Insights into the fate and properties of organic halamines during ultraviolet irradiation: Implications for drinking water safety.

ABSTRACT

Organic halamines compounds present a significant threat to the safety of drinking water due to their potential toxicity and stability. While Ultraviolet (UV) disinfection is commonly used for water treatment, its specific effects on organic halamines and the underlying mechanisms remain poorly understood. In this study, we investigated eight amino acid-derived organic chlor- and bromamines as representative compounds. Our findings revealed that organic halamines have a slow hydrolysis rate (<10-3 M-1 s-1) and can persist in water for extended periods (30-2000 min). However, their disinfection efficacy against Staphylococcus aureus and their ability to degrade micropollutants like carbamazepine were found to be limited. Interestingly, under UV irradiation, the N-X bonds in organic halamines were observed to break, leading to accelerated decomposition and the generation of abundant free radicals. These free radicals synergistically facilitated the removal of micropollutants and the inactivation of pathogenic microorganisms. It is worth noting that this transformation of organic halamines during UV disinfection resulted in a slight increase in the concentrations of nitrogenous disinfection byproducts. These findings shed light on the behavior and characteristics of organic halamines during UV disinfection processes, providing crucial insights for effectively managing drinking water quality impacted by these compounds. By understanding the implications of organic halamines, we can refine water treatment strategies and ensure the safety of drinking water supplies.