Efficient degradation of molasses wastewater from sugar mill by lipase via addition reaction

Abstract

It has been observed that hydrolases such as cutinases have made significant breakthroughs and achieved good results in catalyzing the enzymatic decolorization of molasses wastewater. However, their actual application has been limited by inferior industrialization scale and other drawbacks. The aim of this research was to investigate the potential of lipase in decolorizing molasses wastewater via decolorization experiment, molecular simulations, immobilization technology, etc. It was found that lipase Lecitase Ultra achieved a maximum decolorization yield of 84.62–86.81% among all of the enzymes analyzed. Additionally, compared with cutinases and keratinases, it can be applied on a larger industrial scale. Subsequently, this work adopted a carrier-free immobilization technology and it was observed that upon combined with deep eutectic solvent, the immobilized Lecitase Ultra exhibited excellent enzymatic properties, he highest decolorization yield (58.14–60.55%) as well as other parameters among all of the immobilized enzymes. Furthermore, it only effectively eliminated 77.56% of melanoidins. The binding mode of melanoidins representative substrate to lipase was structured. The results indicated that the lipases could destroy the unsaturated system of olefins and ketones in melanoidins through catalyzing an addition reaction to achieve the effect. Thus, these findings provide a reliable approach for the decolorization of molasses wastewater.