Chemistry: fertilizers – Processes and products
Reexamination Certificate
1999-03-18
2001-03-06
Griffin, Steven P. (Department: 1754)
Chemistry: fertilizers
Processes and products
C071S011000, C071S012000, C071S013000, C071S015000, C071S017000, C071S018000, C071S019000, C071S020000, C071S022000, C071S023000, C588S249000, C588S253000
Reexamination Certificate
active
06197081
ABSTRACT:
FIELD OF THE INVENTION
This invention generally relates to a bio-refining treatment of biological waste materials which denatures pathogenic agents. More particularly, the invention relates to processing of human, animal and plant waste materials, such as food wastes and food processing wastes from household and food services businesses; diseased plants; residual meat and bones from meat and fish packers; livestock, poultry and pet carcasses from farm, feedlots, slaughter houses, and veterinarian clinics; and classified or condemned animal carcasses, body parts, organs and tissues which may be specified by national, regional or community disease and control programs for destruction; animal offal; municipal solid waste containing such waste material; and sewage sludge from wastewater treatment plants; all of which carry or may carry transmittable disease agents infectious to human and animals. This material is processed in combination with organic fibrous material to create and produce sterile, denatured, environmentally safe and value-added plant and animal nutrient products.
BACKGROUND OF THE INVENTION
The problem of treatment and disposal of the municipal organic waste materials, food wastes and animal wastes, such as animal carcasses and road kill, has been a challenge to nations, municipalities and industries since the dawn of civilization. There is a growing critical problem for human health risks due to an increasing variety of communicable diseases and pathogenic agents including fungi, bacteria, viruses and transmittable spongiform encephalopathy (TSE). The recent crisis in Europe relating to TSE diseases such as Mad Cow Disease, has accelerated the need for a benign technology which will inactivate and denature these rogue protons (called prions).
Traditionally, processing of organic waste materials entailed aerobic or anaerobic treatment and/or digestion of the materials, and stabilization of the digested materials. For sewage wastewater, additional steps, such as clarification and stabilization, are required, utilizing settling ponds or tanks, and followed by dewatering in lagoons or with mechanical dewatering systems to yield sewage sludge before final disposal. Incomplete inactivation of pathogenic agents in the organic materials occurred primarily at the thermophilic stage during the digestion process. The conventional waste processing or disposal, however, does not guarantee sterilization of pathogens present in the organic materials, requires enormous land areas for lagoons and settling ponds or for landfills, as well as a period of weeks to months for completion, and presents air and water pollution, nuisance and other problems for the surrounding environment.
A number of other waste treatment methods have been tried over the years with varying degrees of success. They include the following types:
Heat treatment is a process used for disinfection and sterilization of sewage sludge. During heat treatments, enteric viruses in the waste materials are expected to be deactivated at or above 70° C. according to established guidelines of the United States Environmental Protection Agency. The method has been claimed effective in destroying most enteric pathogens in waste materials, especially sewage sludge, over an extended period of time.
Ionizing radiation has also been tried as a method to sterilize sewage sludge. 600-850 keV gamma radiation can be employed at dose levels of 1 Mrad to destroy pathogens present in the sewage sludge.
60
Co and
137
Cs are prime sources of the gamma radiation. A system which uses gamma radiation has been developed by Nordion International of Kanata, Ontario, Canada. This system, however, requires high capital expenditures and, furthermore, alters the physical and chemical properties of the sludge. X-ray and ultraviolet radiation have also been used in efforts to disinfect waste materials, but the results showed that the radiation is effective only for indicator microorganisms, such as coliform, and not effective for most pathogens such as gadia and cholera vibro. These latter agents present greater risk to human health.
Incineration is another organic waste treatment process where temperatures in excess of 1,200° C. are used to completely oxidize the biomass or sludge. If all genetic materials associated with microorganisms are destroyed, the opportunity to recycle sterile organic materials increases the cost-effectiveness of the treatment process. There is, however, still a need to dispose of residues from the incineration operation and incineration facilities are expensive. In addition, air emissions from incineration remain a major environmental concern.
Chemical disinfection is also used in treating liquid wastes. Chlorine compounds, ozone, and other sterilizing substances are used to treat liquid wastes. The chemical treatment may produce residues such as chlorinated hydrocarbons which themselves have to be treated or disposed.
Fumigation using certain toxic gasses is also used to inactivate fingi, bacteria, viruses and other pathogens. While a number of substances have been evaluated for their effectiveness in disinfection or sterilization, application of this technology requires great care to prevent human exposure to the toxic gaseous chemicals through inhalation.
Composting utilizes enhanced aerobic biological activities to stabilize organic wastes. Composting processes may vary with the raw materials and the technologies. There are a variety of composters ranging from composting piles to automated composting chambers. A composting facility may take all types of organics and biomass materials and the operation can be continuous if a plug flow process is designed. It may take from a few days to a few weeks for the compost to mature. Construction costs of a well engineered composting facility can be high and the operation requires a good emission control system to protect the health of the operators.
U.S. Pat. No. 3,385,687 demonstrates composting of comminuted municipal organic wastes in a digester. The nitrogen to carbon ratio in the composted product is at least 1:20. U.S. Pat. No. 3,533,775 discusses use of mixtures of comminuted municipal waste and sewage sludge to make fertilizer. As instructed therein, sewage sludge is mixed with municipal waste to provide a uniform mixture. Thereafter, the mixture of sludge and comminuted waste is aerobically digested. The resulting materials are dried and ground for lawn treatment and other uses. Disposal of sewage sludge by composting the sludge with ammonia is shown in U.S. Pat. No. 3,442,637. Disposal of mixed sewage sludge with shredded municipal waste is shown in U.S. Pat. No. 4,586,659. The resulting mixture is sent to a composter and treated with aerobic bacteria to yield a product useful as a soil conditioner. Composting is not suitable for processing animal carcasses, as composting does not disinfect or sterilize the pathogenic agents contained in the materials to be processed.
Landfilling and landspreading are common. Disposal of animal by-products, diseased carcasses, hide trims, skulls, and hooves from meat processing plants traditionally has been performed by landfilling. Manure is usually stockpiled and spread over fields. Although these materials may be useful as agriculture fertilizers, stockpiling, landfilling, and landspreading of these materials create human health risks. These include air pollution, and groundwater contamination from runoff and provide the breeding grounds for disease-carrying vectors such as flies. Disposal of animal carcasses or other infectious animal wastes, such as hide trim, rotten eggs and the like which are more likely to contain infectious microorganisms, traditionally entailed landfilling. This method, although being cost effective in some places, suffers the disadvantages of contaminating the environment and putting human health at risk. Landfilling and landspreading are not effective for disinfection or eradication of pathogens contained in municipal organic wastes and animal wastes, sewage sludge and other organic wastes, and require
Akin Gump Strauss Hauer & Feld L.L.P.
Griffin Steven P.
Nave Eileen E.
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