Department of Civil and Environmental Engineering, University of Toledo, 2801 W. Bancroft St, Mail Stop 307, 3006 Nitschke Hall, Toledo, OH 43606, USA.
Department of Bioengineering Engineering, University of Toledo, 2801 W. Bancroft St, Mail Stop 303, 5051 Nitschke Hall, Toledo, OH 43606, USA.
J Hazard Mater. 2018 Jun 5;351:293-300. doi: 10.1016/j.jhazmat.2018.02.047. Epub 2018 Mar 3.
The objective of this study is to evaluate the influence of water distribution system conditions (pH, total organic carbon, residual chlorine, and phosphate) on haloacetic acids (HAAs) biodegradation. A series of batch microcosm tests were conducted to determine biodegradation kinetics and collected biomass was used for real time quantitative reverse transcription polymerase chain reaction analyses to monitor how these drinking water distribution system conditions affect the relative expression of bacterial dehalogenase genes. It was observed that tested water distribution system conditions affected HAA biodegradation with different removal efficiencies (0-100%). HAA biodegradation was improved in tested samples with TOC (3 mg/L) and pH 8.5 compared to those of TOC (0 mg/L) and pH 7, respectively. However, slight improvement was observed with the increased PO concentration (3.5 mg/L), and the presence of residual chlorine even at low concentration prohibited biodegradation of HAAs. The observed trend in the relative expression of dehII genes was compatible with the HAA biodegradation trend. Overall relative expression ratio of dehII genes was lower at pH 7, phosphate (0.5 mg/L), and TOC (0 mg/L) in comparison with pH 8.5, phosphate (3.5 mg/L), and TOC (3 mg/L) in the same experimental conditions.
本研究旨在评估水质条件（pH 值、总有机碳、余氯和磷酸盐）对卤乙酸（HAAs）生物降解的影响。进行了一系列批式微宇宙试验以确定生物降解动力学，并收集生物量以进行实时定量逆转录聚合酶链反应分析，以监测这些饮用水分配系统条件如何影响细菌脱卤酶基因的相对表达。结果表明，所测试的水质条件对 HAA 生物降解有不同的去除效率（0-100%）。与 TOC（0 mg/L）和 pH 值 7 相比，在 TOC（3 mg/L）和 pH 值 8.5 的测试样品中观察到 HAA 生物降解得到改善。然而，随着 PO 浓度（3.5 mg/L）的增加，仅观察到轻微的改善，并且即使存在低浓度的余氯也会阻止 HAAAs 的生物降解。脱卤酶基因的相对表达观察到的趋势与 HAA 生物降解趋势一致。在相同的实验条件下，与 pH 值 8.5、磷酸盐（3.5 mg/L）和 TOC（3 mg/L）相比，在 pH 值 7、磷酸盐（0.5 mg/L）和 TOC（0 mg/L）条件下，脱卤酶基因的相对表达比值总体较低。
