不同电子受体低氧条件下生物反硝化过程中氧化亚氮产量

PRODUCTION OF N_2O IN DIFFERENT ELECTRON ACCEPTORS DURING DENITRIFICATION PROCESS UNDER LOW DISSOLVED OXYGEN CONCENTRATION

为了考察低溶解氧条件下,不同电子受体氧化亚氮的产生,试验以SBR反应器,投加乙醇作为反硝化碳源,考查了不同电子受体反硝化过程中氧化亚氮产量。试验过程中控制初始ρ(NOx--N)=40 mg.L-1,溶解氧质量浓度为0.5 mg.L-1。结果表明,硝酸盐反硝化过程中N2O产量为0.762 mg.L-1,亚硝态氮反硝化过程中N2O产量为6.947mg.L-1,是硝酸盐反硝化过程中N2O产量的9.12倍。低氧条件下反硝化过程中大量N2O产生的主要原因可能是:(1)NO2-对氧化亚氮还原酶具有较强的抑制作用;(2)低DO的存在抑制了氧化亚氮还原酶的活性;(3)多种电子受体存在时,氧化亚氮还原酶争夺电子能力较弱。

To investigate the production of nitrous oxide with different electron acceptors during low DO,ethanol was used as carbon source and nitrate and nitrite as electron acceptors by using sequencing batch reactor in this study.The beginning NOx——N was 40 mg·L-1.and DO gradient was 0.5mg·L-1 in the denitrification process.Results showed that the production of N2O was 6.947 mg·L-1 taking nitrite as electron acceptor while nitrate 0.762 mg·L-1.The production of N2O taking nitrite as electron acceptor was 9.12 times than that of nitrate.The reasons of high production of N2O under low DO during denitification process were mainly：（1）NO2-had strong inhibition on N2O reductase;（2）the exist of low DO inhibited the activity of N2O reductase;（3）when a variety of electron acceptors existed,the capacity of electron competition of N2O reductase was weak.