Effect of temperature on continuous dry fermentation of swine manure.
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.
Biogas Institute of Ministry of Agriculture, Chengdu, China; Laboratory of Development and Application of Rural Renewable Energy, Chengdu, China. Electronic address: dengliangwei@caas.cn.
Liangwei
L
Deng
Biogas Institute of Ministry of Agriculture, Chengdu, China.
Chuang
C
Chen
Biogas Institute of Ministry of Agriculture, Chengdu, China; Laboratory of Development and Application of Rural Renewable Energy, Chengdu, China.
Dan
D
Zheng
Biogas Institute of Ministry of Agriculture, Chengdu, China; Laboratory of Development and Application of Rural Renewable Energy, Chengdu, China.
Hongnan
H
Yang
Biogas Institute of Ministry of Agriculture, Chengdu, China; Laboratory of Development and Application of Rural Renewable Energy, Chengdu, China.
Yi
Y
Liu
Biogas Institute of Ministry of Agriculture, Chengdu, China; Laboratory of Development and Application of Rural Renewable Energy, Chengdu, China.
Ziai
Z
Chen
D000641:Ammonia / Q000737:chemistry; D000693:Anaerobiosis; D000818:Animals; D056804:Biofuels; D019149:Bioreactors; D005285:Fermentation; D008372:Manure; D008697:Methane / Q000032:analysis; D013552:Swine; D013696:Temperature
D056804:Biofuels; D008372:Manure; D000641:Ammonia; D008697:Methane
Biogas production; Dry digestion; Swine manure; Temperature