Inhibition Characteristics Of Scum Layer In Straw Anaerobic Fermentation By Bioenhanced Hydrolysis

Biogas production by anaerobic fermentation is one of the main ways of straw resource utilization and energy utilization.However,due to the poor self-sedimentation of corn stalk,it is easy to form a hard scum layer in the process of anaerobic fermentation,which will affect the normal operation of the reactor.The method of breaking the scum layer mechanically consumes more energy and has poor effect.In this paper,according to the composition and structural characteristics of straw,bioenhancement method was adopted to improve the water absorption characteristics of straw raw material,so as to enhance the settling performance of straw in the fermentation process in the tank,and reduce the degree of the formation of scum layer.The hydrolysis of corn straw was enhanced by the solution of Trichoderma virifolia,Trichoderma virifolia and the mixed solution of Trichoderma virifolia,and the substance transformation rule,the state of anaerobic fermentation scum layer and the gas production were analyzed.The main results and conclusions were as follows:(1)In the process of bioenhanced hydrolysis,the hydrolysis time,the amount of bacterial liquid and the hydrolysis temperature had great effects on the hydrolysis effect.When the hydrolysis time was 16 h,the hydrolysis temperature was 30℃,and the amount of bacteria solution was 10%,the hydrolysis degree was the highest.When the hydrolysis time of the mixed bacteria was 16 h,the degradation rate of lignin was 9.2%,which was 19.5% higher than the control group.The concentration of acetic acid increased faster when the hydrolysis time was 0-8h and the amount of bacterial liquid was 2%-6%.(2)Bioenhanced hydrolysis changes the composition and structure of corn stover,breaks the compact state of lignocellulose entwined with each other,increases the pore structure of corn stover,and changes its water absorption and settlement ratio accordingly.In this experiment,the hydrolysis conditions when water absorption and sedimentation reached the maximum were that the mixed bacteria hydrolyzed at 30℃ for 16 h and the bacterial liquid added amount was 10%.The sedimentation ratio of the mixed bacteria reached 54%,which was 86.2% higher than that of water hydrolysis.(3)When the mixed bacteria hydrolyzed at 30℃ for 8h and the amount of bacteria liquid added was 6%,the maximum cumulative methane production of anaerobic fermentation was7370 mL,43.7% higher than that of the control group,and the maximum methane production rate of TS under this condition was 198 mL/g.With the prolongation of hydrolysis time and the addition amount of bacterial liquid increased.The volume ratio of the initial scum layer and the volume ratio of the initial scum layer showed the same characteristics,and the change rate of the volume ratio of the initial scum layer of corn stalk decreased.In order to save the cost and obtain the best gas production performance,the mixed bacteria were used to hydrolyze the straw under these conditions.