The transition towards circular and sustainable urban water systems, embracing a water-wise city approach, results in highly interconnected systems, introducing complexities in managing water quality due to the intricate interplay of pollutant sources, pathways, and receptors in urban environments. This study focuses on assessing the impact of transitioning to a water-wise city approach on water quality. The analysis employs an integrated model-based approach to evaluate the release of micropollutants (PFOA, PFOS, pyrene) in the urban water system, considering potential future changes. We considered Milan (Italy) as a case study and explored sustainable urban water management strategies related to the hydraulic reconnection of canals, including (i) the use of groundwater for energy purposes, (ii) the establishment of a separate stormwater sewer system, and (iii) the indirect reuse of reclaimed water for crop irrigation. Acute and chronic environmental risks were assessed at various locations of the recipients, under different water management and climate change scenarios. Uncertainties on projections related to rainfall and runoff concentrations were also considered. The model accurately predicted average micropollutants concentrations in the current situation. PFOA and PFOS exhibit chronic, but not acute risks in all scenarios; high removal efficiency is required to reduce the risk at acceptable levels. Pyrene poses higher risks for increasing separation fractions of the sewer system, with further increase for climate change, but concentration uncertainty has more influence than precipitation uncertainty on the risk extent. This study provides a water management framework, identifying critical sources and locations under current, future, and climate change scenarios.

中文翻译：

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城市地区向节水方法过渡的影响：阐明微污染物释放的风险

向循环和可持续城市水系统的过渡，采用节水城市方法，导致系统高度互连，由于城市环境中污染物源、路径和受体之间错综复杂的相互作用，带来了水质管理的复杂性。本研究的重点是评估向节水型城市转型对水质的影响。该分析采用基于模型的综合方法来评估城市水系统中微污染物（PFOA、PFOS、芘）的释放，并考虑未来潜在的变化。我们以米兰（意大利）为案例研究，探讨了与运河水力重新连接相关的可持续城市水资源管理策略，包括（i）将地下水用于能源目的，（ii）建立独立的雨水下水道系统，以及(iii) 再生水间接回用用于农作物灌溉。在不同的水管理和气候变化情景下，对接收者不同地点的急性和慢性环境风险进行了评估。还考虑了与降雨和径流浓度相关的预测的不确定性。该模型准确预测了当前情况下的平均微污染物浓度。 PFOA 和 PFOS 在所有情况下都表现出慢性风险，但并非急性风险；需要高去除效率才能将风险降低到可接受的水平。随着气候变化的进一步增加，芘对下水道系统分离部分的增加带来了更高的风险，但浓度不确定性对风险程度的影响大于降水不确定性。这项研究提供了一个水管理框架，确定了当前、未来和气候变化情景下的关键来源和地点。