Optimization of mixed microbes pretreatment on corn straw for enhancing methane production

Abstract

In order to efficiently utilize straw biomass resources, the mixed microbes were used to pretreat corn straw and anaerobic fermentation was carried out. The effects of the straw particle size, the solid-liquid ratio, and the initial pH value on both the pretreatment process and the anaerobic digestion were investigated. On the basis of single factor experiments, the pretreatment conditions were optimized using the response surface method. The pretreatment was conducted at a temperature of 30 °C for a duration of 15 days. The results indicated that the optimal parameters in pretreatment process were as follows: a straw particle size of 20 mesh, a solid-liquid ratio of 1:17, and an initial pH value of 6.5. The predicted cumulative methane production under these conditions was 3740 mL, while the experimental result obtained was (3805 ± 67) mL. With a relative deviation of 1.68% between the predicted and experimental values, the model optimized the pretreatment conditions and improved the prediction of cumulative methane production. The methane yield of corn straw achieved 243 mL/(g-VSadded).