Attempts were made this study to examine of coagulation and flocculation process using ferric chloride and polyelectrolyte (cationic) for the treatment biodiesel wastewater. Removal of SS (suspended solid), color, COD (Chemical Oxygen Demand) and Oil and Grease (O&G) using ferric chloride and organic polyelectrolyte during coagulation/flocculation process were investigated. Also the optimum condition for coagulation/flocculation process, such as pH, coagulant dosage and polyelectrolyte dosage of solution were investigated using jar test experiment. The effect of different dosage of polyelectrolyte in combination with coagulant was also studied. The result revealed that in the range of pH tested, the optimal pH is 6. Percentage removal of 95%, 93%, 63%, 97% for SS, color, COD and O&G respectively, were achieved at optimum dosage value; 350 mg/L. While, 86.3%, 86.7%, 57.2, 81% removal of SS, color, COD, O&G respectively, were achieved with the addition 10 mg/L cationic to 125 mg/L ferric chloride. It can be conclude from this study that coagulation/flocculation may be a useful as a pre-treatment process for biodiesel wastewater.
