Mississippi Technology Alliance

Think Big. Think Often.

University Research

The following University-based AR&D projects have been awarded by the Strategic Biomass Initiative.

Depolymerization of Lignocellulose by Fungal Cells and Immobilized Enzymes

Development of a Bioadsorbent for the Biodiesel Industry

High-Value Lignin Co-Products through Pretreatment and Microbial Conditioning

Energy-Enhanced Biomass from Crops and Crop Residues

Sawdust Conversion to Sugars Suitable for Fermentation to Fuel Grade Ethanol

Depolymerization of Lignocellulose by Fungal Cells and Immobilized Enzymes
P.I.: Huey-Min Hwang, CO-P.I.: Maria Begonia, Ken S. Lee

Jackson State University

In this project, the PI’s at Jackson State University will use whole fungal cells and mixed immobilized oxidation and hydrolysis enzymes (eg. laccases, lignin peroxidase and manganese peroxidase) for depolymerizing lignocellulose to sugars for microbial ethanol fermentation. The scope of the study is depicted in Flow chart 1. The advantages of these microbially-based technologies or systems include avoidance of using concentrated sulfuric acid, no need for adaptation period, short treatment period and recovery of the enzymes. In this study the ethanol yield and cost effectiveness of the immobilized enzymes technology will be compared to the production protocols by using whole lignocellulose degraders (e.g., white rot fungi) and the established protocols using acid hydrolyzates. The first two processes are hypothesized to be more economical and possess strong potentials for commercialization of the know-how protocols and/or the immobilized enzymes product.

The study objectives are:

1. To develop protocols of using immobilized enzymes technology to maximize ethanol yield of microbial fermentation of lignocellulosic biomass

2. To utilize live cultures of fungal whole cells and filtered fungal culture solution or extract to decompose plant lignocelluloses

3. To compare the cost-effectiveness of the immobilized enzymatic hydrolysis technique to depolymerization by whole fungal cells and the developed JSU protocol of acid hydrolysis 

4. To share know-how knowledge of the immobilized enzymes technology and whole cells system with MTA members for biomass/biofuel research.

 Flow chart 1: Three processes to produce ethanol from lignocellulosic biomass.

All the studies will be conducted in a laboratory on the campus of the Jackson State University in accordance with chemical utilization and disposal protocols set forth by the university. The studies will be conducted at a bench scale and the volumes of different chemicals used will be in the milliliter (ml) or milligram (mg) range. For example the adsorption method will involve ten (10) ml of phosphate buffer (pH 7.0) containing 50 mg of enzyme protein that will be directly added to the feedstock pellet  Fungal and bacterial strains (degraders and fermenters) will be purchased from the American Type Culture Collection (ATCC) or if needed, will be isolated from soil or other sources. Additionally fermenting microbes (obtained from ATCC) currently used by the JSU group will be used to ferment glucose or other sugars resulting from feedstock such as wood or corn stalk residue’s degradation into ethanol. None of the fungal or bacterial strains purchased or used will be genetically modified, but these experiments will rely on naturally occurring and commercially available strains. The maximum amount of sulfuric acid required for the acid hydrolysis process is 10 liters and it will be purchase from commercial outfits such as Fisher Scientific and will be used under fume hoods in the laboratory. Back to top.

MississippiState University

Kenaf is proposed as a bioadsorbent for the removal of glycerin contained in the wastewater from biodiesel treatment facilities. Biodiesel is a renewable fuel comprised of a mixture of fatty acid alkyl esters. It is produced from vegetable oils and animal fats. The biodiesel industry has grown significantly in Mississippi over the last 5 years. Presently, there are two established biodiesel facilities in the state with several others in various stages of planning. Mississippi’s biodiesel facilities could generate 30 million gallons of water annually. This water contains glycerin, sodium hydroxide, and soaps. Most Mississippi counties do not have the capability or the facilities to receive this water. Cost effective and efficient alternatives are needed immediately to treat and/or recycle this water and maintain and/or enhance the cost effectiveness of a biodiesel process, not only in Mississippi, but around the country which is experiencing an exponential increase in biodiesel production.

The proposed process involves adsorption of contaminants (adsorbates) onto kenaf fibers, which will serve as the adsorbent. This portion of the process (adsorption step) will be operated much like activated carbon is used as an adsorbent. The process involves packing the kenaf fibers into a column(s) where contaminated water will be passed through the column using up-flow hydraulics to provide intimate contact between the contaminated water and the kenaf. The contaminants are adsorbed onto the sorption sites of the kenaf and the column is operated until all of the kenaf within the column is completely spent or saturated (i.e. all sorption sites are filled). This approach is very similar to that used with activated carbon adsorbers; however, once the kenaf become spent, then the fibers are removed and placed into an anaerobic digester, which is used to reduce the volume of the kenaf mass (the adsorbent) while degrading the glycerin (adsorbate) and producing methane. The anaerobic digester unit could be operated on-site to produce methane (a biofuel) for steam generation, hot water, and electricity. The proposed biosorptive process is believed to be much cheaper than activated carbon and has the potential of reducing operation costs of biodiesel facilities.

The main objective of this project is the development of key performance information on the use of kenaf (bioadsorbent) for its ability to treat and/or recycle water generated during biodiesel production. Other secondary objectives include: (1) Study the effect of numerous washing techniques on kenaf adsorption capacity, (2) Evaluate the benefits of surface oxidation on kenaf adsorption capacity, (3) Evaluate the impacts of product storage on the adsorptive capacity of the kenaf product toward glycerol, (4) Comparison of kenaf adsorption capacity toward glycerol with other inorganic adsorbents, (5) Optimize the digestion of spent kenaf for producing methane, and (6) Pilot demonstration of the proposed technology. A common method to be used in almost all of the experimental tasks is the generation of adsorption isotherm data. The kenaf surface modification resulting in the highest adsorption capacity will be evaluated in a pilot demonstration at a biodiesel production facility. Back to top.

High-Value Lignin Co-Products through Pretreatment and Microbial Conditionin

PI – Clint Williford, Co-PI – Charles Burandt, The University of Mississippi

University of Mississippi

Lignin, the second most abundant biopolymer, comprises 15-25% of most biomass – 15+% for corn stover. It provides structural integrity and protects cellulose from decomposition. While beneficial to plants, this chemical recalcitrance impedes conversion of lignocellulose to ethanol and other chemicals. Commercial use of lignin has been limited by its complex structure, dependence of the structure on plant and growth-specific properties, and the extraction process (Thielmans and Wool, 2002). Capital-intensive pretreatments remove the lignin, but yield a low value product consigned to combustion. DOE has identified these problems as key technical and economic obstacles to commercialization.

The proposed research focuses on lignin, coupling advanced pretreatments with microbial conditioning to simplify pretreatment, reduce inhibitions to enhance ethanol production, and produce higher value lignin co-products. Our project will use corn stover and Mississippi-grown switchgrass. UM and USM scientists and engineers will work closely together to produce the lignin co-products and characterize suitability for use in adhesives and polymeric binders by Mississippi industry.

Project goals are to:

• Reduce pretreatment capital and operating costs for lignocellulose conversion
• Bring switchgrass and corn stover conversion to economic viability
• Produce a higher-value lignin co-product
• Enhance ethanol production rate and yield
• Improve environmental operations – reduce gypsum production

The key components of the project are:

• Field conditioning of switchgrass, prior to physical/chemical pretreatment
• Obtain and derive lignin and lignocellulose from corn stover and switchgrass using advanced pretreatments: acid hydrolysis; ammonia fiber explosion; expander, centrifugation
• Determine conditioning effects by two depolymerizing bacteria
• Determine suitability of and effect on lignin properties critical to adhesives and coatings
• Assess improvements to ethanol production using simultaneous saccharification-fermentation
• Screen additional microbial agents for depolymerization and disengagement of lignin

Industrial partners, MBI and Lee Environmental will provide pretreated biomass that will be purified in our University of Mississippi facilities. Collaborators at The University of Southern Mississippi will assess lignin co-product properties for adhesives and resins use by Mississippi industry. Ethanol production effects and microbial screening will be performed at UM.

Project success will provide three major benefits: first, utilization of a biomass feedstream, switchgrass, readily grown in Mississippi, developing a new segment of the agricultural economy; second, reduced capital costs and simplified operations (meaning closer to the farm operation); and third enhanced production of not one, but two product stream – ethanol for gasoline displacement in Mississippi, and a less polymerized lignin co-product for use in adhesives and resins, again by Mississippi industry. Back to top

Sawdust Conversion to Sugars Suitable for Fermentation to Fuel Grade Ethanol

University of Southern Mississippi

Investigators will finalize development of a continuous concentrated acid hydrolysis process. The aim is to economically convert pine sawdust or chips to fermentable sugars for ethanol production.

In 1982, the biomass program of the Tennessee Valley Authority (TVA) renewed research previously carried out at the USDA Peoria Laboratory² on converting agricultural waste to useful products by using an acid hydrolysis process. Between 1993 and 1998, USM and TVA researchers continued to improve the concentrated acid process. The shearing action of the twin screw extruder reactor=s co-rotating screws increased acid exposure to the biomass structure by continually removing acid treated biomass surface and thereby exposing a new surface to the acid. With an Australian consortium, USM perfected continuous ion exclusion techniques so that sulfuric acid could be separated and reused. With these process improvements, ethanol yield reached 65 gallons of ethanol per ton of dry pine sawdust.

The overall objective of this proposed one year study is to finalize development of a continuous concentrated acid hydrolysis process that will economically convert pine sawdust or chips to fermentable sugars for the production of fuel grade ethanol. To accomplish this, chemistry and engineering studies will be focused on enhancing conversion yields using the new equipment fabricated for this project, reducing operating costs, maximizing operating reliability and minimizing capital investment. Concurrently with these process studies, a plant design will be updated so that the economic feasibility of a commercial plant located within Mississippi can be evaluated. This analysis will evaluate the cost/benefit potential of the new process improvements and the recent increase in the USA ethanol market price from $1.20 to $2.00 per gallon.

The abilities to perform both impregnation and hydrolysis in a single extruder will simplify process operation, reduce material handling, improve mixing, lower equipment cost, and increase cellulose to glucose yields from 40% to above 50% of theoretical values. These improvements would enable a plant to make approximately 65 gallons of ethanol for each ton of dry pine sawdust. Figure 1, shown below, provides a schematic of the proposed process using the new twin screw extruder.

If only 10% of the 4 million tons of wood waste that are produced annually in Mississippi could be chemically transformed into ethanol, then 26 million gallons of product would be produced. Recently¹ ethanol prices have steadily increased from $0.80 per gallon in August 2003 to $1.80 per gallon in August 2005. On Jan. 6, 2006,, the Chicago Board of Trade ethanol futures were trading between $2.12 and $2.42 per gallon. See www.cbot.com/ethanol.  At $2.00 per gallon ethanol, this production would amount to annual sales of 52 million dollars. Therefore research and development efforts to improve waste wood conversion to ethanol are relevant and have a great potential to improve Mississippi's economic future.

New Twin Screw Process

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