Department of Civil and Environmental Engineering, University of Illinois at Urbana-Champaign, Urbana, IL, 61801, USA; Safe Global Water Institute, University of Illinois at Urbana-Champaign, Urbana, IL, 61801, USA.
Department of Civil and Environmental Engineering, University of Illinois at Urbana-Champaign, Urbana, IL, 61801, USA; Safe Global Water Institute, University of Illinois at Urbana-Champaign, Urbana, IL, 61801, USA.
Water Res. 2018 Nov 1;144:482-490. doi: 10.1016/j.watres.2018.07.065. Epub 2018 Jul 27.
Toxicity arising from toxic disinfection byproducts is an unintended result of disinfection during water reclamation. To ensure safe water reclamation treatment, it is important to develop a disinfection strategy with minimal formation of overall toxicity in the reclaimed water. The cumulative disinfectant concentration over time (Ct) is a useful concept for pathogen control during reuse water disinfection. We evaluated the toxicity impact of Ct values and different methods to achieve identical Ct values by ozonation or chlorination of wastewaters from four agricultural sources on mammalian cells. N-acetylcysteine (NAC) reactivity of the wastewater organic extracts was determined to reveal their impact on the thiol-specific biological detoxification mechanism. The results demonstrated that for two sources and for both ozonation and chlorination, higher Ct values enhanced cytotoxicity. The ozonated waters were at least 10% less toxic and as much as 22.4 times less toxic than either the non-disinfected controls or the chlorinated waters. Chlorination consistently induced higher cytotoxicity than ozonation by between 2.2 and 22.4 fold, respectively, and induced similar or higher cytotoxicity than the non-disinfected controls, by at most 4.4 fold. Given the same Ct values, the combination of high disinfectant concentration and short contact time produced finished wastewaters with higher toxicity, than the combination of low disinfectant concentration and long contact time. NAC thiol reactivity was positively and significantly correlated with mammalian cell cytotoxicity, and agreed with 80% of the cytotoxicity rank order. This suggests that the induction of cytotoxicity involved reactions with agents that acted as thiol pool quenchers. The overall results indicate that the cytotoxicity of wastewaters may increase when higher Ct values are applied to inactivate recalcitrant pathogens. To counteract the potential increase in cytotoxicity at high Ct values, for both ozonation and chlorination, lower disinfectant dose and longer contact time may be adopted.
毒性来自有毒消毒副产物，是水回收过程中消毒的意外结果。为确保安全的水回收处理，开发一种消毒策略，使回收水中的总毒性最小化非常重要。随着时间的推移，累积消毒剂浓度（Ct）是重复使用水消毒过程中控制病原体的有用概念。我们评估了 Ct 值的毒性影响以及通过臭氧化或氯化四种农业来源废水来实现相同 Ct 值的不同方法对哺乳动物细胞的影响。测定废水有机提取物的 N-乙酰半胱氨酸（NAC）反应性，以揭示其对硫醇特异性生物解毒机制的影响。结果表明，对于两个来源以及臭氧化和氯化，较高的 Ct 值增强了细胞毒性。与非消毒对照或氯化水相比，臭氧化水的毒性至少低 10%，最多低 22.4 倍。氯化比臭氧化分别高出 2.2 到 22.4 倍，始终诱导更高的细胞毒性，并且与非消毒对照相比，最多高出 4.4 倍。在相同的 Ct 值下，高消毒剂浓度和短接触时间的组合产生的废水毒性更高，而低消毒剂浓度和长接触时间的组合则毒性更低。NAC 巯基反应性与哺乳动物细胞细胞毒性呈正相关且显著相关，并且与 80%的细胞毒性排序一致。这表明细胞毒性的诱导涉及与作为巯基池猝灭剂的试剂的反应。总体结果表明，当应用更高的 Ct 值来灭活顽固病原体时，废水中的细胞毒性可能会增加。为了抵消高 Ct 值时潜在的细胞毒性增加，对于臭氧化和氯化，可能采用较低的消毒剂剂量和较长的接触时间。
