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采用改良A2/O工艺对城市污水进行中试研究,研究了反应系统对各个污染物的去除效果,并考察了温度、DO和混合液回流比对生物脱氮除磷的影响。结果表明：系统稳定运行的情况下,出水COD、TN和氨氮达GB 18918—2002的一级A标准,出水TP达一级B标准。系统对COD、TN、氨氮和TP的平均去除率分别为91%、68%、77.3%和80.6%。温度和DO对COD和TP的去除效果影响较小,对TN和氨氮则影响较大。温度在26.5℃时,对氮的去除效果最好。为保证系统脱氮除磷均能高效进行,DO应控制在2～4 mg/L,混合液回流比取1.5。“,”The modified A2/O process was applied to treat municipal sewage,the purification rate was studied and the influencing factors such as temperature,DO and the mixed liquor reflux ratios were investigated on biological nitrogen and phosphorous removal.The results show that under the steady operation conditions,the average effluent concentrations of COD,TN and NH3-N meet the first level A criteria specified in “Discharge Standard of Pollutants for Municipal Wastewater Treatment Plant”(GB18918—2002) except that TP meets the first level B.The average removal rates of COD,TN,NH3-N and TP are 91%,68%,77.3% and 80.6%,respectively.Temperature and DO have little effect on COD and TP removal,on the contrary,they have greater impact on TN and NH3-N.The highest nitrogen removal rate can be obtained at 26.5℃.In order to ensure efficient nitrogen and phosphorus removal,DO should be controlled at 2~4 mg/L,the mixed liquor reflux ratio should be taken as 1.5.