Effect of biogas slurry pretreatment on biogas production characteristics of anaerobic fermentation of wheat straw

Experiments were carried out in controllable constant-temperature fermentation equipment,in which wheat straws that pretreated by biogas slurry for 0,3,6 d and 9 d were used as the digestion material,and no-treatment was used as control.The results showed that,the C/N ration of wheat straw decreased to 20～30∶1.The biogas production rates of pretreated wheat straws increased more significantly compared with control.With the elongation of pretreated time,the cumulative biogas yields increased,which were 99.9,115.3,149.4 mL/g and 131.4 mL/g VS,and the maximum cumulative biogas yield was made under 6 d pretreatment that was much more then control.The average methane content of pretreated wheat straws were between 64% and 71%,and the VS reduction were between 17.1% and 25.7%.In addition,the total alkalinity of pretreated wheat straws was higher than control,the buffering capacity was strong and VFA decomposition was fast,which resulting in higher biogas production rates at the anaerobic fermentation prophase.Thus biogas slurry pretreatment has a significant effect on increasing biogas production rate of wheat straw.