Wastewater Treatment Challenges and Circular Reuse for One Health Sustainability: A Review

Wastewater is a complex and dynamic issue, particularly at the human–animal–environment interface, bearing biological and chemical hazards that may serve as a resource for transmission pathways for pathogens, antimicrobial resistance (AMR) determinants, heavy metals, pharmaceutical residues, per- and polyfluoroalkyl substances (PFAS), and microplastics. Rising global health issues necessitate effective wastewater treatment and advanced research to support risk-informed circular management within a one health framework, incorporating wastewater-based epidemiology (WBE), multi-omics approaches, nanobiotechnology, and green technologies. Inadequate wastewater treatment and uncontrolled discharge result in the generation of more than 380 billion cubic meters of wastewater annually worldwide, contributing to ecological degradation, the spread of AMR, and long-term toxicological risks. Despite significant advances in wastewater treatment, several challenges remain, including complex contaminant mixtures, limited detection and monitoring technologies, variable treatment efficiency, and weak regulatory and governance frameworks. This review highlights key wastewater treatment issues and presents recent advances in WBE and multi-omics approaches, such as metagenomics, resistome profiling, virome analysis, and chemical fingerprinting for contaminant monitoring and public health risk assessment. This review also examines circular reuse strategies focused on water reclamation, nutrient recovery, bioenergy production, and resource recovery, with particular emphasis on nature-based systems, hybrid biological–physicochemical treatment platforms, and green nanobiotechnology as promising approaches to improve treatment performance while minimizing environmental impacts. In conclusion, this review highlights the importance of integrated and sustainable wastewater management approaches within the One Health framework to address emerging challenges and promote environmental resilience, public health protection, and circular resource recovery.