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EFFECTS OF ROTATION AND SLUDGE ADDITION ON ROTATING
SEDIMENTATION PERFORMANCE IN REMOVING TURBIDITY
PENGARUH PUTARAN DAN PENAMBAHAN LUMPUR PADA PENGENDAP
BERPUTAR DALAM PENYISIHAN KEKERUHAN
Nufikha Indriani1 and James Nobelia I.2
Environmental Engineering Study Program
Faculty of Civil and Environmental Engineering
Institut Teknologi Bandung
Jl Ganesha 10 Bandung 40132
1
[e-mail], [e-mail]
Abstract : One of alternatives to reduce cost of water treatment process using centrifugal sedimentation technique is perhaps the application of slow rotation speed that resembles water movement speed. However, information on optimum rotation speed applied for this technique is very limited. Sludge as byproduct of water treatment is commonly discharged to water bodies, yet it contains a substantial amount of aluminum that can be used as a coagulant. The objective of this study was to elucidate effects of rotation and sludge addition on turbidity removal in a rotating sedimentation process. Water of Cileueur River (Ciamis), and Upper Citarum River (Ciparay, Bandung) were used for this study. Sludge used for this experiment was artificially made in a laboratory. Rotation speeds of 0, 4, 6, 8, 13, and
20 rpm were applied for each of 0 mg/L, 5 mg/L, 10 mg/L, 15 mg/L and 20 mg/L sludge addition. Results of this study showed that rotation speed and sludge addition did not significantly affected turbidity removal efficiency in rotating sedimentation process. Turbidity removal efficiency for Cileueur water increased until 76.6% by rotating at 8 rpm, whereas that for Citarum water increased up to 91.9% by rotating 20 rpm. Addition of 10 mg/L sludge and rotation at a speed of 4 rpm increased turbidity removal of Cileueur water to 82.3%. The highest turbidity removal was 87.3% when
20mg/L of sludge was added and rotation at a speed of 20 rpm. Sludge addition did not significantly increase turbidity removal efficiency of Citarum water.

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