Performances of Membranes during the Treatment of Soybean Cooking Drain from A Miso (Fermented Soy Paste) Factory by Ultrafiltration and Reverse Osmosis

Abstract

Soybean cooking drain from a miso factory was treated by ultrafiltration and reverse osmosis to study the separation of low molecular weight solutes from high molecular weight ones, the recovery of valuable matters and the removal of BOD. The drain contained protein and sugar as valuable matters, and these components were fractionated and recovered by choosing appropriate ultrafiltration and reverse osmosis membranes. Removal of BOD, however, was insufficient, even though the tight reverse osmosis membrane was employed. High molecular weight solutes contained in this drain formed gel layer on membrane surface in both ultrafiltration and reverse osmosis and this layer affected water and solutes permeation phenomena. Performances of membranes with gel layer were very similar to those obtained in our previous studies treating model solutions.