Biological Nutrient Removal 101Biological Nutrient Removal 101
Glen T. Daigger, Ph.D., P.E., BCEE, NAESenior Vice President andChief Technology Officer
1POTW Nutrient Removal Seminar – Salt Lake City, UT 2/8/2009
BN(itrogen)R Removal Occurs by Nitrification and DenitrificationBN(itrogen)R Removal Occurs by Nitrification and DenitrificationNitrification and DenitrificationNitrification and Denitrification
NO3 SupplyNRCY
Food
RAS WASNitrification: NH3 + O2 → NO3
Denitrification: Food + NO → CO + H O + N
2POTW Nutrient Removal Seminar – Salt Lake City, UT2/8/2009
Denitrification: Food + NO3 → CO2 + H2O + N2
Here’s What’s Needed to Do This:Here’s What’s Needed to Do This:
• Nitrification:– Adequate Aerobic SRT
• Denitrification:– Adequate Anoxic SRTAdequate Aerobic SRT
– Adequate Oxygen Supply– Adequate Buffering
(Alkalinity)
Adequate Anoxic SRT– Recycle of Nitrate to
Anoxic ZoneExclude DO(Alkalinity) – Exclude DO
– Enough “Food”
High-Rate Denitrification,Readil Biodegradable
8
10
Day
s)
Readily Biodegradable (Dissolved) Organic Matter
Low-Rate Denitrification,Slowly Biodegradable (Colloidal and Particulate)4
6
um S
RT
(D NitrificationOperatingFactor
Organic Matter
EndogenousRespiration
NO3-N(mg/L)
0
2
Min
imu
NoNitrification
3POTW Nutrient Removal Seminar – Salt Lake City, UT2/8/2009
0 Time0
10 15 20 25 30
Temp (Deg Cent)
Six Key Biological Nitrogen Removal Principals Include:Six Key Biological Nitrogen Removal Principals Include:Principals Include:Principals Include:
• Use Influent Carbon First• Design for Good Sludge Settleability• Use Physical Foam Control• Not All Supplemental Carbon is Created
Equal• SNdeN Becomes Predictable• How Much GHG’s are We Creating?
4POTW Nutrient Removal Seminar – Salt Lake City, UT2/8/2009
Sludge Settleability Dramatically Affects Bioreactor InventorySludge Settleability Dramatically Affects Bioreactor InventoryAffects Bioreactor InventoryAffects Bioreactor Inventory
300
250
300
mL/
g)
150
200
% o
f Val
ue a
t
DoubleMLSS
100
able
MLS
S (% MLSS
Improved
0
50
0 50 100 150 200 250 300 350 400 450
Allo
wa SVI
5POTW Nutrient Removal Seminar – Salt Lake City, UT2/8/2009
0 50 100 150 200 250 300 350 400 450SVI (mL/g)
Anoxic Selector Sized Based on Anoxic SRTAnoxic Selector Sized Based on Anoxic SRTAnoxic SRTAnoxic SRT
•• SRT = 2-3 Days, Depending on TemperatureSRT 2 3 Days, Depending on Temperature• Staging Further Improves Selection
5 mg BOD5/mg NO3-N (8 mg COD/ NO3-N)
• Designed to Nitrify• Staging Improves Selection
Clarifier
6POTW Nutrient Removal Seminar – Salt Lake City, UT2/8/2009
RASRAS WASWAS
Required Aerobic Zone DO Correlates with Respiration RateRequired Aerobic Zone DO Correlates with Respiration Ratewith Respiration Ratewith Respiration Rate
ay Bulking OccurredM
LVSS
, da
VSS,
hr
1 2
1.6
32
44
38
Bulking OccurredBulking Did Not Occur
mov
ed/k
g M
e, m
g O
2/g
0.8
1.2
22
32
28
g C
OD
Rem
ptak
e R
ate
0.4 10
16
F/M
, kg
DO
U
00 1 2 3 4 5 6
4
7POTW Nutrient Removal Seminar – Salt Lake City, UT2/8/2009
Aeration Basin DO, mg/l
Six Key Biological Nitrogen Removal Principals Include:Six Key Biological Nitrogen Removal Principals Include:Principals Include:Principals Include:
• Use Influent Carbon First• Design for Good Sludge Settleability• Use Physical Foam Control• Not All Supplemental Carbon is Created
Equal• SNdeN Becomes Predictable• How Much GHG’s are We Creating?
8POTW Nutrient Removal Seminar – Salt Lake City, UT2/8/2009
Two Professionals Study Foam Problem!Two Professionals Study Foam Problem!Problem!Problem!
NocardiaNocardiaCan Be Fun!Can Be Fun!
9POTW Nutrient Removal Seminar – Salt Lake City, UT2/8/2009
Can Be Fun!Can Be Fun!
Principal Cause of NocardiformFoaming is TrappingPrincipal Cause of NocardiformFoaming is TrappingFoaming is TrappingFoaming is Trapping
• Demonstrated at Laboratory and Full-Scaley• Growth Form Varies with Trapping:
Trapping SystemNo Trapping System
10POTW Nutrient Removal Seminar – Salt Lake City, UT2/8/2009
Selective Foam Wasting is a Proven TechniqueSelective Foam Wasting is a Proven TechniqueTechniqueTechnique
11POTW Nutrient Removal Seminar – Salt Lake City, UT2/8/2009
Six Key Biological Nitrogen Removal Principals Include:Six Key Biological Nitrogen Removal Principals Include:Principals Include:Principals Include:
• Use Influent Carbon First• Design for Good Sludge Settleability• Use Physical Foam Control• Not All Supplemental Carbon is Created
Equal• SNdeN Becomes Predictable• How Much GHG’s are We Creating?
12POTW Nutrient Removal Seminar – Salt Lake City, UT2/8/2009
Denitrification Can Occur Inside Activated Sludge FlocsDenitrification Can Occur Inside Activated Sludge FlocsActivated Sludge FlocsActivated Sludge Flocs
Aerobic AerobicAnoxic
Low DO and/orHigh F/M
High DO and/orLow F/M
13POTW Nutrient Removal Seminar – Salt Lake City, UT2/8/2009
Denitrification Can Also Occur Due to Bioreactor Mixing PatternDenitrification Can Also Occur Due to Bioreactor Mixing PatternBioreactor Mixing PatternBioreactor Mixing Pattern
AerobicAnoxic
Aerator
Aerobic
Aerobic or Anoxic
Anoxic
T Cl ifi
Aerobic or Anoxic
RAS
Influent
To Clarifiers
14POTW Nutrient Removal Seminar – Salt Lake City, UT2/8/2009
Denitrification Can Also Occur Due to Bioreactor Mixing PatternBioreactor Mixing Pattern
High DO
Low DO
C t lli O I t K t R li bl P f !
POTW Nutrient Removal Seminar – Salt Lake City, UT
Controlling Oxygen Input Key to Reliable Performance!
Six Key Biological Nitrogen Removal Principals Include:Six Key Biological Nitrogen Removal Principals Include:Principals Include:Principals Include:
• Use Influent Carbon First• Design for Good Sludge Settleability• Use Physical Foam Control• Not All Supplemental Carbon is Created
Equal• SNdeN Becomes Predictable• How Much GHG’s are We Creating?
Ni Ni i NO N O N– Nitrate → Nitrite → NO → N2O → N2
310 x CO2
16POTW Nutrient Removal Seminar – Salt Lake City, UT2/8/2009
BP(hosphorus)R Requires Anaerobic ZoneBP(hosphorus)R Requires Anaerobic ZoneZoneZone
AnaerobicZone Aerobic
Mixed LiquorRecirculationZone Aerobic
Zone
NRCY
RecirculationAnoxicZones
NRCY
RAS WASRASLocation
17POTW Nutrient Removal Seminar – Salt Lake City, UT2/8/2009
Johannesburg Process
Phosphorus Accumulating Organisms (PAO’s) Include:Phosphorus Accumulating Organisms (PAO’s) Include:(PAO s) Include:(PAO s) Include:
Polyphosphate Granules:•PO4 PO4 PO4 PO4 PO4PO4 PO4 PO4 PO4 PO4•Phosphate Storage•Energy Storage
Poly-β-hydroxy butyrate:Li id•Lipid
•Carbon Storage
18POTW Nutrient Removal Seminar – Salt Lake City, UT2/8/2009
PAO’s Have Unique Anaerobic/ Aerobic MetabolismPAO’s Have Unique Anaerobic/ Aerobic MetabolismAerobic MetabolismAerobic Metabolism
Anaerobic C ditiConditions
PO4-3
Energy
Aerobic Conditions
Acetate
Energy
Aerobic Conditions
PO4-3PO4
Energy
CO2 + H2O
19POTW Nutrient Removal Seminar – Salt Lake City, UT2/8/2009
2 2
O2
Four Key Biological Phosphorus Removal Principals Include:Four Key Biological Phosphorus Removal Principals Include:Removal Principals Include:Removal Principals Include:
• Exclude Nitrate From Anaerobic Zone• It’s Not the Process, It’s the Wastewater• If VFA’s Insufficient, Make Your Own• A Fat Bug is a Happy Bug
20POTW Nutrient Removal Seminar – Salt Lake City, UT2/8/2009
Stoichiometry Controls Phosphorus RemovalStoichiometry Controls Phosphorus RemovalRemovalRemoval
• Efficiency Depends on Organic Matter:– Expressed as BOD5/TPO4 Ratio; Typically Requires 15
to 25 mg BOD5/mg TPO4, Depending on Process.• Specifically Requires VFAs:p y q
– Acetic and Propionic Acid; 7 to 10 mg VFA/mg P Removed by Bio-P
• Sufficient VFAs• Sufficient VFAs– Influent Wastewater (Produced in Collection System)– Produce in Anaerobic Zone– Produce From Influent Organics– Purchase and Add
21POTW Nutrient Removal Seminar – Salt Lake City, UT2/8/2009
Sludge Fermentation Increases VFA Feed to BNR SystemsFeed to BNR Systems
PEPE
S O
Elutriationof VFA’s
PSD FO
3 Day SRTt H d l
FSDto Hydrolyzeand FermentParticulateMatter 0 1 t 0 2 VFA’ / VS F dMatter 0.1 to 0.2 mg VFA’s/mg VS Fed
POTW Nutrient Removal Seminar – Salt Lake City, UT
Many Other Configurations are Possible
Four Key Biological Phosphorus Removal Principals Include:Four Key Biological Phosphorus Removal Principals Include:Removal Principals Include:Removal Principals Include:
• Exclude Nitrate From Anaerobic Zone• It’s Not the Process, It’s the Wastewater• If VFA’s Insufficient, Make Your Own• A Fat Bug is a Happy Bug
23POTW Nutrient Removal Seminar – Salt Lake City, UT2/8/2009
Several Reactions Occur in Bio-P SystemsSeveral Reactions Occur in Bio-P SystemsSystemsSystems
Anaerobic Conditions
PO4-3
Energy
•VFA Uptake and PHA Formation(Phosphorus Release)
•Fermentation of ReadilyBiodegradable Organic Matter
Aerobic Conditions
Acetate
Energy•Denitrification (Undesirable)
Aerobic Conditions
PO4-3
•PHA Oxidation•Poly-P Formation•Poly-P LysisPO4
Energy
CO2 + H2O
y y•PAO Growth•Heterotroph Growth•Decay•Nitrification
24POTW Nutrient Removal Seminar – Salt Lake City, UT2/8/2009
2 2
O2
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