碳氮比对AOA-SBR同步脱氮除磷性能及N2O释放的影响

CHARACTERISTICS OF DENITRIFYING PHOSPHORUS REMOVAL AND N_2O EMISSION OF AN AOA-SBR UNDER DIFFERENT CARBON TO NITROGEN RATIOS(C/N)

通过逐步减少外加碳源降低进水碳氮比(C/N)、降低好氧曝气速率、延长好氧和缺氧阶段停留时间的方式,在厌氧/好氧/缺氧交替运行的SBR反应器(AOA-SBR)内,成功实现了生活污水同步脱氮除磷过程(SNDPR),并利用化学计量学方法考察了不同反应条件下AOA-SBR内PAOs、GAOs间竞争特性,确定了系统脱氮除磷性能及N2O释放。结果表明:C/N降低同时减少好氧曝气量,增加好氧停留时间,有利于AOA-SBR内PAOs增殖,促进了反硝化除磷过程;C/N由7.0降至3.3,反应器平均TN去除率均达到80%以上,平均TP去除率则由65.2%增至81.2%。不同C/N条件下,AOA-SBR内厌氧、缺氧、好氧阶段微生物内源物质变化均呈现PAOs-GAOs共存特性,高COD/N条件下(COD/N=7.0),AOA-SBR倾向于富集GAOs的内源物质变化特性。高C/N条件促进了DGAOs内源反硝化过程,N2O释放量增加,低COD/N条件下(COD/N=3.0),DPAOs大量增殖,DGAOs-DGAOs两者耦合内源反硝化过程,促进了N_(2)O还原,减少了N2O释放;C/N由7.0降至3.3,N_(2)O释放量由2.23 mg/L降至1.05 mg/L,产率由7.21%降至3.94%。DGAOs内源反硝化与DPAOs反硝化除磷过程协同,能够充分利用原水中碳源,破解城市生活污水脱氮瓶颈。

In the paper,the simultaneous nitrogen and phosphorus removal process(SNDPR)of domestic sewage was accomplished in the anaerobic/aerobic/anaerobic SBR(AAO-SBR)by gradually reducing the external carbon source addition,to reduce the carbon nitrogen ratio(C/N)of influent water,reducing the aerobic aeration rate,and increasing the residence time of aerobic and anoxic stages.The competition between PAOs and GAOs in AOA-SBR under different reaction conditions was investigated by the stoichiometric method,and the nitrogen and phosphorus removal performance,as well as the N_2O emission ratio of the system were determined.The results showed that reducing the aerobic aeration rate and increasing the aerobic residence time were conducive to the proliferation of PAOs in AOA-SBR under the condition of low carbon to nitrogen ratio,which promoted denitrification and phosphorus removal.When the C/N ratio decreased from 7.0 to 3.3,the average TN removal rate reached more than 80%,and the average TP removal rate increased from 65.2%to 81.2%.Under different C/N conditions,the changes of microbial endogenous substances in AOA-SBR at anaerobic,anoxic and aerobic stages showed the coexistence characteristics of PAOs-GAO.AOA-SBR tended to enrich the characteristics of GAOs endogenous substances at a higher C/N.Higher C/N condition promoted the endogenous denitrification process of DGAOs and increased the release of N_2O,and lower C/N promoted the proliferation of DPAOs.The coupled endogenous denitrification process of DGAOs-DGAOS promoted the reduction of N_(2)O,which reduced the emission of N_2O.As the C/N decreased from 7.0 to 3.3,the N_(2)O release decreased from 2.23 to 1.05 mg/L,and the emission ratio decreased from 7.21%to 3.94%.The collaboration between DGAOs endogenous denitrification and DPAOs endogenous denitrification phosphorus removal processes can make full use of carbon sources in raw domestic sewage,which may break the bottleneck of nitrogen removal in urban domestic sewage.