PVC合金超滤膜运行7年效能及膜污染特性研究

Performance Evaluation and Membrane Fouling Characteristics of Long-term Operation of PVC Alloy Ultrafiltration Membrane

为研究长期运行的超滤膜污染特性及污染物组成,采用东营南郊水厂一期超滤膜工艺中已运行7年的旧超滤膜与新超滤膜进行对比,分析了膜通量、跨膜压差及运行成本的变化,对膜断面形态及膜丝内部的有机物和无机物种类进行了解析。结果表明,经长期运行后超滤膜的过滤性能明显变差,出现了累积性的膜通量下降、跨膜压差增长速率变大等现象,更换超滤膜更符合经济性。亲水性的低分子质量有机物、腐殖酸类、蛋白质类和色氨酸类等是截留的主要污染物。长期运行的超滤膜附着的Ca CO_3、铝和硅含量明显高于新膜,化学清洗分别仅可去除约62%、28%和37%,造成Ca CO_3、铝和硅在超滤膜表面及内部的持续性沉积;化学清洗过程无法彻底消除长期运行超滤膜的不可逆污染,化学清洗后附着在膜表面和膜孔内的污染物颗粒数量显著减少,但仍有部分污染物颗粒残留在膜孔内。

The first-stage UF membrane process has operated for seven years in Dongying Nanjiao Waterworks. In order to study the fouling characteristics and contaminant composition of the long-term ul- trafihration membrane, a comparison was made between the old UF membrane and the new one. The transmembrane pressure （TMP） difference, flux change, running cost, the organic and inorganic com- pounds on these membranes were analyzed. The results showed that the old membrane had the problems of the membrane flux decreasing gradually and larger growth rate of TMP, and it was more economical to replace the ultrafiltration membrane. Humie acids, proteins, tryptophan and low molecular weight organic matter were the main pollutants causing membrane fouling. CaCO3, A1 and Si in the old membrane was obviously higher than that of the new membrane. Chemical cleaning could only remove 62% of CaCO3, 28% of Al and 37% of Si on the old membrane. After cleaning, the number of membrane pores in-creased and the amount o mained in the membrane membrane. f pollutant particles decreased significantly. However, some of the particles re- pores, which was the important reason leading to irreversible fouling of the old