A comparative study of microbiological and physicochemical characteristics of water distributed from two water treatment plants in Rwanda

Abstract

This paper presents an assessment of water quality distributed from two Rwandan Water and Sanitation Corporation ltd (WASAC) water branches: Kimisagara WASAC water treatment plant and Kizanye WASAC station in Kigali-Rwanda. Water samples collected from those two WASAC water stations were assessed for both microbiological and physicochemical quality (temperature, odor, color and pH) using standard methods. A total of 32 samples were obtained from those stations. At the first sampling, 9 samples from homes supplied by Kizanye water station and 1 sample from its source were analyzed. Following their physicochemical records, their pH values (at 25°C) ranged from 6.61 to 7.01, temperatures ranging from 28 to 30°C, while their turbidity ranged from 1.34 to 4.9 NTU. The MPN count ranges from 0.9 to 14 MPN/100 ml. whereas regarding their microbiological assessment, fecal coliform counts on EMB agar plate ranged between 3.3×10² and 11.8×10² cfu/ml. The 9 samples from homes supplied by Kimisagara water treatment plant and 1 sample on its source were analyzed. Result of physicochemical analysis from Kimisagara plant showed that pH ranged from 7.53 to 7.00 while   temperature and turbidity values ranged from 25 to 28°C and 0.70 to 14.09°C respectively. The MPN count ranges from 1.1 to 17 MPN/100 ml. The fecal coliform counts on EMB agar plate ranged between 0 to 17.8×10² cfu/ml. Specific bacteria were isolated and then identified as Escherchia coli, Enterobacter aerogenes and Klebsiella species. Although Kimisagara and Kizanye water sources meet physicochemical and microbiological standard parameters, almost 50% of their destinations were found falling out of these standard parameters. Thus, as recommendation to WASAC authority, there is a need for improvement in the water management strategy for better water quality especially along the distribution network.

Keywords: Microbiological analysis, physicochemical analysis, coliforms, Most Probable Number, water treatment, WASAC