Effectiveness of combined up-flow roughing filter and up-flow slow sand filter to reduce turbidity in Citarum water as a source of drinking water

Abstract

The turbidity of the Citarum River was high, fluctuating, and used as a drinking water source by PDAM (Regional Drinking Water Company). This study aimed to determine the ability of a combined up-flow roughing filter (URF) and an up-flow slow sand filter (USSF) in reducing turbidity, called multistage filtration (MSF). MSF was varied with and without settlers. Gravel diameters and perviousness: 0.5 cm was 0.243, 1 cm: 0.264, 2 cm: 0.265, 5 cm: 0.302 or 24-30% of URF's volume. When settler was run with surface loading 0.5 m3/m2/hour, flowrate 0.67 l/minute, turbidity 321.16-3,496.53 NTU, the efficiency was 57.9-96.2%. Settler reduced turbidity significantly. URF1 enhanced turbidity removal. However, URF2, URF3, USSF were not effective. In an experiment without a settler, turbidity 130.78-533.00 NTU, but its reduction in URF1 was bad. In URF2 turbidity was almost the same as in the experiment with the settler. Efficiency was 41.9-89.1%. Here URF1 and URF2's functions were almost the same as settler and URF1. URF3 was ineffective, can be removed. USSF was needed even though only able to reach 10-25 NTU. URF and USSF contributed to the higher efficiency of turbidity removal.