Experimental Study On Dry And Liquid Anaerobic Digestion With Vetiveria Zizanioides

As the main raw materials of biomass energy development, the straw has attracted many attentions of the society in recent years. Currently the dry biogas fermentation technology has become a research focus because it can improve the volume biogas production rate. However, because of the characteristic of high cellulose and weak ability to digestion for anaerobic microbial, the application and production of straw biogas has been seriously limited. In order to find out the ways to improve biogas fermentation conversion rate of the straw, using Vetiveria zizanioides as the research object. Experiment research mainly divided into dry and liquid biogas fermentation, the research content were Vetiveria zizanioides bio-pretreatment, semi-continuous liquid biogas fermentation, biogas production in different inoculum quantity treatments and semi-continuous dry biogas fermentation, then the experimental group were performed at 30℃. By comparing the biogas situation in dry and liquid biogas fermentation, it will be found a suitable anaerobic digestion technology Vetiveria zizanioides. The main research achievements are as follows:No.1 and No.2 microbial agents cultured in the Lab were used to make the pretreatment and composting on the Vetiveria zizanioides for 5d. The results showed that the gas production effect of the straw pretreated for 5d by No.1 was the best, its potential gas production was 503mL/g·TS or 550mL/g·VS, and the methane content was 62.68%. However, its volume biogas production rate was only 0.17 mL/mL·d, No.1 had obvious effect on the biogas production and potential by pretreatig Vetiveria zizanioides. The results of semi-continuous liquid biogas fermentation by adding a small amount of feed materials showed that cumulative gas production was 35420 mL and its potential gas production was 420mL/g·TS below the potential gas production 442mL/g of the batch fermentation, and the methane content was 61.29%. However, its volume biogas production rate was only 0.14 mL/mL·d. Further, the efficiency of energy recovery reached 51.89%, but this technology didn’t apply to water-deficient area because it need to supplement moisture.Through the experiment of biogas production in different inoculum quantity treatments, which set them into three same groups and added the inoculum which were 30%, 40%, 50%. The results showed that, the potential of gas production with 50% of the inoculum was 280 m L/g·TS or 306 m L/g·VS, which was higher than the one with 30% and 40% of the inoculum. Its volume biogas production rate was 0.51 m L/m L·d, the methane content of 40% and 50% inoculum was higher than the 30%, and the efficiency of energy recovery with 50% inoculum reached 51.89%. In the experiment of semi-continuous dry fermentation, the results showed that the gas production was higher than batch fermentation, and volume biogas production rate was 0.65 m L/m L·d. The raw materials processing and volume biogas production rate of dry fermentation were higher than liquid fermentation. In a word, the dry anaerobic digestion technology applies to many areas and improves the utilization of the raw materials, then it can be saved the cost of engineering which the operation is more simple.