Operation parameter optimization of dry fermentation equipment with garage style based on flexible roof membrane

Abstract: China produces the biggest amount of agricultural solid waste in the world. The annual production of agricultural solid waste is approximately 40 billion tons, of which 30 billion tons is livestock and poultry manure, 7 billion tons is crop straw, 1.5 billion tons is vegetable waste, and 2.5 billion tons is garbage and human waste. The waste is not only valuable resources, but also a major source of pollution if it has been discharged into environment without proper treatment. Nowadays as the fossil energy has been gradually dried up, the large-scale application of dry fermentation biogas technology is one of the solution to energy shortage, environmental pollution and the demand for more effective disposal of crop straw, livestock manure and garbages. The research of dry fermentation biogas technology has become a popular project in China. Bigger water demand in wet fermentation process, higher cost in biogas slurry processing, single fermentation material, low fermentation density, and low unit volume gas production are the disadvantage of traditional fermentation method. To solve these problems, this paper suggested a dry fermentation process, and the dry fermentation technology optimization condition were studied. The experiment of anaerobic dry fermentation using the garage style with flexible roof membrane was tried with setting mixture of straw and cattle manure as raw materials. The methane production and material degradation rate using different material ratio, fermentation temperature, biogas slurry spraying times, fermentation time were investigated. Working process was optimized by L9(34) orthogonal experimental design. Compared with wet fermentation, the experimental results showed that the optimal working process parameters of the device were material ratio 4:1, fermentation temperature 35℃, biogas slurry spraying times two times per day, fermentation time 35 days. The volume fraction of CH4 was 65%, the volumetric gas production rate was 0.63m3/(m3·d) and the material degradation rate reached 45% under the optimum condition . This results were better than those using wet fermentation methods. The insufficiency of the wet fermentation technology could be overcome by dry fermentation technology, which provide the reference for the scale anaerobic dry fermentation production.