Biogas production potential and characteristics of manure of sheep, duck and rabbit under anaerobic digestion

In order to investigate the biogas production potential of sheep manure, duck manure and rabbit manure for anaerobic digestion and their characteristics, taking the three kinds of manure as the digestion material and the self-culture anaerobic sludge as the inoculation substances, under three different temperatures of (35±1)℃, (25±1)℃and normal temperature (9–19℃), the experiments of anaerobic digestion of sequencing batch reactor were conducted. The biogas production rate, biogas yield, variations of pH value and variations of methane concentration with different pH, and the removal efficiency of COD and NH4+-N of wastewater of three kinds of manure were studied. The results showed that at (35±1)℃, biogas production potential of material (TS) was 0.273 m3/kg for sheep manure, 0.441 m3/kg for duck manure, and 0.210 m3/kg for rabbit manure. At (25±1)℃, biogas production potential (TS) of material was 0.206 m3/kg for sheep manure, 0.359 m3/kg for duck manure, and 0.174 m3/kg for rabbit manure. At normal temperature, biogas production potential of material (TS) was 0.082 m3/kg for duck manure, and 0.098 m3/kg for rabbit manure. Three kinds of feedstocks could achieve pH self-balancing at startup of anaerobic fermentation fed with adequate anaerobic sludge. Anaerobic digestion could evidently remove COD of three kinds of manure, but it could not decrease NH4+-N.