An Analysis On Aerobic And Anaerobic Degradation And Reinforcement Of Straw

Large amount of straw is produced each year in China and most of which is direct combusted or abandoned. This leads to a huge waste of resources and environmental pollution. Anaerobic digestion is an effective method of utilization straw. However, biodegradation of staw is very difficult, which requires very long cycle and gas production efficiency is low. From the aspect of aerobic and anaerobic degradation of straw, the present study focused on the combination of aerobic and anaerobic straw degradation microbial consortia and the improvement of enhancers on straw degradation and methane-producing. And we hope to provide more insights on increasing the rate of straw degradation and conversion. Results are as follows:⑴ Three anaerobic straw degradation microbial consortia(FSC, CEL and H-11) were compared. Based on their physiology, biochemical and community composition, FSC was chosen for subsequent research. After 27 days cultivation, 61.21% methane was produced in the headspace, which corresponded to 39.76 mmol. Straw degradation rate and cellulose degradation rate of FSC were 62.44% and 60.03%, respectively. The dominant species of bacteria in FSC were Unclassified Clostridiales, Unclassified Clostridia and Proteiniphilum. And dominant species of archaea was Methanofollis.⑵ Growth temperature of microbial consortia FSC was 15 ?C-60 ?C, and the optimal temperature was 35 ?C-45 ?C. Initial growth pH was 4.0-10.0, and the optimal pH was 6.0-9.0, which indicated that FSC was well adapted to the variation of pH.⑶ Moreover, three aerobic straw degradation microbial consortia(F1, F2 and F3) were compared.,based on their physiology, biochemical and community composition. The dominant species of bacteria in F1 and F2 were Pusillimonas, Porphyromonadaceae, and Rhodothermus. They both had advantages, in need of further experiments to choose which for subsequent study.⑷ Finally, the performance of aerobic and anaerobic combination on straw degradation were examined. Combined use of microbial consortia FSC and F2 improved accumulative methane production and cellulose degradation rate. Among different ratios of FSC to F2, 2:1 showed the best performance, and which were used for subsequent research. After 35 days cultivation, accumulative methane production was 78% higher than that of single inoculation microbial consortia FSC. Straw cellulose degradation rate was 52.51% higher than that of single inoculation microbial consortia FSC.⑸ Effects of different concentrations of enhancers on methane production, volatile acid peaks and straw degradation rate were various. Addition of enhancers increased the accumulative methane production and straw degradation rate. And the addition of 0.3% enhancer A was the best among enhancers tested in this study. After 35 days cultivation, accumulative methane production was 36% higher than which without adding enhancers. Straw degradation rate was 26.02% higher than which without adding enhancers.In summary, FSC and F2 combination(ratios of FSC to F2, 2:1)and addition of 0.3% enhancer A could improve straw degradation and methane-producing.