Microplastic-Pharmaceutical Interactions and Their Disruptive Impact on UV and Chemical Water Disinfection Efficacy

The presence of microplastics originating from pharmaceutical coatings represents an emerging concern in water quality management, particularly in the context of conventional disinfection methods. This conceptual paper explores the disruptive interactions between pharmaceutical-derived microplastics and two widely adopted water disinfection systems—ultraviolet (UV) irradiation and chemical oxidation (e.g., chlorination, ozonation). It proposes that these microplastics, due to their unique chemical composition, size, and surface morphology, may interfere with the efficacy of disinfection processes through three primary mechanisms: physical shielding, contaminant adsorption, and catalytic transformation. Firstly, the structural attributes of microplastics can create a physical barrier that shields pathogenic microorganisms from direct UV exposure or chemical contact, leading to suboptimal inactivation. Secondly, microplastics possess high surface-area-to-volume ratios and hydrophobic properties that enable the adsorption of both disinfectants and microbial contaminants, potentially reducing free disinfectant availability while fostering microbial persistence and biofilm formation. Thirdly, additives and degradation by-products from pharmaceutical coatings embedded in the microplastics may act as catalysts, altering redox reactions during chemical disinfection and generating disinfection by-products (DBPs) with uncertain toxicological implications. Furthermore, these interactions are theorized to vary depending on the physicochemical properties of the pharmaceutical polymers, environmental conditions such as pH and temperature, and the presence of co-contaminants. The paper underscores the urgent need for targeted empirical studies to validate these hypothesized mechanisms, evaluate the cumulative impact on microbial inactivation efficiency, and assess potential risks to human health and ecosystem stability. In doing so, it calls for the development of refined detection techniques, integrated water quality monitoring frameworks, and innovative pretreatment strategies to address microplastic-pharmaceutical interference. By providing a foundational conceptual model, this study contributes to the growing discourse on emerging pollutants in aquatic systems and offers a roadmap for future research to ensure the robustness of water treatment protocols. It advocates for cross-disciplinary collaboration to enhance the resilience of public water infrastructure in the face of complex, synthetic contaminants.