Water pathways through the ages: Integrated laundry wastewater treatment for pollution prevention

Rapid urbanization and the rising global population have led to the generation of substantial volumes of laundry wastewater. Accordingly, treatment of laundry wastewater has been advocated to curb water pollution and achieve water sustainability. However, technological limitations in treating (specifically) laundry wastewater and the lack of regulations governing the levels of contaminants for such discharges have been perennial problems. This review bridges the knowledge gap by delineating the feasibility of current technologies in laundry wastewater treatment and the experiences of various countries in adopting different approaches. Besides, the feasible methods for collecting laundry wastewater are elaborated. The development of the treatment technologies is highlighted, in which the integrated-treatment processes (physicochemical, biological, and combination of both) are critically discussed based on their functions and methods. A judicious selection of the technologies not only improves the energy efficiency and quality of the treated wastewater, but also mitigates capitals and operational costs. This is projected to enhance public acceptance towards the reuse of laundry wastewater. Thus, the comprehensive assessment herein is envisioned to insightfully guide national policymakers in exploring the viability of the technologies and water-recycling projects. Future research should focus on the techno-economic aspects of the treatment processes, especially their industrial scale-up.