Water Recovery of Black Liquor from Alkaline Pretreatment of Bioethanol Production from Oil Palm Empty Fruit Bunch by Coagulation and Flocculation Method

Abstract

Black liquor from the pretreatment process for bioethanol production from oil palm empty fruit bunch was treated using the coagulation-flocculation process with several coagulants/flocculants under various conditions. Decolorization, total suspended solid (TSS), final pH, and sludge volume were analyzed. The aim of this study was to investigate which coagulant and flocculants, concentration, and optimum pH would be the most effective for water recovery. Alum, PAC, ferrous sulphate, cationic and anionic polyacrylamide acted both as coagulant and flocculants with various combinations and condition. The result showed that the combination of PAC and cationic polyacrylamide with ratio combination of 3:1 and optimum pH of 6.5 was the most effective coagulant/flocculants for treating the black liquor. The combination gave 93.14% decolorization, final pH of 7.2, 40% sludge volume formation and 79.64% TSS decreased percentage.