Enhancing biogas production through photocatalytic pretreatment of rice straw co-digested with cow dung and food waste using a novel g-C3N4/SiO2/bentonite catalyst

Abstract

This study investigates the application of a novel composite photocatalyst, g-C3N4/SiO2/ Bentonite, for rice straw pretreatment, aiming to enhance biogas production in anaerobic digestion. The photocatalytic pretreatment disrupts rice straw's lignin and hemicellulose structures, reducing silica content for improved microbial degradation. Five 2 L anaerobic digesters were employed with rice straw as the substrate and co-digestion materials, including cow dung and food waste. Rice straw treated with the g-C3N4/7.5% SiO2/5% Bentonite catalyst exhibited a remarkable 37% increase in methane yield compared to untreated rice straw. This photocatalytic process led to a 31% increase in cellulose content and a 30% reduction in lignin after 6 hours of pretreatment. Simultaneously, silica content in the rice straw decreased to 6.4% after 6 hours, resulting in a 48% increase in the carbon proportion. These findings underscore the potential of integrated photocatalysts for significantly enhancing biogas production efficiency through the pretreatment of lignocellulosic biomass.