磁场强度对低温污水生物脱氮过程中N_(2)O产生特征的影响

Effect of magnetic field intensity on N_(2)O production characteristics in sewage biological denitrogenation at low temperature

为考察磁场强度对低温序批式活性污泥反应器(SBR)脱氮过程中N_(2)O产生的影响,设置4个SBR(记为R1~R4)分别在0、10、45、75 mT的磁场强度下低温(10℃)运行。结果表明,磁场可有效削减低温SBR硝化和反硝化过程中N_(2)O的产生和释放,并提高COD、总氮和氨氮去除率。这是因为磁场能够增强低温下活性污泥中微生物的活性,进而提升氨单加氧酶(AMO)、硝酸盐还原酶(NAR)、亚硝酸盐还原酶(NIR)、羟胺氧化酶(HAO)和N_(2)O还原酶(NOS)活性。菌群结构分析表明,在磁场作用下,SBR活性污泥中具有反硝化和还原N_(2)O功能的微生物丰度均有明显提升;4个SBR中,R3的N_(2)O释放量最低,相对于R1减少了67.07%,说明45 mT的磁场强度对SBR低温脱氮过程N_(2)O削减效果最明显。

Four sequencing batch reactors(SBR)(referring to R1-R4)were set up and operated at low temperature(10℃)to investigate the effect of magnetic field intensity(0,10,45,75 mT)on N_(2)O production during denitrogenation process in SBR at low temperature.The results showed that magnetic field could effectively reduce the generation and emission of N_(2)O during the nitrification and denitrification process of SBR at low temperature,and the removal efficiency of COD,total nitrogen and ammonia nitrogen was also enhanced.This was because the magnetic field could effectively enhance the microbial activities of activated sludge at low temperature,thereby improving the activities of ammonia monooxygenase(AMO),nitrate reductase(NAR),nitrite reductase(NIR),hydroxylamine oxidase(HAO)and N_(2)O reductase(NOS).Analysis of microbial community structure showed the abundance of denitrifying and N_(2)O reducing bacteria in activated sludge significantly increased under the existence of magnetic field.Among the four SBR,R3 had the lowest N_(2)O emission,which decreased by 67.07%compared with R1,indicating that the 45 mT magnetic field intensity had the most obvious N_(2)O reduction effect in SBR biological denitrogenation process at low temperature.