A Concise Review on Water Treatment for Environmental Sustainability

Water treatment is increasingly challenged by complex pollution mixtures, pollutant transformation, residual streams, and the growing imperative for low-carbon and circular resource management. Conventional treatment processes remain essential components of modern water infrastructure; however, reliance on isolated, single-unit technologies is fundamentally insufficient because contaminants may be only partially removed, transferred into sludge or concentrate phases, or effectively controlled only under narrow and specific operating conditions. The purpose of this review is to systematically analyse and critically discuss recent water-treatment literature in order to explain why sustainable water treatment demands a systems-engineering perspective rather than continued dependence on single-process removal efficiency metrics. This review first examines the inherent limitations of major single treatment processes-including coagulation, adsorption, membrane filtration, and advanced oxidation-when confronted with complex and dynamic pollution conditions. It then develops a comprehensive system-level framework grounded in four interconnected pillars: multi-barrier risk control, circular resource recovery, life-cycle-based low-carbon technology selection, and adaptive real-time monitoring. The review concludes that future water treatment infrastructure should be deliberately designed as an integrated system that explicitly connects pollutant fate and transport, ecological and human health risk reduction, resource recovery, carbon emission reduction, and cross-media environmental governance. This holistic approach is significant because it provides a clearer, more actionable pathway for developing water treatment strategies that are technically effective, environmentally sustainable, and operationally reliable under long-term water-security pressures.