Study On Hydrogen And Methane Production From Sugarcane Bagasse Enhanced By Thermoanaerobacterium Thermosaccharolyticum And Biochar

The utilization of waste biomass for microbial fermentation to prepare biofuel is of great significance for China to develop renewable energy,adjust energy structure,and achieve the goal of carbon peak and carbon neutrality.In order to further improve the production and yield of hydrogen and methane by lignocellulosic fermentation,and at the same time further reduce the production cost,the research on lignocellulose bioconversion to produce biofuel was carried out using sugarcane bagasse as raw material in this paper.An anaerobic fermentation system of sugarcane bagasse enhanced by Thermoanaerobacterium thermosaccharolyticum and biochar was established.By optimizing the process,the co-production of hydrogen and methane by anaerobic fermentation of sugarcane bagasse was significantly promoted,and the energy utilization efficiency of sugarcane bagasse was improved.Through the analysis of the structure and characteristics of biochar,combined with the analysis of the microbial community in the fermentation process,the mechanism of the enhanced hydrogen and methane production by Thermoanaerobacterium thermosaccharolyticum and biochar was clarified.Samples from the river sediment and forest in natural habitat were collected to enrich cellulolytic bacteria under anaerobic conditions.Among them,a stable and efficient hydrogen-producing consortium with Ruminiclostridium as the dominant species was obtained from river sediment.The pure strain Thermoanaerobacterium thermosaccharolyticum MJ2 with efficient hydrogen production capacity was used to strengthen the obtained river sediment consortium.The optimal hydrogen production effect was obtained when MJ2 was initially inoculated into 10 g/L sugarcane bagasse according to60%inoculation ratio.Under the optimal conditions,the maximum hydrogen production of MJ2 bioaugmentation reached 115.28 m M,which was 100.17%higher than that of the control.Moreover,hydrogen yield increased from 219.69 m L H₂/g PSCB_utilized to 405.29 m L H₂/g PSCButilized.Based on the concept of"treating waste with waste",the FML6 biochar made from Ficus microcarpa leaf was added as an additive into the dark fermentation system of MJ2bioaugmentation,and a biochar augmentation system was established.The addition of biochar significantly increased the maximum hydrogen production potential from 2469.60 m L/L to3365.15 m L/L,and the degradation rate of sugarcane bagasse from 64.26%to 90.83%.The addition of FML6 increased the activities of cellulase,hydrogenase and electron transfer system by 12.13%,25.23%and 32.32%,respectively,reduced the oxidation-reduction potential,improved the buffer capacity of the system,and stimulated the growth and metabolism of microorganisms.Microbial community analysis showed that MJ2bioaugmentation significantly increased the relative abundance of Thermoanaerobacterium from 2.05%to 25.08%.The addition of FML6 further enriched to 46.58%,which had a significant effect on the increase of hydrogen production.PICRUSt analysis showed that co-enhancement of MJ2 and FML6 promoted the metabolic pathways related to substrate utilization and microbial activity,such as carbohydrate metabolism and membrane transport.The magnetic biochar Fe-FML6 prepared by FeCl₃ solution soaking-pyrolysis promoted methane production more than FML6 in hydrogen-producing effluent,and greatly improved the maximum methane production rate.The final methane production of Fe-FML6 group was53.28%and 70.92%higher than that of FML6 group and control group,respectively.Fe-FML6 improved the biomass,promoted the utilization efficiency of acetate and butyrate by methanogens,and significantly increased the relative abundance of the pil A gene in conductive pili.The addition of Fe-FML6 significantly enriched potential direct interspecies electron transfer microorganisms Syntrophomonas and Methanosarcina,and enhanced the hydrogenotrophic methanogenesis pathway.The energy recovery analysis showed that 15.84MJ energy could be obtained from 1 kg sugarcane bagasse through the two-stage fermentation by Thermoanaerobacterium thermosaccharolyticum MJ2 and biochar enhancement.It effectively improved the energy recovery efficiency,and laid a foundation for the realization of efficient and economical resource utilization of biomass.