Metal Addition to Enhanced
Biological Filtration Performance
JEAN BAPTISTE ADOLPHE
Jonathan
Objectives
• Explore ways to enhance the properties of
metal-oxide coatings to improve filter
treatment performance
=> An alternative: substitute iron-oxide
sand for GAC
Background
• What is NOM?
- Predominantly humic substances + other
materials
• Problems caused by NOM
- Colored water
- Sometimes water smell and have bad taste
-Can react with chlorine to produce
chloroform and other carcinogens
- Chlorine demand
- Complex with Metals
• What is E. coli?
- Intestinal bacterium of the mammals very
common in the human being
• Problems Caused by E.coli
- diarrhoea and abdominal cramps
- Disease call: haemolytic uremic syndrome
• Problems Caused by Arsenic
- damage the human nervous system
- is a known carcinogen
- is also a teratogen, meaning it can enter the
metabolic system of unborn children
- and many other diseases
• How iron oxide sand can remove NOM
and microorganism?
-NOM adsorption involved ligand exchange
mechanism (Gu et al, 1994)
Me oxide-OH
NOM-COO-
Me oxide-O
+
<->
\
Me oxide-OH
Me oxide-OH---O=C-NOM
These reaction indicate that decreasing pH (more
protonated sites) will be favorable to NOM
adsorption.
Experimental Methodolgy
Sand collection
Sand Cleaning and Preparation
NOM Challenge
Arsenic or E.Coli Challenge
Filter Sand Utilized
-Winthrop (ME) Slow
Sand Filtration water
treatement plant
-Philadelphia (PA) Rapid
Sand Filtration water
treatement plant
Sands were sieved using sieves of 0,6 mm
and 0,85 mm opening
•NOM Challenge Solution:
-Solution realized with a concentrated humic acid
stock solution
-Buffered Water prepared with 168 mg/l of NaHCO3
(alkalinity =100 mg/l as CaCO3 ) and 40 mg/l of
NaCl
- Initial TOC Solution around 7 mg/l
• E.Coli solution:
-Stock solution of 5,45 108 Colony Forming Units
(CFU) / 100ml
-Dilute with buffered water until realize a 5,45
106 CFU/100mL
• Arsenic Challenge Solution:
- Stock solution of 1 g/l Arsenic
- Dilute with buffered water until realize a 2mg/l
arsenic V solution
Setup
Pump
pH controller
CONSORT
R305
Column
Valve
Autosampler
RESULTS
T O C R em o v a l as fu n ctio n o f b ed v o lu m e
Ch a lle n ge p H 5
S a n d Co n d i tio n p H 11
7
T O C (m g/
6
In flu e n t T O C = 7 ,5 4 5 mg /l
5
4
P hilad e lphia
sand
W intro p
sand
3
2
1
0
-5
5
15
be d vo lum e
25
=> Only the Philadelphia sand are Iron Coated Sand
35
Determination of the adsorption reaction order
Determination of adsorption reaction order
60 bed volume run
0
ln(TOC/TOC0)
0
Determination of adsorption reaction order
60 bed volume run
100
200
300
400
500
-0,5
600
R2 = 0,7958
ln(TOC/TOC0) as
function of time
-1
-1,5
-2
time (min)
0,6
1/TOC as
function of time
0,4
0,2
R2 = 0,6853
Determination of adsorption reaction order
60 bed volume run
0
0
100
200
300
400
500
600
time (min)
6
R2 = 0,8681
5
TOC (mg/l)
1/TOC (l/mg)
0,8
4
3
TOC as function
of time
2
1
0
0
100
200
300
time (min)
400
500
600
E.Coli Removal
6,00E+06
CFU/100ml
5,00E+06
4,00E+06
Influent solution
Effluent E.Coli
Philadelphia sand
Efluent E.Coli
Wintrop sand
3,00E+06
2,00E+06
1,00E+06
0,00E+00
3
4
bed volume
E.Coli Removal is quite the same for Iron-Oxide Sand and sand which are not.
E.Coli Removal from Metal Coated Sand
Philadelphia Sand
6,00E+06
CFU/100ml
5,00E+06
4,00E+06
Influent
solution
3,00E+06
Efluent E.Coli
Influent at pH 5
2,00E+06
Efluent E.Coli
Influent at pH 7
1,00E+06
pH 5
0,00E+00
Influent
3
pH 7
pH 5
Influent
pH 7
4
bed volume
The pH of the E.Coli Solution does not have effect on the E.Coli Removal
CONCLUSION
• Iron-Oxide Sand Enhanced NOM Removals
• Contrary has what was envisaged Iron-Oxide
Sand does not exert a significant influence on
E.Coli Removals after preloaded the sand with
NOM
Recommendation
• Challenge with a mixed solution of Arsenic
and NOM
• Determine the influence of the age of the
media on the NOM, E.Coli and Arsenic
Removal