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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