Assessment of physico chemical and bacteriological quality of drinking water in conventional drinking water treatment processes and water supply system in malle woreda, south west Ethiopia

Abstract

Background: The contamination of drinking water quality with different contaminants is causing a serious threat to millions of people across the globe. To raise the quality of drinking water, various treatment methods are needed. However, existing water treatment systems and drinking water quality is not investigated in low-income countries including Ethiopia. Continuous examination of water quality analysis in terms of detection of indicator organisms and physico chemical analysis is among the methods of assessing the safe condition of drinking water treatment system. Objectives: To evaluate the performance of Boshkoro, Lemogento and Kella treatement plant and water supply system regarding their ability to produce quality water and control pathogens in Malle woreda, southwest Ethiopia. Method: A cross-sectional study design was employed during the period from August 1 to October 28, 2021, in Boshkoro, Kella and Lemogento towns of Malle woreda, southwest Ethiopia. A total of eleven water sample was collected from four sampling point of three treatment plant of the study area. The collected samples were analyzed for bacteriological quality and physical parameters. Data was analyzed using Statistical Package for Social Sciences (SPSS) software version 23, and Microsoft Excel 2016. Result: The mean results of municipal conventional drinking water treatment analysis and water supply system samples located in the study area showed that pH, turbidity, and electrical conductivity of the water samples were varied between 6.8–8.10, 1-5 NTU, and 198-5340μS/cm, respectively. Sulfate and nitrate concentrations of the water samples also ranged between 2 and 97 mg/l and 0.30 –7.37 mg/l, respectively.Majority of samples were positive for total coliform bacteria with counts ranging from 0 to 85 CFU/100 ml, except for Lemogento and Kella town treatment reservoir after disinfection and main distribution system. Whereas, fecal coliforms were detected in all sampling points ranging from 0 to 90 CFU/100 ml, except, for Lemogento reservoir and distribution and Kella reservoir samples. Conclusion: In general, majority of physicochemical and some of bacteriological quality of the water samples collected from three treatment plant units lies within the maximum permissible limits of WHO guidelines. But, fluoride, conductivity, copper, iron fecal coliforms and total coliforms were not within the recommended limit of WHO guidelines for drinking water.