Effect of temperature on continuous dry fermentation of swine manure

• Published in: Journal of environmental management Vol. 177; pp. 247 - 252
• Main Authors: Deng, Liangwei, Chen, Chuang, Zheng, Dan, Yang, Hongnan, Liu, Yi, Chen, Ziai
• Format: Journal Article
• Language: English
• Published: England Elsevier Ltd 15.07.2016; Academic Press Ltd
• Subjects: Acidification; Ammonia; Ammonia - chemistry; Anaerobiosis; Animals; Biofuels; Biogas; Biogas production; Bioreactors; Dry digestion; Environmental management; Fermentation; Hogs; Manure; Manures; Methane; Methane - analysis; Swine; Swine manure; Temperature; Temperature; Dry digestion; Biogas production; Swine manure
• ISSN: 0301-4797; 1095-8630
• DOI: 10.1016/j.jenvman.2016.04.029

Laboratory-scale experiments were performed on the dry digestion of solid swine manure in a semi-continuous mode using 4.5 L down plug-flow anaerobic reactors with an organic loading rate of 3.46 kg volatile solids (VS) m−3 d−1 to evaluate the effects of temperature (15, 25 and 35 °C). At 15 °C, biogas production was the poorest due to organic overload and acidification, with a methane yield of 0.036 L CH4 g−1 VS added and a volumetric methane production rate of 0.125 L CH4 L−1 d−1. The methane yield and volumetric methane production rate at 25 °C (0.226 L CH4 g−1 VS added and 0.783 L CH4 L−1 d−1, respectively) were 6.24 times higher than those at 15 °C. However, the methane yield (0.237 L CH4 g−1 VS added) and the volumetric methane production rate (0.821 L CH4 L−1 d−1) at 35 °C were only 4.86% higher than those at 25 °C, which indicated similar results were obtained at 25 °C and 35 °C. The lower biogas production at 35 °C in dry digestion compared with that in wet digestion could be attributed to ammonia inhibition. For a single pig farm, digestion of solid manure is accomplished in small-scale domestic or small-farm bioreactors, for which operating temperatures of 35 °C are sometimes difficult to achieve. Considering biogas production, ammonia inhibition and net energy recovery, an optimum temperature for dry digestion of solid swine manure is 25 °C. •Methane yield and methane production rate at 15, 25 and 35 °C were obtained.•The dry digestion of solid swine manure at 35 °C was inhibited by ammonia.•Given energy recovery and ammonia inhibition, the optimal temperature is 25 °C.