4. Conclusion
This study has shown that coagulation and flocculation is a useful method as a pre-treatment of biodiesel
wastewater. Coagulation and Flocculation is very effective in the suspended solids, color, and Oil and Grease
removal and moderately effective in the COD removal of the biodiesel wastewater. Polyaluminum chloride was
superior to other coagulant at 300 mg/l, removal of suspended solids, color, COD and Oil and Grease. In order to
achieve better percentage removal for COD, suspended solids, color and oil and grease, further treatment is needed.