Effect of mixing on enzymatic hydrolysis of cardboard waste: Saccharification yield and subsequent separation of the solid residue using a pressure filter

Abstract

Cellulosic wastes, from sources such as low-quality cardboard and paper, are regarded as potential feedstocks for bioethanol production. One pathway from these cellulosic materials to ethanol is saccharification (hydrolysis) followed by fermentation. Saccharification is commonly performed using enzymes that are able to cleave the cellulosic structure to smaller units, preferably to glucose monomers. During the hydrolysis, mixing conditions have a considerable impact on the performance of the enzymes. Thus mixing conditions in the hydrolysis tank can also influence the downstream operations and, consequently, the overall economy of the bioethanol process. In this experimental study, four types of impeller, at different hydrolysis conditions were used. The effect of mixing on the glucose yield and on the filtration characteristics of the hydrolysate was evaluated. It was shown that not only the sugar yield depended on the mixing conditions: the effect on the solid-liquid separation step was even more significant.

A discretized model for enzymatic hydrolysis of cellulose in a fed-batch process

“…Reaction rate for each substrate population is calculated with Eqs. (12) and (13). Equation 12includes the inhibitive effect of glucose on the reaction rate.…”

“…When only one substrate population was applied to describe an experiment with multiple substrate additions (not discretized case), the fed-batch model was modified to enable this. In this modification, the substrate conversion (X i ) in equations (11) and (13) was calculated using the overall conversion of the substrate. In total eight small scale batch experiments, six small scale fed-batch experiments, and three reactor scale fed-batch experiments were used in the parameter estimation.…”

“…Also mass transfer limitations at high solids content has been discussed in literature although the results are not unambiguous. However, increased mixing power has been found to have a positive effect on glucose yield or, at least, the optimum mixing conditions has been established in many studies (Hodge et al, 2008;Kinnarinen et al, 2012;Palmqvist et al, 2016; Palmqvist and Liden, 2012; Samaniuk et al, 2011;Wojtusik et al, 2016). In addition, (Hodge et al, 2008) concluded that increasing initial solids concentrations above 20% reduced the conversion after 48 hours and the threshold value for solids concentration was even lower for shorter reaction times.…”

A multiscale three-zone reactive mixing model for engineering a scale separation in enzymatic hydrolysis of cellulose

“…The former includes studies on shear (Reese and Ryu, 1980) and temperature (Andreaus et al, 1999) induced enzyme inactivation, shear induced substrate breakage and reaction surface enhancement (Palmqvist et al, 2011), production of thermally stable enzymes exhibiting higher substrate specificity and reduced product inhibition (Zhang et al, 2006;Sainz, 2009), optimization of enzyme composition (Berlin et al, 2006), rates of enzyme adsorption on cellulose surface (Zhang and Lynd, 2004) and enzyme deactivation (Howell and Mangat, 1978), and the effects of substrate and enzyme loading (Cara et al, 2007;Zhu et al, 2008), product inhibition (Ferchak and Pye, 1983), particle size (Yeh et al, 2010) and reagent addition (Ouyang et al, 2010) on the kinetics of hydrolysis. The reactor engineering route consists in using reactors with different shaking and/or mixing patterns (Ingesson et al, 2001;Roche et al, 2009;Kinnarinen et al, 2012;Lavenson et al, 2014), semi-batch reactors (Gupta et al, 2012), recycling enzymes (Xue et al, 2012), loading enzymes under static and agitated conditions http://dx.doi.org/10.1016/j.biortech.2014.09.088 0960-8524/Ó 2014 Elsevier Ltd. All rights reserved. (Taneda et al, 2012) and process integration (Lennartsson et al, 2012).…”

Solid-state production of cellulase by Melanoporia sp. CCT 7736: a new strain isolated from coconut shell (Cocos nucifera L.)

“…Cellulose is the most abundant polymer in nature and represents 50 % of the natural biomass (Wang et al 2012). This biopolymer is composed of glucose units linked by β-(1-4) glucosidic bonds (Kinnarinen et al 2012). Lignocellulose and lignin are usually found in cellulosic materials in different degrees depending on the biomass source (Wickramasinghe and Grzenia 2008).…”