Study On The Effect Of Microbial Agents Combined With Modified Biochar On Aerobic Composting Of Food Waste

With the improvement of people’s living standards,the amount of kitchen waste has been increasing year by year,so it is urgent to use efficient,economical and environment-friendly technologies to recycle kitchen waste.Composting kitchen waste requires less investment and is convenient and simple to operate.Its compost products can increase soil fertility and improve microbial community.In this paper,the screening of strains for aerobic composting of kitchen waste,the optimization of compound ratio,the modification of biochar and the effect of microbial agents on composting were studied in order to optimize the aerobic composting process of kitchen waste and lay the foundation for the popularization and application of aerobic composting of kitchen waste.The following are the main research contents and results:（1）Screening of multifunctional microbial agents for aerobic composting of kitchen waste.A bacterial suspension was made from the sewage of the cafeteria,self fermented kitchen waste from a few days,soil near the cafeteria kitchen waste room,and soil rich in dead leaves on campus as experimental materials.It was salt-tolerant and the Na Cl tolerance concentration was 5%（w/v）.56 bacterial strains and 23 fungal strains were isolated and purified using beef extract peptone medium（screening bacteria）and potato medium（screening fungi）.Seven strains of starch degrading bacteria,protein degrading bacteria,cellulose degrading bacteria,and fat degrading bacteria were selected through hydrolysis circle method and enzyme activity determination method,respectively.Three strains of deodorizing bacteria were obtained through specific medium screening and absorption method.（2）Optimization of strain compound ratio.Different functional strains were mixed in different proportions and inoculated into kitchen waste compost.The composting was carried out in an 8L reactor for 14 days.After 14 days,the GI values were all greater than 70%,reaching the maturity standard.When starch degrading bacteria:protein degrading bacteria:cellulose degrading bacteria:fat degrading bacteria:deodorizing bacteria=1:1:2:2:2,the optimal ratio scheme can degrade 58.3%starch,39.8%protein,19.4%cellulose,and 32.9%lipids,and the cumulative NH₃emissions are reduced by 31.4%compared to the blank control group.（3）Modification of biochar.Reed biochar was added to a 1 mol/L Fe Cl₃solution with a solid-liquid ratio of 1:10.The mixture was stirred at 25℃at 180 r/min for 24hours before vacuum filtration.The modified biochar was obtained by drying at105℃for 12 hours until constant weight.The characterization analysis results indicate that the modified biochar reduces the proportion of carbon content,reduces the degree of aromatization,and enhances hydrophilicity.Fe element exists in the form of Fe-O and Fe-OH in modified biochar.The modified biochar has an increased specific surface area and a microporous and mesoporous pore structure,providing assistance for subsequent research on the effectiveness of modified biochar in composting.（4）Study on the effect of microbial agents combined with modified biochar on aerobic composting of kitchen waste.The GI values of the two groups treated with inoculants and biochar modified by inoculants were greater than 70%,which reached the maturity standard.After research,it was found that the heap treated with composite microbial agents combined with modified biochar can reach the thermophilic stage faster.And compared with the blank control group,this group had higher degradation rates of starch,protein,cellulose,and lipids,which were 60.7%,45.2%,26.6%,and 38.9%,respectively.The cumulative emissions of NH₃and H₂S were reduced by 36%and 14%compared to the blank control group.In summary,the combination of modified biochar and microbial agents is superior to the composting effect of adding microbial agents and modified biochar alone.