Disinfection of Drinking Water Using Ultra-Violet (UV) Irradiation

Ultraviolet (UV) disinfection is currently one of the most popular alternatives to chlorination as a technology for drinking water disinfection. It has been proven to be highly effective against a broad range of waterborne pathogens, and is the best available technology for the inactivation of chlorine-resistant Cryptosporidium and Giardia, and other emerging biological contaminants. The costs of UV disinfection are also comparable to those for the traditionally-used chlorination, therefore making it the choice disinfection technology for water utilities globally.

This pilot-scale study was undertaken in 2007 to evaluate the effectiveness of UV disinfection under tropical climate conditions and local water quality. A total of three systems – one low-pressure (LP) and two medium-pressure (MP) – are tested in this study, and used to disinfect sand-filtered or membrane-filtered water from two local waterworks spiked with MS2 coliphage. The concentrations of MS2 coliphage before and after disinfection are enumerated to determine the inactivation efficiency of the UV systems. The analysis of water quality parameters such as pH, temperature, TOC concentrations, total iron and manganese concentrations, etc. which are relevant to the study is also performed. In addition, the UV disinfection systems are tested at different flow rates to evaluate the effect of changing flow rates on the inactivation efficiency of the systems.

Currently, preliminary results have shown that both LP and MP UV disinfection can be applied in the waterworks to disinfect MS2 coliphage effectively for sand-filtered water. Under tropical conditions, it is also recommended that residual chlorination be applied after UV disinfection. The systems will be further tested with membrane-filtered water, and the disinfection results for the two types of filtered waters will be compared. The pilot study is expected to be completed by 2008.

Disclaimer: Research collaboration with PUB shall not be construed as PUB’s endorsement of the Company’s technologies.