A turbidity removal strategy from the water resources of bandung city, indonesia

Abstract

Cikapundung and Cisangkuy River are the sources of raw water used by Bandung City. The special characteristics of these water resources are the fluctuations of flow and turbidity in the dry season and the rainy season with the highest turbidity < 600 NTU. The turbidity fluctuation is not significantly followed by the coagulant dose changes. This research was conducted in order to evaluate and strategize the optimal performance of the water treatment plant based on the evaluation of the processed water. The laboratory analysis was carried out to find the dominant parameters, namely turbidity, with the steps such as 1) comparing the coagulation process that has been or has not been through preliminary sedimentation using coagulant polyaluminium Chloride (PAC); 2) observing the stability and efficiency of sediment that resulted by coagulation process for the several variation of time; 3) analyzing the efficiency of the preliminary sedimentation and coagulation process. The results of laboratory analysis show that the optimum time of the deposition processes is 35 minutes with a decrease in turbidity of about < 80%. The highest efficiency of sedimentation processes occur at the initial turbidity of 514 NTU in the amount of 85.02%. The optimum coagulant dosage without using the preliminary sedimentation is reached at initial turbidity of 147 NTU with an efficiency of 99.76%; while those using the preliminary sedimentation are achieved at initial turbidity of 514 NTU with an efficiency of 99.46%. Based on these analyses, it is necessary to adjust the operational process of preliminary sedimentation.