Evaluation of Performance of Conventional Water Treatment System: A Case Study

Most urban centres of the world are already limited by the amount and quality of available water. According to World Health Organization (WHO, 2002), in the next 30 years alone, accessible water is unlikely to increase more than 10 percent but the earth's population is projected to rise by approximately one-third. One of the millennium development goals is to provide access to safe drinking water to all. The existing main water supply system for Kakamega town comprises surface water ion from River Isiukhu, located on the south-eastern boundary of the Municipality. The water supply relies on a two stage pumping regime from the ion to treatment works and thereafter to the town's main storage tanks in Milimani area. This paper presents findings of a study carried out to determine performance of Kakamega water treatment plant. Samples of water were taken from the source and the treated water and were analyzed for physical, chemical and bacteriological parameters of water quality. Kakamega treatment plant employs rapid sand filters that utilize a bed of silica sand and graded gravel of 0.6 m and 0.4 m deep respectively. The sand has effective sizes of 0.66 mm and uniformity coefficient of 1.82, it as well has porosity of 56.1%. While the graded gravel has specific gravity of 2.56 and porosity of 38.1%. This indicates that the filter sand used as filter media fails to comply with most of the requirements of a rapid sand filter.