Chemical pretreatment optimizes thermophilic enzyme activity in lignocellulosic and lipid-rich sesame waste composting

Chemical pretreatment enhances the digestibility of resistant materials, but its effect on complex substrates like sesame wastes rich in lignocellulose and lipids requires validation. This study compared the impact of oxidant, acid, and alkali pretreatments on physicochemical properties and thermophilic degradative enzyme activity during composting. Correlations between thermophilic enzymes and physicochemical factors were analysed to investigate the effects of different pretreatments on lignocellulose and lipid-rich composting. Acid and oxidant pretreatments improved composting efficacy by increasing peak temperature, extending the thermophilic stage, and reducing moisture content. Acid pretreatment accelerated lignocellulose degradation by promoting endo-cellulase and xylanase activity and prevented total nitrogen loss through creating an acidic environment with low protease activity. Alkali pretreatment enhanced lipase activity and lipid degradation, while it also increased protease activity and total nitrogen loss. Correlation analysis indicated temperature and moisture content were the main positive and negative factors affecting degradative enzyme activities, respectively. Despite the merits of each pretreatment, acid pretreatment was most effective for sesame wastes and manure composting. These findings advance the development of efficient composting strategies for recalcitrant agricultural wastes.