Process Analysis Of Anaerobic Fermentation Of Swine Manure And Study Of Treatment Process For Its Fermented Liquid

Livestock and poultry breeding pollution is one of the main agricultural non-point source pollution in China,and also one of the key problems to be solved in the national"13th five-year plan"water pollution prevention and control action plan.At present,aimed at livestock breeding waste treatment,a large number of biogas fermentation projects have been built nationwide,but the focus is basically on biogas production capacity,and the understanding of fermented liquid still needs to be further improved.The composition of fermented liquid is closely related to the anaerobic fermentation.The analysis of anaerobic fermentation process is helpful to understand the composition of fermented liquid and the subsequent research of related processing technology.Therefore,this project takes swine manure as the research object and discusses the transformation of swine manure in solid phase,liquid phase and gas phase during the production of methane by anaerobic fermentation under medium temperature（37±1°C）and normal temperature（<20°C）through comparative research methods.At the same time,GC-MS,FTIR and high-throughput sequencing technologies are used to analyze the material composition and microbial community structure changes in the anaerobic fermentation process of swine manure,and the related processing technology of fermented liquid is preliminarily discussed.This paper draws the following main conclusions:（1）Temperature has a great influence on anaerobic fermentation process of pig manure.Fermentation accured at room temperature（<20°C）will increase difficulties in subsequent treatment for fermented liquid.（2）When the concentration of fermentation substrate TS is 5%,the gas production duration of the medium-temperature fermentation system can reach up to 2months,and the final removal rate of COD and TP can reach 35.38%and 58.90%respectively,while the final removal rate of TS and VS can reach 41.14%and 61.03%respectively,and the gas production can reach 246.14mL/（g·VS）,but the ammonia nitrogen concentration continues to increase,reaching the highest value of 2700mg/L.（3）In the medium temperature fermentation system,the fermented liquid of swine manure is mainly composed of ketones,alkanes,amines,phenols,alcohols,esters,indoles and other substances,among which the soluble organic compounds（DOM）mainly include carbohydrates,aliphatic hydrocarbons,aromatic hydrocarbons,polysaccharides,proteins and humic acids.（4）Methanomassiliicoccus gradually replaces Methanobrevibacter as the bacteria group with the highest proportion in the medium temperature fermentation system,when the concentration of ammonia nitrogen reaches 2500mg/L,indicating that Methanobrevibacter had strong ammonia tolerance.In addition,the former is a methylotrophic methanogen,while the latter is a hydrotrophic methanogen.The methanogen pathway of the fermentation system has a tendency to gradually change from H₂/CO₂ methanogen pathway to H₂ reduction-methyl compound methanogen pathway.（5）The combined process MAP+packed bed+SBR method and packed bed+alkali pre-aeration+anaerobic iron carbon biological bed+SBR method can meet the standard of COD,ammonia nitrogen,TP and SS for fermented liquid treatment in pig farm,which has certain extensibility.