某自来水厂超滤膜污染物成分及化学清洗效果案例分析

以江苏某自来水厂混凝-超滤工艺中PVC中空纤维超滤膜为对象，采用2种化学清洗剂HCl溶液、NaOH溶液对污染膜进行了化学清洗，分析洗脱液成分以确定膜污染的构成，并考察不同清洗剂在实际工程中的应用效果。通过ICP-OES、EEM、TOC分析仪对污染膜洗脱液进行了成分分析，同时采用SEM和ATR-FTIR对清洗前后的膜表面形貌及表面官能团进行表征。结果表明，膜污染物不仅包含蛋白类、多糖类和腐殖酸的有机污染物，还包含以Ca、Mg、Si、Fe元素为主的无机污染物。NaOH溶液除了能够洗脱更多的有机物，还可以有效地去除硅。而HCl溶液则对大分子有机物、疏水性有机物以及Ca、Mg、Fe有较好的清洗效果。HCl溶液的pH越低，或者NaOH溶液的pH越高，清洗效果越好。在工程实际清洗过程中，采用先酸后碱的组合方式，能够获得较高的膜通量。

Case analysis of foulant component on ultrafiltraion membrane and its chemical cleaning effect in a drinking water plant

In this study, PVC hollow-fiber membrane used in coagulation-ultrafiltration process of a drinking water plant in Jiangsu was taken as a research object. Two types of chemical cleaning reagents: HCl and NaOH solutions, were used to clean the fouled membrane. Then the eluants were determined to confirm the components in the membrane foulants, and the effect of the chemical cleaning reagents was investigated in actual application. Inductively coupled plasma atomic emission spectrometry (ICP-OES), three-dimensional excitation-emission matrix (EEM) and TOC analyzer were used to analyze the components of the fouled membrane eluates. Scanning electron microscope (SEM) and attenuated total reflectance-fourier transform infrared spectroscopy (ATR-FT-IR) were used to characterize the membrane surface morphology and functional groups before and after chemical cleaning. The results showed that membrane foulants contained not only organic matters of proteins, polysaccharides and humic acid, but also the main inorganics with Ca, Mg, Si, Fe elements. NaOH solution could clean more organic matters and effectively remove silicon, while HCl had a better cleaning effect on macromolecular organics, hydrophobic organics and inorganics including Ca, Mg, Fe. HCl solution with lower pH and NaOH solution with higher pH had better cleaning effects. In actual application, acid cleaning followed by alkali cleaning can obtain a high flux.