quality improvement and GHG reduction in

Transcription

1 New approaches to the coexistence of water quality improvement and GHG reduction in wastewater treatment Challenges of the Bureau of Sewerage, Tokyo Metropolitan Government toward the shift in operation management of activated sludge process in all Water Reclamation Centers in Tokyo

2 Background GHG Reduction in Japan National Commitment of Japan Regulation by Tokyo Metropolitan Government Earth Plan 2010 Improvement of Water Quality Closed Tokyo Bay Red Tide and Oxygen-Deficient Water Strict Regulation of Nitrogen and Phosphorus 1

3 Sources of GHG on Wastewater and Sludge Treatment CO 2 N 2 O Wastewater Treatment Consumption of Electricity By-product through Nitrification Sludge Treatment Combustion of Fuel Combustion of N 2 2

4 Trade-off between GHG Reduction and Improvement of Water Quality 16 Typical Average Total Nitrogen in Treated Wastewater (mg/l) A 2 /O Process Recycled Nitrification / Denitrification Process Conventional Activated Sludge Process orus in L) tal Phospho ewater (mg/l Average To eated Waste Typical Tr *Size of the circle indicates the ratio of GHG emission. Innovative Ideas are required for the coexistence of GHG reduction and Improvement of Water Quality. 3

5 Approaches on O&M in Wastewater Treatment Air Flow Control using Ammonia + DO Restricted-aeration A 2 /O Feed-forward Air Flow Control using EC Intermittent Operation of Agitator Microscopic i Bubble Aeration and so on. 4

6 Air Flow Control using Ammonia + DO Flow Diagram of the System Control using DO DO meter Controller anaerobic zone aerobic zone Influent Effluent Blower M A zone B zone C zone D zone Direction of air flow Control using DO + Ammonia NH 4 meter DO meter Controller anaerobic zone aerobic zone Influent Effluent Blower M A zone B zone C zone D zone Direction of air flow 5

7 Air Flow Control using Ammonia + DO Oxygen Demand in Aeration tank Oxidation of Organic Loading ~40% Nitrification ~30% Endogenous Respiration 30% ~20% Ammo onia Conce entration, Degree of Treatment Ordinary Aeration Optimized Aeration Preservation of DO Concentration ~10% 6

8 Air Flow Control using Ammonia + DO Investigation Prim mary Sedime entation Tank A zone (anaerobic) Fixed DO control Fixed DO control B zone (aerobic) Fixed DO control(reference) Ammonia+DO Control(Experiment) Ammonia meter C zone (aerobic) DO meter D zone (aerobic) Seco ondary Sedim mentation Tan nk Control Target Value DO (mg/l) Ammonia +DO NH4 -N (mgN/L) Fixed DO DO (mg/L) 7

9 Air Flow Control using Ammonia + DO Results (Transition of Relative Air Flow and Ammonium) Reduction of Air Flow (approx. -10%) and nearly full Nitrification when dry weather 8

10 Air Flow Control using Ammonia + DO Future Plans Optimization through all Seasons Establishment of Operation Conditions during wet weather Installation to other WWTPs 9

11 Restricted-aeration A 2 /O Process A 2 /O Process Flow of the Process Influent effluent Anaerobic Anoxic Oxic Restricted-aeration A 2 /O Process (Adaption from Conventional Process) Partition Wall Influent effluent Circulating Pump Restricted Aeration 10

12 Restricted-aeration A 2 /O Process Water Quality of Influent and Treated Wastewater of each Process Influent water Restrictedaeration A 2 /O process Conventional Activated Sludge Process A 2 /O process Ave. Max. Min. Ave. Max. Min. Ave. Max. Min. Ave. Max. Min. BOD(mg/L) T-N(mg/L) NH4-N(mg/L) T-P(mg/L) PO4-P(mg/L) Removal Efficiency of Restricted-aeration A 2 /O process Nitrogen : same as A 2 /O process Phosphorus : same as Conventional Process 11

13 Restricted-aeration A 2 /O Process Nitrogen removal in restricted-aeration A 2 /O system 100% 80% Secondary effluent Fate of T-N 60% 40% 20% Denitrification in aeration process Denitrification between secondary sedimentation and anaerobic process Emission as excess sludge 0% Restricted-aeration A 2 /O Process Conventional Activated Sludge Process A 2 /O Process 12

14 Restricted-aeration A 2 /O Process Phosphorus removal in restricted-aeration A 2 /O system ity of T-P (g/m 3 /day y) Eliminati ion Quant Restricted-aeration A 2 /O process A 2 /O process BOD Volumetric Loading (kg/m 3 /day) Potential to Remove Phosphorus as much as A 2 /O Process 13

15 Restricted-aeration A 2 /O Process Electric Power Consumption unt per Amou h/m 3 ) nsumption water (kwh Power Con d Wastew Electric P of Treated Agitator Nitrified liquor circulation Blower Conventional Restricted A 2 /O Process Activated -aeration Sludge A 2 /O Process Process 14

16 Restricted-aeration A 2 /O Process Future Plans Optimization for Phosphorus Removal Establishment of Designing Conditions Authorization as Advanced Treatment Process in Japan Installation to other WWTPs 15

17 Feed-forward Air Flow Control using EC DO Concentration during Changing Amount of Influent with Air Flow Control using DO at the End of Aeration Tank Pollution Load Aeration Tank Time Water Flow DO Concentration Oxygen Demand 16

18 Feed-forward Air Flow Control using EC Results (Transition of EC and Correlation with Water Quality) mm), EC (ms/m m) rainfall (m /1 4/1 5/1 6/1 Tendency of Low EC When Wet Weather CO OD (mg/l) NH H 4 -N (mg/l) EC (ms/m) EC (ms/m) Good Correlation between EC and Water Quality 17

19 Feed-forward Air Flow Control using EC Results (EC of Primary Effluent and DO) EC of Influent to Aeration Tank Constant Air Flow DO Controlled (Feedback) Supplied dair Flow DO at the End of the Aeration Tank Optimization of Air Flow with Feed-forward Control using EC? 18

20 Feed-forward Air Flow Control using EC Future Plans Further Investigation Organize Necessary Conditions for Feed-Forward Control Estimation of Cost and GHG Reduction 19

21 Summary Air Flow Control using Ammonia + DO 10%of GHG Reduction with full Nitrification Restricted-aeration A 2 /O GHG Reduction with Similar il Water Quality As Advanced Wastewater Treatment Process Feed-forward Air Flow Control using EC Close Relationship between EC of Influent and Aeration Condition 20

22 This presentation was made on WEFTEC 2011 in Los Angeles. Upload was made possible with the courtesy of the author and WEF. About WEFTEC, please access For more information about the presentation, ti please contact Secretariats of GCUS answer your inquiry on behalf of author after consultation with author. About GCUS, please access