Mesophilic running of dry fermentation biogas system without heating device and its effects

The measure of temperature rising and heat preservation of membrane covered trough (MCT) dry fermentation biogas system, was brought forward as follows: firstly, the substrate’s temperature was increased to that of the upper limit of mesophilicly anaerobic digestion by the process of aerobic pre-treatment of the substrate; secondly, the substrate’s temperature was kept within the temperature range of mesophilicly anaerobic digestion by a good thermal insulation layer covering the MCT bioreactor. Experiment was held at the dry fermentation biogas pilot plant, and the results were described as follows: the substrate’s temperature changed mildly. The max of temperature drop in one day, occuring in the 9th day, was 0.5℃, the minimum of temperature drop in one day, occuring in the 3rd day , was 0.04℃; the substrate’s temperature was rised to 40.62℃ by aerobic pre-treatment process, decreased slowly during 21-day period of biogas fermentation and was 35.41℃ when anaerobic digestion finished; its average cubage biogas yield rate was 0.598 m3/(m3·d), methane content ranged between 55%-60%. Consequently, it is feasible to improve the cubage biogas yield rate and energy benefit of dry fermentation biogas plant by the measure of temperature improvement and heat preservation.