Seeking Sustainability: Multiobjective Evolutionary Optimization for Urban Wastewater Reuse in China

TLDR

Sustainable wastewater reuse in China must balance water resource augmentation, pollutant reduction, and economic profit. The study develops a systematic multiobjective optimization framework to trade off reuse supply and demand, costs and profits, and pollutant reduction. Using a nondominated sorting genetic algorithm, Pareto fronts for 31 provinces were generated and control strategies selected based on regional water resources and environmental status. Nationally, the optimized strategy recommends 15.39 billion cubic meters of reuse, 176.31 kt BOD5 reduction, and 9.68 billion RMB profit, with water‑resource augmentation and pollution control outweighing profit, directing reclaimed water to municipal/domestic/recreational use in quantity‑scarce provinces and industrial use in quality‑scarce provinces, thereby providing policymakers a comprehensive reuse framework.

Abstract

Sustainable design and implementation of wastewater reuse in China have to achieve an optimum compromise among water resources augmenting, pollutants reduction and economic profit. A systematic framework with a multiobjective optimization model is first developed considering the trade-offs among wastewater reuse supplies and demands, costs and profits, as well as pollutants reduction. Pareto fronts of wastewater reuse optimization for 31 provinces of China are obtained through nondominated sorting genetic algorithm trials. The control strategies for each province are selected on the basis of regional water resources and water environment status. On the national level, the control strategies of wastewater reuse scale, BOD5 reduction, and economic profit are 15.39 billion cubic meters, 176.31 kilotons, and 9.68 billion RMB Yuan, respectively. The driving forces of water resources augmenting and water pollution control play more important roles than economic profit during wastewater reuse expanding in China. According to the optimal allocations, reclaimed wastewater should be intensively used in municipal, domestic, and recreative sectors in the regions suffering from quantity-related water scarcity, while it should be focused on industrial users in the regions suffering from quality-related water scarcity. The results present a general picture of wastewater reuse for policy makers in China.