Mainstream Deammonification: Current Projects and Status S. Murthy, B. Wett and M. van Loosdrecht
Incentives for Mainstream Deammonification? 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
C:N ratio will drive combination of nitritation/denitritation and mainstream deammonification 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) influent A-stage B-stage effluent SBR thickener dewatering digester biosolids 3
Fundamentals of Nitrification - Denitrification Autotrophic Aerobic Environment 1 mol Nitrate (NO 3- ) Heterotrophic Anoxic Environment 40% Carbon 25% O 2 1 mol Nitrite (NO 2- ) 1 mol Nitrite (NO 2- ) 60% Carbon 75% O 2 1 mol Ammonia (NH 3 / NH 4 + ) Oxygen demand 4.57 g / g NH + 4-N oxidized Carbon demand 4.77 g COD / g NO - 3-N reduced ½ mol Nitrogen Gas (N 2 )
Fundamentals of Deammonification Autotrophic Aerobic Environment 1 mol Nitrate (NO 3- ) ANAMMOX Heterotrophic Anaerobic Ammonium Anoxic Environment Oxidation Autotrophic Nitrite Reduction (New Planctomycete, 40% Carbon Strous et. al. 1999) NH 4+ + 1.32 NO 2- + 0.066 HCO 3- + 0.13 H + 25% O 2 0.26 NO 3- + 1.02N 2 + 0.066 CH 2 O 0.5 N 0.15 + 2.03 H 2 O 1 mol Nitrite 0.57 mol (NO - 2-2 ) 1 mol Nitrite (NO 2- ) 60% Carbon Partial Nitrification 75% 40% O 2 1 mol Ammonia (NH 3 / NH 4 + ) Oxygen demand 1.9 g / g NH + 4-N oxidized ½ 0.44 mol mol Nitrogen N 2 + 0.11 GasNO - 3 (N 2 )
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 Reference H. Siegrist, D. Salzgeber, J. Eugster, A. Joss, Water Sci. Technol. 57, 383 (2008).
Level of innovation How mature is deammonification technology? Main-stream Deammonification Emerging technology Side-stream Deammonification State of the Art Conventional N-removal technologies Established
Sidestream Deammonification Configurations Reactor configuration examples: SBR-type Process DEMON Attached growth MBBR process Deammon AnitaMox Upflow granulation process CANON/Anammox DEMON SBR MBBR Upflow Granulation Process
Side-stream applications: DEMON DEMON-features ph-based process control cyclone for anammox enrichment 2004 2013
Side-stream applications: Paques Granular Sludge Anammox Features Granular Sludge Based Continuous Aeration Load controlled
How to implement anammox bacteria in municipal wastewater treatment? 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)
Mechanisms for NOB-repression? 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,...) - Oxygen - Nitrite lag
Anammox- Diffusion Resistance Sidestream Process Niche Environments Integrated Fixed Film AS Moving Bed Biofilm Reactor Substrate/Inhibitor Diffusion Resistance Activated Sludge Lowest Granular Sludge- Moderate Carrier Biofilm- Highest D Activated Sludge with Cyclone Granular Sludge Full-Scale Implementation Examples: Activated Sludge = DEMON (2004) AS w/ Cyclone = DEMON (2007) Granular Sludge= CANON/Anammox IFAS = BDG Configuration MBBR = Anitamox, Deammon Activated Sludge Ammonia Oxidizing Bacteria - Diffusion Resistance
Anammox- Diffusion Resistance Mainstream Process Niche Environments Integrated Fixed Film AS Moving Bed Biofilm Reactor Substrate/Inhibitor Diffusion Resistance Activated Sludge Lowest Granular Sludge- Moderate Carrier Biofilm- Highest D Activated Sludge with Cyclone Granular Sludge Activated Sludge Perhaps possible in tropical climates. Anammox retention approaches needed for colder temperatures Ammonia Oxidizing Bacteria - Diffusion Resistance
Anammox enrichment options Anammox enrichment Anammox Bioaugmentation from the sidestream Anammox Retention (long SRT maintained in granules or biofims)
Anammox Retention Approaches Granulation: 1) Settlers (internal or external) 2) Cyclones 3) Sieves Biofilm: 4) Plastic Media
Anammox- Diffusion Resistance Mainstream Process Niche Environments Integrated Fixed Film AS Activated Sludge with Cyclone Uncouple SRTs for AnAOB and AOB/NOBs Ammonia Oxidizing Bacteria - Diffusion Resistance
WERF-Mainstream Deammonification Project 3 different sites and scales DC Water WWTP Strass HRSD
Oxygen- and nitrogen affinities SNPR (mgn/gvss.d) Specific growth rate (1/d) Specific growth rate (1/d) From: Current WERF Study Extracted From: Chandran and Smets (2005) Water Research, 39, 4969 200 180 160 140 120 100 80 60 40 20 0 1 0.8 0.6 0.4 0.2 0 1 0.8 0.6 0.4 0.2 A - AOB A - NOB AOB Monod NOB Monod AOB 0 1 2 3 4 Dissolved Oxygen, mg/l AOB NOB 0.0 0.5 1.0 1.5 2.0 DO (mg/l) NOB 0 0 1 2 3 4 Ammonia (AOB) or nitrite (NOB), mg-n/l
MODEL PARAMETER CALIBRATION Simulation Results DO Profiles N Profiles AMX Activity High/Intermittent aeration -21-
Demonstration of mainstream deammonification Carousel type aeration tank at Strass WWTP providing a DOrange of 0 to 1.7 mg/l along the flow-path. DO=1.4-1.5 mg/l 0.19 mg/l 0.35mg/L 0.6mg/L 0.09mg/L 0.01 1.6-1.7mg/L Cyclones installed at the B- stage in Strass, Cyclone A (left), Cyclone B since early September 2011 (right).
temperature ( C) PE (60gBOD) 350000 300000 250000 2010/2011 loading PE 2011/2012 loading PE Full-scale experiments at WWTP Glarnerland 200000 150000 100000 50000 20 18 16 14 12 10 8 6 4 2 0 0 1-Dec 31-Dec 30-Jan 29-Feb 30-Mar 29-Apr 29-May plant loading profiles (PE) before and after project start 2010/2011 temperature 2011/2012 temperature 1-Dec 31-Dec 30-Jan 29-Feb 30-Mar 29-Apr 29-May comparison of temperature profiles ( C)
nitrogen concentration (mg N/L) nitrogen concentration (mg N/L) 25 2010/2011 NO3-N effluent 2010/2011 NO2-N effluent 2011/2012 NO3-N effluent 2011/2012 NO2-N effluent Full-scale experiments at WWTP Glarnerland 20 15 10 5 0 1-Dec 31-Dec 30-Jan 29-Feb 30-Mar 29-Apr 29-May Comparison of this year s and last year s operational data of the full-scale pilot Strass indicating 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) 60 2010/2011 NH4-N influent 2010/2011 NH4-N effluent 2011/2012 NH4-N influent 2011/2012 NH4-N effluent 50 40 30 20 10 0 Total SRT 1-Dec 31-Dec 30-Jan 29-Feb 30-Mar 29-Apr 29-May
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
Nitrite shunt at PUB s Changi WRP in Singapore Step-feed BNR operated at 2.5 d aerobic SRT shows higher nitrite vs nitrate effluent values: NH4-N NO2-N NO3-N Avg 1.7 1.1 1.0 Q=800.000 m3/d (PUB; Dr. Yeshi Cao)
Anammox- Diffusion Resistance Mainstream Process Niche Environments D Granular Sludge Moving Bed Biofilm Reactor Provide conditions for AnAOB inside granule and AOB/NOBs surface of granule Ammonia Oxidizing Bacteria - Diffusion Resistance
Biomass Segregation in Granular Sludge NOB seem to be outcompete in larger granules NOB, Anammox, AOB NOB have preference for small granules Selection criterium
Test reactor Fed with A-stage effluent Amended with nitrite Pure anoxic 3 gvss/l Conversion capacity at 2.5 kgn/m3.day at 15 C Effective growth of anammox bacteria No negative effect of wastewater COD Growth of anammox bacteria at low T and wastewater conditions is no limitation
WWTP Dokhaven Pilot Size 4 m3 A-stage effluent 10-20 C 75 mgcod/l 30 mg NH4-N/L Granulation O.K.
Pilot-scale reactor Process Parameters: Actual A-stage effluent Continuous system TPS COD: 75 mgcod/l NH 4 : 30-40 mg-n/l COD/N ratio: ~ 2 Volume reactor: 4 m 3 Biomass: ~ 5 gvs/l DO: 0.4-0.5 mg/l Results: Removal Rate: Tot N: 0.03 kgn/m 3 /d Max Tot N: 0.31 kgn/m 3 /d Current B-stage removal rate:: 0.05-0.1 kgn/m 3 /d granules retained in the system No entrapment of influent solids
Summary and conclusions: Different technologies providing different diffusion resistance 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: Potential NOB-outselection strategies Aggressive Aerobic SRT Management Ammonia Residual (online ammonia control) AOB Bioaugmentation Granule size High DO Intermittent Aeration with rapid Transitions to Anoxia