部分硝化/厌氧氨氧化(PN/A)工艺对城市污水厌氧处理单元出水的强化脱氮效果

Enhanced nitrogen removal efficiency of partial nitrification/anaerobic ammonia oxidation(PN/A)on the effluent of municipal wastewater anaerobic treatment unit

为探究部分硝化/厌氧氨氧化(PN/A)工艺对城市污水厌氧处理工艺出水的强化脱氮效能,以厌氧膜生物反应器(AnMBR)出水为研究对象,比较了不同水力停留时间(HRT)下(10、8、6和4 h),PN/A系统的脱氮效率、代谢路径及微生物群落及结构特征。结果表明:随着HRT的逐渐降低,PN/A系统的脱氮效率呈现先升高后降低的趋势;HRT为6 h时脱氮效率达到最高,为81.3%;在稳定运行期间,出水TN和COD分别低至(11.97±2.44 mg)·L^(−1)和(9.98±3.42)mg·L^(−1);随着HRT缩短至4 h,anammox菌丰度随着氮负荷升高而有所提升,但水力冲刷过强破坏污泥形态等原因导致了系统脱氮效率的下降。通过对系统内COD与氮素转化的核算可知,厌氧氨氧化段内发生的部分反硝化(PD)过程是使系统脱氮效率明显提升的根本原因,而HRT为6 h时大约19%的NO_(2)^(-)-N由PD提供。本研究证明了PN/A系统作为城市污水主流脱氮工艺的可行性,可为该系统的应用提供参考。

In order to explore the enhanced nitrogen removal efficiency of partial nitrification/anaerobic ammonia oxidation(PN/A)process on the effluent of municipal wastewater anaerobic treatment process,the effluent of anaerobic membrane bioreactor(AnMBR)was taken as the research object,and the nitrogen removal efficiency,metabolic path,microbial community and structure characteristics of PN/A system under different hydraulic retention times(HRT)(10,8,6 and 4 h)were compared.The results showed that with the gradual decrease of HRT,the nitrogen removal efficiency of PN/A system increased first and then decreased.When HRT was 6 h,the nitrogen removal efficiency reached the highest,which was 81.3%.During stable operation,the total nitrogen(TN)and total chemical oxygen demand(COD)in effluent were as low as(11.97±2.44)mg∙L^(−1) and(9.98±3.42)mg∙L^(−1),respectively.With the reduction of HRT to 4 h,the abundance of anammox bacteria increased with the increased of nitrogen load,while the nitrogen removal efficiency of the system decreased due to strong hydraulic scouring and destruction of sludge morphology.According to the calculation of COD and nitrogen conversion in the system,partial denitrification(PD)process in the Anammox section was the fundamental reason for the significant improvement of nitrogen removal efficiency of the system,about 19% of NO_(2)^(-)-N was provided by PD process when the HRT was 6 h.The research results proved the feasibility of PN/A system as the mainstream nitrogen removal process of municipal wastewater,which can provide reference for the application of the system.