北方某中型污水处理厂短程硝化反硝化案例分析

Shortcut Nitrification and Denitrification in a Medium-sized Sewage Treatment Plant in Northern China

对北方某中型污水处理厂出现的短程硝化反硝化现象进行了分析。该污水厂采用传统活性污泥法工艺，在生化池内DO为0.3～4.5 mg/L、pH值为6.3～8.5的条件下，出水COD、TP、TN、氨氮的平均浓度分别为37.8、0.31、13.4、2.3 mg/L，优于《城镇污水处理厂污染物排放标准》（GB 18918—2002）的一级A标准。在试验监测期间的第45～75天，出水亚硝态氮浓度出现明显的先升高后下降趋势，出水硝态氮浓度出现明显的先降低后升高趋势，由此判断，期间发生了短程硝化反硝化现象。

Shortcut nitrification and denitrification occurred in a northern medium-sized sewage treatment plant were analyzed. The conventional activated sludge process was adopted in this plant. When DO concentration in biochemical tank was 0.3 mg/L to 4.5 mg/L, and pH value was 6.3 to 8.5, the average concentrations of COD, TP, TN and NH3 - N in the effluent were 37.8 mg/L, 0.31 mg/L, 13.4 mg/L and 2.3 mg/L respectively, which were better than the first level A criteria specified in the Discharge Standard of PoUutants for Municipal Wastewater Treatment Plant （GB 18918 -2002）. During the days of 45 to 75, the effluent nitrite nitrogen concentration significantly increased first and then de- creased, and the effluent nitrate nitrogen concentrations significantly decreased first and then increased. It was concluded that the shortcut nitrification and denitrification occurred.