Non-target analysis for wastewater treatment evaluation: strategies, applications, and future directions

Non-target analysis (NTA), based on high-resolution mass spectrometry (HRMS), is increasingly used to characterize the complex chemical composition of wastewater and evaluate the fate of emerging contaminants (EC) during treatment. However, despite its growing application, the use of NTA for wastewater treatment evaluation remains fragmented across the literature, with existing reviews focusing primarily on analytical workflows, contaminant identification, or environmental monitoring rather than treatment performance assessment. This review addresses this gap by providing a comprehensive synthesis of NTA as a framework for evaluating wastewater treatment processes. The principal NTA-based evaluation strategies reported in the literature are consolidated and classified, including assessment of changes in chemical complexity, investigation of contaminant fate throughout treatment trains, and analysis of shifts in physicochemical characteristics inferred from molecular information. Also, the review examines the wastewater-specific NTA workflow and synthesizes emerging themes across recent studies. Particular emphasis is placed on how these approaches can be translated into engineering-relevant metrics for assessing treatment efficiency and evaluating residual chemical risks. By bridging analytical chemistry and wastewater engineering perspectives, this review demonstrates how NTA can move beyond contaminant discovery to support technology comparison, process optimization, and risk-informed decision-making, while highlighting key challenges and research priorities for its broader implementation in wastewater treatment assessment.