复杂进水条件下微滤膜的膜污染解析

Analysis of MF Membrane Fouling under Complex Influent Condition

微滤膜在处理由钢铁废水、生活污水、工业废水等形成的综合废水时出现了膜通量下降、产水量降低的问题。为了解析膜污染原因,对污染膜进行了力学性能测试、膜孔结构表征和膜垢特征元素分析。结果表明,膜丝外表面由无机垢体、大分子有机物、胶体等经长期累积形成了致密的凝胶层;内表面的膜孔则被有机污染物和无机盐沉淀附着,分析原因是反洗水中加入了过量的次氯酸钠所致。降低膜进水浊度和COD、加强反洗和提高错流速度、降低成垢离子浓度是控制膜外表面污染的有效方法;控制反洗水中次氯酸钠投加量,使反洗水pH值<8.0是解决膜丝内表面污染的有效方法。

Membrane flux decline and water production decrease occurred when microfiltration （MF） membrane was used to treat comprehensive wastewater composed of iron and steel wastewater, domestic sewage and industrial wastewater. Mechanical property testing, membrane pore structure observa- tion and typical elements analysis were carried out in order to clarify the causes of membrane fouling. The results showed that there was a dense gel layer on the outer surface of membrane due to the long-term accumulation of inorganic sediments, macromolecular organics and colloids. Pores of the inner surface were attached by organic pollutants and inorganic sediments, which were attributed to excessive addition of sodium hypochlorite into backwashing water. Effective measures to control fouling on membrane outer surface include reducing the influent turbidity and COD, enhancing the backwash, improving the crossflow velocity and decreasing the fouling ion concentration. Effective measures to control fouling on membrane inner surface include controlling the dosage of sodium hypochlorite into backwashing water and keeping pH of backwashing water at less than 8. O.