用地紧张给水厂深度处理工艺改造案例

Reconstruction Case of Advanced Treatment for a WTP with Limited Land Use

砂滤池改造成下向流炭砂滤池和沉淀池后端改造成上向流炭池是水厂土地紧张时生物活性炭深度处理改造的最常用手段。为优化两种改造方式的设计和运行管理,文中调查了国内现有炭砂滤池和沉淀池后端改造炭池的工程案例及技术参数,总结了两者应用时存在的问题,对比了两种工艺的运用特点和各自优缺点。文中建议在土地条件允许情况下,炭砂滤池和上向流炭池上游应设置臭氧接触池。若工艺流程中炭砂滤池后续无超滤膜,则建议砂层厚度>1000 mm,并考虑气水反冲,水冲强度为55 m^(3)/(h·m^(2)),以满足水厂浑浊度控制要求。若后续存在超滤膜工艺,则砂层厚度可减小,炭层厚度应考虑增加至1000 mm以上,并考虑汽水反冲,水冲强度为25 m^(3)/(h·m^(2))。

Reconstruction of sand filter from downflow to upflow carbon tank is the most commonly used means for the advanced treatment of biological activated carbon(BAC)in water treatment plants(WTPs)with limited land use.Engineering cases and technical parameters of the existing WTPs at home are investigated,which include carbon and sand filter or carbon and sand filter transformed from back-end of sedimentation tank.Problems existing in their application are summarized.Application characteristics and advantages and disadvantages of the two processes are compared.It is suggested that if the land conditions permit,ozone contact tank should be set in the upstream process of carbon and sand filter or upward-flow carbon filter.To meet the turbidity control requirements,if there is no ultra filtration(UF)membrane after carbon and sand filter in the process flow,it is suggested that the thickness of sand layer should be more than 1000 mm,and the air-water backwash which the water impact strength is 55 m^(3)/(h·m^(2))should be considered.If there is UF membrane after carbon and sand filter in the process flow,the thickness of sand layer can be reduced,the thickness of carbon layer should be increased to more than 1000 mm,and the air-water backwash which the water impact strength is 25 m^(3)/(h·m^(2))should be considered.