Effectiveness of an Upflow Roughing Filter for High Turbidity Water

In Chakwal, highy turbidity rainwater runoff and streamflows are collected in Khokhar Zar Dam to be used for water supply. Slow sand filtration (SSF) is a low-cost technology for treating raw water with turbidity below 50 NTU. Objectives of the work reported here include: study of current treatment process and highlight problems related to quality management,design and construct a pilot scale upflow roughing filter plant and to determine the optimum coagulant dose for in-line roughing filtration. The pilot plant constructed could reduce raw water turbidity from 450 NTU (Avg) to 2-10 NTU making SSF a viable option. There were a number of promising outcomes: the monitoring of physical parameters (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 2 fold reduced coagulant dose (47 mg/L of alum vs 122mg/L by the facility management and 65 mg/l of Ferric Chloride against the same).