Study On Anaerobic Digestion Of Low - Order Tobacco Leaves

Being a leading country of tobacco planting and consuming, China has a national economy that is occupied by tobacco industry in a large portion. Therefore, it has become a serious problem on how to accelerate the sustainable and circular growth of the tobacco industry.However, the inefficient use of inferior tobacco leaves results in great environmental pollution and energy dissipation. As the leading province in tobacco industry, Yunnan improperly processes a great deal of low-quality tobacco leaves, which are also called the substandard tobacco leaves, on a yearly basis. These substandard tobacco leaves account for 30% to 35% of the annual output of flue-cures tobacco.Due to the inadequate processing method, the energy and resources that are contained in the substandard leaves are not effectively utilized. Moreover, the frequent discard of these leaves brings huge damage to the environment.One of the effective treatments for substandard tobacco leaves is to produce methane from the leaves through anaerobic digestion.Given this premise, we conducted researches on the anaerobic digestion from four different aspects.(1) Because of the high consumption of energy and requirements for equipment, creating a high-temperature environment for anaerobic digestion is impractical. Low-temperature environment is simple to achieve, yet the volume and effectiveness of biogas production may be unsatisfactory. Thus, all of our tests are performed under a normal temperature of 22℃. This approach guarantees both the volume and effectiveness of gas production, as well as the application value in actual methane production.(2) We use Aspergillus Niger and compound enzyme that both have a quality score of 7% to preprocess the tobacco leaves before the anaerobic digestion, and observe the effects on generating methane through the digestion. Results show thatafter the pretreatment using 7% quality score Aspergillus Niger, the amount of cellulose, hemicellulose, and lignin contained in the leaves decreases. This reduces the starting time and enhances the effectiveness of the digestion. Meanwhile, the anaerobic digestion cycle is obviously improved, and the application value of the digestion in actual manufacture is foreseeable.(3) Through the following approaches:A. Culturing the mixture of pig manure, human feces, biogas digester sediment, and corn cob for one year;B. Culturing the mixture of pig manure, human feces, biogas digester sediment, and fresh pig manure for one year;C. Culturing the mixture of enriched cow dung and sweet sorghum stalks for one year;D. Culturing the mixture of enriched cow dung and corn cob for one year;E. Culturing the mixture of pond bottom mud and corn cob for one year;we observed the inoculum that produced by developing these mixtures, and aimed to discover the impact of the inoculum on anaerobic digestion process of substandard taco leaves. Results indicate that the amount of biogas produces by anaerobic digestion using inoculum A is higher than groups B,C, D, and E by 49%、139%、85.8%、55.7% respectively. Besides, the inoculum did not influence the start-up time and regular pattern of the anaerobic digestion.(4) Via analyzing the experimental data of substandard tobacco leave’s anaerobic digestion that has a density of 6%, 8%, 10%, and 12%, we found that 10% anaerobic digestion concentration improves the daily output, accumulated output, and production rate of biogas. Moreover, at 10% concentration, the stagnation duration of anaerobic digestion is shortened, and the whole digestion process is highly smooth. We also conclude that the system’s resistibility for organic acid accumulation is stronger, and the resources in anaerobic digestion containers are more fully used at the given concentration.