Dynamic model of simultaneous enzymatic cellulose hydrolysis and product separation in a membrane bioreactor

Abstract Bioethanol production from lignocellulosic biomass depends on enzymatic cellulose hydrolysis to generate glucose. However, enzyme inhibition by the product is one of the several problems making lignocelluloses refractory to this process. To resolve this, we designed a membrane bioreactor (MBR) with an inverted dead-end filtration concept for simultaneous removal of the product during the reaction. Polyethersulfone membranes were used, and their selectivity in allowing only product permeation was proven. The effects of different water fluxes and initial substrate concentrations were investigated. Additionally, a detailed kinetic model based on the mechanistic steps was developed to predict the dynamic behavior of the system, and the kinetic parameters were estimated by fitting the experimental data. The MBR yield increased from 7% without product separation to 45% with product separation. Both kinetic and statistical models showed good agreement (R2: 0.96 and 0.97, respectively). According to the statistical model, the optimal conditions were a substrate concentration of 2.67 g/L and a water flux of 0.8 mL/min, which achieves a maximum yield of 86.7%. Our novel MBR and kinetic model allow for a better understanding of the dynamic behavior of this important reaction–diffusion system and can be used to predict, design, and optimize similar MBRs.