Emission and Control of Nitrous Oxide from a Biological Wastewater Treatment System with Intermittent Aeration

概要

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Nitrous oxide (N_2O) can be emitted as a by-product of the process of nitrogen removal from wastewater. Two methods of complete denitrification and media application were studied in lab-scale intermittent aeration reactors fed with domestic wastewater to refine methods of controlling the N_2O emission rate. A study on cyclic patterns showed that the highest N_2O emission rate was at the beginning of the aerobic phase rather than the anoxic phase. This was probably because the nitrifying bacteria had accumulated nitrite nitrogen (NO_2^-) under low DO conditions. Methanol as an external carbon source was added during the anoxic phase to reduce nitrate nitrogen (NO_3^-) when denitrification was completed. The N_2O emission rates in both the aerobic and anoxic phases were significantly influenced by residual NO_3^-, increasing monotonically as the concentration of NO_3^- in the reactor increased. Over 95%of average N_2O emissions in both the aerobic and anoxic phases were prevented when methanol was added. The biofilm reactor showed similar patterns to those of the non-biofilm reactor in track behavior, but the former was more effective in the reduction of N_2O emissions.
社団法人日本生物工学会の論文
2000-09-25