Study On The Characteristics Of Lipase Pretreatment And Biochar-Mediated Anaerobic Digestion Of Food Waste

With the rapid development of social economy and urbanization,the amount of food waste production has increased rapidly.At present,the sustainable management of FW has become a global urgent problem.Anaerobic digestion（AD）technology can not only realize the harmless and resource utilization of FW,but also produce clean energy.Chinese FW has the characteristics of a high rate of lipid.Lipid has a great gas production potential,but the hydrolysis rate is low.High content of lipid will lead to lower activity of methanogens and reactor blockage.Therefore,this paper will promote the hydrolysis of lipid and improve the stability of the reaction system through the pretreatment of lipase,the addition of biochar and the synergy of the two,in order to strengthen the performance of anaerobic digestion of FW.The main work and conclusions are as follows:（1）Through the study on the pretreatment of FW with different concentrations of lipase,it was found that R1 group（0.1%lipase）obtained the maximum cumulative methane production of 540.12 m L/（g·VS）,an increase of 12.89%compared with the Control group（470.46 m L/（g·VS））.After lipase pretreatment,the time for each experimental group to complete anaerobic digestion was shortened to 8 days,greatly improving the efficiency of anaerobic digestion.The archaea community in the reactor of the experimental group is dominated by Metanobacterium,which indicates that the system after lipase pretreatment is dominated by hydrogenotrophic methanogenic pathway.（2）Through the study of the effect of different amounts of biochar on the anaerobic digestion of FW,it was found that the addition of biochar could effectively improve the cumulative methane production,in which the L5 reactor obtained the highest cumulative methane production,615.09 m L/（g·VS）,which was 19.36%higher than the control group.The addition of biochar not only greatly increased the concentration of TVFA and SCOD in the system,but also accelerated its degradation rate.This is due to its rich pore structure,which provides a better living environment for Metanosaeta,and to a certain extent ensures the methanogenic pathway of aceticlastic anaerobic digestion pathways and promotes the production of methane.（3）Through the study of the effect of different concentration of lipase pretreatment combined with different amount of biochar on the anaerobic digestion of FW,it was found that the cumulative methane production of each experimental group increased by 2.28%～13.47%compared with the blank group.According to the analysis of three-dimensional fluorescence spectrum results,with the increase of pretreatment concentration,the content of fluorescent substances in the system increases,which is represented by the increase of SCOD concentration,but the fluorescence intensity of region V also increases.Combined with the change of cumulative methane production,it can be seen that the SCOD produced in the system is mostly difficult to biodegradable organic substances,and the activity of microorganisms is inhibited due to the overload operation of the system.In general,the anaerobic digestion effect of 0.1%lipase pretreatment is the best.The concentration of SCOD and TVFA degrades to 2500mg/L and 280mg/L respectively on the 6th and 9th day,and the p H remains between 6.5～7.6.Moreover,due to the adsorption of biochar on NH₄⁺-N,there is no ammonia nitrogen inhibition,and it only takes 9 days to complete the digestion process.The main archaea Metanobacterium has strong resistance to ammonia nitrogen.