某微污染水源自来水厂的纳滤深度处理效果研究

Performance of Nanofiltration for Improving the Drinking Water Quality in a Water Supply Plant with Micropolluted Water Resource

采用一级四段纳滤组合工艺处理南方某微污染水源自来水厂的传统净水工艺段出水,考察了纳滤膜工艺对出水水质的提升效果.结果表明,纳滤对常规水质指标与微量有机物有较好的去除效果,对混凝沉淀池出水中TOC和UV_(254)的去除率在95%以上(出水TOC≤0.3 mg·L^(-1),UV254≤0.005 cm^(-1));对卤乙酸、三卤甲烷前体物、多环芳烃和有机氯农药的截留率分别在62%、85%、50%和95%左右,使用UMU-SOS测试的出水遗传毒性低于检出限,不同段纳滤膜对相对分子质量较大的消毒副产物前体物与有机氯农药的去除率未呈现明显差异,但对相对分子质量较小的多环芳烃去除效果呈现明显差异,表明纳滤主要依靠物理截留去除水中相对分子质量较大的有机物,对相对分子质量较小的有机物则存在较大的局限性.与之相比,水厂目前使用的双级臭氧-生物活性炭深度处理工艺对传统净水工艺出水中多环芳烃、有机氯农药、遗传毒性的去除截留率分别仅为17%、62%、80%左右,显示纳滤对微量有机物的去除效果更为理想.

Four nanofiltration membranes connected in series were used for improving the drinking water quality in a water supply plant in south China with micropolluted water resource. The performance of the nanofiltration for improving the drinking water quality was investigated. The results showed that nanofiltration was efficient for removal of both traditional water pollution indicators and organic toxicants. More than 95% of TOC and UV254 were removed from the effluent of the traditional water purification process in the water supply plant. The NF effluent had a TOC of no higher than 0. 3 mg·L^-1 and a UV254 of below 0. 005 cm^-1. The removal rates of haloacetic formation potential,trihalomathanes formation potential,polycyclic aromatic hydrocarbon（ PAHs） and organochlorinated pesticides（ OCPs） were 62%,85%,50% and 95%,respectively. Genotoxicity of the NF effluent was undetectable in the umu-SOS test. Moreover, no significant difference was observed in the organic pollutants removal of haloacetic formation potential,trihalomathanes formation potential and OCPs among the four NF membranes but in the removal of PAHs with relatively smaller molecular weight. Nanofiltration showed higher removal rate of high-molecular-weight organic matters over low-molecular-weight organic matters. By comparison,only 17% of PAHs,62% of OCPs and 80% of genotoxicity were removed by advanced treatment of ozone（ O3） followed by treatment with biological activated carbon（ BAC） in this water plant,indicating that nanofiltration was better for removal of organic pollutants.