Experimental Study On Biogas Production Of Chicken Manure Anaerobic Digestion By Adding Mediating Materials And Utilization Of Biogas Residues

Under the background of carbon neutrality,the effective treatment and utilization of livestock and poultry waste are of great significance.With the change of breeding mode,it has gradually developed into large-scale and intensive livestock and poultry breeding in China.However,With the increase in the scale of livestock and poultry breeding,a large amount of livestock and poultry manure is produced in a concentrated manner,which poses a serious threat of pollution to the rural water environment and soil.Anaerobic digestion technology is an effective means to deal with dung pollution from livestock and poultry breeding.It can not only reduce the pollution problem of dung pollution from livestock and poultry,but also produce clean energy to supplement agricultural production.At the same time,the biogas residue produced can be used as organic fertilizer to increase soil nutrients in farmland.Most of the Livestock and poultry manure are nitrogen-rich organic materials,which are prone to ammonia inhibition and lead to biogas production failure during anaerobic digestion.The ammonia inhibition problem of chicken manure is especially serious in anaerobic digestion because the nitrogen content is higher than swine manure,cow manure,etc.Based on this,the effects of mediating materials on the biogas production performance of anaerobic digestion of chicken manure and the resource utilization of biogas residue were investigated.The main conclusions are as follows:In this essay,the batch test of anaerobic digestion of chicken manure was firstly conducted.The effects of mediating material type,added concentration and added particle size on the biogas production performance of chicken manure were investigated respectively.The mediating material with the best effect of improving biogas production and its optimal concentration and particle size were screened out.On this basis,a test of semi-continuous anaerobic digestion was used for acclimation with the selected mediating materials to investigate the effects of acclimation of mediating materials on the biogas production performance,feed-liquid characteristics and microbial community characteristics of anaerobic digestion of chicken manure under long-term operation,and further revealed the relevant mechanism of mediating the synergistic domestication of materials to improve the biogas production performance.Finally,the biogas residue produced by anaerobic digestion of chicken manure was added to the soil matrix as biogas fertilizer,and the effect of biogas residue on soil nutrients and the growth of pakchoi was preliminarily explored.(1)In the batch test of anaerobic digestion of chicken manure,compared with the blank group without the addition of mediating materials,the addition of granular activated carbon(GAC)improved the biogas production efficiency of anaerobic digestion of chicken manure to the highest,reaching 26.7%;Thermally modified bentonite(TMB)and magnetite(Mag)also had a certain effect on improving the biogas production efficiency of chicken manure anaerobic digestion,increasing the biogas production efficiency by 8%,17.6% and 2.8%respectively.The optimal concentration of GAC was 100 g/L,and the cumulative biogas yield increased by 39.9%.The optimal particle size of GAC added was 0.5-1 mm,and the cumulative biogas yield was increased by 50.3%.(2)Domestication alone and domestication with the addition of GAC or TMB could improve the biogas production performance of anaerobic digestion of chicken manure to some extent.The GAC group obtained an average volumetric biogas yield of 1.733 L/L/d and an average raw material biogas yield of 0.439 L/g VS/d at a concentration of 20% chicken manure,which was about 57.3% higher than that of the blank group.At the same time,the GAC group had the highest methane content,about 62.18%,which was 1.4 times that of the blank group.(3)The abundant porosity and large specific surface area of GAC provided favorable conditions for the attachment of microorganisms,while GAC addition enhanced the activity of methanogens.After domestication,the relative abundances of the dominant genera of bacteria and archaea changed significantly.After domestication,the dominant genera of each group of bacteria were MBA03,and the dominant genera of archaea were Methanosarcina.GAC improved microbial activity and the biogas production efficiency of anaerobic digestion by participating in direct interspecies electron transfer.(4)The fresh weight and plant height of pakchoi could be increased by the application of biogas residue alone or with the combined activated carbon,and the growth promotion effect of biogas residue with the combined activated carbon was more obvious.The application of biogas residue alone or with combined activated carbon could increase the content of soil organic matter and soil available nutrients(nitrogen,phosphorus,potassium).The contents of soil organic matter,alkali-hydrolyzed nitrogen,available phosphorus and available potassium were increased by 19%,23.4%,17.9% and 24.4% respectively compared with the blank group after applying biogas residue alone.The contents of organic matter,alkali-hydrolyzed nitrogen,available phosphorus and available potassium in the test group of biogas residue with combined 0.9% activated carbon were the highest,which increased by31%,30.7%,34.9% and 36.8% respectively compared with the blank group.After the application of biogas residue alone or with the combined activated carbon,the p H of soil increased to some extent.