Studies On Different Technics And Anaerobic Fermentation To Produce Biogas

Anaerobic fermentation technology is the most commonly method to obtain biomass clean energy,the bio-gas production efficiency could be increased by optimizing and improving the traditional anaerobic fermentation technology.Agricultural wastes andanimalmanurewasanaerobicfermented withdifferentraw materials,concentration of TS,temperature,rate of load conditions and so on in this experiment.At the same time,using denaturing gradient gel electrophoresis（DGGE）technique to analysis the microbial community of the fermentation system to provide a theoretical basis for the control of bio-gas fermentation.Different materials was used in continuous anaerobic fermentation.The results showed that the daily methane overall trend appeared pig>chicken>straw>cow dung,their average daily production of methane was 2.67,2.24,0.99,0.49L.Pig,chicken manure,straw daily methane concentration in the fermentation period could remain above 50%,cow daily methane concentration was less than 30%most of the time.The change trend of ammonia nitrogen content in chicken manure and pig was decreased firstly and then increased.The ammonia nitrogen content of cow dung and straw had been showing a downward trend.The VFA content of pig,chicken and straw always remained at 1000mg/L throughout the fermentation period article 27D.The VFA content of cow dung reached the peak of 5995mg/L at the 27^th day.Advantages of bacterial group were Bacteroidetes,Treponema,Anaerolineaceae and the new advantage bacterium group were Clostridium,Desulfobulbus,Acetivibrio and so on.Advantages of archaea group were Methanobacteriaceae,Methanosarcina,Methanosarcinales and new advantage archaea group were Methanosphaera stadtmanae.Comprehensive the above datas,the pig gas effect is best.Different TS%was used in continuous anaerobic fermentation.The results showed that the daily methane overall trend appeared V（TS6%）>V（TS10%）>V（TS4%）>V（TS8%）>V（TS12%）,their average daily production of methane was 2.67,2.24,0.99,0.49L.The daily methane concentration overall trend appeared c（TS4%）>c（TS6%）>c（TS10%）>c（TS8%）>c（TS12%）.The ammonia nitrogen content overall trend appeared c（TS12%）>c（TS8%）>c（TS6%）>c（TS10%）>c（TS4%）.The VFA concentration was below 307mg/L while the concentration of TS was 4%,the VFA concentration was below 3100mg/L while the concentration of TS was 6%,8%,10%.peak of VFA concentration was below 6303mg/L while the concentration of TS was 12%.Medium temperature（35℃）and high loads was used in continuous anaerobic fermentation.The results showed that V（5d）>V（10d）>V（15d）,their average daily production of methane was 6.45L、5.52L、4.79L,The load rates were 9.46 kg·m^-3·d^-1、4.73kg·m^-3·d^-1、3.15 kg·m^-3·d^-11 respectively.The daily methane concentration overall trend appeared c（10d）>c（15d）>c（5d）,load rates were 4.73 kg·m^-3·d^-1（10d）and 3.15 kg·m^-3·d^-1（15d）,the methane concentrations always remained at 56%,load rates was 9.46kg·m^-3·d^-1（5d）,Methane concentration decreased from the highest value of 62%to the lowest value 49.5%at the first 4 days.The ammonia nitrogen content overall trend appeared c（5d）>c（15d）>c（10d）.The load rates was 4.73 kg·m^-3·d^-1（10d）,the VFA concentration was 351⁶16mg/L,the load rates was 9.46 kg·m^-3·d^-1（5d）the peak of VFA concentration was 4156mg/L at the 6th day.High temperature（55℃）and high loads was used in continuous anaerobic fermentation.The results showed that V（10d）>V（5d）>V（3d）,their average daily production of methane was 3.28L、2.78L、1.96L,load rates were 4.73 kg·m^-3·d^-1、9.46kg·m^-3·d^-1、15.76 kg·m^-3·d^-1.The daily methane concentration overall trend appeared c（10d）>c（5d）>c（3d）,load rates were 4.73 kg·m^-3·d^-11 and 9.46 kg·m^-3·d^-1,the methane concentrations always remained at 62%,load rates was 15.76 kg·m^-3·d^-1,the methane concentrations decreased to 46.1%.The ammonia nitrogen content overall trend appeared c（10d）>c（5d）>c（3d）.The load rates was 4.73 kg·m^-3·d^-1,the VFA concentration was1900mg/L,the load rates was 15.76 kg·m^-3·d^-1the peak of VFA concentration was7502mg/L at the 5th day.Based on the above conclusions,choosing raw material selection of pig manure,concentration of TS was 6%and a temperature of 35℃during continuous fermentation,fermentation system was running with the most stable operation,microbial community and the performance of gas was also the best.