Anaerobic co-digestion of chicken manure and corn stover in batch and continuously stirred tank reactor (CSTR)

Anaerobic co-digestion of chicken manure and corn stover in batch and CSTR were investigated. The batch co-digestion tests were performed at an initial volatile solid (VS) concentration of 3 g VS/L, carbon-to-nitrogen (C/N) ratio of 20, and retention time of 30 d. The methane yield was determined to be 281 +/- 12 mL/g VSadded. Continuous reactor was carried out with feeding concentration of 12% total solids and C/N ratio of 20 at organic loading rates (OLRs) of 1-4 g VS/L/d. Results showed that at OLR of 4 g VS/L/d, stable and preferable methane yield of 223 +/- 7 mL/g VSadded was found, which was equal to energy yield (EY) of 8.0 +/- 0.3 MJ/kg VSadded. Post-digestion of digestate gave extra EY of 1.5-2.6 MJ/kg VSadded. Pyrolysis of digestate provided additional EY of 6.1 MJ/kg VSadded. Pyrolysis can be a promising technique to reduce biogas residues and to produce valuable gas products simultaneously. (C) 2014 Elsevier Ltd. All rights reserved.