PERFORMANCE EVALUATION OF SANGJANI AND RAWAL LAKE WATER TREATMENT PLANTS

Abstract

The physical removal of colloidal particles, microorganisms and other particulate material is an important objective of drinking water utilities. Because of the low concentration of suspended material in drinking water, turbidity and coliform bacteria have been the main water quality parameters for assessing particle removal in water treatment plants. This study describes the performance evaluation of two water treatment plants namely Sangjani and Ravval lake water treatment plants located in the twin cities of Rawalpindi and Islanuabad and overall water quality being supplied by these plants. Portable water testing kits like "OXFAM DELAGUA" and "PANI PARAKH" were used in the field to check physical and microbiological characteristics of water. The treatment processes of two water treatment plants were compared using turbidity and coliform data and individual efficiencies of unit operations and overall efficiencies of two water treatment plants were calculated on the basis of their efficiency in removing turbidity and bacteria. Study results, indicate that overall turbidity removal efficiency of Sangjani water treatment plant is better then that of Rawal lake water treatment plant. Both treatment plants were found to be very efficient in removing total coliforms, fecal coliforms and H2S gas producing bacteria. Samples were also analyzed for their chemical characteristics and results obtained from laboratory analysis reveal that no significant change occurred in chemical characteristics of water during treatment and all samples were well within the WI-IO permissible limits. Prior to evaluating the performance of these plants, quality of raw water being supplied to these plants was also analyzed and it was found that water is biologically contaminated. Finally some recommendations are made, like use of optimum dosage of appropriate coagulant, process optimization, source water protection and appointment of skilled laboratory staff for routine water quality analysis to improve overall efficiency of these water treatment plants.