Composite components from anaerobic digested fibrous materials
Inventors
Dvorak, Stephen W. • Hunt, John F.
Assignees
US Department of Agriculture USDA • DVO Inc
Publication Number
US-8414808-B2
Publication Date
2013-04-09
Expiration Date
2029-10-02
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Abstract
The invention relates to composite components and methods of producing composite components. In yet another embodiment, the present invention relates to a method of producing a composite component using anaerobically digested biomass. In still yet another embodiment, the method further comprises using liquid effluent from the digester. In still yet another embodiment, the method further comprises wet-mat forming and cold pressing the anaerobically digested biomass and wet-mat drying under heat and pressure.
Core Innovation
The invention relates to composite components and methods for producing composite components from fibrous materials, particularly using anaerobically digested biomass. The method comprises digesting waste fibrous material in an anaerobic digester to produce anaerobic digested biomass with refined fibers low in carbohydrates but increased in cellulose and lignin content. The composite components can be produced without the addition of earthworms, chemical resins, waxes, or other bonding additives typically required to enhance fiber-to-fiber bonding.
The method further comprises wet-mat forming and cold pressing the anaerobic digested biomass followed by wet-mat drying under heat and pressure to induce natural fiber-to-fiber and fiber-to-effluent-fiber bonding. The process utilizes the liquid effluent from the digester, which contains proteins that aid bonding during drying by denaturation. Conditions in the anaerobic digester can be controlled, including digestion time, to optimize fiber characteristics such as reduced carbohydrate and increased lignin content, which improve dimensional stability, moisture resistance, and microbial resistance of the composite components.
Claims Coverage
The patent includes three independent claims focusing on methods of producing composite components using anaerobically digested waste fibrous material and liquid effluent.
Method of producing composite components using anaerobically digested biomass and liquid effluent
This method involves digesting waste fibrous material in an anaerobic digester to produce digested biomass and liquid effluent, separating and recombining the biomass and a portion of the effluent, wet-mat forming and cold-pressing the resulting composition, and drying the wet-mat under heat and pressure to form a composite component.
Method of producing composite components with controlled moisture content
The process includes anaerobic digestion producing digested biomass and liquid effluent, separating and mixing them into a composition, wet-mat forming and cold pressing with the mat moisture content about 50-65%, followed by drying under heat and pressure to produce the composite.
Method of producing composite components with protein denaturation bonding and optional cement addition
This method includes anaerobic digestion, separating and mixing digested biomass with liquid effluent, wet-mat forming and cold pressing, and drying under heat and pressure sufficient to denature proteins, thus enhancing fiber-to-fiber and fiber-to-effluent bonding. Optionally, cement powder and cellulosic fibers like recycled paper or old corrugated containers can be mixed with the biomass composition.
The independent claims cover methods that utilize anaerobic digestion of waste fibrous material followed by wet-mat forming, cold pressing, and heat and pressure drying. Key inventive features include use of liquid effluent to enhance protein bonding, controlling moisture content during forming, protein denaturation during drying for bonding, and mixing with cellulosic fibers or cement to produce composite components.
Stated Advantages
Composite components produced have increased water-repellency and improved dimensional stability, making them less susceptible to warping.
The process eliminates the need for added chemical adhesives, resins, or waxes by utilizing natural protein bonding from digested biomass and effluent.
Composite components show higher resistance to mold, fungal, and bacterial attack due to reduced carbohydrate content and increased lignin and cellulose content.
The method allows production of composite components of varied shapes, sizes, and strengths suitable for industrial applications.
Documented Applications
Use of anaerobically digested biomass from animal waste as a fiber resource for producing composite components.
Use of produced biogas (methane) from anaerobic digestion for electricity generation.
Application of liquid effluent as fertilizer or crop application.
Use of composite components in flat or three-dimensional shapes for building materials such as panels, including fiber/cement composites for construction use.
Production of composite products from agricultural residues, recycled paper, old corrugated containers, and other cellulosic fibers.
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