Advanced Wastewater Treatment Process

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1 7 th Workshop on Greenhouse Gas Inventories in Asia Possibly Co-benefit? Advanced Wastewater Treatment Process Tomonori ISHIGAKI Dept. of Environmental Solution Technology Ryukoku University, Japan

2 Introductory topic on GERF B-071 Upgrading of GHGs Inventory and Evaluation of Countermeasure for Emission Reduction in Waste category Joint Research by National Institute for Environmental Studies (NIES), Osaka Univ., Ryukoku Univ. Works by Osaka Univ. (Prof. Ike, Prof. Soda) Detailed outcome will be presented at 3 rd IWAp ASPIRE (Oct. 2009, Taipei)

Institute for Environmental Studies (NIES), Osaka Univ., Ryukoku Univ.

3 Emission Estimation IWWTP, Sewer E =EF x A E : Amount of CH4 or N2O emitted from sewage treatment plants in conjunction with domestic/commercial wastewater treatment (kg CH4, kg N2O) EF : Emission factor (kg CH4/m3, kg N2O/m3) A : Yearly amount of IWW/sewage treated at a treatment plant (m3) Domestic Sewage Treatment Plant (mainly septic tanks) E=Σ(EF i x A i ) E : Emissions of methane and nitrous oxide from the processing of domestic and commercial wastewater at domestic sewage treatment plants (i.e. household septic tanks) (kg CH4, kg N2O) EFi : Emission factor for domestic sewage treatment plant i (kg CH4/person, kg N2O/person) A : Population (persons) requiring waste processing at domestic sewage treatment plant i per year

4 Source category and GHGs emission potential in wastewater sector (2006) Collected Types of treatment and disposal River discharge Sewers (closed and under ground) Untre eated Treated Sewers (open) Ae erobic Centralized aerobic wastewater treatment plants Sludge anaerobic treatment in centralized aerobic wastewater treatment plant CH4 and N2O emission potentials Not a source of CH4/N2O. Stagnant, overloaded open collection sewers or ditches/canals are likely significant sources of CH4. May produce limited CH 4 from anaerobic pockets. Poorly designed or managed aerobic treatment systems produce CH4. Advanced plants with nutrient removal (nitrification and denitrification) are small but distinct sources of N2O. Sludge may be a significant source of CH4 if emitted CH4 is not recovered and flared. Comments Rivers with high organics loadings can turn anaerobic Fast moving, clean. (Insignificant amounts of CH4 from pump stations, ti etc) Open and warm Must be well managed. Some CH4 can be emitted from settling basins and other pockets. Not well managed. Overloaded. CH4 recovery is not considered here. Anaerobic Aerobic shallow ponds Anaerobic lagoons Anaerobic reactors Septic tanks Unlikely source of CH4/N2O. Poorly designed or managed aerobic systems produce CH4. Likely source of CH4. Not a source of N2O. May be a significant source of CH4 if emitted CH4 is not recovered e ed and flared. Frequent solids removal reduces CH4 production. Depth less than 2 metres, use expert judgment. Depth more than 2 metres CH4 recovery is not considered here. Half of BOD settles in anaerobic tank. Uncolle ected Open pits/latrines River discharge Pits/latrines t i are likely l to produce CH4 when temperature and retention time are favourable. See above. Dry climate, ground water table lower than latrine, small family (3-5 persons) Dry climate, ground water table lower than latrine, communal (many users) Wet climate/flush water use, ground water table higher than latrine Regular sediment removal for fertilizer

Stagnant, overloaded open collection sewers or ditches/canals are likely significant sources of CH4. May produce limited CH 4 from anaerobic pockets.

5 Source Category in Japan NIR Sewage (miscellaneous) Human waste (Feces and Urine) Public sewerage system is spreading from large cities to smaller municipalities and used by 65.5% of the population. Domestic wastewater treatment systems (e.g. gappei shori jokasou) are being promoted as an effective means of supplementing sewerage systems in smaller municipalities i with low population densities and little flat land. In 2006, septic tanks (jokasou) were used by 24.1% of the population, with the remainder being treated after collection or on-site.

gappei shori jokasou) are being promoted as an effective means of supplementing sewerage systems in smaller municipalities i with low

6 Jokasou system The gappei-shori and tandoku-shori Jokasous are decentralized wastewater treatment facilities installed at an individual home. The gappei-shori processes feces and urine and miscellaneous wastewater, whereas tandoku-shori processes only feces and urine. A community plant is small-scale sewage facility where urine and the miscellaneous wastewater of each region are processed.

The gappei-shori processes feces and urine and miscellaneous wastewater, whereas tandoku-shori

7 Advanced Wastewater Treatment Conventional Activated Sludge (CAS) Process Benefit Prevention of water pollution Improvement of public water value Eutorophication in closed water body N,P removal by advanced treatment Cost, Energy Environmental impact Drawback

of public water value Eutorophication in closed water body N,P

8 Evaluation of Advanced Treatment Eutrophication potential (EP): PO 4 eq NOx, T N, T P, BOD Global Warming Potential (GWP):CO 2 eq CO2, CH4, N2O Life Cycle Impact Assessment Approach using y p pp g LIME (JEMAI)

9 Statistics on 1500 WWTPs (JSWA) Number of WWTPs a Planned effluent quality, mg/l b Annual treatment, m 3 /y (Typical removal, %) < > 10 8 BOD T-N T-P CAS (90-95) AO < 3 (75-95) Recycled < 20 (65-75) nitrification/denitrification A2O < 20 (65-75) (75 95) Nitrification/endogenous denitrification (75-95) Step-feed nitrification (75-85) denitrification Step aeration (90-95) Oxygen aeration (90-95) 95) Extended aeration (90-95) Oxidation ditch (90-95) < 3 (75-95)

A2O 5 4 2 10-15 < 20 (65-75) 4 1 0 (75 95) Nitrification/endogenous denitrification 4 1 0 (75-95) Step-feed nitrification- 0 3 2 (75-85)

10 Evaluation Target Process: Advanced Treatment for Nutrient removal (A) CAS process (B) AO process Influent PST SST Effluent Influent PST Oxic PR Anaerobic UP Oxic SST Effluent Return sludge Excess sludge Return sludge Excess sludge (C) Recycled nitrification/denitrification process Recirculation DN Influent PST SST Effluent Anoxic Oxic Return sludge Excess sludge (D) A2O process Recirculation PR DN UP Influent PST Anaerobic Oi Oxic SST Effluent Anoxic AM NF AM NF Return sludge Excess sludge (E) Nitrification/endogenous denitrification process (F) Step-feed nitrification-denitrification process Influent PST Oxic AM NF DN Anoxic SST Effluent Influent PST Anoxic Oxic DN Anoxic Oxic SST Effluent AM:ammonification NF:nitrification DN:denitrification Return sludge Excess sludge AM NF Return sludge PR:phosphorus release PU:phosphorus uptake Excess sludge

PR DN UP Influent PST Anaerobic Oi Oxic SST Effluent Anoxic AM NF AM NF Return sludge Excess sludge (E) Nitrification/endogenous denitrification process (F) Step-feed nitrification-denitrification

11 Evaluation Target Process: AT for other purpose (A) Step-aeration process (B) Oxygen aeration process Influent PST AT SST Air Oxygen generator Exhaust gas Return sludge Influent PST AT SST Effluent Return sludge Excess sludge (C) Extended aeration process (D) OD process Influent AT SST Effluent Influent SST Effluent Return sludge Excess sludge Return sludge Excess sludge

SST Effluent Return sludge Excess sludge (C) Extended aeration process (D) OD process

12 Eutrophication Potential T-P P( (efflunet) T-N (efflunet) BOD (efflunet) 15 NOx (electricity) Eutrophication (g-po 4 eq/m 3 ) Raw sewage (617) Conventional (490) Anaerobic-oxic (39) Recycled nitrification/ Denitrification n (13) Anaerobic-anoxic-oxi c (11) Nirification/Endogenous denitrifiation (5) Step-feed nitrification- (5) denitrification Step-aeration (10) Oxygen aeration (7) Extended aeration (26) Oxidation ditch (489)

nitrification/ Denitrification n (13) Anaerobic-anoxic-oxi c (11) Nirification/Endogenous denitrifiation (5)

13 Global Warming potential N2O (receiving waters) CH4 (receiving waters) N2O (biological treatment process) CH4 (biological treatment process) N2O (electricity ) CH4 (electricity) CO2 (electricity) Raw sewagee (617) Conventional (490) Anaerobic-oxic (39) Recycled nitrification/ Denitrificatio on (13) Anaerobic-anoxic-oxic (11) Nirification/Endogenous denitrifiation (5) Step-feed nitrification- (5) denitrification Step-aeratio on (10) Oxygen aeration (7) Extended aeratio on (26) Oxidation ditch (489) Global warming (kg-co 2 eq/m 3 ) 0.0

(electricity) CO2 (electricity) Raw sewagee (617) Conventional (490) Anaerobic-oxic (39) Recycled nitrification/ Denitrificatio on (13)

14 Electricity Consumption Enough nitrification needs Long SRT Electricity for recirculation of nitrified liquor Enough denitrification needs Long HRT Appilication to small scale plant Electricity per unit must be uneffective No recirculation of nitrified liquor No recirculation of nitrified liquor Anoxic tanks in the process Less electricity than full-aeration tanks

Electricity per unit must be uneffective No recirculation of nitrified liquor No

15 Trade-off Relationship Untreated Eutroph hication(g-p PO 4 eq/m 3 ) CAS 法 (490) AO 法 (39) 長時間エアレーション法 (26) OD 法 (489) 11 A2O 法 0 (11) Oxygen aeration (7) 8 CAS 循環式硝化脱窒法 (490) (13) Step OD 6 ステッフ流入式 aeration (489) 多段硝化脱窒法 (5) Extended aeration (26) -305 (10) 硝化内生 AO(39) 4 A2O (11) 脱窒法 (5) Recycled nitrification/ ifi ti 2 denitrification process (13) Step-feed nitrification 1 -denitrification 地 (5) 球温暖化影響 Nitrification/ 指標 (kg-co endogenous 2 /m 3 ) denitrification (5) Global warming(kg-co 2 eq/m 3 )

5-10 Oxygen aeration (7) 8 CAS 循環式硝化脱窒法 (490) -20 7 (13) Step OD 6 ステッフ流入式 aeration (489) 多段硝化脱窒法 (5) Extended aeration (26) -305 (10) 硝化内生 AO(39) 4 A2O (11) 脱

16 Conclusion Importance of Operation-related related GHGs (especially electricity) on GWP evaluation Negative correlation between EP and GWP values of the nutrient removal processes Endeavours to reduce the EP value of 1.0 mg-po 4 eq compensate with increase in the GWP of 86.5 g-co 2 eq. Step-feed nitrification-denitrification process only exception of the trade-off among the nutrient removal processes possible candidate for co-benefit process.

0 mg-po 4 eq compensate with increase in the GWP of 86.5 g-co 2 eq.

WASTEWATER TREATMENT AND DISCHARGE

Chapter 6: Wastewater Treatment and Discharge CHAPTER 6 WASTEWATER TREATMENT AND DISCHARGE 2006 IPCC Guidelines for National Greenhouse Gas Inventories 6.1 Volume 5: Waste Authors Michiel R. J. Doorn (Netherlands),