Paper making and fiber liberation – Processes of chemical liberation – recovery or purification... – Waste paper or textile waste
Reexamination Certificate
1997-11-20
2001-10-23
Chin, Peter (Department: 1731)
Paper making and fiber liberation
Processes of chemical liberation, recovery or purification...
Waste paper or textile waste
C162S021000, C162S055000, C162S068000, C095S230000, C095S235000
Reexamination Certificate
active
06306248
ABSTRACT:
BACKGROUND OF THE INVENTION
The present invention relates to recycling and more particularly to the recycling of diverse pulp and paper products to provide a homogenous cellulosic feedstock having a plurality of beneficial uses.
Fossil materials are finite natural resources, and these materials are rapidly being consumed. The world is also facing many environmentally significant problems associated with the depletion of fossil materials, particularly petroleum, for the production of energy and petrochemicals. A variety of solid, liquid, and volatile organic compounds associated with petroleum extraction, transport, refining, and manufacturing operations have been and are continuing to be released into the environment. However, the most significant environmental factor is the release of carbon dioxide into the atmosphere during the burning of fossil fuels.
The use of fossil fuels has added tremendous quantities of carbon dioxide to the atmosphere. Since this carbon dioxide is being released from fossilized biomass long since effectively removed from the biosphere, there is currently insufficient plant life on earth to consume all of the carbon dioxide being produced. Therefore, the percentage of carbon dioxide in the atmosphere is increasing. Carbon dioxide and other “greenhouse gases” (e.g., volatile organic compounds) allow high energy, short wave length solar radiation to penetrate the atmosphere and to transfer heat to the earth's surface, but the same gases impede the low energy, long wave length radiation that dissipates the absorbed heat from the earth. Thus, heat from the sun is trapped in the earth's atmosphere, which is known as the “Greenhouse Effect.” Reduction or elimination of the use of fossilized carbonaceous materials as combustion fuels would halt and possibly reverse current trends in altering the biosphere. The use of renewable biomass as a replacement for fossilized combustion fuels is a formidable task, but it is an environmentally beneficial task that is well worth the effort, especially when considering the long term effects of continuing current trends.
Another environmental concern facing today's earth is the production and disposal of waste, including municipal solid waste (MSW). The ability to recycle such waste productively and efficiently could significantly reduce the current volume of unused and discarded waste.
Municipal solid waste (MSW) includes, but is not limited to, cellulosic and/or noncellulosic materials such as office wastes, business wastes, institutional wastes, industrial wastes, residential wastes, pulp and paper products, inks, glues, plastics, glass, metals, food wastes, and yard wastes. Within MSW, the cellulosic component (e.g., pulp and paper components) accounts for a relatively large portion of MSW. Therefore, there has been a particular need to try to recycle and utilize the pulp and paper components to reduce the amount of MSW.
Many attempts have been made to use MSW for energy production in so-called resource recovery facilities. Some such facilities incinerate the MSW without any prior separation of potentially recyclable materials, with the possible exception of curb side or drop-off source recycling, to produce steam and/or electricity. These facilities are known as mass-burn incinerators, which are very expensive to site, permit, construct, and operate, in addition to producing large quantities of hazardous or toxic gases and airborne particulates, as well as large quantities of hazardous or toxic fly ash and sometimes bottom ash that must be landfilled. Some other such facilities use MSW that has been shredded with some non-combustibles subsequently removed prior to incineration for energy recovery, which are known as refuse derived fuel (RDF) incinerators. RDF incinerators tend to emit lesser amounts of hazardous or toxic air pollutants and to produce lesser amounts of hazardous or toxic ash than mass-burn facilities. Still other facilities use a combination of manual labor and mechanical devices to separate recyclable materials from the MSW, which are known as MSW materials recovery facilities (dirty MRFs). The non-recyclables from dirty MRFs are usually shredded and incinerated either on-site or off-site for energy recovery. The incinerator fuel from dirty MRFs produce lesser amounts of air pollutants and ash than either mass-burn or RDF incineration facilities. Some attempts have also been made to cap and recover the gases from MSW landfills for energy production. Landfill gas recovery and use does reduce the emission of greenhouse gases that would otherwise be emitted to the atmosphere, particularly volatile organic compounds from household and industrial chemicals in MSW and methane and carbon dioxide from anaerobic digestion of the putresible materials in MSW. Carbon dioxide from the incineration of chemically unaltered biomass (e.g., wood, yard wastes, and food wastes) and even chemically altered biomass (e.g., pulp and paper products, leather, rubber, and some other polymers of plants) does not result in a net increase in the concentration of carbon dioxide in the atmosphere, unlike fossilized biomass. The recent biomass, as opposed to fossil biomass, is renewable, since growing plants fix sufficient carbon dioxide into new biomass to essentially recycle the atmospheric carbon dioxide produced by their eventual decay or combustion. As pointed out earlier, combustion of fossilized biomass (e.g., petroleum, coal, etc.) does cause a net increase in atmospheric carbon dioxide.
The use of renewable plant biomass, including such materials as waste pulp and paper products in MSW, for producing solid, liquid, and gaseous fuels, chemicals, fertilizers, and other useful products, in addition to energy via direct combustion, would reduce or eliminate dependence on fossil materials and the unwanted secondary effects of the use of fossil materials as noted above, and, at the same time, would reduce unused and discarded waste.
In order to be able to fully utilize plant biomass to replace fossilized carbonaceous materials, it is necessary to transform the plant biomass, particularly woody biomass, into a form that is easily accessible to various chemicals, enzymes and/or microbes to convert the biomass into the desired end products. Natural biodegradation is an excellent means to break down plant biomass to its basic substituents, but the process is too slow to meet the demand for raw materials in industrialized societies. Therefore, if plant biomass is to be effectively used, it must be rapidly degraded.
Woody biomass is a hard substance that provides few points of entry for chemicals, enzymes and microbes to gain access to the composite molecules. The pulp and paper industry has already devised ways to at least partially break down the structure of woody biomass through mechanical size reduction and chemical treatments, but since the desired end products of this industry must retain a fibrous consistency with tensile strength and rigidity, additional treatments are necessary to transform these pulp and paper products into a homogenous cellulosic feedstock suitable for the final molecular breakdown into other useful products, such as fuels, chemicals and fertilizers.
The fibrous materials of pulp and paper products have been obtained from wood. Wood, like other plant materials, is a product of a biological process known as photosynthesis, in which plants consume simple inorganic minerals, carbon dioxide and water using sunlight as an energy source, and metabolically manufacture all of the different types of organic molecules consistent with living organisms. Photosynthetic organisms, mostly green plants, are at the top of the food chain, and they also yield oxygen as a by-product of the photosynthetic process. Such plants are not only a source of food and fiber for all other living organisms, but they also consume a greenhouse gas, carbon dioxide, and emit oxygen, which is required by all living organisms, including photosynthetic plants for metabolic “combustion” of carbonaceous molecules called respiratio
Chin Peter
The University of Alabama in Huntsville
Thompson Hine LLP
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