Performance Evaluation of an Up-flow Roughing Filter for Treatment of High Turbidity Water at Chakwal

Abstract

ABSTRACT In Chakwal, High Turbidity rainwater runoff and seasonal streamflows are collected in Khokhar Zar Dam. This dam serves as community's major source of domestic supplies. Slow sand filtration (SSF) is a low-cost technology for treating raw water with turbidity below 50 NTU. The process, however, is sensitive to high raw water turbidity that often leads to premature clogging of the filter and frequent cleaning requirements. The research work reported here had three objectives: to study current treatment process and highlight problems related to quality management, to design and construct a pilot scale UFRF treatment plant to investigate the most appropriate treatment scheme and to determine the optimum coagulant dose for in-line roughing filtration using common coagulants such as Alum & Ferric chloride The pilot plant was operated for 9 months to evaluate if multistage and multilayer Up-flow Roughing Filter (UFRF) could reduce the high turbidity (200-3000 NTU) water to an extent to make SSF a viable option. There were a number of promising outcomes: the monitoring of physical parameteri (turbidity, pH and conductivity) of raw and treated water at Chakwal water treatment plant (CWTP), the performance evaluation of multistage and multilayer UFRF, 30-50 percent removal efficiency by multistage UFRF and 30 percent by multilayer UFRF, the in-line coagulation to UFRF reveals 99 percent removal efficiency at fold reduced coagulant dose (47 mg/l of alum vs 122mg/l by the facility management and 65 mg/l of Ferric Chloride against th