compared over 473 days in semi-continuously fed mesophilic reactors with trace elements supplementation,
at organic loading rates (OLRs) of 2, 3, 4 and 6 kg volatile solids (VS)/m3 d. Methane yields at all
OLR were 5–10% higher for untreated FW (maximum 0.483 ± 0.013 m3 CH4/kg VS at 3 kg VS/m3 d) than
autoclaved FW (maximum 0.439 ± 0.020 m3 CH4/kg VS at 4 kg VS/m3 d). The residual methane potential
of both digestates at all OLRs was less than 0.110 m3 CH4/kg VS, indicating efficient methanation in all
cases. Use of acclimated inoculum allowed very rapid increases in OLR. Reactors fed on autoclaved FW
showed lower ammonium and hydrogen sulphide concentrations, probably due to reduced protein
hydrolysis as a result of formation of Maillard compounds. In the current study this reduced biodegradability
appears to outweigh any benefit due to thermal hydrolysis of ligno-cellulosic components.