Experimental Study Of Corn Stalks And Cow Dung Anaerobic Co-fermentation Effect On Microstructure Evolution And Biogas Productivity

The purpose of this study was to improve comprehensive gas production capacity and the utilization ratio of maize straw in the process of mixing anaerobic fermentation,to explore changes in microstructure of straw and the characteristics of bacteria in the liquid.The anaerobic co-fermentation of corn stalks inoculated by cow dung was found to achieve higher biogas production and cellulose biodegradation.In this study,the effect of mixing corn stalks with cow dung at five different fermentation stages(0,7,15,23,and 31 days of the total fermentation cycle of 60 days)on the further co-fermentation process was explored.In this study,the gas production characteristics and degradation properties of organic compounds were detected.In addition,the straw microstructure evolution was investigated by the SEM and XRD methods and the micro flora was studied.Experimental results: the five test groups exhibited nearly identical total biogas productivity values,but strongly differed by daily biogas yields(the maximal biogas generation rate being 524.3ml/d).Based on the degradation characteristics of total solids(TS),volatile solids(VS),and lignocellulose,groups #1 and #3(0 and 15 days)had the most significant degradation rates of VS(43.73%)and TS(42.07%),respectively,while the largest degradation rates of cellulose(62.70%)and hemicellulose(50.49%)were observed in group #4(22 days)and group #1(0 days),respectively.The SEM analysis revealed strong microstructural changes in corn stalks after fermentation manifested by multiple cracks and striations,while the XRD results proved the decrease in peak intensity of cellulose <002> crystal surface and the reduced crystallinity(the highest degradation rate is 39.03% in the group #5)after co-fermentation.The micro flora analysis found that the bacteria in the mixed anaerobic fermentation were more abundant than the single raw material fermentation.The results of this study are assumed to be quite instrumental to the further optimization of the corn stalk anaerobic digestion by inoculation with digested manure for lignocellulose degradation enhancement and biogas productivity improvement.