山地城市污水特细砂除砂系统目标粒径确定

Target particle size of ultra-fine grit removal system of moutainous urban

三峡库区重庆段污水处理厂长期受污水特细砂影响;污水中特细砂平均粒径仅182.6μm,而传统沉砂池通常以粒径大于200μm砂粒去除率来衡量沉砂池除砂效果;参考国外传统除砂设备性能参数估算特细砂总去除率仅为51.2%,若考虑砂水分离器效率等因素,则实际去除率更低。基于重庆'特细砂'的粒径分布特征、除砂效率理论计算分析认为,特细砂除砂装置的设计研发时,除砂粒径分界点或目标粒径为100μm,并以粒径≥100μm细砂去除率来衡量沉砂池的除砂效果,能保证粒径分布曲线中70%~95%的特细砂得到有效去除,能满足污水处理厂对特细砂的去除要求。

The wastewater treatment plants at Chongqing Section of Three Gorges Reservoir have been influenced by ultra-fine grits in sewage for a long time. The average particle size of the ultra-fine grits in sewage is only 182. 6 μm,as for a traditional sand basin,however,the sand-removal rate with particle size of more than 200μm is usually adopted to balance its sand-removal effect. Referring to the performance parameters of foreign traditional sand-removal equipment,the removal rate of ultra-fine grit estimated is only 51. 2%,and the actual removal rate is much lower if the factors are considered,such as sand-water separation efficiency and so on. Based on the particle size characteristics of'ultra-fine grit'in Chongqing,it believes through the sand-removal efficiency theory calculation and analysis that the sand-removal particle diameter dividing point or target particle size is 100 μm and the fine sand removal rate with particle diameter of no less than 100 μm is adopted to balance the sand-removal effect of the sand basin when an ultra-fine grit removal device is designed and developed,which can ensure70% ~ 95% ultra-fine grits in the particle diameter distribution curve can be removed effectively and meet the requirement for sand removal in sewage treatment plants.