College of Civil Engineering and Architecture, Zhejiang University, Hangzhou 310027, China.
College of Civil Engineering and Architecture, Zhejiang University, Hangzhou 310027, China.
Water Res. 2016 Dec 1;106:41-50. doi: 10.1016/j.watres.2016.09.047. Epub 2016 Sep 25.
The degradation and transformation products of 17β-estradiol (E2) by chloramines in a pilot-scale water distribution system (WDS) were investigated using varying conditions including multiple mass ratios of chlorine to nitrogen (Cl/N), changing concentrations of chloramines, and different pH and pipe materials. The degradation of E2 was complete in ≤9 h in both deionized water (DW) and in the WDS under studied conditions. When the degradation rate of E2 was compared in WDS and DW, the degradation rate was appreciably greater in the WDS than in the DW at Cl/N mass ratios of 3, 4 and 6. However, at Cl/N mass ratios of 8 and 9, degradation was faster in the DW than in the WDS. The degradation rate of E2 was greatly affected by the initial total chloramine concentration, and the degradation of E2 in DW was consistent with second-order kinetics. The degradation rate of E2 in both the DW and the WDS increased with increasing pH. The order of degradation rate of E2in different pipes was: ductile iron loop (loop A) > polyethylene (PE) loop (loop B)> stainless steel loop (loop C). Ten specific degradation products of E2, produced by chloramination, were identified. Most of the degradation products of E2 chloramination were stable for more than 10 h. The degradation pathways of E2 in the WDS are proposed and briefly discussed. The concentrations of trihalomethanes (THMs), haloacetic acids (HAAs), and halogenated nitromethane (HNMs) during the degradation E2 in WDS were also determined.
在中试规模的供水管网（WDS）中，采用不同的条件（包括氯与氮的多种质量比（Cl/N）、改变的氯胺浓度以及不同的 pH 值和管材）研究了 17β-雌二醇（E2）在氯胺作用下的降解和转化产物。在研究条件下，去离子水（DW）和 WDS 中 E2 的降解在 ≤9 h 内完全。当在 WDS 和 DW 中比较 E2 的降解速率时，在 Cl/N 质量比为 3、4 和 6 时，WDS 中的降解速率明显大于 DW 中的降解速率。然而，在 Cl/N 质量比为 8 和 9 时，DW 中的降解速率大于 WDS 中的降解速率。E2 的降解速率受初始总氯胺浓度的显著影响，且 E2 在 DW 中的降解符合二级动力学。E2 在 DW 和 WDS 中的降解速率均随 pH 值的增加而增加。不同管材中 E2 降解速率的顺序为：球墨铸铁管环（环 A）>聚乙烯（PE）管环（环 B）>不锈钢管环（环 C）。通过氯胺化产生了 10 种特定的 E2 降解产物，其中大部分 E2 氯胺化降解产物在 10 h 以上仍稳定存在。提出并简要讨论了 WDS 中 E2 的降解途径。还测定了 WDS 中 E2 降解过程中三卤甲烷（THMs）、卤代乙酸（HAAs）和卤代硝基甲烷（HNMs）的浓度。
