臭氧影响超滤膜有机污染的机制及其在线清洗控制膜污染的研究

Membrane separation is regaeded as technique of water treatment during 21st century. However, the most important disadvantage in the application of these membrane processes for water treatment is fouling. Many researches indicated that membrane fouling mainly caused by natural organic matter. Ozone, which is a powerful oxidant, becomes research focus of membrane fouling controlling. No Conclusion for mechanism of membrane organic fouling removal by ozone has been reached yet, whereas many researches have been carried out However, a significant aspect of ozone pretreatment announced while combing with ultrafiltration membrane is safety of drinking water. The project, which analyzes the characteristics of organic matter, investigates effect of ozone on organic matter causing ultrafiltration membrane fouling and illuminates the mechanism of ultrafiltration membrane organic fouling removal by ozone through analysis of organic matter fouled ultrafultraion membrane. Furthermore, to avoid issue of drinking water safety during controlling of membrane fouling by ozone, online cleaning of ozone is introduced. The research of online cleaning, which is the other measure for controlling membrane fouling, focuses on effectiveness of membrane fouling removal by ozone. The project provides thinking of solving membrane fouling during drinking water.

膜分离被誉为21世纪的水处理技术，但其在水处理中的应用面临膜污染问题。研究发现，天然有机物是污染膜的主要物质，臭氧由于较强的氧化分解有机物的能力，使其成为膜有机污染控制的研究热点之一。尽管研究者对臭氧控制膜有机污染的机制进行了一定的研究，但并没形成统一的定论。此外，针对臭氧控制膜污染的技术则侧重于臭氧预氧化，这给饮用水处理带来安全问题。本项目采用超滤膜工艺，从有机物特性角度分析，研究臭氧对影响膜污染的有机物的作用，分析污染超滤膜的有机物特性，阐明臭氧对污染膜的有机物的作用机制。同时，为避免预臭氧控制膜污染过程中带来的饮用水安全问题，引入臭氧在线清洗方法，研究臭氧控制膜污染效能，为膜污染控制提供又一方法和途径。本项目的研究为膜法应用于饮用水处理中面临的膜污染问题提供了一定的理论支持和解决思路。

本项目已按原计划完成。以地表水源水和人工配水为研究对象，研究了超滤膜过滤地表水过程中臭氧化对污染膜的主要物质-天然有机物的影响作用，分析了臭氧化对有机物组分及膜过滤特性的影响，阐明了臭氧缓解膜污染的机制，开展了臭氧在线清洗对膜污染的影响研究。结果表明：（1）臭氧化对天然有机物的影响显著，尽管对DOC的去除率相对较低，但对UV254的去除率高，臭氧能将大分子量的有机物氧化成小分子量的有机物，将疏水性有机物氧化成亲水性有机物。（2）臭氧与超滤膜联用可有效提高膜出水水质，但在高的臭氧投量下，超滤膜对污染物的去除作用不明显。臭氧可有效减缓膜污染，但并不是投加的臭氧量越高膜通量提高越多，而是存在一个最佳的臭氧投量使膜通量达到最大。（3）臭氧对膜通量的提高主要的机理在于臭氧化改变了污染超滤膜的有机物的结构，从而使截留在超滤膜表面的有机物的堆积较为松散，进而降低了膜污染阻力（4）臭氧在线通入超滤膜可有效提高膜通量主要是通过如下2方面实现的：氧化污染膜的有机物和对膜表面造成一定的扰动。