Method for processing lignocellulosic material

A process for continuously converting solid lignocellulosic biomass material into ethanol wherein all or part of process water is recycled, the process comprising the steps of:

• (i) providing an aqueous slurry of the biomass material;
• (ii) subjecting, in a reaction vessel, said aqueous slurry to elevated temperature conditions, to an oxygen enriched atmosphere or to a combination of elevated temperature conditions and an oxygen enriched atmosphere, to obtain a slurry in which at least partial separation of the biomass material into cellulose, hemicellulose and lignin has occurred;
• (iii) subjecting the slurry resulting from step (ii), an aqueous phase of the slurry resulting from step (ii) or a combination of the slurry resulting from step (ii) and an aqueous phase of the slurry resulting from step (ii) to a treatment resulting in at least partial hydrolysis of the cellulose and hemicellulose to obtain a slurry, an aqueous phase, or a combination of the slurry and the aqueous phase, comprising an amount of microbially fermentable sugars that permits the slurry, the aqueous phase or the combination of the slurry and the aqueous phase to be used as an ethanol fermentation medium
• (iv) subjecting the slurry, the aqueous phase or the combination of the slurry and the aqueous phase of step (iii) to at least one ethanol fermentation step;
• (v) separating the ethanol from the fermentation medium resulting from step (iv), resulting in a fermentation wastewater effluent containing a level of inhibitory substances that, if present in any of the preceding steps (ii) to (iv) would be rate limiting or inhibitory;
• (vi) subjecting said wastewater effluent to a treatment whereby the level of the inhibitory substances is reduced to a level that, if the wastewater effluent is introduced into any of the preceding steps (ii) to (iv) is not rate limiting or inhibitory;
• (vii) introducing all or part of the thus treated wastewater effluent into any of the preceding steps (ii) to (iv);
• and
• (viii) continuously repeating steps (i) to (vii).