Phosphorus Removal in a Membrane Reactor SystemA Demonstration Study

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Phosphorus Removal in a Membrane Reactor SystemA
Demonstration Study

• Wayne Lorenz, P.E. and Matthew J. GavinWright
  Water Engineers, Inc.
• and
• Newell Wright, P.E.Arapahoe County Water and
  Wastewater Authority

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MEMBRANE BIOREACTOR (MBR)
SAMPLE POINT 3PERMEATE
SAMPLE POINT 1INFLUENT
FERRIC CHLORIDE
INFLUENT
UV DISINFECT
ANOXIC BASIN
AEROBIC BASIN
MEMBRANES
DISCHARGE
MEMBRANE VACUUM/PERMEATE PUMPS
INFLUENT PUMP STATION
MECHANICALLY CLEANED BAR SCREEN
RECYCLE
SOLIDS
SAMPLE POINT 2MBR
PROCESS SCHEMATIC LONE TREE CREEK WASTEWATER
TREATMENT FACILITY
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MEMBRANE BIOREACTOR (MBR)
ANOXIC BASIN
AEROBIC BASIN
MEMBRANES
RECYCLE
SOLIDS
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ZeeWeed Membrane
Immersible, Ultra Low Pressure, Oxidant
Resistant, High Strength
Process Tank (Influent)
Inner reinforcing structure covered with a
composite polymer outer layer
Filtered Water
Membrane Layer
Pore Size 0.085 micron (nominal) 0.1 micron
(absolute)
Inner Reinforcing Structure
Operates at -2 psi to -6 psi when filtering and 3
psi on backpulse
X-Section
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3
3
FePO4(S)
AlPO4(S)
4
4
Fe(PO4)(X-3)/3 (OH)X(S)
Al(PO4)(X-3)/3 (OH)X(S)
Log Molar Soluble Phosphorus
5
5
Fe(OH)3(S)
6
6
Al(OH)3(S)
7
7
2
4
6
8
3
5
7
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pH Value
pH Value
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FERRIC CHLORIDEFe3 HnPO4n-3 ? FePO4
nHFeCl3 3H2O ? Fe(OH)3 3H 3Cl-
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SODIUM ALUMINATEAl3 HnPO4n-3 ? AlPO4
nHNa2Al2O4 4 H2O ? 2 Na Al2(OH)4 4
(OH-)
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Note Samples filtered through a 0.45-micron
filter.
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Notes 1. Samples filtered through 0.45 micron
filter. 2. pH adjusted to 6.5 using sulfuric
acid.
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Phase 1 Conditions

• Conducted over 15 weeksDecember through March
• Average Daily Inflow 0.98 mgd
• Membrane Filtration Area - 96,000 ft2
• Average Filtration Rate 10.2 gpd/ft2
• Ferric Chloride Dosage 80 to 100 mg/L
• No pH Adjustment

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Note Phosphorus analyses performed by Chadwick
Ecological Consultants.
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MBR Average Effluent Quality

• Total Phosphorus 0.035 mg/L
• BOD5 2.8 mg/L
• Ammonia 1.3 mg/L
• Nitrate 5.8 mg/L
• pH 7.0

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CONCLUSIONS

• Phosphorus Goal of 0.05 mg/L was met using ferric
  chloride at a dosage of 80 to 100 mg/L
• Average Phosphorus Concentration was 0.035 mg/L
• Phosphorus removed to 0.05 mg/L regardless of
  temperature

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CONCLUSIONS

• Addition of chemical to precipitate Phosphorus
  impacts pH and alkalinity
• pH conditions are key in optimizing Phosphorus
  removal
• Activated sludge was not affected by dosages in
  study

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Phase 2 Testing

• Demonstrate 0.02 mg/L P removal, or less
• Different chemicals
• Limit of biomass viability
• Membrane maintenance