Development of innovative approaches for the main stages of 2G ethanol production: continuous pretreatment using hydrodynamic cavitation and evaluation of SSCF process with interconnected reactors

Abstract

Hydrodynamic Cavitation (HC) is a promising technology used for different industrial applications as water treatment, biodiesel synthesis and others. This technology was recently used for pretreatment of sugarcane bagasse, resulting in hydrolysis yields of carbohydrate fractions in the pretreated material of more than 90%. The main HC effects correspond to a high lignin removal and an increase in the porosity of the material, which are associated to the chemical and mechanical effects of the cavitation phenomenon. HC has potential to be adapted for use in continuous process and industrial scale application. In this sense, design and construction of a technology based on hydrodynamic cavitation systems for the continuous pre-treatment of sugarcane bagasse is proposed. Firstly, the project will deal with the design and construction of the system based on fluid flow fundamentals, required pressure calculations and cavitation number. After, initial pretreatment experiments will be carried out and, considering the collected data, the fluid flow through the system will be simulated by computational fluid dynamics (CFD). Fluent® software will be used to determine the fluid velocity profile throughout the system, static pressure drop mainly in the cavitation source (orifice plate) and stagnation zones. The simulated results will be experimentally validated by measurements using instruments inserted in different parts of the system, namely temperature, velocity and pressure sensors. CFD results will also be used to improve the performance of the hydrodynamic cavitation system for continuous pretreatment. Subsequently, the most influential variables in the process will be evaluated and optimized using experiment design as a tool. The material pretreated in continuous mode under optimized conditions will be used to evaluate the production of second generation ethanol by immobilized cells of Sheffersomyces stipis in simultaneous hydrolysis and co-fermentation process (SSCF) in interconnected column reactors. The yeast S. stipitis will be evaluated considering its ability to metabolize both the hexoses and the pentoses present in the sugarcane bagasse enzymatic hydrolyzate. This new configuration, based on interconnected reactors, will allow developing each process (hydrolysis and fermentation) under optimized temperature conditions. In addition, it will allow using high solids content, besides avoiding the inhibition of the enzymatic activity by product. Thus, this project is focused on the development of innovative approaches for the main stages of the production of 2G ethanol: continuous pretreatment using hydrodynamic cavitation and evaluation of SSCF process with interconnected reactors. By developing this project, relevant scientific and technological knowledge are expected to be generated in applications of national and global interest.