Research On Key Technology Of Organic Waste Anaerobic Dry Fermentationm In Northern Small Towns

Biogas as a product of anaerobic fermentation of biomass, providing clean energy for human beings, at the same time can also be degradation of organic waste by the anaerobic process and achieve the purpose of harmless handling. In recent years, with the rapid development of small town construction in our country, small towns are processed with biogas engineering organic waste more and more get people’s attention. This study combined with the "12th five-year" national science and technology support project" Integration and demonstration of solid state continuous fermentation technology with small and medium-sized city garbage in cold area ". the existence of biogas fermentation process for the northern region of energy input, solid state fermentation fermentation issue such as difference of mass transfer of raw materials, organic waste in northern area of biogas solid state fermentation process energy loss and the effective heat preservation measures, as well as the raw material of fermentation characteristics, anaerobic bacteria group of distribution and improve liquidity of fermentation raw materials and other key issues conducted in-depth research. This study will provide the north area of solid state anaerobic fermentation biogas engineering application of provides the technical support.To study the operation energy consumption and output energy consumption energy balance of the benefit in biogas project under the condition of cold region in north China. In this paper, according to the characteristics of the climate of the northern cold region in Harbin Shuangcheng city’s biogas engineering as an example, calculated the different heat loss factors of the project total heat loss, it is concluded that winter and annual average heat loss were 14694.4MJ,12185.7MJ. Through the analysis of several warming methods applied in this project, it is concluded that the project to achieve the year and the winter average daily maintain engineering work still need to increase the heat energy were 1377.4MJ and 3887.2MJ. By calculating the heat energy consumption during the operation of the project to produce gas heat energy, the project in winter and annual to produce biogas energy efficiency were 48.79% and 57.54% respectively. To achieve the stable operation of the cold north area biogas project, the research constructed a set of solar-power waste heat medium temperature anaerobic fermentation warming system. The biogas fermentation heat load, generator set waste heat recycling, solar heating device has carried on the theoretical calculation of key parameters, such as thermal efficiency. Calculation showed that the annual average daily biogas engineering heat loss was 6659.2 MJ, solar-power waste heat medium temperature anaerobic fermentation warming heat was 7017.6 MJ, annual average daily set throughout the year in January and February system only need to biogas generator set an additional 378.6 kW-h and 286 kW-h power, and design of the system can be added to annual average heat loss and maintain engineering and stable operation. Combining gas generator and solar hot water system can reduce the investment, but also according to the warming of the energy needed to proper regulation and operable in practice and the feasibility of the application, this system has both economy benefit and practicability. The system can provide guarantees for cold climates guarantees stable operation of biogas engineering.Use MSW(Municipal Solid Waste) as raw materials, this paper studied the anaerobic fermentation start-up phase and gas phase change of the structure, the characteristics of microbial community distribution and the relationship between the biogas production, the determination of the pH value in the process of fermentation, volatile fatty acid (VFA), oxidation reduction potential and related indicators. The results showed that the early start stage aerobic and facultative anaerobic bacteria was a dominant microbial, acidogenic bacteria proliferation rate higher than that of ammonification bacteria which was dominant bacteria at initiating stage of the degradation of organic matter. Then anaerobic bacteria rapid proliferation, day proliferation rate by 20% to nearly 100% and remained stable. Anaerobic cellulose-decomposing bacteria proliferation was slow at initiating stage, and the cellulose degradation process was in late anaerobic fermentation. Butyric acid content in the raw material’s VFA was most and the highest concentration can be above 4.7mg·mL-1 which accounting more than 46% of the total organic acid. So the anaerobic fermentation type is butyric acid type fermentation. Methane bacteria had no proliferation at the beginning of the ferment process, about at 25d the maximum microbial content to 3.24×1010/ml, and then methane bacteria in the whole produce process hold in this order of magnitudes. Anaerobic cellulose-decomposing bacteria count showed a trend of slow growth which increased until feeding in 45d to 106/ml. The number of anaerobic acidogenic bacteria and methane bacteria both were in the central part is more than the edges and the bottom than at the top; In middle edge and center position, there had more anaerobic ammonification bacteria. At the bottom of tank, there also had more anaerobic cellulose-decomposing bacteria. In addition, the changing tendency of volatile fatty acid, ammonia nitrogen and VFA had the same trend with the number of bacteria on the space changes.In order to improve the anaerobic solid state fermentation liquid, before and after the change of viscosity of the municipal solid waste with municipal sludge solid state fermentation was analyzed in this paper. The results showed that the greater the viscosity and the sludge concentration, the greater the proportional relationship, and the viscosity before fermentation is 1-3 times after fermentation. Hybrid materials at low temperature, viscosity with temperature declining trend was larger, at high temperature, this trend to be slow. The apparent viscosity of different content of organic waste and sludge, increase one sludge before fermentation the viscosity increased by 15.41%, and increase an organic matter the viscosity reducing 12.79%. Increased one portion sludge the viscosity could increase by 10.26% after fermentation, increased one portion organic matter the viscosity reduced 6.92%. With the increase of shear rate the apparent viscosity was gradually reduced to stable at last.