基于污染物受纳量的城镇生活污水处理率指标研究

我国通过污水处理率来评价生活污水处理水平，但污水处理率仅考虑了污水处理设施进水处理的水量，忽略了雨污合流、地下水混入、抽取河水处理等原因导致的污染物收集水平不足.以成都市岷江外江流域为研究区域，开展了城镇生活污水收集和评价指标优化研究，提出了基于污染物受纳量的城镇生活污水污染物处理率概念和核算方法体系，在划分控制单元基础上，核算生活污水污染物的产生量和处理量.研究发现，该流域污水处理厂进水浓度普遍偏低，进水水质存在季节性波动，说明可能存在丰水期雨水、河水或地下水混入稀释的情况，枯水期的进水数据更能反映区域生活污水排放情况；传统污水处理率计算显示该流域污水处理率高于100%，但全流域的COD_Cr、氨氮和总磷污染物处理率分别为37.50%、36.25%和30.14%，与该流域的水环境质量特征和污水管网建设水平相符；在污水管网未完善的地区，采用污染物处理率更能有效评价和反映区域污水收集和处理程度.

Use the indicator of receivied pollutant to evaluate domestic sewage treatment status

The ratio of treated domestic sewage was used to evaluate the sewage treatment level in China. However, due to the current situation of incomplete sewer networks and rain sewage mixed flow in drainage system, clean water from raining or river flowed into wastewater treatment plant together with wastewater, therefore, herein sewage treatment ratio was referred to the amount of how much wastewater was treated, but not the amount of treated pollutant. A new indicator was used to evaluate the domestic sewage treatment status in a southwestern city of China based on pollutant treated. The concentration of concerned pollutants in influent to wastewater treatment plants (WWTP) was generally low and also fluctuated with seasons, which indicating the dilution by rainwater, river water or groundwater during the raining season. Thus, the influent data of WWTP in dry seasons was considered more suitable for the real concentration of regional domestic sewage. The sewage in our study basin was 100% treated if the traditional indicator of sewage treatment was applied. But in fact, the treatment ratios of COD_Cr, NH₃-N and TP in the whole basin were 37.50%, 36.25% and 30.14%, respectively, based on our new evaluation method. It meant more than half of the pollutants were discharged directly into the environment, which was consistent with the water quality characteristics and incomplete sewer network of the basin. In conclusion, pollutant treatment ratio is a better and more effective indicator to evaluate the level of regional sewage collection and treatment in area where the sewer network are not widespread.