Scale-up of biodiesel synthesis in a closed-loop packed-bed bioreactor system using the fermented solid produced by Burkholderia lata LTEB11

The enzymatic route for biodiesel production is environmentally attractive, but costs need to be reduced and reaction times shortened. Costs can be reduced by producing lipases by solid-state fermentation and using the fermented solids directly to catalyze the ethyl-esterification of fatty acids in solvent-free media. However, the esterification studies done to date with fermented solids have involved 12 g or less of fermented solids and reaction times greater than 30 h. The aim of the current work was therefore to increase the scale of the process by an order of magnitude, while also decreasing the reaction time, using bi-distilled olein as the source of fatty acids. The best result was obtained with a molar ratio of ethanol to fatty acids of 1.5:1, in a process in which 245 g of ethanol and 1000 g of olein were circulated in a closed-loop system through a column containing 120 g of dry fermented solids. A two-compartment reservoir was used, with the water in the outflow of the column being decanted in the first compartment. The organic phase that passed to the second compartment was agitated and fed back to the column. This system gave 88% conversion in 24 h. This system was used in 6 successive 48-h batches with the same dry fermented solids, in which a total of 4.6 kg of ester was produced. These are promising results that lay the basis for further scale-up studies.