Bacteriological and Physicochemical Analyses of the Raw and Treated Water of Saidabad Water Treatment Plant, Dhaka

Abstract

Bacteriological and physicochemical parameters of the raw and treated water of the Saidabad Water Treatment Plant were analysed during the period January through December 2004. It was found that during dry season Sitalakhya River water was adversely polluted and most of the bacteriological and physicochemical parameters increased to an alarming level. Total coliform and thermotolerant-coliform counts of raw water were highest in months of January through March and lowest during the months of April through November. Ammonia concentration of the raw water was very high (3.08-7.06 mg/l) during the dry months from January to April that coincided with high (2.57-6.08 mg/l) ammonia contamination in the treated water. The others physicochemical parameters like turbidity, conductivity, total dry solid (TDS), hardness and alkalinity were high during the dry months. The residual chlorine in treated water was always below 0.50 mg/l. The study clearly indicated that the load of coliform increased when the concentration of ammonia was high in raw water that, to some extent, influenced the aesthetic properties of the treated water like turbidity, colour, taste, odour, alkalinity, TDS, etc. In spit of that the treated water could be used for domestic and drinking purposes for most of the year.