超低压反渗透与纳滤处理太湖水的对比试验

Comparative study on ultra-low pressure reverse osmosis and nanofiltration for treatment of Taihu water

对比试验以太湖水为原水,使用超滤作为前处理工艺,选取超低压反渗透和纳滤膜进行对比研究,分析各自的产水水质和运行工况.结果表明,两者对有机物的去除效果总体上相当,CODMn去除率均在76.94%以上,三维荧光检测显示反渗透去除溶解性有机物(DOM)优于纳滤,凝胶色谱检测表明两者对于原水中分子量主要集中于10000 Da的组分均表现出良好的去除效果,甚至纳滤表现出去除小分子优于反渗透.选取一价离子和二价离子共8种,利用离子色谱检测反渗透与纳滤的产水,反渗透脱盐率>86.16%,纳滤对硫酸根去除率>88.85%,其余离子去除效果一般.以通量和运行压力作为评价运行工况的指标,纳滤比反渗透拥有更为稳定的通量,但运行压力会随时间逐步上升,对此有必要采取前处理或加大化学清洗频率.

With a pretreatment process of ultrafiltration,this comparative study used Taihu water as the original water to compare ultra-low pressure reverse osmosis with nanofiltration membrane in terms of product water quality and operating condition.The results showed that the removal effect of organic compounds was similar,and the removal rates of CODMn were both over 76.94%.Three dimensional fluorescence detection indicated that the reverse osmosis removal of dissolved organic matter(DOM) was better than nanofiltration.Gel chromatography displayed that both had good removal effect on the components which were mainly concentrated in 10000 Da in the raw water.Nanofiltration showed greater capacity of removing small molecules than reverse osmosis.By delecting 4 monovalent and 4 divalet ions respectively and analysing permeate water of reverse osmosis and nanofiltration by ion chromatography,it was found that reverse osmosis desalination rate was over 86.16%,sulfate removal rate of nanofiltration was over 88.85%,and the removal effect of other ions was average.Considering flux and operating pressure as index for evaluating operating conditions,nanofiltration had more stable flux than reverse osmosis,but the operating pressure would increase with the process of time.Therefore,it was necessary to adopt pretreatment or increase the frequency of chemical cleaning to release the pressure.