城镇污水处理提质增效的内涵与思路

污水管道旱季高水位、低流速导致的颗粒物沉降是我国独有的现象,也是我国城镇污水处理厂进水污染物浓度低、碳氮磷比例失调的根本原因;入渗/入流污水管道的清水、低浓度污水排口截流,以及排入雨水管道并经末端截流进入污水管网的施工降水或基坑排水,是城镇污水处理厂旱季进水污染物浓度偏低、处理水量远超污水排放量的重要原因;降雨期间大量雨水涌入污水管道和合流制管道,冲刷并携带旱季沉积物进入城镇水体,是水体雨后黑臭、底泥问题无法彻底根除的核心缘由,也是大部分城镇"生活污水集中收集率"偏低的直接根源。结合城镇污水处理提质增效工作的实施,从污水处理行业监管、收集设施效能评估、雨污水管网建设改造、降雨污染控制和工业废水管控等方面提出了重点工作方向。明确指出,全面恢复市政污水管网旱季流速、降低清水入渗入流量、推进降雨污染控制是根治现阶段我国特有城镇水环境问题的最现实、有效的途径。

Connotation and Way of Quality and Efficiency Improvement of Municipal Wastewater Treatment

Settlement of particles in wastewater pipeline caused by high water level and low flow rate in dry season is common in China but rare in developed countries,which leads to low influent organics concentration and imbalance ratio of carbon,nitrogen and phosphorus of the wastewater treatment plants.Infiltration/inflow clear water,closure of low concentration wastewater,and drainage of construction works or foundation pit discharged into rainwater pipeline and then into wastewater pipeline through end interception,inevitably results in the lower concentration of influent and larger amount of wastewater than that is discharged.Particle sediment in wastewater and combined pipelines flushed and carried by rainfall flowing into urban water body is the core reason of recurring black-and-odor water and sludge issue which cannot be completely resolved after rain,which also directly leads to the low centralized collection rate of domestic wastewater in most cities and towns.Based on quality and efficiency improvement of wastewater collection and treatment,key work directions were put forward from aspects of wastewater industry supervision,effectiveness evaluation of collecting facilities,construction and transformation of drainage pipeline,pollution control of rainfall,and industrial wastewater discharge control.It was suggested that the most realistic and effective way to completely solve the water environment problems in China was to fully restore design flow rate of wastewater pipeline,reduce the infiltration/inflow of clear water,and promote the control of rainfall pollution.