Water Research ( IF 12.8 ) Pub Date : 2021-10-27 , DOI: 10.1016/j.watres.2021.117806 Daniel W Smith 1 , Mahfuza Islam 2 , Kirin E Furst 1 , Shobnom Mustaree 3 , Yoshika S Crider 4 , Nazrin Akter 2 , Syed Anjerul Islam 2 , Sonia Sultana 2 , Zahid H Mahmud 3 , Mahbubur Rahman 2 , William A Mitch 1 , Jennifer Davis 5
Expanding drinking water chlorination could substantially reduce the burden of disease in low- and middle-income countries, but the taste of chlorinated water often impedes adoption. We developed a Monte Carlo simulation to estimate the effect of people's choice to accept or reject drinking water based on chlorine taste and their subsequent exposure to E. coli and trihalomethanes, a class of disinfection byproduct (DBP). The simulation used empirical data from Dhaka, Bangladesh, a megacity with endemic waterborne disease. We drew on published taste acceptability thresholds from Dhaka residents, measured residual chlorine and thermotolerant E. coli inactivation following the addition of six chlorine doses (0.25–3.0 mg/L as Cl2) to untreated piped water samples from 100 locations, and analyzed trihalomethane formation in 54 samples. A dose of 0.5 mg/L, 75% lower than the 2 mg/L dose typically recommended for household chlorination of low-turbidity waters, minimized overall exposure to E. coli. Doses of 1–2 mg/L maximized overall exposure to trihalomethanes. Accounting for chlorine taste aversion indicates that microbiological exposure increases and DBP exposure decreases above certain doses as a higher proportion of people reject chlorinated water in favor of untreated water. Taken together with findings from other modeling analyses, empirical studies, and field trials, our results suggest that taste acceptability should be a critical consideration in establishing chlorination dosing guidelines. Particularly when chlorination is first implemented in water supplies with low chlorine demand, lower doses than those generally recommended for household water treatment can help avoid taste-related objections while still meaningfully reducing contaminant exposure.
中文翻译:
氯的味道会增加对粪便污染和供水中消毒副产品的模拟暴露
扩大饮用水氯化可以大大减轻低收入和中等收入国家的疾病负担,但氯化水的味道往往会阻碍采用。我们开发了蒙特卡罗模拟来估计人们根据氯的味道选择接受或拒绝饮用水的影响,以及他们随后接触大肠杆菌和三卤甲烷,一类消毒副产品 (DBP)。模拟使用来自孟加拉国达卡的经验数据,达卡是一个流行水传播疾病的特大城市。我们画上公布味道合格阈值从达卡居民,测定残留氯和耐热大肠杆菌灭活加入六个氯剂量(0.25-3.0毫克/升例如Cl以下2) 对来自 100 个地点的未经处理的管道水样品进行分析,并分析了 54 个样品中三卤甲烷的形成。0.5 毫克/升的剂量,比通常推荐用于低浊度水的家庭氯化的 2 毫克/升剂量低 75%,最大限度地减少了对大肠杆菌的总体暴露. 1–2 mg/L 的剂量使三卤甲烷的总体暴露最大化。对氯味厌恶的解释表明,微生物暴露增加而 DBP 暴露减少超过特定剂量,因为更高比例的人拒绝氯化水而支持未经处理的水。结合其他建模分析、实证研究和现场试验的结果,我们的结果表明,味道可接受性应该是建立氯化剂量指南的关键考虑因素。尤其是在氯需求量低的供水中首次实施氯化时,比通常建议用于家庭水处理的剂量更低的剂量有助于避免与味道相关的反对,同时仍然有意义地减少污染物暴露。