污水处理厂二级出水深床滤池超深度脱氮研究

采用深床滤池处理污水厂二级出水,以使出水TN提升至地表Ⅳ类水水质。在中试系统进水TN和NH4+-N的平均值分别为13.88和0.68 mg/L、碳源(99%的乙酸)投加量为60mg/L条件下,当空床水力停留时间分别为15和30 min时,出水TN平均值分别为0.81、0.74 mg/L,TN平均去除率分别为94.16%、94.67%,反硝化滤池的平均容积负荷为0.64~1.28 kg/(m^3·d)(以硝态氮计)。当进水TN和NH4+-N的平均值分别升高至18.05和1.40 mg/L、碳源投加量为40 mg/L时,同样运行条件下出水TN平均值分别为5.04和2.36 mg/L,去除率分别为72.08%和86.93%。中试结果表明,控制二级出水TN和NH4+-N分别在15和0.5 mg/L以内、空床水力停留时间为30 min、碳源投加量(C/N值=4.5)足够时,深床滤池反硝化脱氮系统能稳定保证出水TN达到地表Ⅳ类水水质标准。

Advanced Denitrification of Secondary Effluent of a Wastewater Treatment Plant in Deep Bed Filter

The secondary effluent from a wastewater treatment plant was treated by a deep bed filter,so as to improve TN in the effluent to the surface water classⅣcriteria.When the average TN and NH4+-N concentrations in the influent of the pilot-scale system were 13.88 mg/L and 0.68 mg/L,dosage of the carbon source(99%acetic acid)was 60 mg/L and empty bed hydraulic retention time was15 min and 30 min,the average TN concentrations in the effluent were 0.81 mg/L and 0.74 mg/L,the corresponding average removal rates were 94.16%and 94.67%,respectively,and the average volumetric loading rate was 0.64-1.28 kg/(m^3·d)(in terms of NO3--N).When the average TN and NH4+-N concentrations in the influent increased to 18.05 mg/L and 1.40 mg/L,and the dosage of carbon source was 40 mg/L,the average TN concentrations in the effluent were 5.04 mg/L and 2.36 mg/L,and the removal rates were 72.08%and 86.93%under the same operational conditions.When TN and NH4+-N in the secondary effluent were controlled to be less than 15 mg/L and 0.5 mg/L,empty bed hydraulic retention time was 30 min and dosage of the carbon source(C/N=4.5)was sufficient in the pilot-scale system,TN in the effluent of the deep bed filter denitrification system could always meet the surface water classⅣcriteria.