Study On The Performance Of Dry Anaerobic Digestion Of Rice Straw And Swine Manure

Anaerobic digestion is a frequently-used method for organic waste treatment, which can reduce carbon emission and produce clean energy-biogas. Taking biogas slurry and dewatered sludge as inoculums, the impact of different concentrations of biogas slurry, different amounts of sewage sludge, different pretreatment technologies for rice straw, different C/N ratio and different TS contents on the performance of dry anaerobic co-digestion of rice straw and swine manure were studied. According to biogas production, methane yield and basic physicochemical properties of feedstocks, the optimal reaction parameters had been determined. Finally, the biogas production performance was analyzed using the first-order kinetic model, kinetic parameters of different conditions were compared and the reaction mechanism was further discussed.The results showed that, appropriate amounts of inoculum could improve biogas yield, heighten biogas production peak and accelerate biogas production, but it had no significant effect on cumulative biogas production. When saturated sodium bicarbonate solution was used as buffer solution to adjust the pH value, the activity of methanogens and other microorganisms would be inhibiated and the biogas production rate of the materials would drop nearly50%. The pretreatment of hot alkali for rice straw could greatly improve the biogas production efficiency and shorten the retention time of the materials. The digestion system with C/N ratio of20was better for biogas production. The co-digestion of swine manure and rice straw could get higher biogas production efficiency than swine manure or rice straw fermented separately. The methane content in all the experiments was more than80%from the stable biogas production period to the end of the reaction.According to the kinetic model, it could be found that the model could be well applied to the co-digestion process of swine manure and rice straw. Especially for the experiment of the different pretreatments for rice straw, it could be found that the pretreatments of hot alkali and hot alkali with microwave appeared an obvious two-stage process, and the rate constant of the second stage was greater than the first stage, which was consistent with the actual biogas production.