Enzymatic hydrolysis of babassu oil in a membrane bioreactor

This work deals with the enzymatic hydrolysis of babassu oil by immobilized lipase in a membrane bioreactor using unmixed aqueous and lipid streams. The experimental work was carried out in a flat plate membrane module with two different membranes: hydrophobic (nylon) and hydrophilic [mixed cellulose esters (MCE)], with different nominal pore sizes ranging from 0.10 to 0.65 mu m. Candida cylindracea lipase was adsorbed on the membrane surface area, and the reactor was operated in batch mode. The initial enzymatic rate increased from 80 to 150 mu mol H super(+)/min when the organic phase velocity increased from 1.0x10 super(-3) to 3.0x10 super(-3) m/s, indicating that mass transfer in that phase was the process-limiting step. Calcium ions had a marked effect on immobilized lipase activity, increasing around twofold the lipolytic activity. Long-term experimental runs showed that the immobilized lipase remained stable for at least 8 d. The values for immobilized protein and maximal productivities observed for 0.45 mu m membranes were: 1.01 g/m super(2) and 193 mu mol H super(+)/m super(2) times s for MCE membrane and 0.78 g/m super(2) and 220 mu mol H super(+)/m super(2) times s for nylon membrane. The productivities obtained are among the highest values reported in the technical literature.