Effect of Activated Cow Dung as Inoculum on Methane Production of Steam-Exploded Rice Husks

Abstract

To investigate methane production from a single substrate with steam explosion pretreatment and activated cow dung as natural resources for cellulolytic microflora to enhance biogas production from agricultural biomass waste. The recalcitrant of the lignin-carbohydrate complex (LCC) of rice husk was dismounted using a steam explosion pretreatment at 2.53 MPa (224 °C) for 5 and 7 min of steaming time, followed with and without water extraction. All the residue from the extraction process, either solid or liquid, was used for the biogas feedstock. Anaerobic digestion (AD) was conducted under mesophilic condition at 37 °C with two different inoculums: sludge and a mixed inoculum containing sludge and activated cow dung. The predicted methane production was calculated using the stoichiometric formula. The steam explosion pretreatment and mixed inoculum significantly enhanced the cumulative methane production. The 7-min steaming time led to the breaking up of 41% cellulose, and 199 ml/g of methane was produced from the total cumulative methane yield of the solid and liquid feedstock, with a 96.1% yield of the predicted methane amount. The enhancement of methane production was achieved using a combination of steam explosion pretreatment and mixed inoculum between sludge and activated cow dung.