mainstream deammonification: current projects …...mainstream deammonification: current projects...

Mainstream Deammonification: Current Projects and Status

S. Murthy, B. Wett and M. van Loosdrecht

• Carbon redirection from aerobic treatment to anaerobic digestion for improved energy balance (A/B process e.g. at WWTP Strass and WWTP Rotterdam)

• Enhanced N-removal efficiency

• Mitigating alkalinity limitations

Incentives for Mainstream Deammonification?

3

C:N ratio will drive combination of nitritation/denitritation and mainstream deammonification

dewatering

SBR

thickener

digester

biosolids

effluent

influentA-stage B-stage

dewatering

SBR

thickener

digester

biosolids

effluent

influentA-stage B-stage

dewatering

SBR

thickener

digester

biosolids

effluent

influentA-stage B-stage

• High Rate, CEPT or A-Stage: 50-80 % COD removal

• Typical C:N Ratios: CEPT – 3:1 to 6:1 (add Fe )

A- Stage – 3:1 to 10:1 (SRT of 0.25d to 0.5 d)

Fundamentals of Nitrification - Denitrification

Oxygen demand 4.57 g / g NH+4-N oxidized

Carbon demand 4.77 g COD / g NO-3-N reduced

1 mol Ammonia

(NH3/ NH4 +)

1 mol Nitrite(NO2

- )

1 mol Nitrate(NO3

- )

75% O2

Autotrophic

Aerobic Environment

1 mol Nitrite(NO2

- )

½ mol Nitrogen Gas(N2 )

25% O2

40% Carbon

60% Carbon

HeterotrophicAnoxic Environment

Fundamentals of Deammonification

Oxygen demand 1.9 g / g NH+4-N oxidized

1 mol Ammonia

(NH3/ NH4 +)

1 mol Nitrate(NO3

- )

75% O2

½ mol Nitrogen Gas(N2 )

25% O2

40% Carbon

60% Carbon

HeterotrophicAnoxic Environment

1 mol Nitrite(NO2

- )1 mol Nitrite

(NO2- )

NH4+ + 1.32 NO2

- + 0.066 HCO3- + 0.13 H+

0.26 NO3- + 1.02N2 + 0.066 CH2O0.5N0.15 + 2.03 H2O

0.44 mol N2+ 0.11 NO3-

0.57 mol NO2-

Partial Nitrification

40% O2

Autotrophic

Aerobic Environment

ANAMMOX Anaerobic Ammonium Oxidation

Autotrophic Nitrite Reduction(New Planctomycete, Strous et. al. 1999)

Net energy consumption for 3 WWTP variants

• Case A: Conventional treatment

• Case B: Conventional treatment with anammox in the side-stream

• Case C: Optimized treatment with anammox in the main-stream

ReferenceH. Siegrist, D. Salzgeber, J. Eugster, A. Joss, Water Sci. Technol. 57, 383 (2008).

How mature is deammonification technology?

Main-stream Deammonification

Emerging technology

Side-stream Deammonification

State of the Art

Conventional N-removal technologies

Established

Leve

l of

inn

ova

tio

n

Sidestream Deammonification Configurations

Reactor configuration examples:

• SBR-type Process –

– DEMON ®

• Attached growth MBBR process– Deammon ®– AnitaMox ®

• Upflow granulation process – CANON/Anammox ®

Upflow Granulation Process

DEMON SBR

MBBR

DEMON-features –• pH-based process control• cyclone for anammox enrichment

Side-stream applications: DEMON

2004 2013

Granular Sludge Anammox Features• Granular Sludge Based• Continuous Aeration – Load controlled

Side-stream applications: Paques

• Find new ways to outcompete NOB‘s

• High effluent quality required compared to side stream

• Low process temperature, slow growing bacteria→ Reliable anammox biomass retention required

• Higher C/N ratio → heterotrophs dilute the autotrophic biomass

Biomass selection to enhance short-cut metabolism depends on diffusion resistance provided from process environment (apparent half-saturation values for inhibitions and limitations)

How to implement anammox bacteria in municipal wastewater treatment?

• Competition (growth or bioaugmentation of competitors; Heterotrophs and anammox for nitrite; Heterotrophs and AOB for oxygen)

• Outselection by unfavorable process conditions (DO-level, ...)

• Lag-phase in nitrite availability (intermittent aeration)

• Inhibiting or toxic impacts on NOB (e.g. NH3, NO, ...)

Mechanisms for NOB-repression?

- Oxygen

- Nitrite

lag

Sidestream Process Niche Environments

Full-Scale Implementation Examples:Activated Sludge = DEMON (2004)AS w/ Cyclone = DEMON (2007)Granular Sludge= CANON/AnammoxIFAS = BDG ConfigurationMBBR = Anitamox, Deammon

D

Activated Sludge

Integrated Fixed Film AS

Moving BedBiofilm Reactor

Activated Sludgewith Cyclone Granular Sludge

Ammonia Oxidizing Bacteria - Diffusion Resistance

An

amm

ox-

Dif

fusi

on

Re

sist

ance

Substrate/Inhibitor Diffusion ResistanceActivated Sludge – LowestGranular Sludge- ModerateCarrier Biofilm- Highest

Mainstream Process Niche Environments

D

Activated Sludge

Integrated Fixed Film AS

Moving BedBiofilm Reactor

Activated Sludgewith Cyclone Granular Sludge

Ammonia Oxidizing Bacteria - Diffusion Resistance

An

amm

ox-

Dif

fusi

on

Re

sist

ance

Substrate/Inhibitor Diffusion ResistanceActivated Sludge – LowestGranular Sludge- ModerateCarrier Biofilm- Highest

Perhaps possible in tropical climates. Anammox retention approachesneeded for colder temperatures

• Anammox enrichment

– Anammox Bioaugmentation from the sidestream

– Anammox Retention (long SRT maintained in granules or biofims)

Anammox enrichment options

Anammox Retention

Approaches

Granulation:

1) Settlers (internal or external)

2) Cyclones

3) Sieves

Biofilm:

4) Plastic Media

Mainstream Process Niche Environments

Integrated Fixed Film AS

Activated Sludgewith Cyclone

Ammonia Oxidizing Bacteria - Diffusion Resistance

An

amm

ox-

Dif

fusi

on

Re

sist

ance

Uncouple SRTs for AnAOB and AOB/NOBs

WERF-Mainstream Deammonification Project3 different sites and scales

DC Water WWTP Strass HRSD

0

0.2

0.4

0.6

0.8

1

0 1 2 3 4Sp

ecif

ic g

row

th r

ate

(1

/d)

Dissolved Oxygen, mg/L

AOB

NOB

0

0.2

0.4

0.6

0.8

1

0 1 2 3 4Sp

ecif

ic g

row

th r

ate

(1

/d)

Ammonia (AOB) or nitrite (NOB), mg-N/L

AOB

NOBExtracted From: Chandran and Smets (2005)Water Research, 39, 4969

From:Current WERF Study

0

20

40

60

80

100

120

140

160

180

200

0.0 0.5 1.0 1.5 2.0

SNPR

(mgN

/gV

SS.d

)

DO (mg/L)

A - AOB A - NOB AOB Monod NOB Monod

Oxygen- and nitrogen affinities

MODEL PARAMETER CALIBRATIONSimulation Results

-21-

High/Intermittent aeration

DO Profiles N Profiles AMX Activity

• Carousel type aeration tank at Strass WWTP providing a DO-range of 0 to 1.7 mg/L along the flow-path.

-22-

Cyclones installed at the B-stage in Strass, Cyclone A (left), Cyclone B since early September 2011 (right).

DO=1.4-1.5 mg/L 0.19 mg/L 0.35mg/L

0.010.09mg/L0.6mg/L 1.6-1.7mg/L

Demonstration of mainstream deammonification

Full-scale experiments at WWTP Glarnerland

plant loading profiles (PE) before and after project start

comparison of temperature profiles (°C)

0

50000

100000

150000

200000

250000

300000

350000

1-Dec 31-Dec 30-Jan 29-Feb 30-Mar 29-Apr 29-May

2010/2011 loading PE 2011/2012 loading PEP

E (6

0gB

OD

)

0

2

4

6

8

10

12

14

16

18

20

1-Dec 31-Dec 30-Jan 29-Feb 30-Mar 29-Apr 29-May

2010/2011 temperature 2011/2012 temperature

tem

per

atu

re (°

C)

Full-scale experiments at WWTP Glarnerland

Comparison of this year’s and last year’s operational data of the full-scale pilot Strassindicating advanced NOB-repression (typically high nitrate level at Christmas peak-load; similar temperature conditions of ca. 10°C , load conditions and ammonia effluent concentrations of ca. 2-5 mgN/L for both years)

Total SRT

0

5

10

15

20

25

1-Dec 31-Dec 30-Jan 29-Feb 30-Mar 29-Apr 29-May

2010/2011 NO3-N effluent 2010/2011 NO2-N effluent 2011/2012 NO3-N effluent 2011/2012 NO2-N effluentn

itro

ge

n c

on

cen

tra

tio

n (

mg

N/L

)

0

10

20

30

40

50

60

1-Dec 31-Dec 30-Jan 29-Feb 30-Mar 29-Apr 29-May

2010/2011 NH4-N influent 2010/2011 NH4-N effluent 2011/2012 NH4-N influent 2011/2012 NH4-N effluent

nit

roge

n c

on

cent

rati

on

(mg

N/L

)

The last samples show

ammonia removal

during anaerobic

activity test (anammox

activity)

Only 25% of NOx

produced from

ammonia oxidation is

converted to nitrate

during aerobic

activity test of the

last sample

-26-

Step-feed BNR operated at 2.5 d aerobic SRT shows higher nitrite vsnitrate effluent values:

NH4-N NO2-N NO3-NAvg 1.7 1.1 1.0

Nitrite shunt at PUB’s Changi WRP in Singapore

Q=800.000 m3/d

(PUB; Dr. Yeshi Cao)

D

Mainstream Process Niche Environments

Moving BedBiofilm Reactor

Granular Sludge

Ammonia Oxidizing Bacteria - Diffusion Resistance

An

amm

ox-

Dif

fusi

on

Re

sist

ance

Provide conditions for AnAOB inside granule

and AOB/NOBs surface of granule

Biomass Segregation in Granular SludgeNOB seem to be outcompete in larger granules

NOB, Anammox, AOB

NOB have preference for small granules

Selection criterium

Test reactor

Fed with A-stage effluentAmended with nitritePure anoxic3 gVSS/L

Conversion capacity at 2.5 kgN/m3.day at 15 CEffective growth of anammox bacteriaNo negative effect of wastewater COD

Growth of anammox bacteria at low T and wastewater conditions is no limitation

WWTP Dokhaven Pilot

Size 4 m3A-stage effluent10-20 C75 mgCOD/L30 mg NH4-N/L

Granulation O.K.

Pilot-scale reactor

Process Parameters:Actual A-stage effluentContinuous systemTPSCOD: 75 mgCOD/LNH4 : 30-40 mg-N/L COD/N ratio: ~ 2Volume reactor: 4 m3

Biomass: ~ 5 gVS/LDO: 0.4-0.5 mg/L

Results:Removal Rate:Tot N: 0.03 kgN/m3/dMax Tot N: 0.31 kgN/m3/dCurrent B-stage removal rate::0.05 - 0.1 kgN/m3/d

• granules retained in the system• No entrapment of influent solids

– Per se nothing good or bad about diffusion resistance

– “Real” half-saturation values are close to zero while

“apparent” half-saturation is mainly affected by diffusion

– Each technology needs to differentiate niche environments

to provide appropriate SRT and diffusion conditions for

selected microbial community

Summary and conclusions: Different technologies providing different diffusion resistance

– Aggressive Aerobic SRT Management

– Ammonia Residual (online ammonia control)

– AOB Bioaugmentation

– Granule size

– High DO

– Intermittent Aeration with rapid Transitions to Anoxia

Summary and conclusions: Potential NOB-outselectionstrategies