Decolorization of Molasses Wastewater by Immobilized Dual Thermo-Acidophilic Enzymes Under Extreme Conditions

Abstract

Colorants in molasses wastewater, such as melanoidins and phenols pigment, are rarely degraded through conventional biological processes. Decolorization is the focus of molasses wastewater treatment. Unfortunately, enzymatic decolorization is severely restricted by extreme conditions. In the present study, screened thermo-acidophilic laccase and glucose oxidase were immobilized on a cheap-modified bagasse cellulose carrier. The immobilized dual thermo-acidophilic enzymes exhibited a decolorization yield of 96.81% on untreated molasses wastewater at 80 °C (pH 4.5), which was higher than all other yields reported. The immobilized enzymes eliminated 60.24% of colorants for 7 days when 10% of fresh untreated molasses wastewater was added each day. Glucose oxidase was the most critical enzyme in decolorization, reducing sugar apparently influenced decolorization. The generated hydrogen peroxide oxidized melanoidins and other pigments, leading to decolorization. Accordingly, this study provided new insight into in decolorization of molasses wastewater under extreme conditions and analyzed the underlying mechanism.