On-farm integrated high-solids processing system for biomass
Inventors
Nokes, Sue E. • Lynn, Bert C. • Rankin, Stephen • Knutson, Barbara • Montross, Michael D. • Flythe, Michael
Assignees
University of Kentucky Research Foundation • US Department of Agriculture USDA
Publication Number
US-9376697-B2
Publication Date
2016-06-28
Expiration Date
2033-10-25
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Abstract
A method for on-farm processing a biomass feedstock into a useful industrial chemicals includes the steps of (a) delignifying the biomass feedstock to produce a delignified biomass, (b) subjecting the delignified biomass to cellulase production, (c) subjecting the delignified biomass with attached cellulase to simultaneous cellulolytic and solventogenic reactions to produce useful industrial chemicals (d) collecting and separating the useful industrial chemical from the fermentation broth and (e) collecting the fermentation residues.
Core Innovation
The invention relates to a consolidated high-solids on-farm biomass processing system that converts biomass feedstock into useful industrial chemicals through a series of integrated biological and chemical steps conducted within existing agricultural storage structures. The method involves delignifying the biomass feedstock to produce delignified biomass, producing cellulase enzymes by subjecting the delignified biomass to specific anaerobic microorganisms, and then performing simultaneous cellulolytic hydrolysis and solventogenic fermentation reactions within the same sealed reaction vessel. The industrial chemicals are collected and separated from the fermentation broth, and the residues are returned to the farm for various uses.
The problem addressed is the need for an efficient, integrated, on-farm processing method that eliminates the need for biomass size reduction, sterilization, and liquid fermentation systems, which are energy-intensive and complicate existing methods. The invention solves this by using a solid-substrate fermentation system in which biomass is processed in place at specific packing densities in sealed agricultural bulk storage vessels, using biological or biomimetic delignification methods and anaerobic microorganism inoculation steps at controlled mesophilic and thermophilic temperature conditions. This approach integrates with existing on-farm systems, reduces processing energy and complexity, and provides a consolidated production method for petrochemical replacements, thereby enhancing farm profitability and rural employment.
Claims Coverage
The patent contains one independent method claim encompassing several inventive features describing a consolidated on-farm biomass processing method, followed by dependent claims that specify particular embodiments, microorganisms, conditions, and processing techniques. The following are the main inventive features identified from the independent claim and key dependent claims.
Integration of solid-substrate biomass processing in a sealed vessel
The method involves placing a non-sterilized biomass feedstock at a specific density or as bales on a false floor within a single sealed reaction vessel equipped with an overhead delivery system for chemical and microbial additions and percolation of media.
In situ delignification using transition metal and peroxide
Delignification of biomass is performed in situ within the sealed vessel by adding a transition metal (e.g., iron) and peroxide to produce delignified biomass suitable for enzymatic processing.
Thermophilic anaerobic cellulase production via inoculation
The delignified biomass is subjected to a solid-substrate reaction for cellulase production by inoculating with a thermophilic anaerobic microorganism (selected from genera such as Clostridium, Thermobifida, Fibrobacter, Ruminococcus, Butyrivibrio) and maintaining the sealed vessel at 50-65° C. to promote cellulase synthesis and fermentative residue production.
Simultaneous cellulolytic and solventogenic fermentation at mesophilic conditions
Following cellulase production, the biomass with attached cellulase undergoes a simultaneous cellulolytic and solventogenic solid-substrate reaction by inoculating with anaerobic microorganisms (selected from Clostridium, Saccharomyces, and their combinations) and maintaining anaerobic conditions at 25-40° C. to produce industrial chemicals and fermentation residues.
Percolation and media recycling for product removal and process maintenance
Media is percolated through the biomass during cellulase production and solventogenic phases via the overhead delivery system to remove fermentation residues and industrial chemicals, which are collected from beneath the false floor and separated from the media. The media is then recycled back for reuse in the process.
The claims cover a method for consolidated on-farm biomass processing that integrates chemical delignification, thermophilic cellulase production, and mesophilic simultaneous cellulolytic and solventogenic fermentation within a single sealed reactor vessel. The method uniquely employs solid-substrate fermentation, specific microbial inoculations, controlled temperature phases, media percolation for product removal, and recycling to optimize production of industrial chemicals from untreated biomass feedstock at the farm site.
Stated Advantages
The process integrates well into existing agricultural storage technologies, allowing on-farm processing with minimal disruption to current farming practices.
It eliminates the need for biomass particle size reduction and sterilization, thereby reducing energy inputs and simplifying reactor loading.
The method produces useful petrochemical replacements, enhancing farm profitability and supporting rural job creation.
By performing cellulase production and solventogenic reactions in separate temperature-controlled phases within the same vessel, the method optimizes microbial activity and increases processing efficiency.
The recycling of media and removal of fermentation products via percolation helps maintain favorable microbial growth conditions and process stability.
Documented Applications
On-farm processing of biomass feedstock such as agricultural residues (corn stover, wheat straw) or energy crops (switchgrass, miscanthus) into industrial chemicals including acetone, acetic acid, lactic acid, ethanol, and n-butanol.
Use of existing on-farm storage structures like bunkers, vertical/horizontal silos, or ag-bags as reaction vessels for biomass delignification and fermentation.
Application of the fermentation residues returned to the farm for uses such as animal feed, gasification, combustion, or land application as fertilizer.
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