Bacterial Decomposition
any hydrolysis
Organic Nitrogen
(proteins; urea)
Nitrification
Ammonia Nitrogen
O2
Nitrate (NO-2)
Lysis and Autooxidation
Organic Nitrogen
(bacterial cells)
Nitrate (NO-3)
Organic Carbon
Nitrogen Gas (N2)
Denitrification
Assimilation
O2
Organic Nitrogen
(net growth)
Figure by MIT OCW.
Adapted from: G. Tchobanoglous, F. L. Burton, and H. D. Stensel. Wastewater Engineering: Treatment
and Reuse. 4th ed. Metcalf & Eddy Inc., New York, NY: McGraw-Hill, 2003, p. 617.
O2
Facultative bacteria
Phosphorus removing bacteria
Carbon
storage
Energy
y
rg
ne PHB
P
PHB
E
Short-chain
fatty acids
on
Carb
ge
stora
+
P
CO2 + H2O
Fermentation Products
Cell wall
Soluble COD
Substrate
New cell production
ANAEROBIC
AEROBIC
Removal mechanisms for excess biological phosphorus (COD = chemical oxygen demand, PHB = poly-β-hydroxybutyrate).
Figure by MIT OCW.
Adapted from: Rittman, Bruce E., and Perry L. McCarty. Environmental Biotechnology: Principals
and Applications. New York, NY: McGraw-Hill, 2001.
15
50
Bacteria absorb BOD by
releasing phosphorus
ATP ADP + PO4 + energy
40
10
30
Influent ortho phosphorus
concentration
Soluble BOD
20
5
Soluble BOD, mg/L
Nominal ortho phosphorus concentration, mg/L as P
Ortho Phosphorus
Stored phosphorus in bacteria
is removed in waste sludge
Bacteria store phosphorus
during growth to compete
for BOD when they get
back to anaerobic zone
1
0
5
Anaerobic
First Anoxic
10
ADP + PO4
10
energy
ATP
15
Aerobic
0
20
Second Reaeration
Anoxic
Nominal Hydraulic Retention Time, Hours (Based on Influent Flow only)
Typical profile of soluble phosphorus concentrations in a biological nutrient removal process (ATP = adenosine
triphosphate, ADP = adenosine diphosphate).
Figure by MIT OCW.
Adapted from: Rittman, Bruce E., and Perry L. McCarty. Environmental Biotechnology: Principals
and Applications. New York, NY: McGraw-Hill, 2001.
Aerobic
CONCENTRATION
Anaerobic
Or
tho
ph
Sol
os
ph
oru
s
ubl
eB
OD
TIME
Fate of soluble BOD and phosphorus in nutrient removal reactor.
Figure by MIT OCW.
Adapted from: G. Tchobanoglous, F. L. Burton, and H. D. Stensel. Wastewater Engineering: Treatment
and Reuse. 4th ed. Metcalf & Eddy Inc., New York, NY: McGraw-Hill, 2003, p. 626.
Inorganic Chemicals Used Most Commonly for Coagulation and
Precipitation Processes in Wastewater Treatment
AVAILABILITY
Chemical
Alum
Formula
Molecular
Weight
Al2(SO4)3.18H2O#
666.5
Al2(SO4)3.14H2O#
Aluminum Chloride
AlCl3
Calcium Hydroxide
(lime)
Ca(OH)2
Ferric Chloride
Equivalent
Weight
594.4
Ferric Sulfate
Fe2(SO4)3
Ferrous Sulfate
(copperas)
Sodium Aluminate
Percent
Liquid
8.5 (Al2O3)
Lump
17 (Al2O3)
Liquid
8.5 (Al2O3)
Lump
17 (Al2O3)
133.3
44
Liquid
56.1 as CaO
40
Lump
162.2
FeCl3
114
Form
91
63-73 as CaO
Powder
85-99
Slurry
15-20
Liquid
20 (Fe)
Lump
20 (Fe)
400
51.5
Granular
18.5 (Fe)
FeSO4.7H2O
278.1
139
Granular
20 (Fe)
Na2Al2O4
163.9
100
Flake
# Number of bound water molecules will typically vary from 14 to 18
Figure by MIT OCW.
Adapted from : Metcalf, and Eddy. 2003
46 (Al2O3)
North Budapest Wastewater Treatment Plant
Comparison of Influent vs. Pre-aeration Raw Water
100
COD Influent Conc. = 515 mg/l
COD Pre-aeration Conc. = 594 mg/l
% COD Removal
80
60
Jar Test - Influent
Jar Test - Pre-aeration
40
Primary Effluent: Cin = 515 mg/l
20
0
Primary Effluent: Cin = 594 mg/l
0
20
40
60
80
100
Ferric Chloride Sulfate Concentration (mg/l)
(no polymer)
Topolcany Wastewater Treatment Plant
BOD and COD % Removal vs. Ferric Chloride Concentration
70
60
% Removal
50
BOD % Removal
40
COD % Removal
30
20
10
0
0
20
40
30
40
50
60
Ferric Chloride Concentration (mg/l)
(no polymer)
Figure by MIT OCW.
Adapted from: Murcott, and Hurleman. 1994, p. 24
Primary
Clarifier
Grit
chamber
a. Existing primary treatment plant
Low dose Cationic
Fe/Al
Polymer
Anionic
Polyme
r
High dose
Fe/Al
Optional
Mixer
Primary
Clarifier
Grit
chamber
Possibly
Anionic
Polymer
Primary
Clarifier
Grit
chamber
b. CEPT (left) and primary precipitation (right)
Fe/Al
Mixer
Primary
Clarifier
AST
Aeration
Secondary
Clarifier
Grit
chamber
c. Preprecipitation (or CEPT) followed by ASP
Carbon
source
Fe/Al
Mixer
Primary
Clarifier
AST
Aeration
Denitrification
D
Grit
chamber
d. Preprecipitation with ASP and postdenitrification
Multi-stage upgrading of an existing
primary treatment plant
Secondary
Clarifier
Without Chemical Addition
100
80
60
40
20
Suspended Solid Removal (%)
0
Ferric Chloride Addition
100
80
60
40
20
0
Ferric Chloride Plus Polymer Addition
100
80
60
40
20
0
50
100
Overflow Rate
150 cu m/sq.m/d
Overflow Rate Verses TSS Removal for Sarnia Treatment Plant
Figure by MIT OCW.