化学混凝-两级BAF工艺处理低温城市污水中试研究

Pilot study on treatment of municipal wastewater at low temperature by combined process of chemical coagulation and two-stage biological aerated filter

以大庆东城污水处理厂进水为实验原水,采用化学混凝-两级曝气生物滤池(BAF)组合工艺进行现场中试研究(12 m3/d),重点考察了在化学混凝的强化作用下,曝气生物滤池工艺对低温城市污水中有机物、氮和磷等污染物的净化效能。实验结果表明,单独采用两级曝气生物滤池工艺,当原水COD、NH3-N、TN和TP的平均浓度分别为450、45、60和6mg/L左右时,曝气生物滤池可在25 d内完成挂膜;系统运行稳定后,常温条件下(>10℃)COD、NH3-N、TN和TP的平均去除率分别为94.3%、97.5%、77.71%和95.6%;低温条件下(6～10℃),采用化学混凝-两级BAF组合工艺时,在混凝剂硫酸铝投量为25～30 mg/L条件下,组合工艺出水的COD、NH3-N、TN和TP平均浓度分别为45.2、3.26、12.56和0.43 mg/L,满足《城镇污水处理厂污染物排放标准》(GB18918-2002)中一级A排放要求。

The combined process of chemical coagulation and two-stage biological aerated filter（BAF） was adopted to treat the municipal wastewater in pilot scale,particularly the removal efficiencies of organic matters,nitrogen and phosphorus at low temperature by the combined process were investigated.The wastewater was collected from Dongcheng Sewage Treatment Plant in Daqing City and the average concentrations of COD,NH3-N,TN and TP were 450 mg/L,45 mg/L,60 mg/L and 6 mg/L,respectively.Experimental results show that biofilms in the two-stage BAF could be formed completely within 25 days.When the temperature was above 10 ℃,the removal efficiencies of COD,NH3-N,TN and TP by sole two-stage BAF were 94.3%,97.5%,77.71% and 95.6%,respectively.While the temperature was 6~10 ℃,the combined process of chemical coagulation and two-stage BAF was applied to maintain the treatment efficiency of wastewater.When the dosage of aluminum sulfate as the coagulant was 25~30 mg/L,COD,NH3-N,TN and TP of the effluent were 45.2 mg/L,3.26 mg/L,12.56 mg/L and 0.43 mg/L,respectively,which all meet level A for municipal wastewater discharge standards of China.