Study on the Methane Production Capacity and Energy Output of Different Temperatures during Anaerobic Digestion of Swine Manure

This study was carried out by experimenting with the self-manufactured digestion devices which were fed with swine manure as material with a domesticated inoculums added as yeast. The experiment was on the condition of 6.6% mass fraction of total solid, the digestion temperatures were set at room temperature, 20°C, 35°C, and 55°C, and the biogas yield of the four temperatures were recorded in 41 days. Through the testing of methane content, the cumulative methane yield and net energy output computation, this paper researched into the optimum temperature during anaerobic digestion of swine manure. The results indicated that the low temperature went against the methane production which increased along with the increasing temperatures. Giving consideration to both digestion time and energy produce, that was more suitable treating the animal excrement of large scale livestock and poultry breeding farm on condition of mesophilic fermentation (35°C) with 31 days as the fermentation period. The normal temperature fermentation (20°C) was also achieved energy benefit better, but with longer fermentation time, it was appropriate for the smaller scale breeding farm which produced less animal manure, and it was also suitable for the household using in most area of south China where annual average temperature was about 20°C. In order to increase the energy output during anaerobic digestion, the digestion device must be improved, and the heat insulation measures have to be strengthen to make sure the use efficiency of the imported energy and to reduce the radiation loss.