Research On The In-situ Synthesis Of Methane From Exogenous Hydrogen By Anaerobic Fermentation

Shortage of renewable energy and utilization of biomass waste are major projects in the world today. Therefore, improving the traditional anaerobic fermentation with straw has become a hotspot.The exogenous H2 and CO2 were used to synthesize CH4 in-situ in a fermentation bottle(500 m L)or fully mixed fermenter(30 L) based on nutrient solution or rice straw as substrate respectively. The effects of parameters such as temperature, mixing intensity,exogenous H2 proportion(H2/CO2) and its flow rate on the biogas production and its component were investigated to determine the suitable technological conditions. The change laws of the biogas contents and production rate were discussed according to the performance of M. thermautotrophicus delta H using hydrogen and carbon under different conditions. The solubility of hydrogen in the liquid phase is very low and strengthening mixing intensity can improve the overall utilization of exogenous hydrogen. Under constant mixing conditions, with the increasing of temperature, exogenous gas flow and H2 proportion(H2/CO2), the content of methane increased. The optimum temperature was between 55 ℃ ~ 65 ℃, and there was little changes of the biogas content when the temperature continue to rise above 55 ℃. In the anaerobic fermentation process with nutrient solution as substrate, the addition of exogenous gas can promote the methane content and the production of biogas. The optimum temperature was between 55℃~65℃ and exogenous gas ratio(H2/CO2)was 5︰1. Pure H2 was suitable exogenous gas in anaerobic fermentation with straw as substrate.The appreciate temperature was 55℃,H2 flow was 1110 m L/(L·d) and mixing intensity was 100 r/min under which relative methane content in biogas would reach 83.8%.