A capillary membrane bioreactor using immobilized polyphenol oxidase for the removal of phenols from industrial effluents

A capillary membrane bioreactor has been developed and tested for the remov al of phenolic compounds from synthetic and industrial effluents. Polypheno l oxidase was immobilized on single capillary membranes in a small-scale bi oreactor using two morphologically different polymeric membranes. One has a novel structure with no external supporting skin layer. This membrane allo ws greater flux and was shown to facilitate high efficiency in removal of r eaction products from the reactor Using this high flux membrane, 949 mu mol phenolics were removed from a solution containing 4 mM total phenolics usi ng 45 U polyphenol oxidase in 8 h as compared with 120 mu mol removed using non-immobilized enzyme which was inactivated (due to product inhibition) a fter 7 h. No precipitated melanoid products were observed in the permeate f rom the capillary membrane bioreactor, and in order to remove the colored q uinone-type products of the reaction, a packed column containing chitosan w as integrated into the system. Almost complete removal of the colored quino nes and associated polymers from the permeate was observed. (C) 1998 Elsevi er Science Inc.