Optimum Dosage of Coagulant and Flocculant on Sea Water Purification Process

Abstract

This study aims to determine the appropriate dose in the use of coagulant and flocculant, thereby make the use of chemicals This study used a design of experiment methods to determine the effect of treatment variation on water quality, ie coagulant and flocculant dose, raw material flow rate and sea water condition to turbidity and pH. As a reference, pH and turbidity must be below the maximum allowed for process water. The test was done in laboratory by using jar test method. The chemicals used as coagulants and flocculants was PAC polymers (poly amylum chloride). The results showed that coagulant and flocculant dose, flow rate and sea water condition had significant effect on turbidity and pH. The condition of seawater studied here is the tidal and low tide conditions. After variation of dosage and flow rate in sea tide and low tide conditions, the following conclusions were obtained; in tidal conditions, the optimum dose of coagulant and flocculant was 70 ppm at a flow rate of 450 m3 with reference turbidity 0.9 NTU and pH 6.9. While at low tide conditions, the optimum dose of coagulant and flocculant was 70 ppm at a flow rate of 420 m3 with reference turbidity 1.1 NTU and pH 6.9. This result is expected to be applied to factories that use seawater as raw material for process water.