Achieving maximum sugar yield

Many Factors Impact Final Yield

Saccharification, the process to depolymerize cellulose and hemicellulose into fermentable sugars, is a considerable cost component in the biochemical conversion of biomass and feedstock to bioproducts.

In developing a high-yielding saccharification process, we take into consideration a combination of several factors:

  • Biomass composition
  • Type of pretreatment
  • Dosage and efficiency of the hydrolytic catalyst or enzymes
Microbe Produces Ethanol from Switchgrass Without Pretreatment. Read article on »

Integrating Upstream and Downstream Processes

Chemical pretreatment and saccharification are closely linked processes. While a particular pretreatment process might be effective against biomass recalcitrance, it may inhibit saccharification.

At ABPDU we place significant emphasis on the integration between pretreatment and saccharification to establish the optimum process parameters and selection of methodologies.

Our Equipment

Saccharification Process Options

Cocktail Optimization of Enzymes
As the severity factor of the pretreatment process decreases, the sugar yield after enzymatic hydrolysis also decreases. Hence the requirement for different types of enzymes and their higher dosages to achieve maximum sugar yield from cellulose and hemicellulose fractions of the pretreated biomass. We offer a cocktail of enzymes such as cellulases, hemicellulases, and other accessory enzymes for complete hydrolysis.
High Solids Enzymatic Hydrolysis
Maintaining high solids concentrations throughout the biomass conversion process is important for final product yield with reduced intensity of the separation process. High substrate concentration allows for the production of a concentrated sugar solution, which, in turn, is beneficial in separation processes after fermentation. The extent to which solids loading can be increased in hydrolysis varies with the type of feedstock, pretreatment process, and enzyme/catalyst. At the ABPDU, we are able to generate cellulosic sugars up to 150 g/L concentration.
Solid/Liquid Separation
After saccharification, lignin-rich solid is separated from the sugar-rich aqueous phase using a decanter or basket centrifuge depending on the scale of the process.
Simultaneous Saccharification and Fermentation (SSF)
During saccharification, the enzyme or catalyst can be constrained by the presence of some inhibitors generated during pretreatment. The fermentation process can be combined with saccharification in an SSF process, where enzymes are applied simultaneously with the micro-organism. In such cases, the enzymatic action is maximized due to the presence of low amounts of the inhibitory product, as the sugar is being metabolized upon release. SSF is thought to be an ideal process for biochemical conversion of biomass to bioproducts.
Mass/Energy Balance
A mass balance, also called a material balance, is a meticulous accounting of material entering and leaving a system. Mass balance is essential to establish a process as it is required to calculated the actual conversion of feedstock, monitor process flow, identify bottle-necks in processes, and model large scale process in desired reactors. Similarly, an energy balance can be established across a process by assuming that net energy loss from a reactor is zero.

Related Papers, Articles, and Presentations

Predictive modeling to de-risk bio-based manufacturing by adapting to variability in lignocellulosic biomass supply


Commercial-scale bio-refineries are designed to process 2000 tons/day of single lignocellulosic biomass. Several geographical areas in the United States generate diverse feedstocks that, when combined, can be substantial for bio-based manufacturing. Blending multiple feedstocks is a strategy being investigated to expand bio-based manufacturing outside Corn Belt. In this study, the ABPDU in collaboration with Idaho and Sandia National Laboratories developed a model to predict continuous envelopes of biomass blends that are optimal for a given pretreatment condition to achieve a predetermined sugar yield or vice versa. For example, the model predicted more than 60% glucose yield can be achieved by treating an equal part blend of energy cane, corn stover, and switchgrass with alkali pretreatment at 120 °C for 14.8 h. By using ionic liquid to pretreat an equal part blend of the biomass feedstocks at 160 °C for 2.2 h, we achieved 87.6% glucose yield. Such a predictive model can potentially overcome dependence on a single feedstock.

Download to read more:

Reducing Nutrient Supply in Mixed Feedstock Fermentation

Mixed feedstocks can help reduce the risk associated with feedstock availability for bio-based production of fuels and chemicals. This study was performed to evaluate cellulosic hydrolysates for fermentation to biofuels and also probe the possibility of reducing nutrient concentration in the broth media.

The study demonstrated that mixed feedstocks can release 80 -100% of the sugar that is obtained from corn stover alone. A hundred percent of the released sugars from mixed feedstocks can be converted to ethanol. The study also showed that alkali pretreated mixed feedstock has higher ethanol yield but lower glucose yield compared to IL pretreated mixed feedstock due to inhibition of microbial growth by residual EmimAcetate. The same ethanol yield can be achieved with lower nutrient supplied but with longer fermentation time.

Scale-Up and Process Integration of Municipal Solid Waste Conversion Process

This paper presents two case studies on the scale-up and process integration of municipal solid waste conversion technology. In a partnership with Idaho National Labs, we successfully demonstrated 200-fold scale up of MSW blends IL acidolysis. We also developed an integrated process for ionic liquid based deconstruction technologies for MSW blends conversion. The scale up attempt will leverage the opportunity towards a cost-effective MSW blends conversion technology.

Under a DOE Work-For-Others agreement with FATER, ABPDU has been developing and validating an integrated waste-to-energy process. Key outcomes indicate that post-consumer absorbent hygiene products (AHPs) can be readily and economically converted — without using harsh or expensive pretreatment routes — to sugars and fuel intermediates.

Evaluation of Storage Effect on the Biomass Conversion to Sugars

Dry matter loss (DML) occurs in high-moisture storage conditions; it remains unclear how storage conditions and degradation impact sugar release and fermentation inhibitor production during conversion. In collaboration with Idaho National Labs, two feedstocks, switchgrass and corn stover, were compared using compositional analysis, alkaline pretreatment, and enzymatic saccharification. Under the tested conditions, switchgrass with 10% and 20% DML and corn stover with 30% DML achieved higher sugar yields compared to samples before storage.

Predictive Modeling and Rheological Estimation of Mixed Biomass Feedstocks

In a collaborative effort with INL, SNL, and JBEI, predictive modeling was used to evaluate and optimize traditional pretreatment methods for biomass mixture compositions to maximize sugar yield and minimize furfural production. The collaboration encompassed compositional analysis of feedstocks, solids loading during pretreatment for mixed feedstock, enzymatic hydrolysis on unwashed solids, and sugar and furfural analysis. Predictive modeling could effectively identify the pretreatment catalyst and treatment conditions for an “optimal” biomass mixture and the optimal biomass mixture for a particular pretreatment system.


Process Scale-up of Municipal Solid Waste and Corn Stover Blends Conversion into Sugars

A collaboration between ABPDU, INL, and SNL as to whether blends of municipal solid waste (MSW) and corn stover (CS) could meet cost and quality targets yielded valuable results. The team successfully developed an integrated process for ionic liquid (IL) based deconstruction technologies. They also demonstrated a 200-fold scale up MSW/CS blends IL acidolysis. The scale up attempt and process integration will leverage the opportunity towards a cost-effective sugar/lignin production technology.

Determining the Impact of MSW as a Feedstock Blending Agent on Pretreatment Efficacy

Sixteen MSW blends provided by INL were screened using the 10mL tube reactor to identify the most promising blend (CS/MSW 4:1) for scaling up test based on the sugar yields as well as the feedstock cost. The collaboration also successfully demonstrated 600-fold (10mL to 6L) scale up of MSW/CS blends IL acidolysis.

FATER ABPDU Waste-to-Bioenergy Process Partnership

ABPDU has been developing and validating an integrated waste-to-energy process under a DOE work-for-others (WFO) agreement with FATER, an Italian JV between Procter & Gamble and the Angelini Industrial Group.

Key outcomes indicate that post-consumer absorbent hygiene products (AHP) can be readily and economically converted — without using harsh or expensive pretreatment routes — to fermentable sugar intermediates as well as biofuel and bio-based chemical products.

Blending Municipal Solid Waste with Corn Stover for Sugar Production Using Ionic Liquid Process

Blending Municipal Solid Waste with Corn Stover for Sugar Production Using Ionic Liquid Process

Municipal solid waste (MSW) represents an attractive cellulosic resource for sustainable fuel production. However, its heterogeneity is the major barrier to efficient conversion to biofuels. MSW paper mix was generated and blended with corn stover (CS). It has been shown that both of them can be efficiently pretreated in some ionic liquid (ILs) processes with high yields of fermentable sugars. After pretreatment in 1-ethyl-3-methylimidazolium acetate ([C2C1Im][OAc]), over 80% glucose has been released with enzymatic saccharification. We have also applied an enzyme-free process by adding mineral acid and water directly into the IL/biomass slurry to induce hydrolysis. With the acidolysis process in 1-ethyl-3-methylimidazolium chloride ([C2C1Im]Cl), up to 80% glucose and 90% xylose are released. There is a correlation between the viscosity profile and hydrolysis efficiency; low viscosity of the hydrolysate generally corresponds to high sugar yields. Overall, the results indicate the feasibility of incorporating MSW as a robust blending agent for biorefineries.


Predictive Modeling Can De-Risk Bio-based Production

Predictive Modeling Can De-Risk Bio-based Production

Technologies developed for bio-based production are based on single feedstock types. While this approach is applicable for corn stover in the MidWest, for states such as California, with abundant but diverse feedstocks, technologies should be developed to accommodate multiple feedstock input to a single biorefinery. This project established the influence of mixing feedstocks on downstream sugar recovery and thereby fuel production for Imperial County as a case study. To de-risk bio-based production, we relied on statistical approaches and developed a predictive model to identify optimal biomass concentrations and reaction types, temperatures, and times to maximize sugar yield and minimize furfural production.