Separation of methyl ester from water in a wet neutralization process

Abstract

The surfactant-water mixture generated from the industrial biodiesel (methyl ester) production washing process generates wastewater that is usually treated in a sludge pond by the addition of bacteria prior to being discharged into water courses. Nonetheless, the treatment is inadequate and it poses an ecological threat to the environment. Treatment of this mixture can take the form of conventional treatment methods for surfactant-water emulsions such as chemical, mechanical and thermal treatments. However, the disadvantages of such methods are low removal efficiency, operational difficulties and high operation cost. An ultra-filtration membrane can be used to separate water from the mixture, in spite of membrane fouling problems and a relatively low permeating flux. In this study, the membrane performances, inclusive of moisture contents in the recovered methyl ester, due to the types of membrane (hydrophobic or hydrophilic), cross-flow velocity and trans-membrane pressures are compared. The surfactant-water mixture used in this work was obtained from washing the palm-derived methyl ester (PME) with water during the product purifying processes from the biodiesel transesterification catalyzed with sodium hydroxide.