Biogas Production Of Fermentation With Mixed Straw And Manure And Anaerobic Microecology Molecular Analysis

The co-digestion of different ratio of maize straw and pig manure were tested in500mL anaerobic bottles. The results show that the highest cumulative methane yields weregotten by adding equal materials of maize straw and pig manure (counted by total solid).The characteristics of biogas production within co-digestion of maize straw and pig manurewere studied in10L anaerobic reactor compared with single material. The biogasproduction of maize straw can be quickly increased by fermentating the mixture of strawand pig manure. Its highest biogas daily production increased by47.36%and32.22%andthe cumulative biogas yields increased by66.33%and28.25%within13days, comparedwith the test of single materials of straw and manure. The methane volume fraction andtotal VFA of the test of straw were lower than the others. The pH of the entire tests wasabout8.20. There was a significant positive correlation between the VFA and daily biogasproduction in fermentation of materials with straw (P<0.01). We find that the structure ofarchaeal community is different between three kinds of system with different substrates bythe molecular biological (PCR-DGGE) analysis of the domain species within thefermentation. Then different species also change in different ways through the process offermentation. An uncultured euryarchaeote-like Archaea exsisted steadily in thestraw-ferment-system, while its ratio in archaeal community decreased gradually in theMiddle-Later Period of fermentation with swine manure. A methanobrevibacter-likeArchaea only exsisted in the system of fermentation added swine manure. There’s a similarchanging tendency in the fermentation with different materials. With the progressing offermentation, Methanocorpusculum-like archaea develops to be the dominant population ofcommunities gradually. It is useful for methane-producing to keep the structure of archaealcommunity stable. At the different stage of fermentation, the structure of bacterialcommunity also changed, but it’s not so distinct as archaea. The BacteroidetesBandacterium-like bacteria develops to be the dominant population of bacterialcommunities of both three systems gradually. The Aspergillus oryzae-like andFusarium-like fungi exsisted steadily in the fermentation system, the structure of fungal community is comparatively simple. Increasing the ratio of straw in the materials at thebeginning and decreasing it in the middle stage of fermentation will shorten the time ofstarting and get a better effection of gas production.