Investigation On Effect Of Mixing And Biogas Slurry Reflux On Sequencing Batch Anaerobic Digestion Performance Of Wheat Straw

Anaerobic digestion reaction was investigated at start phase in this paper. And the effect of mixing and biogas slurry reflux on anaerobic digestion performance was studied. Using wheat straw as stuff, anaerobic digestion parameters of biogas production, VFA, ammonia, hemicellulose, cellulose, lignin, pH value and methane content were tested using sequencing batch feed way. Research results as follows:The loading rate of 50g-L-1 was recommended for start phase. Then loading rate was changed from 50g-L-1 to 65g-L-1 at anaerobic digestion system stability. The loading rate of 50g-L-1 did not obviously happen acidification. The pH values and methane content were maintained between 6.8-7.5 and 50%-60%, respectively. The average daily biogas production was 5.89L·d-1, biogas production of unit TS was 0.36L-g-1.The biogas production was increased with mixing frequency increasing. But the mixing frequency did not have obvious effect on the pH value and methane content. The mixing frequency of once per 1 hour was recommended for the anaerobic digestion process. The average daily biogas production was 6.1L·d-1, biogas production unit of TS was 0.47L·g-1, biogas production of unit VS was 0.56L·g-1.The daily biogas production, biogas production unit of TS and VS started to increase then decrease with increasing biogas slurry reflux ratio. The biogas production was highest when biogas slurry reflux was 30%. Daily biogas production was 5.60L·d-1. Biogas production unit of TS and VS was 0.44L·g-1 and 0.69L·g-1, respectively. The cellulose and hemicellulose decreased by 49.2%and 68.8%. The pH value and methane content did not obvious change. The nitrogen content decreased gradually during the biogas slurry reflux process. Therefore, nitrogen should be added at the proper time.Therefore, the loading rate of 50g·L-1 was recommended for start phase of anaerobic digestion of pure straw. Then loading rate was changed from 50g·L-1 to 65g·L-1 at anaerobic digestion system stability. The mixing frequency of once per 1 hour was recommended and biogas slurry reflux was 30% for the anaerobic digestion process. This study would provide guideline for designing straw biogas plant.