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.