Design and application of dry anaerobic fermentation system using flexible membrane-covered garage

Abstract: Relative to wet fermentation, dry fermentation (the density of fermentable dry substrate materials ≥ 20%) is a new technology that anaerobia are used to decompose animal manure, straw and other organic solid wastes into CH4 and CO2. This technology is an effective way to deal with rural organic wastes. However, considering the status of current research and application of dry fermentation, the technology developed in other countries has complex facility structure, high investment, complicated operation and higher safe operation requirements of the system. Domestic dry fermentation, which mainly focuses on ways to improve the rate of gas production and the pretreatment of fermentation feedstock rather than optimizing the structural design, enhancing heat and mass transfer, improving warming and insulation effects, and reducing production costs, has been hardly seen in large-scale production and its research has been limited in the pilot or experimental study. For the flexible membrane covered garage dry anaerobic fermentation introduced in this paper, we have combined the typical mature German garage dry fermentation with domestic flexible membrane covering to achieve technological integration and innovation. Our research provided data reference and technical support for large scale application of anaerobic dry fermentation in China. To overcome high costs, inefficiency, intensive labor, and time and human resources required for treating large quantity of biogas slurry residue, the difficulty of raw material pretreatment, high water consumption, and poor adaptability of raw materials in present anaerobic fermentation, the system in this paper was suitable for the mixed anaerobic fermentation of organic materials of various sources. Based on processing requirements of dry anaerobic fermentation, the new system had defined the key structural and operational parameters and designed facilities including dry fermentation reservoir, temperature enhancement system in winter and the spray enhanced heat and mass transfer system which was also under experiment. According to the production and application, the structure design of dry fermentation reservoir was reasonable. The design of temperature increased in the system that met the requirement in dry fermentation engineering and the spray system achieved the purpose of heat and mass transfer. The tests showed that the system was in good condition with gas production of 0.81 m3/(m3?d), 67% CH4, and 48% degradation of raw materials. The stability of the system had greatly improved the ability of processing rural organic wastes and promoted the sustainable, healthy and rapid development of anaerobic fermentation.