微污染水源水中有机物的分布特征及微滤膜对其的影响作用

Distribution characteristics of organic matters in micro-polluted water and variation after microfiltration

本试验是在微污染水源水中有机物分布调查的基础上,采用聚偏氟乙烯（PVDF）微滤膜（MF）过滤微污染地表水,考察微滤膜对天然水中有机物的影响作用.试验结果表明,黄浦江微污染水源水中的有机物分子质量主要集中在3~5 k Da和0.2 k Da附近,且疏水性有机物和亲水性有机物所占的比例相当.有机物季节性分布特征明显,冬季溶解性有机碳（DOC）的值偏高,而UV254和比紫外吸光度值（SUVA）则在夏季偏高.黄浦江原水经微滤膜过滤后,有机物构成发生明显变化,膜出水中的亲水性有机物的比例增加,而疏水性有机物的比例降低,DOC和UV254的平均去除率分别为17.73%和15.75%.黄浦江原水及经0.45μm滤膜过滤以去除悬浮物的黄浦江原水分别进行微滤膜过滤,膜比通量的对比发现,在较短时间内两者的膜比通量下降都很明显,而后膜比通量都趋于平缓,变化趋势及结果基本一致,可见,黄浦江水中造成膜通量下降的物质并不是悬浮物,而是溶解性的有机物质.

Based on the investigation on distribution of the organic matters in micro-polluted water,the effects of polyvinylidene fluoride（ PVDF）microfiltration（ MF） membrane on the organic matters were studied. The results show that the molecular weight（ MW） of organic matters was concentrated in the range of 3 ~ 5 k Da,or close to 0. 2 k Da for the water samples from Huangpu River. Meanwhile,the proportion of hydrophobic and hydrophilic organic matters is nearly the same. The dissolved organic carbon（ DOC） was higher in winter; however,UV254 and SUVA were higher in summer. The membrane filtration results show that the fraction of organic matters was markedly changed. The proportion of hydrophilic organic matter was increased and hydrophobic organic matter was decreased in permeate. The removal rate of DOC and UV254 is 17.73% and 15.75%,respectively. When raw water and its permeate upon 0.45 μm filteration were filtrated by MF membrane respectively,the membrane flux markedly declined during initial filtration period and then decreased gently. Finally,the membrane flux of the two processes approaches to be similar. Therefore,the matter fouling on the membrane is dissolved organic matter,instead of suspended matter.