焦化废水回用膜污染成因及控制策略分析

The Analysis of Membrane Fouling Cause and Prevention Stagey in Coking Wastewater Reuse

采用超滤-反渗透工艺进行焦化废水回用研究,运行结果表明系统总产水各项指标均远优于《工业循环冷却水处理设计规范》中间冷开式循环冷却水系统补充水水质,系统对COD,BOD_5,总溶解固体(TDS)和Cl^-指标的去除率分别保持在98.6%,98.1%,99.0%和98.8%以上。对超滤膜和反渗透膜进行膜表面污染沉积物检测,发现焦化废水中影响超滤膜运行的因素主要为有机物和Fe絮凝体,影响反渗透膜运行的因素主要为有机物和钙盐结垢。采用碱洗+酸洗的方式可有效恢复超滤膜和反渗透膜的运行性能。但针对反渗透膜的硫酸钙结垢,酸洗时需要加入一定量的乙二胺四乙酸(EDTA),且一旦发生污堵,需立即进行化学清洗。

The study of coking wastewater reuse was conducted using ultrafiltration and reverse osmosis.The operation results indicated that the product water quality was significantly better than the supplementary water quality for cold open circulating cooling water system described in<Code for design of industrial recirculating cooling water treatment>.The removal efficiency of COD,BOD5,TDS and Cl-was achieved to the level of above 98.6%,98.1%,99.0%and 98.8%respectively.By determining the sediment on the surface of ultrafiltration and reverse osmosis membrane,the dominant factor influencing stable operation of membrane was organic matter/Fe floc for ultrafiltration and organic matter/calcium scale for reverse osmosis,respectively.The filtration performance of ultrafiltration and reverse osmosis could be resumed using alkali cleaning and acid cleaning.However,as per calcium sulfate scale,it was necessary to add the EDTA to cleaning solution during acid cleaning and the immediate cleaning was needed once the fouling occurred.