医院污水污染膜的污染特征及清洗技术研究

Properties of Fouled Membrane by Hospital Wastewater and Its Cleaning

医院污水水质水量变化大而且成分十分复杂,含有大量病毒等有毒有害物质。膜生物反应器(Membrane bioreactor,MBR)技术已在工业废水领域得到广泛应用,但膜污染始终是制约其稳定运行的关键问题之一。针对医院污水MBR处理工程的污染膜,采用x射线能谱分析仪(Energy dispersive x-ray spectroscopy,EDX)分析其表面元素组成,确定最适清洗方案,可为MBR技术的稳定运行提供有益参考。结果表明,与其他季节相比,秋季污染膜表面元素组成最为复杂,为有机和无机交叉污染。室温条件下,质量分数0.5%柠檬酸和质量分数0.1%次氯酸钠可分别有效清除污染膜表面的无机和有机污染物。关于清洗顺序,先柠檬酸后次氯酸钠清洗的效果较佳,柠檬酸去除无机物使得膜污染层变得疏松,为后续次氯酸钠清洗创造了有利条件,清洗膜的膜表面元素组成与新膜基本一致,其孔隙率、平均孔径及接触角与新膜也相差不大,分别为0.858、0.104μm和(69.20±0.115)°。

With a large amount of hazardous matter,such as virus,hospital wastewater experiences frequent variation in wastewater quality and quantity. Membrane bioreactor(MBR) technology has been extensively used in industrial wastewater treatment plants. However,membrane fouling always is one of key bottlenecks to obstacle the stable operation of MBR. Aimed at fouled membrane from hospital wastewater treatment plant,the optimal chemical cleaning strategy can be determined based on surface fouling element analysis using energy dispersive x-ray spectroscopy(EDX). It is helpful for chemical cleaning of fouled membrane modules in wastewater treatment plant. The results showed that,compared with other seasons,the elements in/on fouled membrane surface in autumn season was most complicated,and organic elements were overlapped with inorganic. Under room temperature,organic and inorganic elements were effectively removed by 0.5% citric acid and 0.1%sodium hypochlorite,respectively. Concerning the cleaning order,the better method was firstly citric acid cleaning followed by sodium hypochlorite. The removal of inorganic elements by citric acid made fouling layer softer and was favorable for subsequent sodium hypochlorite cleaning. The element components of cleaned membrane surface were similar to those of new one. Also,the porosity rate,average pore size and contact angle of cleaned membrane with 0.858,0.104 μm and69.20±0.115° was approximate to those of new one.