预处理+多级膜浓缩+蒸发结晶+膜电解组合工艺在造纸废水零排放工程上的应用

以国内某工业园区中水回用示范项目1.75万m3/d造纸废水零排放工程为例，对工程采用的预处理+多级膜浓缩+蒸发结晶+膜电解组合工艺流程及设计参数情况进行了重点说明，对部分工艺单元的运行数据进行了技术分析。运行数据表明:臭氧活性炭生物滤池对造纸废水二级出水残留COD的去除率>50%，机械加速沉清池对一级反渗透浓水硬度的去除率达到70%，离子交换器出水硬度稳定在0~4 mg/L，NaCl浓缩反渗透单元对Cl-的再浓缩比约为3倍。最后介绍了对于膜浓缩和蒸发结晶系统改造的工程经验，并从技术总结的角度阐明完善的工艺流程及技术保障措施是该工业废水零排放工程获得成功的根本。

APPLICATION OF PRETREATMENT+MULTISTAGE MEMBRANE CONCENTRATION+EVAPORATIVE CRYSTALLIZATION+MEMBRANE ELECTROLYSIS COMBINED PROCESS IN A ZERO DISCHARGE PROJECT OF PAPERMAKING WASTEWATER

In order to share the successful experience of a 17500 m3/d papermaking wastewater zero discharge project in a domestic industrial park in China, this paper focused on design parameters of the combined process, pretreatment+multi-stage membrane concentration+evaporative crystallization+membrane electrolysis, and analyzed the operation data of some process units. The operation data showed that the removal rate of residual COD in the secondary effluent of papermaking wastewater by ozone activated carbon biofilter was more than 50%, the removal rate of hardness index in the first RO concentration by mechanical accelerated clarifier was 70%, the effluent hardness of ion exchanger was stable at 0~4 mg/L, and the reconcentration ratio of chloride ion by sodium chloride concentration RO unit was about 3 times. Finally, the paper introduced the engineering experience of membrane concentration and evaporation crystallization system transformation, and illustrated that the perfect process flow and technical guarantee measures were the key to the success of this zero discharge project of industrial wastewater from the perspective of technical summary.