以超滤为核心的短流程净水工艺在给水厂中的应用

A Shortened Water Purification Process with Core of Ultrafiltration Membrane Unit in Water Supply Plant

以超滤为核心的短流程净水工艺采用低通量、低跨膜压差、变通量的运行方式,有利于减轻膜污染、节约能耗、提高系统产水率。永清县南水北调地表水厂以南水北调水源为原水,采用以超滤为核心的短流程净水工艺,原水经过絮凝之后进入膜池,膜池进行过滤的同时实现反洗水回收,采用在线化学清洗的方式,降低了劳动强度,方便了现场管理。实际运行数据表明,膜部分直接生产成本为0.023 7元/m^3,出水浊度<0.02 NTU。结合南通芦泾水厂运行经验,项目设计中做了以下优化,将化学清洗方式由离线清洗改为在线清洗、膜元件由帘式膜元件改为水草式膜元件、膜组件改为每支膜元件可以单独插拔的形式、产水方式由虹吸产水改为重力产水。

The operation mode of uhrafihration membrane unit in the shortened water purification process was characterized by relatively low flux, low transmembrane pressure difference and variable flux. This operation mode is conducive to lessening membrane fouling, saving energy and enhancing water production. The water transferred from South-to-North Water Diversion Project was taken as the raw water of the surface water purification plant in Yongqing town. The shortened ultrafihration membrane process is used in this water purification plant. The raw water was treated firstly via flocculation. It was followed by the membrane filtration at where the backwash water was recovered. The membrane was cleaned with on- line chemical dosage to reduce the labor intensity and on-site management difficulty. The actual operation data showed that the turbidity of the effluent is lower than 0.02 NTU while the direct cost of the membrane unit was0. 023 7 yuan/m^3. According to the operation experience of Nantong Lujing water plant, a number of improvements were made in the design process. These include on-line chemical cleaning; re- placing the membrane element of the curtain type by the water weed type; the membrane module being separated into membrane elements which could be inserted independently; resultant water by gravity, rather than the siphon.