饮用水处理过程中全氟化合物的分布、转化及去向

Distribution,Tansformation,and Fate of Per-and Polyfluoroalkyl Substances in Drinking Water Treatment

全氟和多氟烷基物质(PFASs)存在于地表水、自来水甚至商业饮用水中,对人类健康构成威胁.在以太湖为源头的某大型饮用水处理厂(DWTPs)中研究了14种PFASs的检出和转化.结果表明,共有10种PFASs在水样中被检测到,说明PFASs在饮用水中分布广泛.原水中的PFASs总浓度为127.4ng·L^(-1),其中最高浓度为全氟辛酸(PFOA,49.8ng·L^(-1)).预臭氧会导致PFASs的浓度反向升高,这可能是由于前体物的存在或由短链向长链进行转化导致.常规处理工艺无法有效去除PFASs,O_(3)-BAC在DWTPs的处理过程中对PFASs的去除(20.74%)具有主导作用.O_(3)-BAC作为DWTPs的主要去除工艺,其反冲洗水中含有浓度较高的PFASs,分布特征与原水相似.利用中试装置,对比了5种常见的滤池反冲洗水处理工艺,结果表明,GAC-超滤可以在保证浊度较高去除率(99.08%)的基础上,吸附并截留一定量的PFASs.从三维荧光分析可得,GAC-超滤也可去除大部分荧光微污染物,对于原水含有较高浓度的PFASs的DWTPs来说,将其作为滤池反冲洗水回用处理工艺是实际可行的.

Per-and polyfluoroalkyl substances(PFASs)are present in surface water,tap water,and even commercial drinking water and pose a threat to human health.In this study,the occurrence and transformation of 14 PFASs were studied in large drinking water treatment plants(DWTPs)with Taihu Lake as the source,and the results showed that a total of 10 PFASs were detected in the water samples,indicating that PFAS were widely distributed in drinking water.The total concentration of PFASs in raw water was 127.4 ng·L^(-1),with the highest concentration being that of pentadecafluorooctanoic acid(PFOA,49.8 ng·L^(-1)).Pre-ozone caused a reverse increase in the concentration of PFASs,which may have been due to the presence of precursors or conversion from short to long chains.PFASs were not effectively removed by conventional treatment processes,andozone-biological activated carbon(O_(3)-BAC)had a dominant role in the removal of PFASs(20.74%)from DWTPs.O_(3)-BAC,the main removal process for DWTPs,contained high concentrations of PFASs in the backwash water with similar distribution characteristics to the raw water.Using a pilot plant,five common filter backwash water treatment processes were compared,and the results showed that GAC-ultrafiltration could adsorb and retain a certain amount of PFASs while ensuring a high removal rate of turbidity(99.08%).The 3D-EEM analysis indicated that GAC-ultrafiltration could also remove most of the fluorescent micro-pollutants,and for raw water containing high concentrations of PFASs DWTPs,it is practical to use it as a filter backwash water reuse treatment process.