Process for the conversion of lignocellulose material into an organic acid

A process for the conversion of lignocellulose into an organic acid, the process comprising the following steps:

• a) pretreating a feed comprising lignocellulose material with an alkaline agent comprising a divalent cation, wherein the divalent cation is a calcium or magnesium cation, in the presence of water at a pretreatment temperature, to obtain an aqueous slurry of alkaline pretreated lignocellulose material;
• b) supplying at least part of the slurry of alkaline pretreated lignocellulose material to a fermentation zone and subjecting the pretreated lignocellulose material, in the fermentation zone in the presence of a hydrolytic enzyme and a micro-organism that is able to convert saccharides into an organic acid, to enzymatic hydrolysis and fermentation to obtain a fermentation broth comprising insoluble lignocellulose, precipitated and dissolved salt of the organic acid with the divalent cation, and enzyme;
• c) discharging fermentation broth obtained in step b) from the fermentation zone;
• d) separating from the discharged fermentation broth a liquid phase comprising the dissolved salt of the organic acid and a solid phase comprising insoluble lignocellulose and the precipitated salt of the organic acid, washing the separated solid phase with water at a temperature in the range of from 10 to 50° C. to obtain a washed solid phase and wash water;
• and supplying at least part of the wash water to step a);
• e) recycling at least part of the liquid phase separated in step d) to said alkaline pre-treatment step a) and/or to the fermentation zone;
• and,
• f) recovering the salt of the organic acid from the washed solid phase separated in step d) by extracting said washed solid phase with water at a temperature in the range of from 60 to 100° C. to obtain a solution of the salt of the organic acid and an extracted solid phase.