Sludge liquid treatment with Combined Nitritation / Anammox

Transcription

1 Sludge liquid treatment with Combined Nitritation / Anammox Adriano Joss, Clémentine Cyprien, Sabine Burger, Michel Blunschi, Steffen Zuleeg, Hansruedi Siegrist Neptune Meeting 26 March 21 Quebec Neptune workshop: Technical Solutions for Nutrient and Micropollutants Removal in WWTPs Université Laval, Québec, March 2526, 21

2 Contents Scope of sludge liquid treatment The process Process control Greenhouse gas emission Nitritation/Anammox ZürichWerdhölzli Conclusion 2

3 Nitrogen fluxes in wastewater treatment Primary settling tank 156% Nitrification Settling tank 257% 1% Supernatant 12% 2% 152% Sludge 152% Digestor Sludge thickening 3

4 Nitrogen fluxes in wastewater treatment Primary settling tank 156% Nitrification Settling tank 257% 156% 1% Treated supernatant 12% 2% 152% 3% Sludge 152% % N 2 Separate biological treatment Digestor Sludge thickening 4

5 Nitrogen fluxes in wastewater treatment HRT: 1h 2h Aeration: 156% 25% Primary settling Nitrification tank Settling tank 257% 156% 1% Treated supernatant 12% 2% Digestor Biogas: 25% 152% 3% Sludge Sludge thickening 152% % N 2 Separate biological treatment 5

6 Nitrogen fluxes in wastewater treatment Primary settling tank 156% Nitrification Settling tank 257% 156% 1% Treated supernatant 12% 2% 152% 3% Sludge % N 2 Separate biological treatment Codigestion of organic waste: 152% Increase biogas Digestor Sludge thickening Production Energy neutral wastewater treatment (WWTP Zurich, WWTP Strass) 6

7 Nitrogen elimination: conventional or anammox? Nitrification NH 4 Partial Nitritation NH 4 2 O 2 (1%) CSource (p.e. methanol: 2.2 kg/kgn) NO 3.45 NH 4 Anammox.84 O 2 (42%).55 NO 2 Nitriteoxid. NO 3.5 N 2.44 N 2.12 NO 3 Denitrification Anaerobic ammonia oxidation Advantages of anammox No organic carbon addition Reduced energy for aeration (58% saving) Less excess sludge produced Cost saving (1.55 /kgn elimin. instead of 3.1 /kgn elimin ) Disadvantages of anammox Slow growth of anammox bacteria Sensitive to nitrite, oxygen and ammonia (substrates) Three microorganisms: NH 4 oxid., NO 2 oxid., anammox 7

8 Nitritation and anammox combined in a single SBR (sequencing batch reactor) 1. Fill with supernatant 2. Aeration: partial nitritation NH O 2 NO 2 3 H 2 O 3. Stirring: anammox.45 NH 4.55 NO 2.44 N 2.12 NO 3 4. Sedimentation Piloting with a 4L reactor 5. Discharge DEMON : first single reactor process with ph control (B. Wett, Water Science & Technology, 27) 8

9 Nitritation and anammox combined in a single SBR (sequencing batch reactor) 1. Fill with supernatant 23 Simultaneous nitritation/anammox NH O 2 NO 2 3 H 2 O.45 NH 4.55 NO 2.44 N 2.12 NO 3 4. Sedimentation Piloting with a 4L reactor 5. Discharge Joss et al., Environ. Sci. Technol., 29 9

10 ms/cm mgo2/l mgnh4n/l mgno3n/l ms/cm mgo 2 /L mgnh 4 N/L mgno 3 N/L SBR cycle: two options Intermittent aeration Simultaneous nitritation and anammox O2 8 Conductivity 2 7 NH4 NO O2 Conductivity NH4 NO Continuous aeration Time (h) Time (h) (h) Aeration off Joss et al., Environ. Sci. Technol., 29 1

11 Contents Nitritation/Anammox Niederglatt Scope of sludge liquid treatment The process Process control Greenhouse gas emission Conclusion 11

12 Control parameters Crucial O 2 : inhibits anammox bacteria.5 mgo 2 /L during aeration Substrate for O 2 consumption: always >1 mgnh 4 N/L NH 3 : toxic <1 mgnh 3 N/L corresponds to <2 mgnh 4 N/L (ph 7 to 8) Sedimentation: avoid loss of biomass (bulking) Rarely required (startup): flocculant addition Nitrite oxidizers: steal NO 2, accumulate NO 3 Concentration of NO 2 <1 mgno 2 N/L Sludge withdrawal: 6 d sludge age Not crucial Temperature: only little heat generated (2 C to 35 C) 12

13 ms/cm mgo 2 /L mgnh 4 N/L mgno 3 N/L Control parameters NH 4 Recognize end of aeration & start sedimentation Decrease rate = reactor activity (oxidation and anammox) "Oxygen" Conductivity "NH4" NO Time (h) 13

14 ms/cm mgo 2 /L mgnh 4 N/L mgno 3 N/L Control parameters NH 4 Recognize end of aeration & start sedimentation Decrease rate = reactor activity (oxidation and anammox) NO 2 Accumulation can occur within hours Inhibition of anammox Condition for nitrite oxidizer growth O 2 supply too high Action: reduce O 2 supply "Oxygen" Conductivity "NH4" NO3 End of aeration >1 mgnh 4 N/L Time (h) 14

15 ms/cm mgo 2 /L mgnh 4 N/L mgno 3 N/L Control parameters NH 4 Recognize end of aeration & start sedimentation Decrease rate = reactor activity (oxidation and anammox) NO 2 Accumulation can occur within hours Inhibition of anammox Condition for nitrite oxidizer growth O 2 supply too high Action: reduce O 2 supply NO 3 Changes slow, over weeks or months Normal: 1% of NH 4 NO 3 (anammox) ph 7. Nitrite oxidizers growing into the system >2% NH 4 NO 3 ph < 6.8 Action: check NO 2 accumulation sludge retention time 6d "Oxygen" Conductivity "NH4" NO Time (h)

16 Nitritoxidation: conditions for washout NH 4 Ammonia Oxidation O 2.55 NO 2 Nitrite Oxidation? NO 3 Anammox.44 N 2.12 NO 3 <CH 2 O> Heterotrophic Denitrification? N 2 16

17 Nitritoxidation: conditions for washout NH 4 Ammonia Oxidation O 2.55 NO 2 Nitrite Oxidation? NO 3 Anammox.44 N 2.12 NO 3 <CH 2 O> Heterotrophic Denitrification? N 2 Regular operation 1. Limiting NOB growth: keep low O 2 and NO 2 2. Sludge wastage: washout 17

18 Max anammox, net rate (mgn/(l*d)) Nitrite oxidizers wash out Anammox Maximal Nitritation / Anammox delta(no3) / delta(nh4) 45% 4% 35% 3% 25% 2% 15% 1% 5% NO 3 formed per NH 4 removed (%) % Time (d) Start: sludge full of nitrite oxidizers Max anammox = substrate not limiting (NO 2 addition) Net rate = NH 4 removed / HRT Operating conditions: O 2.2 mgo 2 /L NO 2.5 mgn/l NO 3 < 2% Sludge age: 6d 18

19 Lower greenhouse gas emission Aeration energy:.7 kwh/kgo 2 Energy equivalents: 3 kgco 2 /kwh electric Methanol equivalents: 1.4 kgco 2 /kgmeoh N 2 O equivalents: 31 kgco 2 /kgn 2 O Conventional Nitrific./Denitr. Combined Nitrit.Anammox O 2 consumption kgo 2 / kg N elim Aeration energy kwh / kg N elim Aeration (CO 2 equiv.) kgco 2 / kg N elim Carbon source kg MeOH / kg N elim 2.2 Carbon source (CO 2 equ) kgco 2 / kg N elim 3.1 N 2 O production gn 2 O / kg N elim.1 to 17 4 N 2 O production (CO 2 equ) kgco 2 / kg N elim to Total CO 2 equivalents kgco 2 / kg N elim 4.5 to Katrik Chandran, personal communication, 21 Joss et al. 29, Environ. Sci. Technol. 19

20 Conclusion Combined nitritation/anammox in a single SBR: a robust solution Online sensors for process control: O 2, NH 4, NO 3 3 microbial populations are important: NH 4 O 2 Ammoniaoxid Ṅitriteoxid. Anammox NO 2 NO 3 N 2 Avoid nitrite oxidation: low O 2 NO 2 and sludge wastage Compared to conventional nitrification/denitrification: saves half of the costs for N removal reduces greenhouse impact allows energy neutral wastewater treatment 2

21 Thank you for your attention Thanks to the EU for financing NEPTUNE, 6 th Framework Programme 21