Production of ethanol and xylitol from mixtures of biomass by-products from South and North America, in a bubble column reactor operated in a fluidized bed mode

Abstract

Ethanol is the impending biofuel replacing the oil since it is less damaging to the environment and can be obtained from renewable sources. Already xylitol is a sugar-alcohol widely used for being a product with several applications in the branches of medicine, food industry among others. Several countries have invested in research on the production of bioproducts from various biomasses and their by-products, one of the most common examples being the production of second generation ethanol from sugarcane bagasse in Brazil. In addition to Brazil, Canada has also invested in the production of ethanol from corn and wheat. For xylitol, for example, since 2008, the Canadian biochemical industry has focused on developing a cheaper production process, while Brazil remains importing most of this important product. In fact, these same Canadian raw materials are also produced in Brazil, but their by-products are most often used as animal feed or energy sources from burning. In this context, the present project will aim to evaluate the biotechnological production of ethanol and xylitol from the biomass mixture in two sets. The first will be formed by mixing the by-products of some of Brazil's main biomasses (straw and sugarcane bagasse), and the second by mixing the by-products of some of Canada's main biomass (corn cob and wheat straw) . This process will be conducted in a bubble column reactor operated in a fluidized bed mode. In a first step, an acid pretreatment of each set will be performed in a high pressure reactor, evaluating the processes separately. Subsequently the hemicellulosic hydrolysates (in separate processes) will be chemically prepared and used as carbon source to evaluate the production of xylitol by yeast Candida guilliermondii in a bubble column reactor. In a further step, the remaining solid portion (cellulignin) will be washed, dried and pretreated in alkaline medium in bubble column reactor aiming at the delignification and increase of the enzymatic digestibility of this fraction of the biomass. The remaining solid portion will be conducted to enzymatic pretreatment, the saccharification process also being carried out in a bubble column reactor operated in a fluidized bed configuration. Subsequently the resulting hydrolyzate will be used as a carbon source for ethanol production, using the yeast Scheffersomyces shehatae. By these results, it will be possible to compare the viability of the use of each set of raw materials, as well as to evaluate chemical, enzymatic and fermentation pre-treatments in a bubble column reactor. With this project, it is hoped to obtain results that strengthen the technology of the biotechnological production process of ethanol and xylitol from different sets of biomasses, in a fermentation process that will contribute to the development of current biorefineries, besides contributing with the technical- appropriate to the student of scientific initiation.