AO两级生物滤池的同步硝化反硝化脱氮试验

Experiment of Simultaneous Nitrification and Denitrification for Nitrogen Removal in Two-Stage AO Biological Filter

针对现行污水处理厂市政二级出水脱氮效果差的问题,文中构建了具有同步硝化反硝化功能的缺氧-好氧(AO)两级生物滤池工艺,研究了进水碳氮比(C/N)、回流比及溶解氧(DO)浓度对反应器脱氮效果的影响,并在最优工况条件下进行了处理效能试验。结果表明:进水的C/N为4∶1时,系统的脱氮效果最佳,并且在缺氧段实现了氨氮与硝态氮同步去除,持续提高C/N,系统整体处理效果并无明显增强;系统的脱氮效能随着回流比的提高而降低,选用最低回流比(100%)为最佳处理工况之一;好氧柱中的DO含量为2 mg/L时,回流至缺氧段的DO浓度最低,系统处理效果最佳。在选定的最优工况条件下,反应器运行稳定,系统出水中氨氮、总氮和化学需氧量(COD_(Cr))的平均质量浓度分别为(0.026±0.001)、(4.210±0.352)mg/L和(12.560±1.033)mg/L。数据表明该系统在最优工况条件下运行情况良好,脱氮效果明显,处理后水质指标达到一级A排放标准。

In order to solve the problem of poor nitrogen removal efficiency of municipal secondary effluent in the current wastewater treatment plant,two-stage anoxic-oxic(AO)biological filter process with simultaneous nitrification and denitrification(SND)was constructed.Effect of C/N in influent,reflux ratio and dissolved oxygen concentration(DO)on the nitrogen removal efficiency of the reactor were studied,meanwhile,the treatment efficiency tests were carried out under the optimal working conditions.Results showed that system had the best nitrogen removal effect when the influent C/N was 4∶1,also the simultaneous removal of ammonia nitrogen and nitrate nitrogen was realized in the anoxic section;even though the C/N was continuously improved,the overall treatment effect of the system was not enhanced significantly.With the increase of reflux ratio,the nitrogen removal efficiency of the system was decreased,thus the lowest reflux ratio(100%)was chosen as one of the best treatment working conditions.When the DO in the aerobic column was 2 mg/L,the concentration of dissolved oxygen reflux to the anoxic section was the lowest,and system treatment was the best in the same time.Concentration of ammonia nitrogen,total nitrogen and chemical oxygen demand(COD_(Cr))in the effluent was(0.026±0.001),(4.210±0.352)mg/L and(12.560±1.033)mg/L,respectively.Datas illustrate that the system works well under the optimal working conditions,and the nitrogen removal effect is obvious,therefore the treated water quality completely meets the requirement of frist grade A criteria.