Effects of pretreatments with steam-explosion using solar energy and microwave irradiation on biogas production of corn stalk

To improve the biogas production efficiency, steam-explosion using solar energy and microwave irradiation were employed as pretreatments for corn stalks in this study. The effects of two pretreatments on biogas production were investigated at 35℃ fermentation temperature. The results showed that with the inoculum of 200 g, fermentation temperature of 35℃ and organic loading rate of 22.6 g/L, two pretreatments could disrupt the rigid structure of corn stalks, which make them expose more accessible surface area of substrate to anaerobic microorganism. The content of cellulose, hemicellulose and lignin of corn stalks pretreated by solar energy steam-explosion and microwave irradiation were reduced by 7.82%, 50.56%, 36.33% and 20.13%, 20.97%, 54.03%, respectively. The total solid (TS) biogas production rate of two pretreated samples were reach to 239.89 and 281.45 mL/g, while the VS (volatile solids) rate were 296.02 and 332.28 mL/g, respectively with solar energy steam-explosion and microwave irradiation pretreatment. Moreover, compared with the control, the average daily biogas yields of two pretreated samples were 320 and 334 mL, which were increased by 15.11% and 20.14%, and the hydraulic retention time (HRT) was decreased by 42.11% and 31.58%. The present work provides a reference for the crop stalks pretreatment and improving the efficiency of biogas plant.