N2O Generation,Key Influencing Factors,and Emission Reduction Strategies of A2O Process in Municipal Wastewater Treatment Plant
To achieve non-carbon dioxide greenhouse gas emission reduction and control in municipal wastewater treatment plants(WWTPs),this study conducted one-year long-term monitoring of nitrous oxide(N20)in the anaerobic-anoxic-aerobic(A20)process of a large-scale municipal wastewater treatment plant in Beijing.The experimental results showed that the anaerobic and anoxic zones of the A20 process could effectively remove dissolved N2O contained in the return sludge,while the aerobic zone was the main area for N20 generation and emission,and its generation pathway may have been dominated by ammonia oxidizing bacteria(AOB)denitrification.A significant difference was observed between winter and summer N20 production,and the difference in the average N20 release flux was up to 7.6 times,and the average monthly N20 emission in winter was 32.75 kg,which was significantly higher than that in summer(6.06 kg).The accumulation of nitrite(NO2--N)and the concentration of dissolved oxygen(DO)had a significant impact on N20 production.Therefore,to achieve N2O reduction in the A20 process,the concentration of NO2--N in the aerobic zone should be controlled below 0.40 mg·L-1 in winter and 0.10 mg·L-1 in summer,while the DO concentration should be maintained above 1.2 mg·L-1.
municipal wastewater treatment plantanaerobic-anoxic-aerobic(A2O)nitrous oxide(N20)key influencing factorsabatement strategies
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