The main concept underpinning the project relies on a new pretreatment process able to run all the operations from the processing of the lignocellulosic biomass to the enzymatic pre-hydrolysis in a one-stage-reactor. There is no need for transferring substrates other than directly to the saccharification/fermentation vessels, nor requirements for external washing, cooling, neutralising, detoxifying and concentrating the substrates outside the reactor. The slurry resulting from the new pretreatment process is delivered under favourable conditions ready for further hydrolysis and fermentation in external tanks. This new concept offers the most integrated and compact solution for the pretreatment of lignocellulosic biomass which has been designed and studied so far. All the operations necessary to increase the access for the enzymes to the carbohydrates (deconstruction, defibrillation and depolymerisation) and start the solubilisation of sugars are carried out in a single twin-screw extruder with high throughput.
The advance beyond the state-of-the-art provided by the new pretreatment process can be summarised in one sentence: one step-one reactor process, few minutes residence time from the raw biomass feeding to the saccharification reactor and three pumps to inject the reagents. The new technology concentrates in one reactor all the reactions (thermal-mechanical-chemical-enzymatic) necessary to reach favourable conditions for saccharification. Moreover, it is the only process of the state-of-the-art where enzymatic hydrolysis is initiated in the pretreatment reactor itself.