Software para simulação do processo de sacarificação e fermentação simultâneas de biomassas lignocelulósicas para produção de etanol de segunda geração

Abstract

Concern about the environmental impacts associated to the consumption of fossil fuels and the need to generate power through renewable resources, is shown to be necessary to study the use of alternative materials aiming the production of clean energy and the reduction of pollutants in the atmosphere such as the use of lignocellulosic biomass to produce second generation ethanol (2G). This work consists in simulating the 2G ethanol production, from a mathematical model for simultaneous saccharification and fermentation (SSF) of lignocellulosic biomass existing in the literature, optimizing the process in batch reactor and comparing batch and continuous reactors under the same conditions. The simulation of the SSF process of 2G ethanol production was performed using a developing software in Matlab program, with optimization of batch process through a rotational central composite design (RCCD) and the results were used in simulation for continuous reactor (CSTR). The conditions of the process studied were 36°C, pH 4.8 and agitation of 300 rpm, microcrystalline cellulose (Avicel PH 101) were used as substrate, cellulase complex enzyme Novozymes NS50052, with activity of 97 FPU/g ( initially used 4 g /l with the same enzyme loading of 9.7 FPU/g substrate) and as inoculum Saccharomyces cerevisiae ATCC´s collection, with initial concentration of 0.3 g/l. Studying the effects of the process variables, it was found that the higher interferences are cellulose concentration, followed by enzymes and cells concentrations. Greater concentrations of the product in batch process are obtained with the maximum cellulose concentrations (60 g/l), cells (0.468 g/l) and enzyme (5.58 g/l). In continuous reactor, using such concentrations, the dilution rate of 0.01 h-1 and higher initial culture cellulose concentration, the ethanol production increases. It was found, by simulating the SSF process in batch and continuous reactors in software, under the same conditions of cellulose, enzymes and cells concentrations for 48h process, the continuous reactor has a higher ethanol concentration in product that batch reactor.