Study On Anaerobic Digestion Process And Dynamics Of Microbial Community In Corn Stalk

As a big agricultural country,china has rich resources of crop straw.Making full use of agricultural waste to produce clean energy,not only reduces the pollution to the environment,but also meets the demand of energy for people.Anaerobic fermentation technology can use crop straw,make waste profitable and achieve a win-win situation of environment and energy.This paper mainly research the gas production performan-ce for the start stage of anaerobic fermentation,the three storage methods of corn straw,he different mixing intensity of silage straw and the biogas slurry reflux.The results showed that:1.The pH for the start stage is about 6.2,which is in the normal pH of microbial physiological activities;average daily gas production is 1.1 L,slightly higher than the gas production of the biogas project;the COD removal rate of the two reactor were in more than 50%,the reactor started successfully.2.The result for different storage methods of corn straw showed the gas production,cumulative gas production and methane content,the maximum biogas production rate and the maximum methane generation rate was higher for fresh straw than silage straw and dry yellow straw;principal component analysis showed that the fermentation time was positively correlated with the content of methane,gas production,organic acid,cumulative gas production etc.There were 11 kinds of methanogen composition in the reactor at the family level the abundance of Archaea_unclassified in silage straw,fresh straw,and dry straw was 36.50%,20.61%,and 29.03%,respectively.The abundance of Methanobacteriaceae in silage straw,fresh straw,and dry straw was 26.47%,35.86%,and 41.42%,respectively.The abundance of Methanosaetaceae in silage straw,fresh straw,and dry straw was 2.98%,18.67%and 28.25%respectively.The abundance of Miscellaneous_Crenarchaeotic_Group`N orank in silage straw,fresh straw,and dry straw was 0.2%,81.29%,and 99.05%,respectively.And Shannon-Weaver index was 1.87 for fresh straw,whereas silage straw and dry straw had Shannon-Weaverindices of 9.6 and 17.11,respectively.The DGGE bands of bacterial analysis showed that the dominant bands of three different storage methods wereb and h.The bacterial diversity in the operation stage of fresh straw was more than that of dry yellow straw and straw silage.3.The gas production and the maximum rate of methane production for different mixing intensity of silage straw was 30 min/2h>30 min/4h>30 min/h,and the maximum methane production rate is 30 min/4h>30 min/2h>30 min/h.The principal component analysis showed that the organic acid accumulation could be caused by excessive agitation.The DGGE bands of bacterial analysis showed that compared with 30 min/2h,the bands in 30 min/4h and 30 min/h were more,and the bands c,e and h are dominant bands in the three mixing intensities.4.The average daily gas production of biogas slurry reflux in about 1.1 L,reached the requirements of biogas engineering.The band c and g are the dominant bands of the slurry reflux,and always exist in the whole process of slurry recirculation.