Enhanced Inactivation of E. coli in Drinking Water Using Sequential UV Irradiation and Chlorination for Improved Disinfection Efficiency in Northern Cyprus.

Abstract:

Clean water is essential for human health, as it greatly reduces the risk of disease; however, water can also serve as a vehicle for pathogens. To safeguard public health, the Environmental Protection Agency (EPA) has established drinking water standards to control microbial contamination and disinfection byproducts. This study investigated the combined use of UV irradiation followed by chlorination to inactivate Escherichia coli under low UV doses and short contact times. The results showed that UV irradiation alone achieved a 2-log₁₀ reduction after 30 seconds, whereas chlorination alone was more effective, achieving a 2-log reduction at chlorine doses of 0.5, 1, 2, and 3 mg/L within 60, 5, 1, and 1 minute, respectively. The combined UV–chlorine treatment outperformed either method alone, demonstrating that UV disinfection is significantly enhanced when followed by low-dose chlorination.