1/11/2013
Membrane Bioreactor Phosphorus Removal Demonstration Study
Steve Berggruen, P.E. – Regional ManagerMilwaukee, Wisconsin
1/11/2013
Background
• Testing conducted at the Ridgewood Estates WWTP – Milford, Michigan
• Test Period: Nine months (October – June)
•
Testing Program: Physical/Chemical Phosphorus Removal through a
Membrane Bioreactor (MBR) System. Reduction of nitrogen compounds and
Bio‐P (attempted)
1/11/2013
Pilot Plant Objectives
• Show capability of MBR system to reduced effluent TP to < 0.03 mg/l
•
Demonstrate ability of system to removed conventional pollutants including
nitrogen species
• Demonstrate long‐term system operation with little or no maintenance
•
Produce design information regarding sustainable flux at varying MLSS
concentrations and waste temperatures
1/11/2013
Membrane Bioreactor (MBR)
•High Quality Effluent
• Small Footprint
• Simple to Operate
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Membrane Bioreactors
Modification of the traditional activated sludge processCombine aeration, clarification and filtration into a
single step (reduced footprint)
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Process and System Overview
•Automatic 3‐mm fine screen
•Anoxic (AX) Basin
•Pre‐Aeration (PA) Basin
•Membrane Bioreactor (MBR) Basin
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Pilot Study Process Configuration
AX Zone PA Zone MBR
Recycle
P1Feed
Permeate
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Pilot Study Process Configuration
(Alternate – Phase 2)
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MBR System
1/11/2013
Anoxic (AX) Basin
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Pre‐Aeration Basin
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MBR with Submerged Membrane Unit
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Flat‐Plate Membrane Structure
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The Submerged Membrane Unit (SMU)
ManifoldMembrane case
Membrane cartridge
Diffuser case
Diffuser
Permeate Tube
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15
CIP Cartridge Distribution
•
Cleaning takes approximately 2‐4 hour / MBR basin, using a dilute solution of 0.5% Sodium
Hypochlorite or Citric Acid
•
In‐situ cleaning of membranes without draining MLSS•
Chlorine dosage less than that typically used for filamentous microorganism control•
No tank liners required
1/11/2013
Wastewater Characteristics
Parameter Average Minimum Maximum Unit
CBOD5 392.6 180.0 1095.0 mg/l
NH3 26.1 15.5 52.8 mg/l
T‐P 5.6 3.2 8.2 mg/l
TSS 626.5 147.5 1970.0 mg/l
Note: Flow to pilot plant set at 1.5 gpm (2,160 gpd)
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Testing Program ‐
Phosphorus
• Data collected over a four month period
• Two alum dosing rates tested (1 gpd / 2 gpd)
• Effluent TP rise at 1 gpd alum
• Average effluent TP < 0.03 mg/l
• 43 effluent samples
• TP less than detectable in 28% of samples
• No SA conducted on optimal dose or point
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Impact of Chemical Addition Location on Phosphorus Removal
0.01.02.03.04.05.06.07.08.0
0.0 1.0 2.0 3.0 4.0 5.0
PO
4-P
Con
cen
trat
ion
Al/P molar ratio
Example of applied Al/P molar ratiofor effluent P conc.
Anoxic
INTERNAL RECYCLE
M
AerobicAerobic
Anaerobic
0.01.02.03.04.05.06.07.08.0
0.0 1.0 2.0 3.0 4.0 5.0
PO
4-P
Con
cen
trat
ion
Al/P molar ratio
Example of applied Al/P molar ratiofor effluent P conc.
Anoxic
INTERNAL RECYCLE
M
AerobicAerobic
Anaerobic
Chemical addition point affects Al/P ratio
(Stensel, 2003)
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Pilot Operating Conditions & Results
•MLSS
•Temperature
•Effluent BOD
•Effluent Nitrogen
•Effluent Phosphorus
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Operational Overview
•MLSS:
6,940 –
26,180 mg/l
•Temperature:
6.2 – 15.8 degrees C
•HRT:
21 hours
•SRT:
57 days
•F:M
0.03 1/day or less
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Effluent Overview
• Effluent TSS:
2.5 mg/l (ave)
• Effluent BOD:
16.8 mg/l (Phase 1), 5.4 mg/l (Phase 2)*
• Effluent N:
11.4 mg/l NH3‐N (Phase 1), 0.3 mg/l NH3‐N (Phase 2)*
13.6 mg/l TIN (Phase 1), 2.6 mg/l TIN (Phase 2)*
• Effluent P:
0.05 mg/l (all data points)
0.03 mg/l (at optimal dosage)
*Phase 2 included increased blower speed for full nitrification and increased recycle of nitrates back to AX
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MBR MLSS Concentration Profile
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Recorded Water (Sludge) Temperatures
0
2
4
6
8
10
12
14
16
18
11/8 11/22 12/6 12/20 1/3 1/17 1/31 2/14 2/28 3/14 3/28
Date
Tem
pera
ture
(deg
C)
Design Temperature
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Permeate BOD Profile
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Permeate Nitrogen Profile
Phase 2
Phase 2→
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Phosphorus Trending
0
1
2
3
4
5
6
7
10/14 10/28 11/11 11/25 12/9 12/23 1/6 1/20 2/3 2/17 3/3 3/17 3/31
Date
Con
cent
ratio
n (m
g/l)
INF P
EFF PAlum Dosing
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Membrane Performance
• Sustained Flux:
10 gfd•
Excellent results despite variable MLSS and low T• Transmembrane Pressure (TMP):
•
0.4 – 0.6 psi (ave) •
1.6. – 1.8 psi (peak)
• Permeability:
42 gfd/psi (ave) during both phases• Membrane Maintenance:
•
No irreversible or permanent fouling detected•
Only one clean‐in‐place (CIP) procedure in 9 months•
3‐hour cleaning period using 0.5% bleach solution
1/11/2013
Conclusions
•Show capability of MBR system to reduced effluent TP to < 0.03 mg/l. YES
•Demonstrate ability of system to removed conventional pollutants
including nitrogen
species. YES (somewhat)
•Demonstrate long‐term system operation with little or no maintenance YES
•Produce design information regarding sustainable flux at varying
MLSS concentrations
and waste temperatures YES
1/11/2013
Thank You