Photolysis of Chloramine Disinfection Residuals in Drinking Water Using UV Irradiation Systems

Abstract

Chloramine is widely used as a secondary disinfectant in drinking water distribution systems due to its stability and prolonged residual disinfection capability. However, the persistence of chloramine residuals may contribute to the formation of undesirable disinfection byproducts and affect water quality during treatment and reuse processes. The present study investigates the photolysis of chloramine disinfection residuals in drinking water using ultraviolet irradiation systems under controlled operating conditions. The research focuses on evaluating chloramine degradation efficiency, reaction kinetics, byproduct formation, and process optimization associated with UV-based photolytic treatment. Experimental analysis was conducted to examine the influence of UV intensity, exposure time, water pH, chloramine concentration, and dissolved organic matter on photolysis performance and residual reduction behavior. Results demonstrate that ultraviolet irradiation effectively decomposes chloramine compounds through photochemical reactions involving reactive radical species and bond cleavage mechanisms, resulting in significant reduction of disinfectant residuals. The study further reveals that increased UV dose and optimized operating conditions substantially enhance chloramine degradation while minimizing the formation of harmful secondary byproducts. Reaction kinetic analysis indicates that photolysis efficiency is strongly dependent on irradiation exposure and water quality characteristics. Comparative assessment with conventional chemical dechlorination methods confirms the advantages of UV photolysis, including reduced chemical consumption, improved operational safety, and lower risk of secondary contamination.