Key Laboratory of Drinking Water Science and Technology, Research Center for Eco-Environmental Sciences, Chinese Academy of Sciences, Beijing 100085, China; University of Chinese Academy of Sciences, Beijing 100049, China.
Key Laboratory of Drinking Water Science and Technology, Research Center for Eco-Environmental Sciences, Chinese Academy of Sciences, Beijing 100085, China.
Water Res. 2018 Aug 1;139:168-176. doi: 10.1016/j.watres.2018.03.073. Epub 2018 Mar 29.
The effects of ozone-biologically activated carbon (O-BAC) treatment with various phosphate doses (0, 0.3 or 0.6 mg/L) were investigated on the formation of disinfection by-products (DBPs) and occurrence of opportunistic pathogens (OPs) in drinking water distribution systems (DWDSs) simulated by annular reactors (ARs). It was found that the lowest DBPs and the highest inactivation of OPs such as Mycobacterium spp., Mycobacterium avium, Aeromonas spp., Pseudomonas aeruginosa and Hartmanella vermiformis, occurred in the effluent of the AR with 0.6 mg/L phosphate addition. Based on the results of different characterization techniques, for the AR with 0.6 mg/L phosphate-enhanced O-BAC treatment, dissolved organic carbon in the influent exhibited the lowest concentration and most stable fraction due to the improved biodegradation effect. Moreover, the total amount of suspended extracellular polymeric substances (EPS) in the bulk water of the AR decreased greatly, resulting in the lowest chlorine consumption and DBPs formation in the AR. In Fourier transform infrared spectra of the suspended EPS, the amide II band (1600-1500 cm) disappeared and the protein/polysaccharide ratio decreased remarkably, indicating the destruction of protein and a decrease in hydrophobicity. Moreover, β-sheets and α-helices in the protein secondary structures were degraded while the random coils increased sharply as phosphate addition increased to 0.6 mg/L, inhibiting microbial aggregation and hence weakening the chlorine-resistance capability. Thus, most of the OPs in suspended biofilms were more easily inactivated by residual chlorine, resulting in the lowest OPs occurrence in the effluent of the AR. Our findings indicated that enhancing the efficiency of the BAC filter by adding phosphate is a promising method for improving water quality in DWDSs.
采用环状反应器（AR）模拟饮用水分配系统（DWDS），考察了不同磷酸盐剂量（0、0.3 或 0.6mg/L）下臭氧-生物活性炭（O-BAC）处理对饮用水中消毒副产物（DBPs）形成和机会性病原体（OPs）出现的影响。结果表明，在添加 0.6mg/L 磷酸盐的 AR 出水中，DBPs 最低，分枝杆菌属、鸟分枝杆菌、气单胞菌属、铜绿假单胞菌和变形虫属等 OPs 的灭活率最高。基于不同表征技术的结果，对于添加 0.6mg/L 磷酸盐增强 O-BAC 处理的 AR，由于改善了生物降解效果，进水溶解性有机碳（DOC）浓度最低且最稳定。此外，AR 中大部分水体悬浮细胞外聚合物物质（EPS）总量大幅减少，导致 AR 中氯消耗和 DBPs 生成量最低。在悬浮 EPS 的傅里叶变换红外光谱中，酰胺 II 带（1600-1500cm）消失，蛋白质/多糖比显著降低，表明蛋白质被破坏，疏水性降低。此外，随着磷酸盐添加量增加到 0.6mg/L，蛋白质二级结构中的β-折叠和α-螺旋被降解，而无规卷曲急剧增加，抑制了微生物聚集，从而减弱了其抗氯能力。因此，悬浮生物膜中的大多数 OPs 更容易被余氯灭活，导致 AR 出水中 OPs 出现率最低。研究结果表明，通过添加磷酸盐提高 BAC 滤池的效率是改善 DWDS 水质的一种有前途的方法。
