Research On Biogas Production Of Different Materials And Proportions And Methanogenic Diversity In Biogas Slurry

Biogas is one of the important technologies which are able to make use of bio-mass as a resource. In this process, several elements can be of great influence, for example, environmental conditions, fermented materials and different proportion of materials. However, research on biogas anaerobic fermentation of Gansu is rare. Under this condition, based on the environment and material availability of rural areas in Gansu, we research into the biogas production under different temperatures, differ-ent materials and different proportions; also methanogenic diversity in the anaerobic fermentation process.In our research, we measure the biogas production of four fermented materials in the temperature of35℃,25℃and15℃:swine manure, cattle manure, wheat straw and maize straw, and look at four aspects:daily biogas production, cumulative biogas production, total biogas production and total methane production. Additionally, we analyze the methanogenic diversity in the biogas slurry collected from the biogas di-gesters in Linxia, Gansu by culture-dependent methods. From our research, we con-clude that:1. Biogas production is greatly affected by the temperature. With the decrease of temperature, the biogas production is also declining. At35℃performance of biogas fermentation is optimal. Which material is fermented affects the anaerobic process. Based on the data of total biogas production and total methane production, the per-formance of swine manure is better than cattle manure, and maize straw is better than wheat straw. Different proportions of materials also influence the biogas production. Looking at total biogas production and total methane production, at35℃when the proportion of swine manure and maize straw is3:1or2:1, or the proportion of swine manure and wheat straw is3:1, they all have better performance than the other mate-rials and proportions. Different materials have different optimal proportions.2. At15℃, the process of anaerobic fermentation is distinct with that at35℃and 25℃. During the whole process, there is no peak of biogas production, and daily bio-gas production is all lower than500mL/d. The optimal proportion of different mate-rials also changes due to the low environmental temperature. The temperature affects the growth of mesophilic micro-organism and prevents them from making use of nu-trients. Additionally, the proportion of nutrients which favors by the mesophiles is different from that of psychrophiles.3. In the analysis of methanogenic diversity in biogas slurry, we discovered42strains of methanogenic micro-organisms. Among them, there are21strains sharing the highest sequence homology (99%) with Methanosarcina mazei,12strains (Group GLZ-1) are99%similar to clone K09237, and8strains (Group GLZ-2) are99%similar to clone K09231and1strain (Group GLZ-3) is94%similar to clone T19. The methanogenic diversity of biogas slurry is relatively low. The dominant groups are Methanosarcina mazei (50%), Group GLZ-1(29%) and Group GLZ-2(19%). In this research, we discovered two new dominant groups:Group GLZ-1and Group GLZ-2. The new dominant groups are associated with the characteristic environment and fermented materials. Further research on the function of these two groups would benefit their application in the biogas production.In conclusion, temperature, material and proportion are the key factors of im-proving biogas production. In Gansu Province, temperature is the main factor affect-ing the biogas anaerobic fermentation and exploring in the area of psychrophiles would be an effective way to solve the restriction of low temperature in the biogas production. Additionally, dominant methanogenic groups would change with the change of environment and fermented materials. In the region of Gansu, the metha-nogenic diversity also reflects the environmental characteristics. And the discovery of new methanogenic group would have an important effect on the application of biogas anaerobic fermentation.