Emerging contaminants in water pathways: sources, impacts, conventional, and cold-plasma-based cleaner technology...

Emerging contaminants (EC) pose a major challenge to sustainable water and wastewater treatment because of their persistence, continuous release, biological activity, and resistance to conventional remediation. This review provides a critical assessment of EC occurrence, environmental fate, analytical detection, conventional treatment technologies, and cold plasma technology (CPT). Comparative analysis demonstrates that the principal challenge in EC remediation lies not in the absence of effective technologies but in the mismatch between contaminant properties and treatment mechanisms. Adsorption and membrane processes efficiently separate EC but generate secondary waste streams, biological treatment is constrained by microbial selectivity and slow degradation kinetics, and advanced oxidation processes achieve rapid oxidation but remain limited by energy demand, incomplete mineralization, transformation-product formation, and operational complexity. Hybrid systems improve treatment performance by integrating complementary mechanisms but increase process complexity and cost. CPT is critically evaluated as an emerging process-intensification platform capable of generating diverse reactive oxygen and nitrogen species in situ for broad-spectrum EC degradation. Current advances in plasma chemistry, reactor engineering, plasma-liquid interaction, and hybrid plasma systems are assessed alongside challenges related to energy efficiency, reactor scalability, standardized performance metrics, and real wastewater validation. The review identifies key mechanistic framework for developing efficient, scalable, and sustainable EC remediation technologies.