Continuous production of biodiesel using whole-cell biocatalysts: Sequential conversion of an aqueous oil emulsion into anhydrous product

A continuous production of biodiesel from an aqueous plant oil emulsion was attempted using immobilized fungal whole cells. Six packed-bed reactors were connected in series and operated with stepwise methanol addition. In the first column, more than 3% water was necessary for methanolysis to proceed. Despite the low initial water content of 0.36%, the methyl ester content in the effluent from the second column increased similarly in a wide range of contents of water (0–20%) added, which shows the water-content-independent reaction in this column in contrast to the reaction in the first column. Further investigations using reaction mixture models suggested a contribution of the composition of the reaction mixture to the phenomenon. On the basis of these findings, the sequential methanolysis through six columns was attempted, where the upper layer of the effluent from each column was supplied into the next column without further addition of water. Consequently, an aqueous plant oil emulsion with 3% water was converted into the final product with 96.1% methyl ester and 0.15% water. Therefore, the system developed is useful for producing biodiesel enzymatically from water-containing feedstocks.

► A continuous production of biodiesel using recombinant fungal whole-cells. ► Packed-bed reactors were applied to methanolysis of an aqueous plant oil emulsion. ► Significant difference in dependence of methanolysis activity on water content. ► An aqueous oil emulsion was sequentially converted into the anhydrous product.