Developments in Mainstream Deammonification and Nitrite Shunt Haydée De Clippeleir

Transcription

1 Developments in Mainstream Deammonification and Nitrite Shunt Haydée De Clippeleir LIFT Shortcut Nitrogen Removal Focus Group Webmeeting October 27, 2015

2 Outline Short-cut N removal Why mainstream? Challenges Technological approaches Achievements

3 Autotrophic Bacteria Aerobic Environment Nitrogen Removal Conventional Nitritation-Denitritation Nitrification-Denitrification = Nitrite Shunt Heterotrophic Bacteria Anoxic Environment 75% O 2 (energy) ~100% Alkalinity 25% O 2 (energy) 1 mole Nitrite (NO 2- ) Ammonia Oxidizing Bacteria (AOB) 1 mole Nitrate (NO 3- ) Nitrite Oxidizing. Bacteria (NOB) 40% Carbon (BOD) 1 mole Nitrite (NO 2- ) 60% Carbon (BOD) 1 mole Ammonia (NH 3 / NH 4 + ) Nitrification Nitritation Denitritation Denitrification ½ mol Nitrogen Gas (N 2 )

4 Nitrogen Removal 3.0 Partial Nitritation-Anammox = Deammonification Autotrophic Bacteria Aerobic Environment 37% O 2 (energy) ~50% Alkalinity ½ mole Nitrite (NO 2- ) 1 mole Ammonia (NH 3 / NH 4 + ) Ammonia Oxidizing Bacteria (AOB) Autotrophic Bacteria Anoxic Environment ½ mol Nitrogen Gas (N 2 ) + some Nitrate(NO 3- ) Advantages: 63% reduction in oxygen demand (energy) Nearly 100% reduction in carbon demand 80% reduction in biomass production

5 Cost Savings, $MM/Yr Payback Period, Yrs Drivers for mainstream External C source costs $14 $12 $10 Cost Savings $8 2.0 $6 1.5 $4 1.0 $2 0.5 $ % 20% 40% 60% 80% 100% Nitrogen Removed by Deammonification, % Carbon Electricity Total Cost Payback (Years) Energy as short-cut N removal: decreases aeration demand for N removal decreases need for C

6 Global concept short-cut N deammonification Minimum energy consumption for concentration and polishing of remaining C and N Maximum energy recovery from concentrated organics

7 Energy autarky? No shortcut needed; Nitrite shunt; Deammonification in sidestream; Deammonification in mainstream A minimum COD capture in primary sludge of 50% is needed From COD/N < 10, mainstream deammonification becomes essential to achieve energy autarky Reference: WEF and WERF, 2015, Shortcut nitrogen removal nitrite shunt and deammonification, Chapter 7

8 Challenges Management of populations 1. NOB out-selection (max. AerAOB rates) 2. AnAOB retention

9 Approaches Fully granular system Biofilm system Hybrid (Floc/granule) system 2-stage: 2-step: Suspended + biofilm

10 Leading research groups TU Delft (NL)/Paques (NL) Ghent University/Colsen (BE) University in Santiago de Compostela / Aqualia (Spain) - Veolia - Eawag - Lund University (E. Plaza) - Karlsruhe Institute of Technology (Susanne Lackner) - Columbia University (Kartik Chandran) WERF team (including DC Water, HRSD, AraConsult, etc) PUB Singapore VCS Denmark, AlexRenew (CH2M) - WERF team (including DC Water, HRSD, AraConsult, etc) - Beijing University of Technology

11 GENERAL CONCEPT INFO

12 Fully granular system All in one - granule

13 Biofilm system All in one - biofilm

14 Hybrid (Floc/granule) system Deammonification AnAOB only granule + AerAOB/NOB/OHO floc

15 NH4-N DO = set point DO Controller/ PLC Aerobic Duration Controller/ PLC NOx-N/NH4-N = setpoint 2-stage: 2-step: Suspended + biofilm D.O. D.O. D.O. D.O. NO2-N NO3-N AerAOB/NOB/OHO floc AnAOB biofilm M S Air A-stage HRAS B-stage AVN Anammox MBB WAS Inf Air Grady et al (2011) Biological Wastewater Treatment, 3rd Edition IMLR Batchelor, B (1983). Simulation of single-sludge nitrogen removal. Journal of Environmental Engineering RWI Influent Air RAS WAS RAS

16 ANAOB RETENTION

17 AnAOB retention Granule Biofilm (+ enrichment) Hybrid (Floc/granule) system 2-stage: Suspended Biofilm + biofilm

18 SRT separation by external selectors (cyclone/screen) ml/g Retained Mixed liquor Filtrate SVI SVI bioaugmentation

19 SRT separation 1 SRT AnAOB retention Granule Biofilm (+ enrichment) SRT separation by Hybrid external selectors (cyclone/screen) (Floc/granule) system Bio-augmentation 2-stage: Suspended Biofilm + biofilm

20 NOB OUT-SELECTION

21 Approaches - Aerobic volume control (DO ~ 1 mg O 2 /L dependent on N load) - Ammonium residual - Nitrite levels are low - SRT of flocs = HRT = ~2.5h Biofilm system Hendrickx et al. 2015, mainstream deammonification workshop, Beijing, China

22 Nitrite accumulation ratio (NO2-N/NOx-N) NOB out-selection Low DO ( mg O2/L) Ammonium residual Biofilm thickness control Centrate exposure R#1 R#2 R#3 R#4 R#5 R#6 R#7 R#8 R# M# M# M# M# M# M# M# M# M# day

23 Specific growth rate (1/d) mgn/l.d Operation at high DO (1.5 mg O2/L) Operation at NH4 residual (1-2 mg N/L) mg/l (AOB:NH 4+ -N, NOB:NO 2- -N) 3. Aerobic anoxic transitions (low NO2-N 0 to aerobic cells) mu-aob mu-nob 4. Aggressive aerobic SRT operation AOB rate Ko AOB ~ 0.5 mg/l DO (mg/l) NOB rate high DO (1.5 mg O2/L) NH4 residual (1-2 mg N/L) Aerobic anoxic transitions (low NO2- N to aerobic cells) Aggressive aerobic SRT operation high DO (1.5 mg O2/L) 2-stage: NH4 residual (1-2 mg N/L) Suspended + biofilm Aerobic anoxic transitions (low NO2- N to aerobic cells) Aggressive aerobic SRT operation

24 NOB out-selection Ammonium residual Aerobic volume control (DO ~ 1 mg O 2 /L dependent on N load) Ammonium residual Nitrite levels are low SRT of flocs = HRT = ~2.5h Low DO ( mg O2/L) Ammonium residual Biofilm thickness control Centrate exposure S P A C E high DO (1.5 mg O2/L) NH4 residual (1-2 mg N/L) Aerobic anoxic transitions (low NO2-N to aerobic cells) Aggressive aerobic SRT operation high DO (1.5 mg O2/L) NH4 residual 2-stage: (1-2 mg N/L) Aerobic anoxic transitions (low NO2-N to aerobic cells) Aggressive aerobic SRT operation Suspended + biofilm T I M E

25 IN GENERAL.

26 NOB out-selection Main challenge Based in achieving high AerAOB rates Maintain NH 4 residual Avoid nitrite availability in aerobic zones minimal Use DO to control final AerAOB rate Balance aerobic rate with anoxic activity AnAOB retention retain excess AnAOB mass (granule/biofilm)

27 SHORT- CUT N REMOVAL ACHIEVEMENTS

28 Achievements Veolia Paques DC Water HRSD NH4 removal % ±7 79/87 N total removal % ±6 60/77 NO3 prod /NH4 cons % ±5 17/13 NH4 out mg N/L ±1.7 7/4 NO2 out mg N/L ±0.5 2/0.1 NO3 out mg N/L - - 5±1 4/3.6 Hendrickx et al and Hong et al 2015 mainstream deammonification workshop, Beijing, China DC Water: summer proof of concept data Regmi et al. 2105, WS&T, average data.

29 Thanks Haydee De Clippeleir, PhD.