Effect of aeration rate on the emission of N_2O in anoxic-aerobic sequencing batch reactors (A/O SBRs)(ENVIRONMENTAL BIOTECHNOLOGY)

概要

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Nitrous oxide (N_2O) is a significant greenhouse gas, and biological nitrogen removal systems have been shown to be a significant N_2O source. To evaluate the control parameters for N_2O emission in the wastewater treatment process, N_2O emissions were compared in the activated sludge from anoxic-aerobic sequencing batch reactors (A/O SBRs) acclimated under different aeration rates, and fed with synthetic wastewater. Results showed that a higher aeration rate led to a smaller N_2O emission, while reactors acclimated under mild aeration performed the best in terms of nitrogen removal efficiency. Most of the N_2O was produced during the aerobic phase, regardless of the aeration rate. Trace studies showed that incomplete denitrification appeared to be the major process responsible for high N_2O emission at a low aeration rate (Run 1), while incomplete nitrification was the reason for N_2O emission at a higher aeration rate (Run 2 and Run 3). For enhancing the efficiency of nitrogen removal while lowering energy consumption and reducing N_2O emission, the optimal aeration rate would be 2.7 L_<air>/(L_<reactor>・h), in terms of the synthetic wastewater used.