Fed-batch Hydrolysis Research Articles

An enhanced in situ fed-batch hydrolysis and kinetic study for producing biomass-based levulinic acid at high solid loadings

Levulinic acid (LA), regarded as one of the top twelve biomass-based platform chemicals, has been extensively studied by numerous researchers. In this study, a high LA concentration and yield were obtained through an enhanced in situ feeding strategy with a high loading of furfural residue (FR). The effects of batch process, one-time feeding and two-time feeding strategy on the hydrolysis performance (LA yield and concentrations, as well as intermediate glucose yield and concentrations) were investigated. The humin-based byproducts generated during different processes were also characterized by SEM, FT-IR and XRD analysis. The best results of one-time feeding strategy were obtained at 3 wt% H2SO4, 170 °C for 60 min with an initial FR concentration of 15% supplemented to 20% at 0th min. Under these conditions, the LA concentration and yield reached 30.00 g/L and 15% (51.1 mol%), respectively. Furthermore, a hybrid model integrated with the shrinking core model and a quasi-first-order kinetic model was adopted to elucidate the kinetic behavior of LA production from highly concentrated substrates through batch and feeding processes. The results indicated that a one-time feeding strategy can lower the activation energy required for FR degradation to glucose to 96.6 kJ/mol (R2 > 0.97). Similarly, the activation energy for the conversion of glucose to 5-hydroxymethylfurfural (5-HMF) and the subsequent formation of LA from 5-HMF were reduced to 80.9 kJ/mol (R2 > 0.97) and 23.3 kJ/mol (R2 > 0.97), respectively. Notably, the reaction rate of glucose to form humins was slightly reduced. This research helps to optimize the LA yield and concentration directly via an enhanced in situ feeding approach, providing valuable process operation and kinetic information for the industrial LA production from FR.

Fed-batch enzymatic hydrolysis of steam-exploded sugarcane bagasse

Statistical design and mathematical modeling were used to investigate the fed-batch enzymatic hydrolysis of steam-exploded sugarcane bagasse (195 °C, 7.5 min). First, a Box-Behnken experimental design was used to evaluate the effect of enzyme loading (8, 24, and 40 FPU g-1 glucans of Cellic CTec3®), stirring speed (100, 150, and 200 rpm), and substrate total solids (5, 12.5, and 20 wt%) on the release of glucose equivalents (GlcEq, mostly glucose) after hydrolysis for 48 h in batch mode. A simplified kinetic model was used to fit the experimental data, in which specific activities in Cellic CTec3 were not differentiated, enzyme adsorption was ignored, and end-product inhibition was only attributed to glucose accumulation. The adjusted kinetic model was used to predict the effects of substrate and enzyme intermittent feedings in fed-batch hydrolysis experiments. Compared with batch experiments at 20 wt%, the proposed fed-batch procedure was able to increase GlcEq productivity by nearly 68% using the same enzyme loading, producing substrate hydrolysates containing 91.8 g L-1 GlcEq.

Nutritional improvement of copra meal for swine feed

Copra meal as a feed ingredient in swine is limited due to the high content of non-starch polysaccharides (NSPs), and enhancing it in a batch setting limits enzyme activity because of high water-substrate absorption. Thus, optimum hydrolysis conditions for improving copra meal using mannanase from Bacillus circulans NT 6.7 in fed-batch setting were investigated using response surface methodology. The experimental results and expected responses were in good agreement after model validation. The effects of simulated swine gastrointestinal (GI) digestion of hydrolyzed copra meal (HCM) from fed-batch and conventional copra meal (CM) were also studied. Batch hydrolysis yielded an experimental value of reducing sugar of 13.05 ± 0.12 mg/mL and a total oligosaccharide 18.44 mg/mL. A higher reducing sugar of 25.74 ± 0.13 mg/mL and a total oligosaccharide of 30.95 mg/mL were obtained using fed-batch hydrolysis under optimal conditions (substrate concentration of 25 g, start time of 1 h, and number of times of 3 once), enzyme concentration of 18 U/mL, and hydrolysis at 50 °C for 6 h. Proximate analyses revealed that 50% of neutral detergent fiber (NDF) and acid detergent fiber (ADF), 37.29% cellulose, 47.5% hemicellulose and almost all lignin were reduced by mannanase. As evidenced by SEM images of copra meal and hydrolyzed copra meal (HCM), significant degradation of copra meal microfibrils occurred. The simulated digestion revealed that HCM was digested more easily than CM, resulting in lower dry weight and more oligosaccharide released. This work outlined the optimum conditions to improve the functionality of copra meal in a fed-batch setting.

Improved saccharification of pretreated lignocellulose by Clostridium thermocellum with the addition of surfactant, low loading of cellulose

Saccharification of lignocellulose is prerequisite for the biorefinery. Clostridium thermocellum is a promising candidate for the hydrolysis of lignocellulose. A study on the saccharification by Clostridium thermocellum combined with surfactant and cellulase addition was investigated. The reducing sugars content increased with increasing substrate loading in the fermentation of C. thermocllum with isooctyl alcohol polyoxyethylene ether (IAPE) addition. Based on IAPE addition, the glucose content of two-step saccharification was higher than that of the batch saccharification. Besides, the addition of IAPE and Triton X-100 had the same effect on saccharification. The saccharification performance was related to the substrate, especially the lignin content. For the fed-batch hydrolysis of 20 % (w/v) rice straw pretreated by hydrogen peroxide-acetic acid (HPAC), 66.9 g/L glucose and 19.5 g/L xylose were obtained by using C. thermocellum DSM 1313 and 1 FPU/g substrate cellulase with 0.1 % (w/v) IAPE addition, and the glucose and xylose yield reached 63.2 % and 37.4 % respectively.

Production of high-concentration fermentable sugars from lignocellulosic biomass by using high solids fed-batch enzymatic hydrolysis

The synergy of multiple lignocellulolytic enzymes for lignocellulosic biomass saccharification at high substrate loading to obtain high-concentration fermentable sugar is of great economic interest for industrial biorefineries. In this study, the mixture of cellulase, β-glucosidase, hemicellulose, and pectinase was optimized for hydrolysis of different cellulosic feedstocks at different substrate concentrations. It was found that the enzyme combination of 43.8% cellulase, 41.8% hemicellulase, 14.4% pectinase was more suitable for high-concentration alkaline hydrogen peroxide pretreated corncob hydrolysis. The optimized enzyme mixture was then applied to fed-batch enzymatic hydrolysis. The cumulative solid loading was 40% (w / w). After 48 h of hydrolysis, the glucose and xylose concentration reached 110.47 g/L and 61.88 g/L, respectively. The fermentable sugar productivity was up to 3.6 g/L/h. In addition, the enzyme components for high-concentration substrate hydrolysis were optimized. The substrate concentration was increased by fed-batch hydrolysis, and the high-concentration fermentable sugar was obtained in a shorter time.

A integrated process for nitrilase-catalyzed asymmetric hydrolysis and easy biocatalyst recycling by introducing biocompatible biphasic system

The whole-cell nitrilase-catalyzed asymmetric hydrolysis of nitriles is a green and efficient preparation approach for chiral carboxylic acids, but often suffers from toxicity and cell lysis from organic substrates. In this work, a novel integrated process for whole-cell nitrilase-catalyzed asymmetric hydrolysis was developed for the first time by introducing a biocompatible ionic liquid (IL)-based biphasic system. The whole-cell nitrilases displayed an outstanding stability and recyclability in the biphasic system and still retained > 85% activity even after 7 cycles reaction. A preparative-scale fed-batch hydrolysis of o-chloromandelonitrile to (R)-o-chloromandelic acid (R-CMA) was performed using the integrated process. The results revealed a yield of 91.3% and a space–time yield of 746.4 g·L−1·d−1, which are currently the highest reported values for R-CMA biosynthesis. The proposed integrated process avoids substrate inhibition, facilitates the reusability of whole-cell nitrilases, and thus shows great potential for the sustainable production of chiral carboxylic acids.

Enhanced sugars production with high conversion efficiency from alkali-pretreated sugarcane bagasse by enzymatic mixtures

Complementary enzymes can considerably enhance the hydrolysis effectiveness of cellulase. The influence of hemicellulase supplementation on high solids saccharification of alkali-pretreated sugarcane bagasse was assessed. Hemicellulase addition of 1200 IU/g substrate with cellulase loading of 10 FPU/g substrate achieved high sugars yield with glucose and xylose conversion efficiency of 95.4% and 87.4%, respectively. To further improve the substrate conversion efficiency based on high sugars production, fed-batch hydrolysis was employed with high solids loading of 20% (w/v) to 25% (w/v). After 96 h hydrolysis with 25% solids loading at cellulase and hemicellulase loading of 20 FPU/g and 1200 IU/g substrate, respectively, the obtained highest total sugars was 242 g/L, with glucose and xylose conversion efficiencies of 98.6% and 94.9%, respectively. An increase in substrate digestibility upon supplementation of mixture enzymes with high sugars production can be realized in high solids fed-batch system with proper cellulase and hemicellulase synergism.

Estimation of Biomass Enzymatic Hydrolysis State in Stirred Tank Reactor through Moving Horizon Algorithms with Fixed and Dynamic Fuzzy Weights

Second generation ethanol faces challenges before profitable implementation. Biomass hydrolysis is one of the bottlenecks, especially when this process occurs at high solids loading and with enzymatic catalysts. Under this setting, kinetic modeling and reaction monitoring are hindered due to the conditions of the medium, while increasing the mixing power. An algorithm that addresses these challenges might improve the reactor performance. In this work, a soft sensor that is based on agitation power measurements that uses an Artificial Neural Network (ANN) as an internal model is proposed in order to predict free carbohydrates concentrations. The developed soft sensor is used in a Moving Horizon Estimator (MHE) algorithm to improve the prediction of state variables during biomass hydrolysis. The algorithm is developed and used for batch and fed-batch hydrolysis experimental runs. An alteration of the classical MHE is proposed for improving prediction, using a novel fuzzy rule to alter the filter weights online. This alteration improved the prediction when compared to the original MHE in both training data sets (tracking error decreased 13%) and in test data sets, where the error reduction obtained is 44%.

Fed-batch enzymatic hydrolysis of alkaline organosolv-pretreated corn stover facilitating high concentrations and yields of fermentable sugars for microbial lipid production

BackgroundLignocellulosic biomass has been commonly regarded as a potential feedstock for the production of biofuels and biochemicals. High sugar yields and the complete bioconversion of all the lignocellulosic sugars into valuable products are attractive for the utilization of lignocelluloses. It is essential to pretreat and hydrolyze lignocelluloses at high solids loadings during industrial processes, which is more economical and environmentally friendly as capital cost, energy consumption, and water usage can be reduced. However, oligosaccharides are inevitably released during the high solids loading enzymatic hydrolysis and they are more recalcitrant than monosaccharides for microorganisms.ResultsA fed-batch enzymatic hydrolysis of corn stover pretreated by the sodium hydroxide–methanol solution (SMs) at high solids loading was demonstrated to reach the high concentrations and yields of fermentable sugars. Glucose, xylose, cello-oligosaccharides, and xylo-oligosaccharides achieved 146.7 g/L, 58.7 g/L, 15.6 g/L, and 24.7 g/L, respectively, when the fed-batch hydrolysis was started at 12% (w/v) solids loading, and 7% fresh substrate and a standardized blend of cellulase, β-glucosidase, and hemicellulase were fed consecutively at 3, 6, 24, and 48 h to achieve a final solids loading of 40% (w/v). The total conversion of glucan and xylan reached 89.5% and 88.5%, respectively, when the oligosaccharides were taken into account. Then, a fed-batch culture on the hydrolysates was investigated for lipid production by Cutaneotrichosporon oleaginosum. Biomass, lipid content, and lipid yield were 50.7 g/L, 61.7%, and 0.18 g/g, respectively. The overall consumptions of cello-oligosaccharides and xylo-oligosaccharides reached 74.1% and 68.2%, respectively.ConclusionsHigh sugars concentrations and yields were achieved when the enzyme blend was supplemented simultaneously with the substrate at each time point of feeding during the fed-batch enzymatic hydrolysis. Oligosaccharides were co-utilized with monosaccharides during the fed-batch culture of C. oleaginosum. These results provide a promising strategy to hydrolyze alkaline organosolv-pretreated corn stover into fermentable sugars with high concentrations and yields for microbial lipid production.

Techno-Economic Implications of Fed-Batch Enzymatic Hydrolysis

Fed-batch enzymatic hydrolysis has the potential to improve the overall process of converting cellulosic biomass into ethanol. This paper utilizes a process simulation approach to identify and quantify techno-economic differences between batch and fed-batch enzymatic hydrolysis in cellulosic ethanol production. The entire process of converting corn stover into ethanol was simulated using SuperPro Designer simulation software. The analysis was conducted for a plant capacity of 2000 metric tons of dry biomass per day. A literature review was used to identify baseline parameters for the process. The sensitivity of the ethanol production cost to changes in sugar conversion efficiency, plant capacity, biomass cost, power cost, labor cost, and enzyme cost was evaluated using the process simulation. For the base scenario, the ethanol unit production cost was approximately $0.10/gallon lower for fed-batch hydrolysis. The greatest differences were seen in facilities costs, labor costs, and capital costs. Using a fed-batch operation decreased facilities costs by 41%, labor costs by 21%, and capital costs by 15%. The sensitivity analysis found that cost of biomass had the greatest effect on ethanol production cost, and in general, the results support the proposition that fed-batch enzymatic hydrolysis does improve the techno-economics of cellulosic ethanol production.

Study of a New Process for the Preparation of Butyl Levulinate from Cellulose.

Butyl levulinate (BL) is a versatile chemical utilized widely in food and chemical industries, the production of which by using cellulose in biomass resources is of great significance to its sustainable development. Traditional synthesis processes for n-butyl levulinate are confronted with various problems such as high cost of raw materials, difficulty in separating products, etc. In this paper, a novel process for the preparation of BL from cellulose is proposed. The process is composed of five main unit operations including fed-batch hydrolysis, decolorization, extraction, esterification and purification. A 171.63 g/L concentration of the intermediate levulinic acid was obtained at the fifth feeding through the fed-batch hydrolysis process. The resin-activated carbon secondary decolorization method was adopted to remove the soluble humin byproducts with an accumulative decolorization rate of 89%. In the extraction process, the product BL was chosen as the extractant to avoid the introduction of new impurities. After purification, the purity of the final product BL reaches up to 98 wt %. The proposed technique allows for cost-effective and eco-friendly production of BL from biomass resources.

Improved high solid loading enzymatic hydrolysis of low-temperature aqueous ammonia soaked sugarcane bagasse using laccase-mediator system and high concentration ethanol production

High solids loading hydrolysis (HSLEH) of sugarcane bagasse (SCB) pretreated by low temperature aqueous ammonia soaking (AAS) was performed to obtain high concentrations of glucose and further fermentation to high concentration of ethanol. HSLEH was performed by fed batch addition of substrate and one-time enzyme feed at starting point. When the solids loading at 40% was tried in fed-batch hydrolysis, the observed concentrations of glucose and ethanol were 119 g/l and 58.4 g/l respectively. When laccase (200 U/g solids) with 1-HBT (25 mg/g solids) as a mediator was added to cellulase in HSLEH, the glucose and ethanol concentrations were further enhanced to 157 g/l and 72.4 g/l. The present glucan conversion of 74% in HSLEH was higher when compared with the reported values for biomass pretreated by high temperature steam explosion, acid and alkali pretreatments. The present ethanol concentration (72.4 g/l) was also higher than the reported levels of ethanol in the second-generation bioethanol production. As HSLEH of biomass by low temperature AAS has not been reported so far, the present results clearly demonstrates that LMS assisted HSLEH of biomass pretreated by low temperature AAS is promising for cellulosic ethanol production.

Enhanced High-Solids Fed-Batch Enzymatic Hydrolysis of Sugar Cane Bagasse with Accessory Enzymes and Additives at Low Cellulase Loading

High cellulase loading is still a major impediment in the production of fermentative sugars from high-solids enzymatic hydrolysis of lignocellulosic substrates in the enzyme-based “biorefinery” industry. This study attempted a high-solids (20%) enzymatic hydrolysis of lignocellulosic substrate at a very low cellulase loading with mixed use of additives and accessory enzymes by fed-batch mode. To avoid the high initial biomass viscosity, the high-solids enzymatic hydrolysis of lignocellulosic substrates was initiated with a solids content of 8%. Thereafter, 4% of the additional substrates were consecutively fed into the hydrolysis system after 6, 12, and 18 h to reach a final solids content of 20%. Some additive mixtures (40 mg/g substrateTween 80 + 10 mg/g substrate tea saponin +20 mg/g substrate BSA) were observed to enable this fed-batch hydrolysis to increase 30% of the glucose yield after the 48 h. The combination of these additives and accessory enzymes (2.4 mg/g substrate xylanase and 1 mg/g substra...

Evaluation of the solvent water effect on high solids saccharification of alkali-pretreated sugarcane bagasse

Solvent water is an essential factor for high solids enzymatic hydrolysis. To investigate its effect on substrate conversion efficiency in high solids hydrolysis of sugarcane bagasse (SCB), oleyl alcohol was used to partially substitute the solvent water. The results in batch hydrolysis tests in which diverse ratio of solvent water was replaced found that the majority of the substrate was insoluble. Then high solids fed-batch hydrolysis with the reaction solution mixed with solvent water and oleyl alcohol in the ratio of 3:1 (solids concentration correspond to 24% (w/v)) was carried out at the final real solids loading of 18% (w/v). The produced sugars were found to be less than pure water system, which indicated that water played a significant role in high solids hydrolysis process, and solids effect was related to the solvent water content.

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

In the enzymatic hydrolysis of cellulose, several phenomena have been proposed to cause a decrease in the reaction rate with increasing conversion. The importance of each phenomenon is difficult to distinguish from batch hydrolysis data. Thus, kinetic models for the enzymatic hydrolysis of cellulose often suffer from poor parameter identifiability. This work presents a model that is applicable to fed-batch hydrolysis by discretizing the substrate based on the feeding time. Different scenarios are tested to explain the observed decrease in reaction rate with increasing conversion, and comprehensive assessment of the parameter sensitivities is carried out. The proposed model performed well in the broad range of experimental conditions used in this study and when compared to literature data. Furthermore, the use of data from fed-batch experiments and discretization of the model substrate to populations was found to be very informative when assessing the importance of the rate-decreasing phenomena in the model.

Highly efficient conversion of sugarcane bagasse pretreated with liquid hot water into ethanol at high solid loading

ABSTRACTLiquid hot water (LHW), an environmental-friendly physico-chemical treatment, was applied to pretreat the sugarcane bagasse (SCB). Tween80, a non-ionic surfactant, was used to enhance the enzymatic hydrolysis of the pretreated SCB. It found that 0.125 mL Tween80 /g dry matter could make the maximum increase (33.2%) of the glycan conversion of the LHW-pretreated SCB. A self-designed laboratory facility with a plate-and-frame impeller was applied to conduct batch hydrolysis, fed-batch hydrolysis, and the process of high-temperature (50°C) fed-batch hydrolysis following low-temperature (30°C) simultaneous saccharification and fermentation (SSF) which was adopted to overcome the incompatible optimum temperature of saccharification and fermentation in the SSF process. After hydrolyzing LHW-pretreated SCB for 120 h with commercial cellulase, the total sugar concentration and glycan conversion obtained from fed-batch hydrolysis were 91.6 g/L and 68.3%, respectively, which were 9.7 g/L and 7.3% higher than those obtained from batch hydrolysis. With Saccharomyces cerevisiae Y2034 fermenting under the non-sterile condition, the ethanol production and theoretical yield obtained from the process of SSF after fed-batch hydrolysis were 55.4 g/L and 88.3% for 72h, respectively, which were 15.5 g/L and 24.7% higher than those from separate fed-batch hydrolysis and fermentation. The result of this work was superior to the reported results obtained from the LHW-pretreated SCB.

Production of Short Chain Arabinooligosaccharides by Hydrolysis of Arabinan Using a Commercial Mixed Glycanase Preparations

Oligosaccharides are bioactive carbohydrates that have properties beyond their content of calories; however, structure and degree of polymerisation were believed to play a major role in such bioactivity in particular the ones with degree of polymerisation 2-10. Oligosaccharides of specific degree of polymerisation were prepared by hydrolysis of arabinan using a commercial mixed glycanase preparation (VISCOZYME™ L) in a membrane reactor. A lab scale ultrafiltration unit was operated at a pressure of 1 bar, a stirrer speed of 250 rpm and a working volume of 200 ml. The temperature was controlled at 35°C and pH at 4.5. Enzymatic hydrolysis of arabinan produced oligosaccharides with a wide range of degree of polymerisation values but favoured degree of polymerization > 10. In batch reaction arabinan concentration 5% WV-1 was higher in terms of quantities of oligosaccharides than 2.5% though the production delayed (5 h vs. 3 h for 5% and 2.5% respectively). Oligosaccharides of degree of polymerisation 2-10 were produced after 2 hrs of reaction time when arabinan concentration was 5% WV-1 using fed-batch hydrolysis. Diafiltration using buffer as substitute for hydrolysate has failed to produce similar results in comparison to fed-batch. Small amount of AOS of dp 2-10 were produced only at 3 h. We showed that production of arabino-oligosaccharides with specific degree of polymerisation was achievable within short time (2 h). Overall results suggested that hydrolysis of arabinan in a controlled reactor to produce short chain AOS was mainly affected by; substrate concentration and time of reaction.

Optimization of high solids fed-batch saccharification of sugarcane bagasse based on system viscosity changes

Viscosity trends in alkali-pretreated sugarcane bagasse (SCB) slurries undergoing high solids fed-batch enzymatic hydrolysis were measured for a range of solids loading from 15% to 36%. Solids liquefaction times were related to system viscosity changes. The viscosity decreased quickly for low solids loading, and increased with increasing solids content. Fed-batch hydrolysis was initiated with 15% solids loading, and an additional 8%, 7% and 6% were successively added after the system viscosity decreased to stable values to achieve a final solids content of 36%. Two enzyme-adding modes with 8.5FPU/g solid were investigated. The batch mode with all enzyme being added at the beginning of the reaction produced the highest yields, with approximately 231.7g/L total sugars and 134.9g/L glucose being obtained after 96h with nearly 60% of the final glucan conversion rate. This finding indicates that under the right conditions, the fed-batch strategy might be a plausible way to produce high sugars under high solids.

Enhanced enzymatic hydrolysis of lignocellulose by integrated decrystallization and fed-batch operation

High solids enzymatic hydrolysis is a promising process to increase the concentrations of fermentable sugars for ethanol production. Here, we reported an integrated strategy incorporating decrystallization and fed-batch operation to enhance the enzymatic hydrolysis of lignocellulose at high solid loadings. The effect of concentration of phosphoric acid on the decrystallization and enzymatic hydrolysis of cellulose was investigated. The results showed that 86 wt% phosphoric acid could completely break the crystalline structure, achieving a high cellulose conversion and hydrolysis rate (89% within 4 h) in batch operation (5% solid loading). In the fed-batch operation, we designed two different enzyme feeding strategies, in which the enzymes were added either at start-up or along with the fresh substrate. The results indicated that fed-batch hydrolysis can be carried out at a final high solids loading of 30%, resulting in a glucose concentration as high as 143.5 g L−1 within 27 hours. Meanwhile, a stable and high cellulose conversion was achieved in fed-batch operation with the enzymes divided over the substrate feed, which should be dependent on the decrystallization of the substrate. Our findings provide a practical way to enhance enzymatic hydrolysis at high solid loadings and also propose a feasible enzyme feeding strategy in fed-batch operation.

Continuous enzymatic hydrolysis of lignocellulosic biomass with simultaneous detoxification and enzyme recovery.

Recovering hydrolysis enzymes and/or alternative enzyme addition strategies are two potential mechanisms for reducing the cost during the biochemical conversion of lignocellulosic materials into renewable biofuels and biochemicals. Here, we show that enzymatic hydrolysis of acid-pretreated pine wood with continuous and/or fed-batch enzyme addition improved sugar conversion efficiencies by over sixfold. In addition, specific activity of the hydrolysis enzymes (cellulases, hemicellulases, etc.) increased as a result of continuously washing the residual solids with removal of glucose (avoiding the end product inhibition) and other enzymatic inhibitory compounds (e.g., furfural, hydroxymethyl furfural, organic acids, and phenolics). As part of the continuous hydrolysis, anion exchange resin was tested for its dual application of simultaneous enzyme recovery and removal of potential enzymatic and fermentation inhibitors. Amberlite IRA-96 showed favorable adsorption profiles of inhibitors, especially furfural, hydroxymethyl furfural, and acetic acid with low affinity toward sugars. Affinity of hydrolysis enzymes to adsorb onto the resin allowed for up to 92% of the enzymatic activity to be recovered using a relatively low-molar NaCl wash solution. Integration of an ion exchange column with enzyme recovery into the proposed fed-batch hydrolysis process can improve the overall biorefinery efficiency and can greatly reduce the production costs of lignocellulosic biorenewable products.