一种基于膜污染指数的超滤膜污染评价方法

An approach used for ultrafiltration membrane fouling evaluation based on membrane fouling index

利用浸没式中空纤维膜小试系统,基于膜污染指数(FI)建立超滤膜污染的评价和试验方法。通过试验考察超滤膜污染变化规律,以及运行周期对膜污染指数计算的影响,并确定计算膜污染指数的运行周期;并对膜污染指数评价方法的可重复性进行检验;对化学清洗前后膜污染指数进行比较。试验表明,在过滤初期,滤饼污染和吸附污染并存,所以初期水力不可逆膜污染指数(HIFI)增长较快;中期超滤膜的吸附能力不断减弱,膜污染主要是滤饼污染,所以膜污染较为稳定;后期跨膜压力过大,压缩滤饼层,减小滤饼孔隙率,增加滤饼阻力,所以HIFI有所增加。同时短期的膜污染试验可以用来反映长期的膜污染情况,该超滤膜污染的评价方法重复性好,污染后的超滤膜经过化学清洗后,可以重复利用。

A method for evaluation and test on ultrafiltration membrane fouling was established using sub- merged immersion-hollow fiber membrane test system based on membrane fouling index （FI）. Through the inves- tigation on the variation rules of ultrafihration membrane fouling and the influence of operation cycle on the cal- culation of membrane fouling index, the proper operation cycle for membrane fouling index calculation was de- termined with the test on the repeatability of the method for membrane fouling index evaluation carried out as well. Besides, the membrane fouling indexes before and after chemical cleaning was compared. The results of the test showed that, as both filter cake pollution and adsorption pollution existed at the beginning of the filtration, hydraulic irreversible fouling index （HIFI） grew rapidly at this stage; at the middle stage of the filtration, affected by the weakened adsorption capability of the uhrafihration membrane, membrane fouling was mainly filter cake pollution and the fouling was more stable; at the late stage of the filtration, with the increasing of transmembrane pressure, the filter cake layer was compressed, the porosity of the cake was reduced, and the resistance of it was increased, therefore, HIFI increased. It was pointed out that, long-term membrane fouling could be reflected by short-term membrane fouling experiment, the said evaluation method had great repeatability, and fouled uhrafil- tration membrane could be reused after chemical cleaning.