Biological Nutrient Removal

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


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?


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


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


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


Aeration Basin DO, mg/l





Two Professionals Study Foam Problem!Two Professionals Study Foam Problem!Problem!Problem!

NocardiaNocardiaCan Be Fun!Can Be Fun!


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


Selective Foam Wasting is a Proven TechniqueSelective Foam Wasting is a Proven TechniqueTechniqueTechnique






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


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


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!




Ni Ni i NO N O N– Nitrate → Nitrite → NO → N2O → N2

310 x CO2


BP(hosphorus)R Requires Anaerobic ZoneBP(hosphorus)R Requires Anaerobic ZoneZoneZone

AnaerobicZone Aerobic

Mixed LiquorRecirculationZone Aerobic

Zone

NRCY

RecirculationAnoxicZones

NRCY

RAS WASRASLocation


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


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


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


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


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


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


2 2

O2

Biological Nutrient Removal 101Biological Nutrient Removal 101

Glen T. Daigger, Ph.D., P.E., BCEE, NAESenior Vice President andChief Technology Officer

25POTW Nutrient Removal Seminar – Salt Lake City, UT 2/8/2009

Documents

Biological Nutrient Removal