Design and development of automatic village water disinfection system using ultraviolet radiation

Abstract

Most village water supply systems in the country continue to face problems related to microbial contamination, resulting in water quality that does not meet the potable water standards set by the Department of Health. This research was conducted with the objective of designing and developing an automatic Ultraviolet radiation (UV) disinfection system for village water supply at the laboratory scale. It also aims to contribute knowledge that can be further developed for replacing chlorine solutions traditionally used for disinfection in rural water supply systems. The design emphasizes simplicity, high efficiency, low cost, and safety. The research methodology involved problem analysis, design, construction and development, laboratory testing, and microbiological water quality assessment. The results of the study indicated that the design and development of the automatic UV disinfection system, using a low-pressure mercury UV lamp with a power of 18 watts, produced UV irradiance (E_UV) calculated by the Keitz formula at 27.6 milliwatts per square centimeter (mW/cm²). With an exposure time of 1 second, the UV dose reached 27.6 milliwatt-seconds per square centimeter (mW·s/cm²), which is higher than the dose required to reduce E. coli and most pathogens by 99% (2-log or D₉₉). Laboratory testing of the developed system revealed that, when treating settled raw water with a turbidity of 1.37 NTU and pH of 6.7, UV exposure of more than 5 minutes resulted in no detectable coliform bacteria in the water samples. Therefore, this system can be scaled up through design and calculation of the appropriate UV dose relative to water volume, flow rate, and raw water quality for use in village water supply systems. The system can be installed at elevated water tanks prior to distribution, helping reduce microbial contamination and enabling water to meet potable standards as defined by the Department of Health.