Study On Swine Manure Treatmentby Strengthening The Anaerobic Fermentation

In recent years,the large-scale swine breeding farms has developed rapidly,resulting in a lot of waste water which brings a series of serious pollution to the environment.Swine manure from large-scale breeding farms has the characteristics such as high organic and ammonia load,large water volume,concentrated discharging etc.Anaerobic fermentation can effectively degrade organic matter in swine manure and produce biogas.Biogas is a recyclable energy with good economic benefits.In this paper,three methods,co-anaerobic fermentation of swine manure and distiller's grains,added Fe₃O₄ and nanoscale Fe₃O₄,pretreatment by soaking pig manure,were used to strengthen the anaerobic fermentation of swine manure.The enhancement effect was evaluated from methane production,methane production rate and organic matter removal.Kinetics and three pH buffer system in anaerobic fermentation process were studied.The swine manure and distiller's grains were used as fermentation raw materials.Anaerobic co-digestion were carried to investigate methane production potential.The highest unit VS methane yield occurred at the TS ratio proportion of 95:5,6.2%higher than that of swine manure.The cumulative methane production of two fermentation groups fitted with the modified Gompertz equation very well,and had no significant lag period.Due to distiller's grains rich in sulfate,it affected the methane production.Because of low pH and alkalinity in the distiller's grains,with increase of adding distiller's grains,the pH of the system deviated from the proper pH buffer area delaying the anaerobic fermentation.The swine manure was used as fermentation raw materials.ferrosoferric oxide?Fe₃O₄?and nanoscale ferrosoferric oxide?Nano-Fe₃O₄?were used as additive.The results showed that the best effect was achieved at 350 mmol/L and 75 mmol/L,respectively.The maximum methane production was increased by 11%and 12%,respectively,compared with the pure manure.The modified Gompertz equation can well fit each group's anaerobic fermentation process,and the fitting value is not very different from the measured value.And there is no obvious late stage in five anaerobic fermentation.Fe₃O₄ and Nano-Fe₃O₄ provides an electron transfer carrier for the oxidation of propionate and the reduction of carbon dioxide.So they promote the conversion of propionic acid.Fe₃O₄ and Nano-Fe₃O₄ have no effect on the formation of three buffer zone during anaerobic fermentation of swine manure.And the migration changes in the region also have not been affected.Swine manure after soaking pretreatment and fresh swine manure were used as raw materials for anaerobic fermentation.The results showed that soaking pretreatment can enhance methane production of anaerobic fermentation.Without increasing the amount of water and increasing the amount of water during the soaking period,the amount of methane production was increased by 59%and 49%.The anaerobic fermentation process of soaking pretreatment and no pretreatment can be well fitted by the modified Gompertz equation,and have no obvious lag.After soaking treatment,proteins and polysaccharides were separated from solid particles and dissolved in liquid.The macromolecule organic matter was decomposed into VFAs and other organic matter.These organics are more easily used by microorganisms,and have high utilization efficiency.There are three weak acid/alkali salts of ammonia nitrogen,alkalinity(H₂CO₃,CO₃^2-and HCO₃^-)and VFAs in the system.They make anaerobic fermentation system have strong buffering capacity,and the pH of the fermentation system was suitable for the growth and metabolism of methanogens.