Temperature Methanogenic Flora Analysis

75% of the domestic biogas fermentations are affected by low temperature in winter in our country. This phenomenon is serious in the northern regions. And biogas fermentation is a complex biochemical reaction accomplished by multiple strains. We should have an accurate, comprehensive understanding of the low-temperature methanogen flora, and establish some effective method to control biogas fermentation. Only in this way, can we completely solve the question of methane yield in the low temperature condition. This research focuses on the diversity of the low temperature methanogen groups by using PCR-DGGE, and studies the effects of the substrate concentration and temperature to biogas fermentation. Main results are summarized as follows:1. The microbial diversity can be tracked by using PCR-denaturing gradient gel electrophoresis (DGGE). The results showed: There is a little of difference between with the original wetland silt collected from Zhaoyuan and the enrichment cultured silt F1 in bacterial diversity. After enrichment training, Fibrobacter sp.and Firmicutes who have more ability to decompose raw material become dominant. To methanoarchaea, Methanogenic bacterium enrichment culture clone Me-c24 and uncultured bacteria is dominant. These uncultured bacteria are mostly separated from the silt of river bottom, silt of Mediterranean cold sea, rice paddy and methan tank. This should be the new methanogenesis species separated from the original low-temperature wetland.2. Choose cow muck as fermentation substrate. The effects of different substrate concentration(2%,4%,6%,8%,10%),different temperature(8℃,10℃,15℃)to anaerobic digestion were studied. The results show that the total quantity of gas and methane content are significantly higher than the other three groups in 6, 8% experimental groups. And pH is within the normal range. Therefore the best substrate concentrations should be controlled in 6-8%. The fermentation performance of each temperature group (8℃, 10℃, 15℃) has no significant differences. Three experimental groups all can ferment normally. Average gas yield can reach 1:0.2. It proved the possibility of low temperature biogas fermentation by using low temperature methanogens flora in 8℃. It saves a lot of energy that is used for improving fermentation temperature. It shows a good application prospect for low temperature fermentation energy.