Polymer-Enhanced Recovery of Filter Backwash Water for Circular Reuse in Semi-Arid Drinking Water Treatment Systems

Water reuse is increasingly recognized as a key strategy for sustainable water management in semi-arid regions, where drinking water treatment plants generate significant volumes of filter backwash water with limited reuse. This study evaluates the effectiveness of assisted clarification for enhancing backwash water recovery under full-scale operational conditions in a semi-arid Moroccan treatment facility. Settling experiments were conducted with and without coagulant addition, and clarification performance was monitored through physicochemical parameters and statistical analysis. Coagulant addition markedly accelerated sedimentation kinetics, enabling clarified water recovery exceeding 90% within 20 min compared with substantially lower recovery in the control condition. A two-way ANOVA confirmed a significant treatment effect and a strong interaction between coagulant addition and settling time. These findings demonstrate that coagulant-assisted clarification can substantially improve backwash water recovery under real operating conditions. The results highlight the potential of this approach as a practical and scalable option for promoting circular water reuse in water-stressed environments while maintaining operational simplicity.