Fig. 1

a Accumulated methane production from non-pretreated waste residues (WR) and pulp residues (PR) at 37 °C and at 55 °C. Average values (n = 3) are plotted and error bars indicate standard error. b Accumulated methane production at 37 °C from pretreated wood residues (WR). au autoclave pretreatment, us ultrasound pretreatment, al alkaline pretreatment, mo commercial microorganism mixture pretreatment, en enzyme pretreatment. Average values (n = 3) are plotted and error bars indicate standard error. c Accumulated methane production at 37 °C from pretreated pulp residues (PR). Average values (n = 3) are plotted and error bars indicate standard error