Different pre-treatment severities by thermo-alkaline conditions (100 degrees C, Ca(OH)(2)) on press mud were evaluated for different pre-treatment time and lime loading. COD solubilization and the methane yield enhancement were assessed. The biochemical methane potential was determined in batch assays under mesophilic conditions (37 +/- 1 degrees C). The best pre-treatment resulted in a surplus of 72% of methane yield, adding 10 g Ca(OH)(2) 100 g(-1), TS-1 for 1 h. Pre-treatment also increased the COD solubilization, but the optimal severity for COD solubilization as determined by response surface methodology did not ensure the highest methane production. Inhibitory effects on anaerobic digestion were noticed when the severity was increased. These results demonstrate the relevance of thermo-alkaline pre-treatment severity in terms of both lime loading and pre-treatment time to obtain.optimal anaerobic biodegradability of lignocellulosic biomass from press mud. (C) 2013 Elsevier Ltd. All rights reserved.