Bio-ethanol production. Chemical and physical characterisation of pretreated lignocellulose and identification of valuable end products and waste products

Lignocellulose utilization whether from primary (forestry or non-food energy crops), or secondary sources (agricultural or forestry waste products) represent an unutilized source of energy and chemical feedstocks. To this extent, the conversion of rape straw, wheat straw and willow into the CO2 neutral biofuel, ethanol, is an attractive approach for an agricultural country like Denmark. The complicated matrix of lignocellulose protests the biomass against microbial degradation, a structure which gives technical and microbial difficulties when applying this biomass for bio-ethanol production. The Technical University of Denmark and RISØ National Laboratory have developed a concept for fractionating and fermentation of polysaccharides in lignocellulose, especially the hemicellulose carbohydrate D-xylose. In this process, it has been recognised that more basic knowledge of the structure of hemicellulose is neccesary for identification of bottle-necks in the fermentation step. In this project the two research institutions will conduct a thorough investigation in characterisation of the soluble hemicellulose fraction produced during pretreatment of the biomass. This will increase our present knowledge of the chemical and physical changes occuring in the biomass during different pretreatment technologies (wet oxidation, steam explosion and hydro-thermal processes). Furthermore, this knowledge will make it possible to discover which enzymes are needed for a total hydrolysis of the polymers into monomeric sugars needed for fermentation into ethanol. Economical analyses have shown that to have a viable lignocellulosic bioconversion process, besides the conversion af cellulose, the hemicellulose fraction needs to be efficient conveted to ethanol. The economy of the process could be improved by the possibility of exploitation of other products such as wax as a commercial trase commodity. These exploitations will be examined in this project. The project will fund one Ph.D. student. The project will be divided into the following phases: 1) Litterature reading. 2) Choice of extraction method for pretreatment and by-products. 3) Quantitatively identification of selected compounds in the biomass. 4) Identification of inhibitory compounds in the biomass after pretreatment. 5) Fermentation of the hemicellulose fraction into ethanol