Utilization of recycled wood in biorefineries: preliminary results of steam explosion and ethanol/water organosolv pulping without a catalyst

Abstract

With overall higher use of wood and wooden materials in the future, the importance of recycled wood will increase. Recycled wood is currently used for the production of wood based composites and for combustion. In the future, use of recycled wood will also be important as feedstock for biorefineries for the production of bio-based chemicals and biofuels. The present paper gives preliminary results on the feasibility of A I recycled wood (German classification, natural wood only treated mechanically) in a steam explosion and organosolv pre-treatment process. The presence of inorganic pollutants and non-wooden material in recycled wood material was investigated. The effect of recycled wood heterogeneity (e.g., variable wood species and wide particle size distribution) on performance of wood pretreatment and subsequent enzymatic hydrolysis was also evaluated. Microeconomic analysis of lignocellulosic feedstock for a biorefinery using organosolv cooking was calculated with various price scenarios and various proportions of recycled wood instead of fresh beech chips. The results show that the concentration of inorganic pollutants is higher than in fresh wood but below the limit values for polluted wood. Preliminary results on steam explosion and ethanol based organosolv cooking without an acid catalyst showed typical behaviour of softwood for recycled wood of A I quality in respect of hydrolysability, thus being a potential future raw material for sugar production. A I recycled wood can be used in a biorefinery without major problems and can significantly improve the economics of investment in an industrial scale biorefinery.