MONITORING WATER QUALITY OF FILTRATION PLANTS AND COMPARATIVE ANALYSIS OF BIOFILM FORMATION

Abstract

Globally, at least 2 billion people are forced to use drinking water source contaminated with faeces. Drinking Water Distribution System (DWDS) function as microbiological and physicochemical reactors which interact with drinking water and, in turn, impact upon the quality of water supplied to customers. The presence of biofilms in the drinking water distribution system may play a role in the presence of potential pathogens in drinking water supply. Biofilm in DWDS causes fouling of filtration membranes, impairs taste, degrade quality of drinking water and transmits harmful pathogens. Disinfection along with filtration helps to remove pathogens and suspended particles. The water filtration plants have different stages with varying media and pore size to remove all insoluble suspended particles and organic substances as well as taste and odor. The UV sterilizer in the last stage, sterilizes water by scrambling microbial DNA, thus provides absolutely safe water for drinking and cooking. The aim of this study was to monitor the changes in physicochemical and biofilms related to pre and post filtration plants by evaluating polyvinyl chloride (PVC) pipe coupons. The physicochemical and microbial parameters of drinking water in pre and post filtration plants were evaluated in this research. Water samples were collected from water tanks and filtration plants of NUST to monitor the microbial parameters following standard protocols for coliforms, E. coli and total viable count at 37 °C. The heterotrophic plate counts were determined for both the planktonic and biofilm phases of water samples. Scanning Electron Microscopy (SEM) images were captured to evaluate the surface topography of biofilm formed in the pre and post filtration plants and revealed that structure of biofilm alters drastically after passing through filtration process. A total of 16 strains of bacteria were isolated from 15 sampling points employing biochemical and morphological tests.