Integrated Water Treatment Approaches for Pollution Control and Environmental Sustainability

Water treatment is increasingly shifting from a narrow “pollutant removal” objective toward an integrated environmental-protection model in which water quality, residuals, energy demand, resource recovery, climate resilience and safe reuse are evaluated together. This expanded review develops a source-to-reuse framework for sustainable water and wastewater treatment by integrating conventional treatment, advanced separation, biological processes, membranes, electrochemical approaches, advanced oxidation, nature-based solutions, artificial-intelligence-assisted monitoring and circular resource recovery. The study uses the previously supplied review on water pollution and microplastics as a foundational source and extends it with recent peer-reviewed literature and international wastewater-treatment evidence. Particular attention is given to microplastics because they illustrate a broader problem: a treatment process may transfer contaminants from water to sludge or concentrate without eliminating their environmental risk. Recent evidence indicates reported microplastic removal ranges of 74–99.2% for physical methods, 65–99.2% for chemical methods and 77–100% for biological methods, while large variation in influent and effluent concentrations reflects differences in sampling and analytical protocols [1–5]. Global reporting for 2022 indicated that, among the countries for which relevant calculations were possible, 76% of reported wastewater flows received some treatment while 60% received at least secondary treatment; these figures are not a complete global estimate because reporting coverage was limited [6,7]. The paper proposes a novel conceptual model named the CLEAR-WATER 360° Framework—Control at source, Laboratory/AI-enabled monitoring, Efficient treatment, Assessment of residuals, Resource recovery, Water reuse, Environmental verification, and continuous feedback. The framework is intended to support future empirical studies in municipal, institutional, industrial and decentralized treatment systems.