Continuous and Semicontinuous Reaction Systems for High-Solids Enzymatic Hydrolysis of Lignocellulosics

Abstract

-An attractive operation strategy for the enzymatic hydrolysis of lignocellulosics results from dividing the process into three stages with complementary goals: continuous enzyme adsorption at low-solids loading (5% w/w) with recycling of the liquid phase; continuous liquefaction at high-solids content (up to 20% w/w); and, finally, continuous or semicontinuous hydrolysis with supplementation of fresh enzymes. This paper presents a detailed modeling and simulation framework for the aforementioned operation strategies. The limiting micromixing situations of macrofluid and microfluid are used to predict conversions. The adsorption and liquefaction stages are modeled as a continuous stirred tank and a plug flow reactor, respectively. Two alternatives for the third stage are studied: a train of five cascading stirred tanks and a battery of batch reactors in parallel. Simulation results show that glucose concentrations greater than 100 g L -1 could be reached with both of the alternatives for the third stage.

Influence of High-Pressure Steam Pretreatment on the Structure of Rice Husk and Enzymatic Saccharification in a Two-Step System

“…The two step enzyme saccharification increased the reducing sugar due to high sugar concentration which may block further enzyme hydration. It was previously reported that removal of accumulated sugar prevents feedback inhibition experienced in the initial step (Qi et al 2011;Ouyang et al 2013;Quiroga et al 2015).…”

Kinetic Characterization of Enzymatic Hydrolysis of Apple Pomace as Feedstock for a Sugar-Based Biorefinery

“…The two-step process was based on the optimization of the enzyme adsorption on the biomass during the first short stage of the process (about 1 h) and the successive optimization of extensive hydrolysis during the second, long stage of the process (up to 48 h). A similar strategy was modelled by González Quiroga et al [9]. They proposed a two-step enzymatic hydrolysis at different biomass loadings in different continuous reactors.The further development of the proposed two-step strategies asks for the quantitative characterization of the hydrolysis of cellulose in real biomass.…”

“…Gusakov et al [7] tested the cellulose conversion in a batch reactor and in a plug-flow reactor to select the best configuration in terms of cellulose conversion. Nowadays, further studies are focused on innovative strategies to combine two fundamental targets: the maximization of both sugar concentration in the hydrolysate and polysaccharides conversion [8,9]. Typically, these two targets are in contrast with one another: high biomass loading (15-20 wt%) favours high soluble sugar concentration and low polysaccharides conversion, and low biomass loading (about 5 wt%) provides low sugar concentration and high polysaccharides conversion.…”

Oscillating flow bioreactors: An enabling technology for sustainable biorefining operations?

“…There are a number of indications that enzymatic hydrolysis could benefit from a continuous process partly due to the potential to overcome product inhibitions. It is known that the enzymes used for the saccharification of cellulose are inhibited by the presence of glucose and cellobiose, limiting the possible sugar concentration in the hydrolyzed liquid .…”