Qiao-guang Xie, Wirach Taweepreda, Charongpun Musikavong and Chaisri Suksaroj

pp. 699 - 703

Abstract

Raw waste glycerol is a by-product of biodiesel production from transesterification, which is high in salt, and has a high
pH value (more than 9.6). The purpose of this research is to reduce the water pollution from waste glycerol by using a
coagulation process and discussing the possibility of waste glycerol reuse. The commercial coagulant (2% by weight), which
was composed by cationic polyamine (PA) 6% and poly-aluminium chloride (PACl) 94% (w/w), was used as coagulant to
treat waste glycerol. The results showed that after acidification and coagulation process, most of the chemical oxygen demand
(COD), biochemical oxygen demand (BOD₅
), total suspended solids (TSS), and oily sludge (such as fatty acid, methyl ester,
methanol and soap) in raw waste glycerol were removed, except glycerol. The removal efficiencies of COD, BOD₅
, TSS, soap
and methanol were 96.2%, 93.3%, 98.1%, 100%, and 85.8%, respectively, but the removal efficiency of glycerol was only
65.4%. There was still a certain amount of glycerol (about 147.5g/L) in the solution, which is separated from oily sludge. 

Keywords

• coagulation
• glycerol recovering
• oily sludge
• water pollution
• waste glycerol