Increasing water stress necessitates adopting wastewater reuse for sustainable living in urban environment. Trade-offs exist between different wastewater reuse applications and their environmental impacts. The impacts associated with developing urban water systems (UWSs) are not known, and city scale wastewater reuse in general is not well understood. This study investigates indirect, direct, non-potable and hybrid wastewater reuse scenarios in a real UWS to suggest environmentally sustainable reuse strategy using life cycle approach. The study develops a comprehensive life cycle inventory of actual water and wastewater utilities. Results show that all environmental impacts except eutrophication increases for direct potable and hybrid reuse. The centralized non-potable reuse (NPR) had lowest impact scores related with ecotoxicities while impacts including global warming were equivalent to the baseline. The study recommends adopting centralized NPR in developing UWSs while highlighting the treatment processes and impacts for reuse scenarios favorable in high to extreme water stressed regions.

中文翻译：

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城市供水系统废水回用替代方案的生命周期评估

日益严重的水资源压力需要采用废水再利用来实现城市环境的可持续生活。不同的废水回用应用及其环境影响之间存在权衡。与发展城市供水系统 (UWS) 相关的影响尚不清楚，城市规模的废水再利用总体上也不是很清楚。本研究调查了真实 UWS 中的间接、直接、非饮用水和混合废水再利用方案，以提出使用生命周期方法的环境可持续再利用策略。该研究开发了实际供水和废水处理设施的全面生命周期清单。结果表明，直接饮用和混合再利用时，除富营养化外的所有环境影响都会增加。集中式非饮用水再利用（NPR）与生态毒性相关的影响得分最低，而包括全球变暖在内的影响与基线相当。该研究建议在开发UWS时采用集中式NPR，同时强调在高至极端缺水地区有利的处理过程和再利用方案的影响。