almost a l l the d i f f e r e n t
phosphorus
aerobic
removal p r o c e s s (such as anaerobic phosphorus
phosphorus
uptake,
overall
storage and carbon consumption)
carbon
elements of the b i o l o g i c a l excess
substrates
expressed i n terms
used
of
in
phosphorus
release,
removal, carbon
compared w e l l among the d i f f e r e n t
this
readily
study when t h e i r dosages were
biodegradable
COD,
r a t h e r than
t o t a l COD, moles,moles
of carbon e t c . . In other words, r e l a t i v e l y
the
the excess
same behaviour of
observed,
readily
with
biodegradable
e n t e r i n g the
all
different
the
phosphorus
carbon
removal
elements
mechanism
system was
r e a d i l y b i o d e g r a d a b l e COD)
used as the u n i t
mentioned
removal
s u b s t r a t e a d d i t i o n s , when the
s u b s t r a t e s (as
system were
above
phosphorus
of
of measurement. A l s o ,
the
biological
excess
i n c r e a s e d with i n c r e a s i n g
readily
biodegradable s u b s t r a t e s e n t e r i n g the system.
T h e r e f o r e , i t may be
given sewage
for biological
concluded
the
sewage; t h i s
biodegradable
COD
c h a r a c t e r i z a t i o n of
phosphorus
the
excess phosphorus
d i r e c t l y with the c o n c e n t r a t i o n of the
of
that
readily
efficacy
of a
removal w i l l vary
biodegradable COD
i n d i c a t e s the v a l i d i t y of u s i n g the r e a d i l y
as
a
major
parameter
for
a
general
sewage w i t h respect to the b i o l o g i c a l excess
removal.
T h i s c o n c l u s i o n was r e i n f o r c e d when the sewage used d u r i n g
one of the runs i n t h i s study c o n t a i n e d abnormally h i g h l e v e l s of
acetate.
The
biodegradable
increase
COD
in
the
concentration
of the feed was the f i r s t
of
the
readily
indication
of t h i s
-1 4 3 -
situation
and
explained
phosphorus
removal e f f i c i e n c y . T h e r e f o r e , the measurement
r e a d i l y biodegradable
the
observed
process,
i n c r e a s e i n the
COD e n t e r i n g the system e i t h e r
feed or through the fermenter e f f l u e n t ,
to e f f e c t i v e l y
drastic
of the
through the
i f p r e s e n t , c o u l d be used
optimize the b i o l o g i c a l excess phosphorus
especially
with
regard
to
the
removal
requirements
of the
e x t e r n a l supplementary simple carbon sources n e c e s s a r y t o p r o v i d e
the d e s i r e d degree of phosphorus
5.1.2
removal.
OTHER CONCLUSIONS RELATED TO READILY BIODEGRADABLE
COMPOUNDS IN GENERAL
(1)
A direct
uptake
in
anaerobic
release
l i n e a r r e l a t i o n s h i p e x i s t e d between
the
zone.
promoted
resulting
aerobic
In
zone
other
higher
and the phosphorus
words,
aerobic
i n good o v e r a l l phosphorus
relationship
between
the
t h e phosphorus
aerobic
higher
r e l e a s e i n the
a n a e r o b i c phosphorus
phosphorus uptake and thereby
removal
by the
phosphorus
system. The
uptake
and the
2
anaerobic phosphorus
r e l e a s e was found t o be as
being 0.970 (where R i s the c o r r e l a t i o n
P uptake
T h i s equation
first
term
coefficient).
(mg/L) = 1.21 + 1.701 x P r e l e a s e (mg/L)
of best f i t i s s c i e n t i f i c a l l y d e f e n s i b l e , w i t h the
r e p r e s e n t i n g the
t o t a l biomass
f o l l o w s , with R
i n the system,
b a s i c metabolic
requirement of the
w h i l e the c o e f f i c i e n t
of the second
-1 44-
term i s
determined by the degree to which i n f l u e n t
preferred substrate
is
limiting
the
process,
phosphorus or
as
discussed in
S e c t i o n 4.6.2.
(2)
The
presence of r e a d i l y
e n t e r i n g the a n a e r o b i c
removal
system
aerobic
phosphorus
removal.
minimum of 25 mg/L
anaerobic
zone
zone
ensured
subsequent
biodegradable
of
a
good
uptake,
results
of r e a d i l y
f o r any
biological
anaerobic
phosphorus
The
A definite
and
the
direct
phosphorus
of
phosphorus
this
feed
excess phosphorus
and
biodegradable
release,
overall
study
COD
excess
showed t h a t a
should enter
the
s i g n i f i c a n t b i o l o g i c a l excess phosphorus
removal to take p l a c e , as d i s c u s s e d
(3)
s u b s t r a t e s i n the
link
e x i s t e d between
release
process. This observation
in Section
during
supports
4.8.
the carbon
the anaerobic
the
kinetic
storage
phase of
model
the
f o r the
b i o l o g i c a l excess phosphorus removal mechanism proposed by Comeau
et a l . ( 1 9 8 5 ) , as
phosphorus
discussed
occurs
to
Section
facilitate
carbon s u b s t r a t e s
(such as
c e l l wall
s t o r e d as
to be
in
the
carbon
the
PHB
or
consumption
PHV
by
l i n k was
and
The
transport
acetate, propionate
motive f o r c e i n the c e l l . A s i m i l a r
between
4.7.1.
the
r e l e a s e of
of the
simple
etc.) across
maintaining
also
a
the
proton
found to e x i s t
uptake of phosphorus
d u r i n g the a e r o b i c phase ( S e c t i o n 4.7.2).
(4)
Whenever there was
simple
carbon
a
substrates,
reduction in
there
was
the dosage
a
lag
of the added
period
before a
-1 45-
deterioration
i n phosphorus removal o c c u r r e d .
In other words, the
s t e a d y - s t a t e b i o l o g i c a l excess phosphorus removal c o n t i n u e d
short p e r i o d
of time
at the same higher
l e v e l before
to the new lower l e v e l , r e f l e c t i n g the reduced
T h i s l a g p e r i o d was
longer
between higher dosages and
transitions
between
smaller
(1
to
dosages.
2
decreasing
s u b s t r a t e dosage.
(4 to 5 days) d u r i n g
shorter
the t r a n s i t i o n s
days)
d u r i n g the
As a c o r o l l a r y , when the
dosage of the simple carbon s u b s t r a t e s was i n c r e a s e d ,
phosphorus removal
any
significant
behaviour
i n c r e a s e d immediately without
lag period,
could
as d i s c u s s e d
successfully
be
fora
the excess
the presence of
in Section
4.11. T h i s
used i n o p t i m i z i n g
biological
excess phosphorus removal systems.
5.1.3
OTHER CONCLUSIONS RELATED TO SPECIFIC READILY
BIODEGRADABLE COMPOUNDS
(1)
The degree
inverse
function
of
biodegradability
of
the
complexity
was
of
molecule. For the same dosage as COD, the
the f o l l o w i n g decreasing
appeared
the
to
added
be some
substrate
v a r i o u s s u b s t r a t e s had
order of e f f e c t i v e n e s s i n terms of t h e i r
degree of b i o d e g r a d a b i l i t y .
a c e t a t e > propionate
> butyrate > g l u c o s e
Oxygen uptake r a t e r e s u l t s showed that 1 mg
p r o v i d e d approximately
of a c e t a t e
0.80 mg of r e a d i l y biodegradable
(as COD)
COD.
The
-1 46-
corresponding
0.75,
(2)
values
f o r p r o p i o n a t e , butyrate and glucose were
0.45 and 0.27 r e s p e c t i v e l y .
Different
simple
carbon
substrates
exhibited
a
range of
e f f e c t i v e n e s s i n phosphorus r e l e a s e d u r i n g the anaerobic phase of
the b i o l o g i c a l excess phosphorus
removal
process
when
COD was
used as the u n i t of measurement. The anaerobic phosphorus r e l e a s e
appeared t o
be
molecule
the added
of
a
direct
function
of
s u b s t r a t e . For
v a r i o u s s u b s t r a t e s had the
the
simplicity
of the
the same
COD dosage, the
following decreasing
order of e f f e c t
with r e s p e c t t o anaerobic phosphorus r e l e a s e .
a c e t a t e , propionate > b u t y r a t e > glucose
(3)
Carbon was s t o r e d i n t r a c e l l u l a r l y d u r i n g the a n a e r o b i c phase
and consumed d u r i n g the a e r o b i c phase. The primary carbon
compound was
carbon
poly-B-hydroxybutyrate
s u b s t r a t e was
for the
butyrate
a d d i t i o n of
simple carbon
and
(PHB)
simple
p o l y - B - h y d r o x y v a l e r a t e (PHV)
p r o p i o n a t e . The
substrate involved
when the added
storage
two
a d d i t i o n of glucose as the
carbon
storage compounds,
PHB and g l y c o g e n .
Contrary to
in the a n a e r o b i c
the
glucose
what happened with PHB, glycogen was consumed
zone and s y n t h e s i z e d i n the a e r o b i c zone, during
runs,
supporting
the o b s e r v a t i o n s made by Mino et
a l . ( 198.7). I t i s s p e c u l a t e d that glycogen
consumption d u r i n g the
anaerobic phase p r o v i d e d the NADH r e q u i r e d f o r the PHB s y n t h e s i s ,
-1
47-
through Embden-Meyerhof-Parnas (EMP)
dicussed
in
Section
4.7.4.
e x i s t e d between the PHB
with the
PHB
(4)
s y n t h e s i s and
estimated mean
o x i d a t i o n , as
linear
relationship
the glycogen
consumption,
value f o r the i n c r e a s e i n the amount of
0.41,
on a
basis.
For the same amount of chemical
COD)
the
overall
d e c r e a s i n g order
this indicates
for
excellent
and
per u n i t of glycogen consumed being approximately
weight
as
An
pathway
phosphorus
of e f f e c t
the degree
s u b s t r a t e dosage
removal
among the
had
following
v a r i o u s s u b s t r a t e s added;
of e f f e c t i v e n e s s
b i o l o g i c a l excess phosphorus
the
(expressed
of these s u b s t r a t e s
removal.
a c e t a t e > propionate > b u t y r a t e > g l u c o s e
(5)
The presence
of glucose i n the b i o l o g i c a l excess
removal system promoted
zone.
These
bacteria
fermentative
conditions
probably
( f a c u l t a t i v e anaerobes)
denitrifiers".
Thus,
a c t i v e i n the anoxic
phosphorus uptake,
the
enriched
at
"bio-P
zone, c a u s i n g
the
a
h i g h e r than
the anoxic
biocommunity
expense
denitrifiers"
in
of
of
"non-bio-P
might have been
expected
anoxic
as d i c u s s e d i n S e c t i o n 4.6.3. T h i s o b s e r v a t i o n
i n d i c a t e s that a sub-population
denitrifiers.
conditions
phosphorus
of the
bio-P b a c t e r i a
are a l s o
-1 48-
5.2
RECOMMENDATIONS
Further
research
work
i s recommended
i n the f o l l o w i n g
areas.
(1)
Development of a simpler and p r e f e r a b l y a chemical
technique
f o r the measurement of the r e a d i l y biodegradable COD of the f e e d ,
s i n c e the method used
i n t h i s study r e q u i r e d
the o p e r a t i o n
of a
short sludge age continuous a c t i v a t e d sludge system.
(2)
The r o l e
of secondary
carbon
PHB and PHV) such as glycogen
t h i s study
should be
to the presence
storage compounds (other than
found d u r i n g
the glucose
runs o f
i n v e s t i g a t e d . A t t e n t i o n should be given t o
of carbohydrates
in
feed, t h e i r
storage i n c e l l
mass and t h e i r d i r e c t or i n d i r e c t c o n t r i b u t i o n s t o the b i o l o g i c a l
excess phosphorus removal mechanism.
(3)
A s e r i e s of batch t e s t s c o u l d be performed
fate
excess
of
the added
phosphorus
simple
removal
l a b e l i n g techniques.
more than one storage
carbon
s u b s t r a t e s i n the b i o l o g i c a l
process,
T h i s would
compound
t o determine t h e
using
radioactive isotope
be of p a r t i c u l a r
i s involved
in
i n t e r e s t , when
the phosphorus
removal mechanism.
(4)
The
behaviour
removal f o r a s h o r t
simple
carbon
of
the c o n t i n u e d higher excess
period after
s u b s t r a t e s and the
phosphorus
a reduction
i n the dosage o f
immediate
improvement of the
-1 49-
phosphorus
further
could
after
an
investigated. A better
be
incorporated
removal
removal
very
important,
increase
i n the dosage should be
understanding
since
it
could
of
this
behaviour
successfully
be
i n t o the designs of the b i o l o g i c a l excess phosphorus
systems to optimize them.
-1 50-
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P a r i s , Sept.,
1984.
W e n t z e l l , M.C., L o t t e r , L . H . , Loewenthal, R.E. and M a r a i s , G.v.R.
(1986), "Metabolic Behaviour of A c i n e t o b a c t e r spp. i n Enhanced
Biological
Phosphorus
Removal - A B i o c h e m i c a l Model", Water
S.A., 12, 4, 209-224.
W i l d e r e r , P.A., Jones, W.L. and Dau, U. (1987),
"Competition i n
Denitrification
Systems
Affecting
Reduction
Rates
and
Accumulation of N i t r i t e " , Wat. Res., 21, 2, 239-245.
W.P.C.F. (1977), "Wastewater Treatment
P l a n t D e s i g n " , Manual of
P r a c t i c e No.8, Water P o l l u t i o n C o n t r o l F e d e r a t i o n , Washington,
D.C.
- 1 5 7 -
APPENDIX A1
DEVELOPMENT OF THE METHOD USED FOR THE
DETERMINATION OF THE READILY BIODEGRADABLE COD
-1 58-
A1.1
INTRODUCTION
This gives a
method used
COD
brief
f o r the
outline
of
the
development
d e t e r m i n a t i o n of
the r e a d i l y
laboratory scale
systems,
of the
biodegradable
of the f e e d .
Two
schematic
identical
diagram
in
Fig.Al.l(a),
were
as
shown by the
operated a f t e r
having
decided to use the s t e p change i n the oxygen uptake
r a t e , at the
termination
the
of
the
biodegradable COD
A1.2
feed,
as
the
basis
for
readily
measurement.
SYSTEM START-UP
The
two continuous
systems were
flow
completely mixed
operated a t a sludge age of 6 days. The
in the s t a r t - u p of these u n i t s was
of the p i l o t
a c t v a t e d sludge
o b t a i n e d from the a e r o b i c zone
s c a l e b i o l o g i c a l excess phosphorus removal
p l a n t s i t u a t e d a t the U n i v e r s i t y of B r i t i s h Columbia
p i l o t plant
was
the
for
sludge
c o n s i d e r e d to
sludge used
treatment
campus. The
o p e r a t i n g at a sludge age of 20 days a t the time
these
units
be a c h i e v e d
the c o n c e n t r a t i o n
of the
showed a p p r o x i m a t e l y
were
taken.
Steady
state
when the d a i l y oxygen uptake
a e r o b i c mixed
steady v a l u e s .
was
r a t e and
l i q u o r suspended s o l i d s
-159-
A1.3
INITIAL OPERATION
During
the p e r i o d of steady
nitrification
l e v e l s were
in
systems
around 20-25
between 20 and
was
both
30 mg/L.
mg/L
No
was
rate
high.
with
The
at
the
nitrate
values
varying
i n f l u e n t TKN
feed
of ammonia
systems.
to the high degree of n i t r i f i c a t i o n ,
drop,
aerobic
s i g n i f i c a n t concentration
found in the e f f l u e n t s of the
Due
s t a t e o p e r a t i o n , the degree of
termination,
not
the oxygen uptake
only
included
c e s s a t i o n of oxygen requirement f o r the metabolism of the
biodegradable
oxygen
COD
for
nitrification.
oxygen uptake r a t e drops than those
A1.4
s u b s t r a t e s alone,
T h i s r e s u l t e d i n higher
expected due
i n the
to the
readily
feed.
SUPPRESSION OF UNWANTED NITRIFICATION
The
estimates
of
c o n c e n t r a t i o n of the feed
expected, due
Since t h i s
the
readily
of the feed, but a l s o i n c l u d e d the c e s s a t i o n of
requirement
biodegradable
the
readily
to the
biodegradable
readily
using these
presence of
s i t u a t i o n was
taken to suppress the
the
systems were
h i g h degree of
unacceptable
COD
of the
for
higher
COD
than
nitrification.
the d e t e r m i n a t i o n
of
feed, v a r i o u s steps were
n i t r i f i c a t i o n . These
in the f o l l o w i n g s e c t i o n s .
biodegradable
are b r i e f l y
outlined
-1 60-
A1.4.1
REDUCTION OF SLUDGE AGE
The sludge
age was
reduced i n
steps from
6 days to 2.5
days w i t h no apparent change i n the degree of n i t r i f i c a t i o n .
at
the
short sludge
aerobic
of
i n d i c a t i n g a high degree
nitrification.
nitrifying
to
2.5 days, the n i t r a t e l e v e l s i n the
r e a c t o r averaged around 20 mg/L,
S i n c e the
the
age of
Even
systems were
initially
p o p u l a t i o n of micro-organisms (from the p i l o t p l a n t a t
U n i v e r s i t y of B r i t i s h
restart
Columbia), i t was d e c i d e d at t h i s stage
the systems using a
mixed l i q u o r
p o p u l a t i o n , o b t a i n e d from the f u l l
Squamish,
A1.4.2
s t a r t e d - u p u s i n g a good
British
with low
nitrifying
s c a l e sewage teatment p l a n t i n
Columbia.
USE OF LOW
NITRIFYING MIXED LIQUOR
The two systems were r e s t a r t e d , at a sludge age of 3 days,
using
the
aerobic
plant
in
Squamish,
mixed
liquor
British
from the f u l l
Columbia.
The
s c a l e treatment
aerobic
c o n c e n t r a t i o n of the p l a n t , at the time the sludge was
around 5
nitrate
taken, was
mg/L.
However, the n i t r a t e l e v e l s of the a e r o b i c r e a c t o r s of the
laboratory
days,
systems
started
reached a steady
to
i n c r e a s e s t e a d i l y and w i t h i n
c o n c e n t r a t i o n of approximately
20
30
mg/L.
-161-
Following
t h i s unsuccessful
nitrification
in
the
attempt
systems,
to
control
i t was
the
decided
degree of
to
use
a
nitrification inhibitor.
A1.4.3
ADDITION OF NITRIFICATION INHIBITOR
2 chloro
i n h i b i t o r to
- 6 ( t r i c h l o r o methyl)
control n i t r i f i c a t i o n .
standard BOD t e s t , a t a
p y r i d i n e was
This
concentration
used as the
i s widely used i n the
of
10
mg/L,
to i n h i b i t
nitrification.
The
nitrification
i n h i b i t o r was
added t o
systems i n four d i f f e r e n t ways and the r e s u l t s
Table
A1.1.
During
the
period
of
this
one of the two
are summarized i n
addition,
system II
(without the a d d i t i o n of i n h i b i t o r ) c o n s i s t e n t l y
had high degree
of n i t r i f i c a t i o n
the a d d i t i o n of
compared t o
the system I (with
i n h i b i t o r ) . As expected, i t was a l s o noted that
rate
of
the
system
decreased
with
the oxygen uptake
increased
a d d i t i o n of the
inhibitor.
A1.4.4
REDUCTION OF HYDRAULIC RETENTION TIME (HRT)
The
results
presented
in
e f f e c t i v e c o n t r o l of n i t r i f i c a t i o n
a continuous
addition
Table
could
of the i n h i b i t o r ,
A1.1
only
show
that
the
be achieved through
a t c o n c e n t r a t i o n s above
-1 62-
Table Al.1.
Summary o f t h e i n h i b i t o r
effects
on t h e p r o c e s s
i n t h e measurement o f r e a d i l y b i o d e g r a d a b l e
CONCENTRATION OF
INHIBITOR
DURATION OF
used
COD
RESULTS
ADDITION
I.
10 mg/1 with respect
Instantaneous
No change
Instantaneous
N i t r a t e l e v e l dropped from 22 mg/1
to reactor volume
II.
100 mg/1 with respect
to 8 mg/1 the next day; gradually
to reactor volume
increased to around 20 mg/1 i n 12
days
III.
100 mg/1 with respect
2 days
to l e s s than 0.5 mg/1
to i n f l u e n t
75 mg/1 with respect
N i t r a t e l e v e l reduced from 21 mg/1
2 days
Less than 0.5 mg/1
2 days
Less than 0.5 mg/1
2 days
Less than 0.5 mg/1
to i n f l u e n t
50 mg/1 with respect
to i n f l u e n t
25 mg/1 with respect
to i n f l u e n t
10 mg/1 with respect
to i n f l u e n t
20 days
Slowly increased to 16 mg/1 i n 20
days and was s t i l l i n c r e a s i n g ;
decided to increase the duration of
i n h i b i t o r addition
- 1 6 3 -
Table A l . l .
(continued)
CONCENTRATION Cf
INHIBITOR
DURATION OF
ADDITION
RESULTS
IV.
100 mg/1 with respect
4- days
Nitrate l e v e l decreased to 0.8 mg/1
4 days
Less than 0.5 mg/1
k days
Less than 0.5 mg/1
to i n f l u e n t
75 mg/1 with respect
to i n f l u e n t
50 mg/1 with respect
to i n f l u e n t
25 mg/1 with respect
20 days
to 3 mg/1 and stayed around 3 mg/1
to i n f l u e n t
10 mg/1 with respect
to i n f l u e n t
Within 10 days n i t r a t e l e v e l increased
18 days
Slowly increased to 12 mg/1 and was
showing an upward trend
-164-
10 mg/L.
Since the
a d d i t i o n of
i n h i b i t o r during
oxygen uptake r a t e d e t e r m i n a t i o n s was
to decrease the HRT
of
the
systems.
the p e r i o d s of
not d e s i r e d , i t was d e c i d e d
The
nominal
HRT
of both
systems were reduced from 6 hours, i n steps of 2 hours.
(a) HRT
of 4 hours
During the 15 days of o p e r a t i o n at 4 hours of nominal
the average c o n c e n t r a t i o n of n i t r a t e s i n
10 mg/L,
compared t o
15-20
mg/L
system I
i n system
e s t i m a t e s of the r e a d i l y biodegradable COD
was
HRT,
l e s s than
I I . T h i s caused the
using system
II to be
c o n s i s t e n t l y higher than those o b t a i n e d using system I .
(b) HRT
of 2 hours
During the
30 days
of o p e r a t i o n at t h i s nominal HRT,
n i t r a t e c o n c e n t r a t i o n i n system I was
to 5-10
mg/L
l e s s than
5 mg/L,
i n system I I . However, both systems gave
e s t i m a t e s of the r e a d i l y biodegradable COD
of the
the
compared
comparable
f e e d . At
this
p o i n t , i t was d e c i d e d to operate one s c a l e d down system, as shown
by the schematic diagram i n F i g . A 1 . 1 ( b ) ,
h i g h requirement of feed.
i n order
to reduce the
-1 65-
A1.5
SLUDGE BULKING
After
about
4
months
of s u c c e s s f u l o p e r a t i o n , a
b u l k i n g problem o c c u r r e d and
the system began to
the
through
solids
examination
of
significant
The
being
lost
the
mixed
filamentous
following
liquor
the
c o l l a p s e due
effluent.
revealed
severe
the
to
Microscopic
presence
of
growth.
remedies were
taken
to
c o n t r o l the
sludge
b u l k i n g and none of them worked.
(1)
The d i s s o l v e d oxygen c o n c e n t r a t i o n of the a e r o b i c r e a c t o r
was
2.5
(2)
(3)
i n c r e a s e d above 4 mg/L
-
The d i s s o l v e d oxygen c o n c e n t r a t i o n of the a e r o b i c r e a c t o r
was
decreased
The
e n t i r e system was
The
below 1
mg/L.
r e s t a r t e d with a f r a c t i o n of i t s
liquor.
supply of a i r was
terminated
for d i f f e r e n t
time to c r e a t e temporary anaerobic
c a r r i e d out with and without
(5)
1.5
mg/L.
s e t t l e d mixed
(4)
from the normal l e v e l of
The
environments. These were
feeding.
organic l o a d i n g to the system was
high food to micro-organism
lengths of
ratio.
i n c r e a s e d to c r e a t e a
-166-
(6)
(7)
The
o r g a n i c l o a d i n g to the system was
low
food to micro-organism
decreased
ratio.
Phosphorus c o n c e n t r a t i o n i n the feed was
e l i m i n a t e any
i n c r e a s e d to
possible nutrient deficiency.
(8)
The
system was
fed using a 12 hour c y c l i c
(9)
The
system was
t r e a t e d with hydrogen peroxide
c o n c e n t r a t i o n s of 100,
to the f e e d , over
(10) The
system was
150,
200
and
250 mg/L,
subjected to anaerobic
the system was
eliminating
the
system
redesigned
r e t e n t i o n tank
During
the
reduced
to 0.5
due
sludge
f o r the
optimization
bulking
to
found
r e s t a r t e d with
incorporate
r e t u r n sludge,
period,
HRT.
in
proved
the
l i t r e s per hour, without
to the i n c r e a s e d
respect
to
of hydrogen
of mixed l i q u o r suspended
When every p o s s i b l e remedy
was
with
treatment.
f o r 48 hours,
100 mg/L
at
conditions prior
(11) A f t e r t r e a t i n g the system with 300 mg/L
than
loading.
24 hour p e r i o d s .
the hydrogen peroxide
peroxide
to c r e a t e a
solids.
the
to be
a
less
l i t e r a t u r e for
ineffective,
permanent
the
anaerobic
as shown i n F i g . A 1 . 1 ( c ) .
influent
any
flow
nitrification
rate
was
problem
-1 6 7 -
Inf.
a)
(b)
1 1/h
V
Waste
A
E
R
O
B
I
C
f. 1 1
Vol = 6 1J • Vol\ef=
1:1 Recycle
Waste
Inf. / AEROBIC Y \ / eff.
1 1/h
' Vol = 1 1
1:1 Recycle
Vvol = 1 1J
\
(c)
1:1 Recycle
Fig.
Al.l.
Different
stages
i n the development
used i n t h e measurement
of r e a d i l y
of the process
biodegradable
COD
- 1 6 8 -
Th i s s y s t e m
with
performed
n e i t h e r h i g h degree of
being
present.
mg/L
was
An
always
oxygen u t i l i z a t i o n
cessation
of
effluent
nitrification
the
throughout
nor
sludge
ammonia c o n c e n t r a t i o n
maintained
at
successfully
to
eliminate
termination
nitrification.
of
the
any
the
bulking
of a t
decrease
feed
study,
due
ever
least
5
in
the
to
the
-1 6 9 -
APPENDIX
RAW
DATA
FROM T H E V A R I O U S
A2
E X P E R I M E N T A L RUNS
-170-
RAW DATA OF PHOSPHORUS FROM THE ACETATE RUNS
Dosage i n Day #
anaerobic
after
zone as
steady
mg COD/L s t a t e
Total P
(mg/L)
inf
eff
Ortho - P
(mg/L)
i n f anae
anox
aero e f f
Aero.
Slud.
%P
1
4
7
1 1
14
4.6
4.4
4.6
4.6
4.5
<0.2
<0.2
<0.2
<0.2
<0.2
3.2
3.0
3.1
3.4
3.3
18.2
18.6
17.8
17.9
18.0
16.2
16.8
14.3
15.1
15.4
<0. 1
<0. 1
<0. 1
<0.1
<0. 1
<0.1
<0.1
<0.1
<0.1
<0.1
5.8
5.9
5.5
5.6
5.9
1
4
8
11
15
4.3
4.2
4.2
4.4
3.9
<0.2
<0.2
<0.2
<0.2
<0.2
3.2
3.4
3.3
3.0
3.1
16.4
15.8
16.6
14.4
16.6
13.4
15.9
14.4
11.6
12.4
<0. 1
<0.1
<0.1
<0. 1
<0.1
<0.1
<0.1
<0.1
<0.1
<0.1
5.4
5.6
5.1
5.8
5.5
1
5
8
12
15
19
4.2
4.0
4.2
4.0
4.1
4.2
0.-4
0,2
0.4
0.4
0.5
0.3
3.2
3.3
3.3
2.9
3.1
3.4
11.6
1 1 .4
8.4
10.6
10.4
10.6
8.4
9.2
7.9
8.8
8.4
6.4
0.2
0.2
0.4
0.4
o.a
0.2
0.3
0.2
0.4
0.3
0.3
0.3
4.6
4.7
5.0
4.8
4.7
5. 1
1
5
8
12
15
19
4.4
4.3
4.3
4.6
4.2
4.3
0.8
0.6
0.7
0.8
1.0
0.8
3.1
3.3
3.4
3.4
2.9
3.3
6.8
3.4
7.1
5.4
5.6
2.8
4.2
2.9
7.1
5.8
3.2
3.2
0.4
0.5
0.8
0.7
0.6
0.8
0.8
0.7
0.8
0.7
0.8
0.8
4.5
4.8
4.6
4.5
4.7
4.3
1
5
8
12
15
4.1
4.0
3.9
4.1
4.2
1.7
1.8
1.9
1.8
2.1
2.9
3.1
3.1
3.2
2.9
3.9
3.9
3.8
3.4
2.9
3.8
4.0
2.7
3.2
2.9
1.7
1 .6
1.8
1 .6
1.8
1.7
1 .8
1.8
1 .8
1.9
3.2
2.9
3.0
2.7
3.1
1
5
8
12
15
4.3
4.5
4.2
4.4
4.5
3.4
3.4
3.3
3.5
3.5
3.2
3.6
3.4
3.6
2.8
3.5
3.2
3.3
3.6
3.5
3.2
3.6
3.4
3.6
3.8
3.4
3.3
2.8
2.9
3.1
3.4
3.4
3.3
3.3
3.4
1 .6
1 .3
1 .7
1 .7
1 .4
-171-
RAW DATA OF NITROGEN FROM THE ACETATE RUNS
Dosage i n
anaerobic
zone as
mg COD/L
Day #
after
steady
state
TKN
(mg/L)
inf eff
NO
(mg?L)
inf
anae
anox
aero
eff
30
1
4
7
11
14
27.5
26.9
26.4
27.1
27.8
1.8
1.8
1.3
2.4
2.9
0.1
0.1
<0.1
<0.1
<0.1
<0.1
<0.1
<0.1
<0.1
<0.1
0.2
0.2
0.1
<0.1
<0.1
10.4
9.8
8.8
9.1
9.8
10.3
9.4
8.8
8.9
9.8
25
1
4
8
11
15
27.8
26.6
27.6
27.2
28.7
2.4
2.2
1.8
2.8
2.4
0.1
0.2
<0.1
<0.1
0.3
<0.1
<0.1
<0.1
<0.1
0.1
0.2
0.3
0.1
<0.1
0.2
10.3
10.0
10.6
9.4
8.6
10.6
9.8
10.6
9.2
8.2
1
5
8
12
15
19
26.9
27.3
28.2
26.8
27.4
27.6
2.6
3.1
2.3
3.2
3.4
2.1
0.2
<0.1
<0.1
0.1
<0.1
<0.1
<0. 1
<0. 1
<0. 1
<0. 1
<0.1
<0.1
0.2
0.3
0.3
0.2
0.1
<0. 1
9.8
8.6
10.2
10.6
10.9
11.2
9.6
8.4
9.8
10.4
10.6
11.6
1
5
8
12
15
19
29.4
29.8
28.4
28.0
30.2
29.0
3.6
3.8
4.8
5.1
3.3
3.5
0.2
0.2
0.1
<0. 1
<0. 1
0.1
<0.
<0.
<0.
<0.
<0.
<0.
1
1
1
1
1
1
<0.1
<0.1
0.1
0.1
0.3
0.2
9.8
1 1 .8
8.8
8.4
10.6
10.7
9.6
1 1 .6
8.8
8.4
10.4
10.7
1
5
8
12
15
29.6
30. 1
29.4
28.6
29.4
4.4
3.9
3.3
4.8
4.5
0.2
0.2
0.1
0.1
<0.1
<0.
<0.
<0.
<0.
<0.
1
1
1
1
1
0.2
<0.1
<0.1
0.2
0.3
11.6
1 1 .6
10.3
8.8
8.6
1 1 .4
11.6
10.5
8.6
8.6
1
5
8
12
15
28.4
29. 1
28.1
29.2
28.8
3.4
3.8
3.3
2.9
4.2
<0.1
0.2
<0. 1
<0.1
0.2
<0. 1
<0. 1
<0. 1
<0.1
<0. 1
0.2
0.2
<0. 1
<0.1
<0.1
10.4
10.8
11.6
9.6
10.6
10.2
10.8
1 1 .4
9.8
10.6
-1 72-
RAW
Dosage i n
anaerobic
zone as
mg COD/L
DATA OF SOLIDS FROM THE ACETATE RUNS
Day #
after
steady
state
TSS
(mg/L)
VSS
(mg/L)
anae
anox
aero
eff
anae
anox
aero
eff
1
4
7
1 1
14
1220
1260
1310
1240
1200
2380
2380
2340
2360
2380
2340
2340
2320
2290
2300
20
29
21
10
16
850
880
890
840
800
1920
1880
1940
1960
1900
1960
1990
1930
1960
1820
14
18
18
1
4
8
1 1
15
1280
1240
1 1 30
1280
1220
2340
2310
2320
2360
2380
2320
2300
2340
2290
2330
1 1
15
27
39
34
820
870
880
900
810
1960
1920
1880
1870
1840
1720
1920
1890
1880
1760
6
14
23
30
25
1
5
8
12
15
19
1210
1200
1 1 20
1320
1 340
1290
2320
2350
2280
2340
2300
2340
2340
2340
2250
2360
2280
2320
39
35
1 1
10
25
19
920
860
840
890
880
910
1820
1860
1740
1840
1730
1710
1810
1860
1830
1820
1700
1800
26
22
6
1
5
8
12
15
19
1210
1 1 30
1 190
1260
1200
1 180
2340
2280
2300
2300
2320
2370
2320
2240
2290
2300
2320
2310
20
29
14
23
26
30
740
810
800
800
770
730
1820
1630
1780
1810
1830
1800
1760
1740
1690
1820
1870
1740
14
22
10
16
20
23
1
5
8
12
15
1200
1 180
1220
1230
1 1 90
231 0
2290
2340
2360
2300
2280
2240
2300
2320
2290
29
20
16
15
9
840
850
860
920
900
1800
1770
1 780
1820
1850
1890
1820
1880
1790
1820
22
14
9
10
1
5
8
12
15
1210
1230
1 190
1230
1230
2310
2390
2330
2320
2300
2250
2270
2300
2290
2280
20
15
16
22
17
930
830
850
840
820
1840
1870
1830
1800
1740
1800
1830
1790
1820
1760
18
10
9
14
1 1
-
1 1
-
18
14
-
-1 73-
RAW DATA OF COD AND ORP FROM THE ACETATE RUNS
Dosage i n
anaerobic
zone as
mg COD/L
Day #
after
steady
state
Influent
COD
(mg/L)
Effluent
COD
(mg/L)
Total
RBD COD
of feed
(mg COD/L)
ORP
(mV)
anae
anox
30
1
4
7
1 1
14
219
227
203
221
227
32
35
30
41
38
87
79
83
86
85
-342
-346
-341
-348
-350
-168
-167
-156
-164
-142
25
1
4
8
1 1
15
228
231
219
226
218
43
37
31
49
41
74
78
80
79
73
-341
-338
-340
-340
-329
-158
-156
-160
-1 72
-1 54
20
1
5
8
12
15
19
242
218
235
224
230
231
32
27
34
36
32
31
73
71
73
69
70
69
-321
-319
-315
-319
-320
-322
-128
-120
-1 45
-149
-149
-1 54
15
1
5
8
12
15
19
227
238
244
220
236
240
27
33
31
22
29
31
63
59
64
68
60
66
-31 1
-332
-328
-310
-316
-321
-1 40
-143
-1 39
-1 38
-141
-151
10
1
5
8
12
15
251
238
235
228
249
34
29
33
37
28
57
59
54
51
54
-326
-314
-298
-300
-294
-146
-1 46
-123
-1 46
-142
5
1
5
8
12
15
241
239
256
249
246
29
39
43
33
38
46
49
48
47
49
-289
-220
-288
-297
-281
-143
-139
-147
-1 52
-1 42
-174-
RAW DATA OF PHOSPHORUS FROM THE PROPIONATE RUNS
Dosage i n
anaerobic
zone as
mg COD/L
Day #
after
steady
state
inf
eff
inf
anae
anox
25
1
5
8
12
15
4.3
4.3
4.4
4.3
4.2
0.3
0.4
0.3
0.2
0.2
3.2
3.2
3.4
3.0
3.0
14.1
13.6
13.9
13.8
13.2
11.5
11.2
10.5
1 1 .8
12.4
0.3
0.3
0.3
0.2
0.2
0.3
0.3
0.3
0.2
0.2
5.4
5.6
5.4
5.5
5.5
20
1
4
8
1 1
15
4.0
4.2
4.1
4.1
4.3
0.9
0.8
1.0
1.0
0.9
3.1
2.9
2.9
3.0
3.1
10.4
10.2
9.8
11.2
9.8
8.4
8.6
9.2
8.4
8.8
0.9
0.8
0.9
0.9
0.9
0.9
0.7
0.9
0.8
0.9
4.5
4.3
4.3
4.4
4.4
15
1
5
8
12
15
4.1
4.1
4.2
4.4
4.2
1
1
1
1
1
3.3
3.4
3.2
3.2
3.4
5.4
4.9
5.6
5.6
4.8
4.2
4.6
4.1
3.9
4.0
1
1
1
1
1
1 .5
1.4
1 .6
1 .5
1 .4
3.6
3.7
3.6
3.8
3.6
1
5
8
12
15
3.9
3.9
4.0
3.9
3.8
<0.2
<0.2
<0.2
<0.2
<0.2
2.9
2.9
3.0
2.9
2.8
15.4
15.8
16.2
15.0
14.9
11.2
10.8
1 1 .8
1 1 .4
10.9
<0.1
<0.1
<0.1
<0.1
<0.1
<0. 1
<0.1
<0. 1
<0. 1
<0. 1
5.3
5.4
5.0
5.2
5.2
10
1
4
8
1 1
15
4.0
4.1
4.0
3.9
4.2
2.6
2.7
2.5
2.4
2.6
3.2
3.1
3.1
2.9
3.2
3.3
4.5
3.8
4.6
4.1
3.3
3.8
3.2
3.9
4.0
2.5
2.5
2.5
2.4
2.4
2.4
2.6
2.5
2.3
2.4
2.3
2.1
2.1
2.2
2.1
5
1
5
8
12
15
4.0
3.9
4.1
4.2
4.1
3.1
3.0
3.2
3.2
3.1
2.9
3.0
3.2
3.4
3.3
2.9
3.6
3.7
3.3
3.0
2.7
2.9
3.4
3.1
2.8
3.1
2.9
3.0
3.0
3.1
3.1
3.0
3.0
3.1
3.2
1
1
1
1
1
this
run
*
10
Total P
(mg/L)
.6
.4
.6
.8
.5
Ortho - P
(mg/L)
The
raw
sewage d u r i n g
c o n c e n t r a t i o n of 14.7 mg/L as COD.
aero
eff
.5
.3
.7
.5
.4
had
Aero.
Slud.
%P
an
.5
.4
.5
.3
.3
acetate
-175-
RAW DATA OF NITROGEN FROM THE PROPIONATE RUNS
Dosage i n
anaerobic
zone as
mg COD/L
Day #
after
steady
state
25
1
5
8
12
15
26.2
26.0
25.8
25.7
26.2
20
1
4
8
1 1
15
15
TKN
(mg/L)
inf
NO
(mg?L)
v
inf
anae
anox
aero
eff
2.1
1 .8
1 .4
1 .8
2.0
<0. 1
<0.1
<0. 1
<0.1
<0. 1
<0.1
<0.1
<0.1
<0.1
<0.1
0.1
0.1
<0.1
<0.1
0.1
7.2
6.8
6.6
6.8
7.0
7.0
6.8
6.4
6.6
7.0
25.8
25.8
26.0
26.2
25.7
1 .7
2.1
1.6
1.5
1.5
<0.1
<0.1
<0. 1
<0.1
<0. 1
<0.1
<0.1
<0.1
<0.1
<0.1
0.2
0.1
<0.1
0.1
<0.1
6.8
6.0
6.6
6.5
6.8
6.8
5.9
6.4
6.5
6.2
1
5
8
12
15
24.7
24.6
24.3
24.0
24.8
1.8
1.8
1 .6
1 .4
2.0
<0. 1
<0. 1
<0.1
<0.1
<0.1
<0.1
<0.1
<0. 1
<0.1
<0.1
0.2
0.2
<0.1
0.1
<0.1
7.1
6.9
7.3
7.3
7.5
7.1
7.0
7.2
6.9
7.5
1
5
8
12
15
27.4
27.0
27.2
26.8
27.2
2.1
2.0
2.1
1 .8
1 .6
<0.1
<0. 1
<0.1
<0. 1
<0. 1
<0.1
<0.1
<0.1
<0.1
<0. 1
<0.1
<0.1
<0.1
<0.1
<0.1
5.2
5.1
5.0
5.8
5.2
5.1
5.1
5.0
5.6
5.2
10
1
4
8
1 1
15
23.9
24. 1
24.0
24.5
24.7
1 .7
1.7
1 .6
1.6
1 .7
<0.1
<0. 1
<0. 1
<0. 1
<0.1
<0. 1
0.1
<0. 1
<0.1
0.1
0.1
0.2
0.2
<0.1
0.1
7.2
7.9
7.6
7.6
7.2
7.1
7.9
7.4
7.2
7.2
5
1
5
8
12
15
22.3
22.8
22.8
23. 1
22.9
1 .9
2.1
1 .8
1 .8
1.9
<0.1
<0. 1
<0. 1
<0.1
<0. 1
<0.1
0.1
0.1
<0.1
<0.1
0.1
0.1
<0. 1
0.2
0.1
8.0
6.8
7.8
7.8
8.1
7.9
6.8
7.8
7.6
7.9
10
*
eff
*
The
raw sewage d u r i n g
c o n c e n t r a t i o n of 14.7 mg/L as COD.
this
run
had
an
acetate
-176-
RAW
Dosage i n
anaerobic
zone as
mg COD/L
DATA OF SOLIDS FROM THE PROPIONATE RUNS
Day #
after
steady
state
TSS
(mg/L)
VSS
(mg/L)
anae
anox
aero
eff
anae
anox
aero e f f
1
5
8
12
15
1220
1230
1220
1240
1240
2290
2290
2280
2200
2290
2310
2300
2270
2320
2310
22
24
28
18
20
840
850
880
840
830
1830
1820
1830
1800
1810
1840
1830
1830
1810
1790
16
12
18
13
14
1
4
8
1 1
15
1200
1210
1210
1 220
1210
2280
2300
2280
2300
2290
2300
2300
2290
2280
2270
24
22
27
16
20
820
800
830
810
820
1820
1800
1900
1840
1800
1800
1810
1880
1820
1800
20
24
22
1
5
8
12
15
1200
1 200
1 180
1200
1 190
2260
2240
2240
2260
2230
2290
2280
2300
2280
2310
26
28
26
25
20
860
840
820
820
830.
1800
1860
1840
1800
1820
1790
1840
1850
1810
1810
20
26
19
18
14
1
5
8
12
15
1230
1240
1260
1240
1230
2320
2320
2340
2350
2340
2360
2340
2340
2360
2340
18
26
12
20
15
820
840
860
860
810
1860
1880
1880
1860
1840
1880
1890
1900
1840
1840
8
1 1
1 1
1
4
8
1 1
15
1
1
1
1
1
180
190
190
170
190
2250
2240
2230
2230
2240
2270
2260
2270
2270
2280
28
20
16
10
22
810
800
790
810
790
1810
1800
1800
1810
1790
1820
1800
1 790
1790
1800
22
16
1 1
8
16
1
5
8
12
15
1200
1 160
1 180
1 170
1 180
2250
2250
2220
2230
2260
2270
2260
2240
2260
2290
30
22
20
18
26
800
780
780
800
780
1800
1780
1770
1800
1800
1790
1 790
1780
1790
1790
21
this
run
had
The
raw
sewage d u r i n g
c o n c e n t r a t i o n of 14.7 mg/L as COD.
an
-
15
6
-
18
16
12
14
acetate
-177-
RAW DATA OF COD AND ORP FROM THE PROPIONATE RUNS
Dosage i n
anaerobic
zone as
mg COD/L
Day #
after
steady
state
Influent
COD
(mg/L)
25
1
5
8
12
15
220
225
228
230
227
24
26
27
27
20
20
1
4
8
1 1
15
230
229
224
225
229
1 5
1
5
8
12
15
Effluent
COD
(mg/L)
Total
RBD COD
of feed
(mg COD/L)
ORP
(mV)
anae
anox
68
72
73
72
72
-354
-354
-352
-350
-354
-180
-182
-180
-178
-180
23
28
24
24
24
67
67
66
64
66
-344
-342
-342
-340
-328
-180
-178
-174
-178
-170
230
232
229
239
238
22
21
21
22
20
58
59
58
61
61
-325
-320
-322
-320
-310
-160
-162
-168
-170
-160
1
5
8
12
15
238
235
240
242
240
27
29
24
30
28
70
70
72
73
70
-360
-355
-350
-358
-360
-180
-186
-182
10
1
4
8
1 1
15
234
240
243
245
242
24
22
22
30
26
49
51
52
53
52
-310
-308
-306
-310
-310
-150
-148
-148
-152
-150
5
1
5
8
12
15
240
244
242
248
245
24
23
23
26
24
45
46
46
47
46
-300
-290
-290
-285
-290
-148
-146
-150
-150
-149
*
10
The
raw sewage d u r i n g
c o n c e n t r a t i o n of 14.7 mg/L as COD.
this
run
had
an
-188
-180
acetate
-1 78-'
RAW DATA OF CARBON STORAGE FROM THE PROPIONATE RUNS
Dosage i n
anaerobic
zone as
mg COD/L
Day #
after
steady
state
anae
anox
aero
anae
anox
aero
25
8
11.6
11.5
4.1
15.2
14.9
2.3
20
8
7.2
9.9
2.4
9.6
8.7
2.1
15
12
6.3
4.0
5.9
7.8
7.1
3.3
*
PHB
(mg/L)
PHV
(mg/L)
10
10
5
11.0
9.8
2.4
6.7
4.3
1.7
8
8.1
6.4
4.1
5.7
5.2
3.7
5
8
6.8
3.8
3.5
3.5
3.6
3.3
The
raw
sewage during
c o n c e n t r a t i o n of 14.7 mg/L as COD.
this
run
had
an
acetate
-179-
RAW DATA OF PHOSPHORUS FROM THE BUTYRATE RUNS
Dosage i n Day #
anaerobic
after
zone as
steady
mg COD/L s t a t e
Total P
(mg/L)
Ortho - P
(mg/L)
aero e f f
Aero.
Slud.
%P
inf
eff
i n f anae
anox
1
5
8
12
15
19
4.2
4.2
4.0
4.1
4.0
4.2
0.5
0.6
0.5
0.6
0.5
0.6
3.3
3.4
3.3
3.3
3.4
3.2
12.6
13.2
12.8
13.0
12.6
13.0
9.8
10.0
9.6
9.8
10.0
9.4
0.5
0.5
0.5
0.6
0.5
0.6
0.5
0.4
0.6
0.5
0.6
0.6
4.3
4.6
4.7
4.8
4.8
4.4
1
4
8
1 1
1 5
4.2
4.2
4.0
4.3
4.4
0.9
1 .0
1.0
0.9
0.8
3.2
3.3
3.1
3.1
3.2
10.4
8.8
10.3
9.9
11.3
8.1
7.9
7.4
7.8
7.5
0.9
0.8
0.8
0.9
0.9
1 .1
1.0
0.9
1.1
0.9
4.1
4.3
3.9
4.6
4.4
1
5
8
1 2
15
3.7
3.8
4.1
3.9
4.0
1 .8
1.9
1 .9
1 .7
1 .8
3.1
2.9
3.0
2.8
3.1
7.0
7.4
7.5
8.0
7.1
5.7
5.9
6.4
6.7
5.0
1.7
1.6
1.6
1 .8
1.8
1.8
1.7
1.6
1 .8
1.7
2.7
2.7
3.0
2.6
2.4
1
4
8
1 1
15
4.1
4.2
4.0
4.4
4.3
2.2
2.3
2.3
2.4
2.4
3.1
3.2
3.4
3.2
3.0
5.0
5.1
4.3
4.5
4.7
4.6
3.9
3.8
4.3
4.0
2.4
2.4
2.3
2.3
2.3
2.4
2.4
2.3
2.4
2.5
1.9
2.0
2.4
2.2
1 .8
1
5
8
12
15
4.1
3.8
3.8
4.3
3.9
3.1
3.4
3.0
2.8
3.2
2.8
3.0
3.0
2.9
3.2
3.3
3.4
3.4
3.0
3.7
3.0
3.1
3.2
2.6
3.4
3.2
2.9
2.9
2.8
3.0
3.0
2.9
3.0
2.8
2.9
1.5
1.5
1 .7
1 .6
1 .8
-180-
RAW DATA OF NITROGEN FROM THE BUTYRATE RUNS
Dosage i n
anaerobic
zone as
mg COD/L
Day #
after
steady
state
TKN
(mg/L)
NO
(mg?L)
inf eff
inf
anae
anox
aero
eff
30
1
5
8
12
15
19
24.8
23.2
24.9
24.0
23.8
24.6
2.2
1 .8
2.1
2.2
2.0
2.3
<0. 1
<0.1
<0. 1
0.2
<0.1
0.2
<0.1
<0.1
<0.1
<0.1
<0.1
<0.1
0.1
<0.1
<0.1
0.1
<0.1
0.1
6.0
5.8
6.1
6.0
5.9
6.6
5.8
6.0
6.2
5.8
6.2
5.2
25
1
4
8
1 1
15
22.4
23.0
21.1
21 .2
21 .9
1 .8
2.1
1 .1
1 .1
0.8
<0.1
<0.1
0.1
<0.1
<0. 1
<0.1
<0.1
<0.1
<0.1
<0.1
0.1
0.1
<0.1
<0.1
<0.1
6.0
6.4
5.8
6.0
5.3
6.1
6.4
5.6
5.9
5.3
20
1
5
8
12
15
23.8
24.2
25.0
23.1
23.6
2.0
2.2
1 .3
1 .6
1 .6
<0.1
<0.1
<0.1
<0.1
<0.1
<0.1
<0.1
<0.1
<0. 1
<0.1
<0. 1
<0. 1
0.1
<0.1
<0.1
6.9
7.0
5.7
6.0
6.0
6.8
7.0
5.8
5.9
6.1
15
1
4
8
1 1
15
22.0
22.8
21 .3
23.2
21 .1
1 .1
1.0
0.8
1 .1
1 .7
<0.1
<0.1
<0.1
<0.1
<0.1
<0.1
<0.1
<0.1
<0.1
<0.1
<0.1
0.2
<0.1
<0. 1
0.1
6.8
7.6
7.4
6.0
6.5
6.8
7.4
7.4
6.1
6.5
10
1
5
8
12
15
24.1
23.4
23.8
22.1
23.5
2.1
2.3
3.1
1.6
1 .1
<0.1
0.2
<0.1
<0.1
0.1
<0. 1
<0.1
<0.1
<0.1
<0.1
<0.1
<0. 1
0.2
<0.1
<0.1
7.8
6.9
6.8
6.9
6.2
8.0
6.9
6.8
7.0
6.2
-181-
RAW DATA OF SOLIDS FROM THE BUTYRATE RUNS
Dosage i n
anaerobic
zone as
mg COD/L
Day #
after
steady
state
TSS
(mg/L)
VSS
(mg/L)
anae
anox
aero
eff
anae
anox
aero
eff
1
5
8
12
15
19
1230
1230
1 300
1220
1260
1210
2290
2300
2320
2340
2290
2300
2290
2320
2320
2330
2320
2310
18
23
31
19
12
23
890
900
900
920
890
930
1800
1 790
1830
1880
1820
1800
1820
1820
1850
1830
1800
1840
14
19
24
13
8
12
1
4
8
1 1
15
1 190
1230
1 230
1270
1 180
2260
2400
2370
2290
2210
2280
2390
2390
2270
2190
28
31
21
32
14
930
980
920
990
880
1 720
1770
1690
1 780
1680
1730
1770
1680
1810
1620
21
24
16
22
9
1
5
8
12
15
1 150
1 170
1090
1 140
1020
2230
2230
2180
2190
2080
2200
2230
2220
2210
2060
23
19
31
15
22
870
890
920
860
790
1 620
1690
1580
1610
1490
1600
1710
1600
1640
1490
18
15
27
10
14
1
4
8
1 1
15
1000
1210
1 160
1 040
1060
21 10
2220
2200
2090
2130
2090
2180
2190
2100
2210
30
27
19
9
1 1
760
870
820
790
800
1 600
1660
1690
1 540
1590
1580
1610
1720
1590
1630
22
20
1 1
1
5
8
12
15
1050
990
1010
1 120
980
2100
2070
2090
2210
1990
2170
21 30
2060
2260
2040
18
31
30
19
28
830
710
830
860
690
1610
1570
1560
1690
1480
1630
1610
1550
1700
1520
10
23
21
12
20
-7
-1 82-
RAW DATA OF COD AND ORP FROM THE BUTYRATE RUNS
Dosage i n
anaerobic
zone as
mg COD/L
Day #
after
steady
state
Influent
COD
(mg/L)
Effluent
COD
(mg/L)
Total
RBD COD
of feed
(mg COD/L)
ORP
(mV)
anae
anox
30
1
5
8
12
15
19
222
218
220
216
225
217
29
31
37
36
39
32
71
71
69
68
70
67
-362
-358
-350
-370
-370
-364
-190
-200
-194
-198
-204
-196
25
1
4
8
11
15
226
231
219
225
212
40
43
29
34
43
63
66
70
62
71
-365
-360
-366
-370
-360
-163
-175
-165
-159
-159
20
1
5
8
12
15
236
242
227
219
224
45
51
22
41
39
59
64
68
53
65
-362
-355
-358
-360
-351
-145
-189
-135
-148
-1 47
15
1
4
8
1 1
15
251
230
227
231
229
38
36
41
33
49
63
59
59
51
64
-370
-345
-367
-339
-342
-165
-155
-153
-149
-162
10
1
5
8
12
15
241
255
251
223
236
38
25
42
46
21
48
53
51
56
44
-344
-352
-338
-339
-329
-134
-143
-131
-129
-139
-183-
RAW DATA OF CARBON STORAGE FROM THE BUTYRATE RUNS
Dosage i n
anaerobic
zone as
mg COD/L
Day #
after
steady
state
anae
anox
aero
anae
anox
aero
30
1
8
19
26.8
24.3
25.2
22.4
24.2
22.7
5.8
6.3
4.9
7.9
3.8
5.9
6.2
3.2
4.9
3.6
4.0
3.1
25
1
8
15
17.4
18.4
17.6
15.9
16.6
16.3
5.1
3.9
4.0
3.6
3.0
2.9
2.3
1.9
2.9
0.9
1 .3
1 .5
20
1
12
15
8.9
10.9
12.3
11.1
9.4
9.9
3.3
3.9
2.5
1.9
1 .6
3.0
2.1
2.6
3.0
1 .6
0.9
1 .3
15
1
8
15
4.9
6.2
5.9
6.1
5.4
4.8
3.0
2.1
1.8
0.9
1 .9
1.0 -
1 .6
0.9
1.0
0.2
0.3
0.5
10
1
8
15
4.3
4.9
3.8
4.3
4.1
3.8
1.9
2.3
2.0
0.8
0.6
2.1
0.9
0.7
0.7
0.3
0.5
0.3
PHB
(mg/L)
PHV
(mg/L)
-184-
RAW DATA OF CARBON STORAGE AND PHOSPHORUS FROM THE BUTYRATE RUNS
(Transient
Dosage i n
anaerobic
zone as
mg COD/L
Day #
after
dosage
change
State)
PHB
(mg/L)
anae
anox
Ortho - P
(mg/L)
aero
anae
anox
aero
30
1
3
5
21 .5
19.3
18.1
20.2
18.1
16.8
5.2
4.5
4.2
11.4
10.4
10.2
8.8
8.2
7.9
0.5
0.5
0.8
1
3
5
15.0
12.9
1 1 .0
13.9
12.1
10.6
3.9
3.4
3.2
8.9
8.1
7.8
6.9
6.3
6.1
0.9
0.9
1 .6
1
3
5
8.5
6.6
5.8
8.2
6.4
5.3
2.7
2.4
2.3
6.6
5.7
4.9
5.2
4.6
4.2
1 .7
1 .9
2.1
1
3
4.9
4.5
5.0
4.4
2.1
2.0
4.2 3.8
3.6
3.2
2.6
2.9
25
20
15
10
-185-
RAW DATA OF PHOSPHORUS FROM THE GLUCOSE RUNS
Dosage i n Day #
anaerobic
after
zone as
steady
mg COD/L s t a t e
Total P
(mg/L)
Ortho - P
(mg/L)
anox
aero e f f
Aero.
Slud.
%P
inf
eff
i n f anae
1
5
8
19
23
3.6
3.4
3.6
3.5
3.7
0.7
0.6
0.7
0.7
0.8
2.8
2.4
2.6
2.7
2.8
11.4
10.9
10.8
11.3
11.6
6.7
6.6
6.8
7.1
6.6
0.6
0.6
0.7
0.7
0.7
0.6
0.8
0.6
0.5
0.7
3.5
3.3
3.5
3.6
3.1
1
4
8
1 1
15
3.9
3.6
3.7
3.8
3.7
1.8
1.5
1.7
1.8
1.6
3.0
2.8
2.7
2.8
2.8
6.8
7.4
6.2
6.8
7.0
6.0
6.2
5.9
6.1
6.0
1.7
1 .6
1 .5
1.7
1.6
1 .7
1.5
1 .6
1 .7
1 .6
2.8
2.7
2.7
2.6
2.9
1
5
8
12
15
3.7
3.7
3.9
3.7
3.5
2.4
2.3
2.5
2.5
2.3
2.6
2.8
2.6
2.9
2.8
3.8
4.2
4.4
4.2
3.9
3.0
3.4
3.4
3.0
2.9
2.4
2.4
2.4
2.3
2.3
2.3
2.6
2.4
2.0
2.3
1.7
1 .7
1.8
1.6
1.8
1
6
8
12
15
4.0
3.9
4.1
3.8
3.9
0.2
0.1
0.3
0.1
0.2
3.3
3.3
3.4
3.2
3.1
13.2
13.6
13.8
12.9
12.9
7.1
6.9
7.2
6.6
6.8
<0. 1 <0. 1 4.1
0.1
4.2
0.1
0.2
0.2 4.0
<0.1 <0. 1 4.1
0.1
0.2 3.9
-186-
RAW DATA OF NITROGEN FROM THE GLUCOSE RUNS
Dosage i n Day #
anaerobic
after
zone as
steady
mg COD/L s t a t e
45
TKN
(mg/L)
inf eff
NO
(mg?L)
inf
anae
anox
aero
eff
1
5
8
19
23
23.2
22. 1
24. 1
22.3
21.9
2.1
2.9
1.8
2.0
2.5
<0.1
<0.1
<0.1
<0.1
<0.1
<0.1
<0.1
<0.1
<0.1
<0.1
0.1
0.2
0.2
0.1
0.3
6.2
7.0
7.4
6.8
7.0
6.1
6.8
7.4
6.9
6.9
1
4
8
11
15
22.6
21.3
21.7
20.8
23.4
2.4
1.8
3.4
1.4
2.8
<0.1
<0.1
0.1
<0.1
<0.1
<0.1
<0.1
<0.1
<0.1
<0.1
<0.1
<0.1
<0.1
<0.1
<0.1
6.2
6.4
6.0
5.9
6.1
6.2
6.3
6.2
5.9
6.2
1
5
8
12
15
20.9
22.3
21.4
21.8
20.9
1.8
1.7
1.7
1.6
2.0
<0. 1
<0. 1
<0. 1
<0. 1
<0.. 1
<0.
<0.
<0.
<0.
<0.
1
1
1
1
1
0.1
<0. 1
0.2
0.2
0. 1
6.4
6.9
5.4
6.8
6.6
6.2
6.6
5.2
6.9
6.6
1
6
8
12
15
19.8
18.9
20.0
19.4
18.6
1.2
1.3
1.3
1.4
1 .2
<0. 1
<0. 1
<0.1
0.2
<0. 1
<0.
<0.
<0.
<0.
<0.
1
1
1
1
1
0.2
0.3
0.3
0.2
0.2
8.3
9.8
7.4
7.2
8.1
8.4
9.8
7.1
7.3
8.1
-187-
RAW DATA OF SOLIDS FROM THE GLUCOSE RUNS
Dosage i n Day #
anaerobic
after
zone as
steady
itate
60
TSS
(mg/L)
anae
anox
aero
1
5
8
19
23
1410
1380
1430
1290
1330
2540
2480
2590
2520
2540
2560
2490
2580
2550
2500
1
4
8
1 1
15
1290
1300
1340
1280
1260
2320
2400
2310
2310
2300
1
5
8
12
15
1240
1260
1 190
1240
1290
1
6
8
12
15
1620
1660
1610
1590
1620
VSS
(mg/L)
eff
anae
anox
aero
24
23
10
8
20
1030
1075
11 20
980
1020
2070
1920
2100
2040
1990
2080
1990
2140
2180
2060
18
18
6
4
12
2320
2360
2290
2360
2340
4
18
10
21
20
960
980
1000
990
1020
1850
1900
1870
1820
1860
1860
1920
1800
1790
1900
18
8
16
16
2400
2300
2340
231 0
2430
241 0
2290
2310
2340
2410
10
14
23
22
15
940
960
820
940
990
1790
1740
1810
1810
1820
1770
1780
1820
1810
1830
8
1 1
20
16
10
2800
2800
2810
2740
2790
2810
2790
2840
2820
2740
20
10
5
21
20
1 190
1220
1200
1 180
1260
2250
2190
2320
2310
2240
2300
2210
2330
2310
2260
16
8
eff
-
-
14
13
-1 88-
RAW DATA OF COD AND ORP FROM THE GLUCOSE RUNS
Dosage i n
anaerobic
zone as
mg COD/L
60
Day #
after
steady
state
Influent
COD
(mg/L)
Effluent
COD
(mg/L)
Total
RBD COD
of feed
(mg COD/L)
ORP
(mV)
anae
anox
190
198
176
210
172
36
39
26
32
23
70
74
66
77
64
-398
-390
-393
-382
-390
-136
-131
-121
-129
-1 36
4
8
1 1
15
190
201
176
232
198
26
29
36
43
32
61
66
58
67
59
-386
-362
-344
-366
-362
-179
-171
-169
-188
-1 72
30
1
5
8
12
15
222
206
232
204
208
29
28
31
23
26
58
52
58
47
53
-360
-350
-358
-356
-342
-1 42
-1 44
-148
-151
-1 47
75
1
174
180
204
194
208
29
36
39
38
42
77
79
87
84
88
-401
-412
-408
-390
-406
-129
-131
-128
-110
-1 17
1
5
8
19
23
45
1
6
8
12
15
-189-
RAW DATA OF CARBON STORAGE FROM THE GLUCOSE; RUNS
Dosage i n
anaerobic
zone as
mg COD/L
Day #
after
steady
state
PHB
(mg/L)
Glycogen
(mg/L)
anae
anox
aero
anae
anox
aero
60
1
8
23
23.6
25.2
25.3
16.3
18.7
17.4
5.0
4.3
3.6
183
1 79
180
440
429
421
442
461
475
45
1
8
15
10.9
1 1 .7
11.1
9.7
10.3
2.2
2.9
3.1
169
180
175
380
362
394
389
402
396
30
1
8
15
6.4
5.8
6.0
4.5
3.9
5.4
2.9
2.5
1 .6
1 64
169
151
329
342
335
341
363
322
75
1
6
15
32.4
31 .8
29.9
19.8
20.5
19.0
4.9
4.9
4.2
159
162
172 -
450
422
437
498
463
472
-1 90-
RAW DATA OF THE EFFLUENT ORTHO-P PROFILE
( s e c t i o n 4.11)
Days
1
4
7
1 1
14
15
16
17
18
19
20
21
22
23
24
25
28
32
35
39
40
41
42
43
44
45
46
47
48
49
53
56
60
63
67
68
69
70
71
72
73
74
ACETATE
Ortho-P
0. 1
0.1
0. 1
0. 1
0. 1
0. 1
0. 1
0. 1
0. 1
0. 1
0. 1
0.1
0. 1
0. 1
0.1
0. 1
0. 1
0. 1
0.1
0. 1
0. 1
0. 1
0. 1
0.1
0. 1
0. 1
0. 1
0. 1
0.3
0.3
0.2
0.4
0.3
0.3
0.3
0.3
0.2
0.3
0.3
0.4
0.3
0.7
PROPIONATE
Days
Ortho-P
1
5
8
12
15
16
17
18
19
20
21
22
23
24
25
26
29
33
36
40
41
42
43
44
45
46
47
48
49
50
54
57
61
64
65
66
67
68
69
70
71
75
0.3
0.3
0.3
0.2
0.2
0.2
0.3
0.2
0.2
0.3
0.4
0.6
0.5
0.8
1 .0
0.9
0.7
0.9
0.8
0.9
0.9
0.8
0.9
0.9
1 .1
1 .2
1 .2
1 .4
1 .5
1 .5
1 .4
1 .6
1 .5
1 .4
1 .2
0.1
0.1
0.1
0.1
0.1
0.1
0.1
Days
1
5
8
12
15
19
21
22
23
24
25
26
27
28
29
30
31
32
33
36
40
43
47
49.
50
51
52
53
54
55
56
57
61
64
68
71
73
74
75
76
77
78
BUTYRATE
Ortho-P
0.5
0.4
0.6
0.5
0.6
0.6
0.5
0.6
0.5
0.7
0.8
0.9
0.9
0.8
1.0
0.9
0.9
0.8
1 .1
1 .0
0.9
1 .0
0.9
0.9
0.8
0.9
1 .4
1 .6
1 .8
1 .7
1 .8
1 .8
1.7
1 .6
1 .8
1 .7
1 .7
1 .8
1.9
2.1
2.1
2.3
(continued)
-191-
RAW DATA OF THE EFFLUENT ORTHO-P PROFILE
( s e c t i o n 4.11)
Days
ACETATE
Ortho-P
75
76
77
81
84
88
91
95
98
102
103
104
105
106
107
108
109
1 10
1 1 1
1 12
1 13
116
119
123
127
131
134
135
136
137
138
139
140
141
142
145
148
152
155
159
162
0.8
0.7
0.8
0.9
0.8
0.7
0.8
0.7
0.8
0.8
0.8
0.8
0.9
0.8
0.8
1.0
1.3
1.7
1 .6
1.7
1.7
1.8
1.7
1.8
1.8
1.8
1.9
1 .8
1.8
1 .8
2.1
3.1
3.0
3.5
3.3
3.3
3.4
3.4
3.3
3.3
3.4
PROPIONATE
Days
Ortho-P
78
82
85
86
87
88
89
90
91
92
• 93
94
95
96
99
102
106
110
1 1 1
1 12
113
1 14
115
1 16
1 17
118
1 19
120
124
127
131
134
0.1
0.1
0.1
0.2
0.3
0.3
0.3
0.4
0.7
0.9
1.3
2.0
2.5
2.4
2.6
2.5
2.3
2.4
2.5
2.6
2.8
3.1
3.0
3.2
3.1
3.1
3.2
3.1
3.0
3.0
3.1
3.2
BUTYRATE
Days
Ortho
79
80
81
82
85
89
92
96
98
99
100
101
102
103
104
105
106
110
113
1 17
120
-
2.4
2.4
2.3
2.4
2.4
2.3
2.4
2.5
2.6
2.9
3.0
3.0
2.9
3.0
3.0
3. 1
3.0
2.9
3.0
2.8
2.9
-1 9 2 -
APPENDIX A3
RAW DATA FROM THE COLD STORAGE TESTINGS
-1 93-
RAW DATA FROM THE COLD STORAGE TESTING I
( A l l c o n c e n t r a t i o n s a r e i n mg/L)
Day
#
BOD
COD
NO
Total P
PO.-P
T o t a l VFA
110
119
263
268
<0.1
<0.1
28.3
29.4
4.4
4.1
3.3
3.3
<3
<3
104
112
251
257
<0.1
<0.1
27.6
27.1
4.3
4.3
3.1
3.1
<3
<3
98
107
255
255
<0.1
<0.1
28.1
28.2
4.4
4.5
3.4
3.4
<3
<3
106
106
261
249
<0.1
<0.1
26.9
27.3
4.2
4.1
3.4
3.4
<3
<3
110
104
246
252
0.1
<0.1
27.3
27.9
4.2
4.2
3.3
3.2
<3
<3
10
117
122
237
241
<0.1
<0.1
29.4
28.2
4.4
4.1
3.0
3.0
<3
<3
12
103
99
252
239
<0.1
0.1
26.3
26.9
4.2
4.0
3.3
3.3
<3
<3
14
102
104
248
239
<0.1
<0.1
28.8
27.1
4.3
4.0
3.2
3.1
<3
<3
X
TKN
ft
-1 9 4 -
RAW DATA FROM THE COLD STORAGE TESTING II
( A l l c o n c e n t r a t i o n s are i n mg/L)
TKN
Total P
P0 ~P
T o t a l VFA
<0.1
0.1
24.3
24.6
4.1
4.0
3.2
3.2
<3
<3
228
219
<0.1
<0.1
23.1
22.9
4.2
4.3
3.2
3.1
<3
<3
97
98
227
230
<0.1
<0.1
24.0
24.0
4.2
4.2
3.1
3.1
<3
<3
81
80
234
234
0.1
0.1
24.6
25.1
4.1
4.0
3.3
3.4
<3
<3
86
81
225
219
<0.1
<0.1
23.4
24.0
4.0
3.9
3.3
3.3
<3
<3
10
90
94
217
224
<0.1
<0.1
23.5
23.8
4.2
4.3
3.4
3.4
<3
<3
12
83
85
230
231
<0.1
<0.1
22.4
22.9
4.2
4.1
3.1
3.1
<3
<3
14
79
88
224
218
<0.1
<0.1
23.1
23.6
4.0
4.0
3.3
3.2
<3
<3
Day
#
BOD
COD
NO
89
87
232
236
92
83
x
4