CROSS-REFERENCES TO RELATED APPLICATIONS This application claims priority to U.S. Non-provisional application Ser. No. 13/081,053, filed Apr. 6, 2011, which claims priority to U.S. Provisional Application No. 61/381,304, filed on Sep. 10, 2010, the disclosure of which are is incorporated by reference herein in its entirety.
STATEMENT REGARDING FEDERALLY SPONSORED RESEARCH OR DEVELOPMENT Not Applicable
INCORPORATION-BY-REFERENCE OF MATERIAL SUBMITTED ON A COMPACT DISC Not Applicable
BACKGROUND Currently, anaerobic digestion, composting, gasification, product-packaging separation, trans-esterification, drying, pelleting, and prilling are used as independent processes. Each process requires feedstock as input and is designed to produce a single marketable product as output. Additionally, each of these processes produces by-products that may become an operating expense for disposal or an environmental liability; examples of these by-products are digestate (digestion yields), woody oversized particles (composting yield), ash (gasification yields), and glycerin (trans-esterification yields). Generally, energy output is also considered a by-product. For example, heat production from composting and gasification are by-products. Commonly, design and deployment of facilities that employ anaerobic digestion, composting, gasification, product-packaging separation, trans-esterification, drying, pelleting, or prilling processes requires between 2 and 4 years. They are also typically designed as large, centralized facilities due to the presumption that larger facilities are more cost-efficient due to the larger economy of scale. This presumption has proven to be incorrect in most urban situations due to the high cost of hauling and transportation of feedstocks (as inputs) and by-products (as outputs) over increasingly longer distances.
Organic waste processing facilities are typically designed at a scale of 100 to over 1,000 tons per day. They exist in four industrial sectors: wastewater treatment, manure treatment, industrial plants, and urban organic recycling plants. These processing facilities control feedstock preparation, residence time, temperature, moisture, density, oxygen, pH, and final particle size. They may also control odors with a one-stage treatment system.
There is a need for renewable energy, energy independence, distributed energy generation, diversion of organic waste from disposal and zero waste systems. (“Zero Waste Movement”) Coupling two or more of the above technologies together in a synergistic way to reduce by-product waste and increase usable energy/heat production will help achieve the goals of the Zero Waste Movement. The practice of coupling these technologies can be referred to as by-product synergy or bio-mimicry.
BRIEF DESCRIPTION OF INVENTION An objective of this invention is to provide a multi-modal, bio-mimicry system. Another objective is to provide a prefabricated system that can be quickly deployed for use.
DESCRIPTION OF THE SEVERAL VIEWS OF THE DRAWINGS Other features and advantages of the present invention will become apparent in the following detailed descriptions of the preferred embodiment with reference to the accompanying drawings, of which:
FIG. 1 shows a plan view of a subterranean alternating digester system according to embodiments of the present invention;
FIG. 2 shows a cross-sectional view of a subterranean alternating digester system according to embodiments of the present invention;
FIG. 3 shows a process of alternating subterranean digesting according to embodiments of the present invention;
FIG. 4 shows a cross-sectional view of a bottom surface of a subterranean alternating digester system with conduits according to embodiments of the present invention;
FIG. 5 shows a plan view of a covered conduit with channel cover plates according to embodiments of the present invention;
FIG. 6 schematically shows an anaerobic phase in the alternating subterranean digestion system according to illustrative embodiments of the present invention;
FIG. 7 schematically shows an aerobic phase in the alternating subterranean digestion system according to illustrative embodiments of the present invention;
FIG. 8A schematically shows a side-view of a biofilter pipe according to embodiments of the present invention;
FIG. 8B schematically shows a cross-sectional view of a biofilter pipe along line A-A of FIG. 8A within biofilter material;
FIG. 9 shows biofilter pipes placed on top of a biofilter surface within a biofilter enclosure and surrounded by biofilter media according to embodiments of the present invention;
FIG. 10 schematically shows an illustrative biofilter system that may be used with embodiments of the present invention;
FIG. 11 shows a plan view of the digester enclosure with pivoting screw conveyor and an excavator outside the enclosure during pile restructuring or removal according to embodiments of the present invention;
FIG. 12 shows a spike attached to a machine according to embodiments of the present invention;
FIG. 13 shows a perspective view of a portion of the spike with a sampling corbel according to embodiments of the present invention;
FIG. 14 shows a side-view of the sampling corbel shown in FIG. 13;
FIG. 15 schematically shows various locations of a machine during pile restructuring or removal of the organic matter at the end of the alternating subterranean digesting process according to embodiments of the present invention;
FIG. 16 shows a system for processing seasonal food and landscape waste;
FIG. 17 shows a system for processing food and soiled paper waste;
FIG. 18 shows a system for processing seasonal landscape waste;
FIG. 19 shows a system for processing biosolids, manure, and bedding;
FIG. 20 shows a system for processing wood;
FIG. 21 shows a system for processing packaged and unsaleable food;
FIG. 22 shows a system for processing fats, oils, and grease; and
FIG. 23 shows a system for processing digestate, compost and biochar.
DETAILED DESCRIPTION OF THE INVENTION The present invention is related to a prefabricated, multi-modal, bio-mimicry system. (“Bioenergy System”) In the Bioenergy System one of the above named processes, or their equivalents, rely upon another process to avoid disposal expense and/or environmental liability by utilizing by-product created in a first mode in subsequent modes until by-products are no longer usable or saleable. Multiple embodiments of the invention are described hereinafter with reference to the accompanying drawings. This invention may, however, be embodied in many different forms and should not be construed as limited to the embodiments set forth herein; rather, these embodiments are provided so that this disclosure will be thorough and complete and will fully convey the scope of the invention to those skilled in the art.
Although the Bioenergy System can be embodied in any number of multi-modal combinations, each embodiment is a prefabricated design that can be arranged quickly on the field. Mechanical systems are prefabricated onto modular skids that can be transported by truck or other means and positioned during construction. Mechanical systems include but are not limited to piping, valving, pumping, filtering, separating, and thermal conditioning for solid and semi-solids, such as food waste, liquid or gas circulation. Preferably, each skid is built to fit within a space 8 feet wide by 40 feet long by 9 feet high and can be lifted and installed in one movement with connections for power, controls, inputs, and outputs minimized in number and located at the limits of the skid. Preferably, the Bioenergy System is scaled to operate between 0.1 to 75 tons per day allowing on-site processing and eliminating the cost of hauling and transport.
Referring to FIG. 16, in one embodiment, seasonal food and landscape wastes 200, from resorts, parks, island, and other facilities having intermittent waste generation patterns, may be processed in alternating digester system 210. In an alternating digesting system 210, anaerobic digestion is followed by aerobic digestion. Preferably, the alternating digester system 210 is subterranean, as described below.
FIGS. 1 and 2 schematically show a plan view and a cross-sectional view, respectively, of a subterranean alternating digester system 10, and FIG. 3 shows a process of alternating subterranean digesting according to its several embodiments. Referring to 3, the process begins at step 100 in which a subterranean enclosure 12 is provided. As shown in FIGS. 1 and 2, the subterranean enclosure 12 is configured to hold organic matter and may be constructed of steel sheeting or sheet piling, pre-cast concrete panels with water tight joints, or cast-in-place concrete, or other structural elements designed to withstand subterranean earth pressure and contain the digesting material.
In step 110, the enclosure is covered with a flexible, removable, gas-tight membrane 14. The membrane cover 14 has a gas-tight seal that seals the membrane cover 14 to the perimeter of the subterranean enclosure 12. The cover 14 prevents methane and fugitive odor release and also helps to prevent evaporation loss. As known by those skilled in the art, impermeable covers suitable for use as geomembranes may include High-Density Polyethylene (HDPE), Low-Density Polyethylene, Polypropylene, XR-5® (a woven synthetic fabric of DuPont Dacron Polyester) and periplastid reticulum (PPR) membranes and other flexible membrane materials.
In step 120, a pile 16 of the organic matter is formed on a bottom surface 12a of the subterranean enclosure 12. As shown in FIG. 2, the bottom surface 12a has a series of conduits 18. Details of the conduits 18 and their function will be discussed in more detail below. Preferably, the organic matter includes larger, oversized particles. During periods when larger particle materials are unavailable, the feedstock may be amended with screening oversized material, large woody particles cast off in the screening process, bark, and similar forest product residuals. The removal of the oversized particles may be accomplished at the final screening process after the composting process is complete. The oversized particles may include brush, branches, waxed or un-waxed corrugated cardboard boxes, dimensional wood, pallets, and/or crating. Preferably, the feedstock is a mixture of incoming organic matter, screening oversized particles and woody materials. The feedstock also, preferably, includes high-carbon amendments of at least about 95% carbon. The high-carbon amendments may include cedar bark, wood, sawdust and/or paper.
Because oversized particles are used, initial grinding of the feedstock is eliminated and brush, branches, dimensional wood, broken pallets, paper bags with waste, plastic bags with waste, and crating may be directly and immediately placed into the process without particle size reduction allowing for more rapid feedstock receiving and preparation. The use of oversized particles, along with a pile restructuring apparatus, also eliminates the need for pile turning during the digestion process. The pile restructuring apparatus or spike is discussed in more detail below. As a result, costs and emissions are significantly reduced. Because the un-ground feedstock is lower in bulk density and higher in porosity due to the inclusion of the larger particles, a deeper pile may be used than is commonly used in composting practice. For example, the pile of organic matter may be initially formed with an average height of about 15-25 feet. Thus, embodiments of the present invention provide more cost efficiency than other systems (e.g., approximately $30 per ton processed versus approximately $60 per ton processed) and allow for more seasonal composition, volume, and moisture variations through the use of a deeper pile and the addition of the high-carbon amendments in the pile. For example, the pile may have an initial density of no greater than about 700 pounds per cubic yard with a minimum porosity of about 50% by volume. The pile may also have a density ranging from about 650 to about 850 pounds per cubic yard over the entire residence time.
As shown in FIGS. 1 and 2, the organic matter may be fed into the enclosed space created by the subterranean enclosure 12 and the gas-tight membrane 14 by means of a completely enclosed and gas-tight screw conveyor 20. The conveyor 20 may have a pivot point 20a and multiple discharge chutes 20b. For example, FIG. 1 shows the conveyor 20 in four different positions and FIG. 2 shows the conveyor 20 with two discharge chutes, although multiple positions and discharge chutes may be used. The conveyor 20 may be made gas-tight by means of a resident plug of organic materials in the enclosed screw and housing. The conveyor 20 may include a feed hopper 22 and the screw in the conveyor 20 may determine the maximum particle size of the organic material by means of a natural shearing action and may open any bagged waste material. Although the above discussion discloses that the enclosure 12 is covered with the gas-tight membrane 14 before the pile 16 of organic matter is formed in the enclosure, the pile may also be formed in the enclosure first and then the enclosure 12 covered with the gas-tight membrane 14. Similarly, the pile may be formed in the enclosure first, then the enclosure 12 covered with the gas-tight membrane 14, and then additional organic matter may be fed into the enclosure 12. Thus, the feeding schedule of the conveyor 20 may be continuous, intermittent, or even seasonal, and the digestion pile may be built over time.
Referring again to FIG. 3, in step 130, a liquid percolation system 24 irrigates the top of the pile with liquids. As shown in FIG. 2, the irrigation system 24 may be coupled to the conveyor 20 or may be formed in a top portion of the enclosure 12 (not shown). The liquid to be dispensed on the pile may contain nutrients, buffering, and alkalinity to cultivate and maintain efficient methanogenesis within the organic matter. During this anaerobic phase of the process, liquids from the pile (e.g., produced from the digestion process of the organic matter or from excess liquids dispensed from the irrigation system) may be collected in the conduits 18 at the bottom surface 12a of the enclosure 12.
The conduits 18 may be channels formed in the bottom surface 12a, such as shown in FIGS. 2 and 4, or may be pipes placed on the bottom surface or in channels formed in the bottom surface (not shown). The pipes have holes that allow fluid to flow from an area outside of the pipe to within the pipe. When channels are used, the series of conduits 18 may each have one or more channel cover plates 26. As shown in greater detail in FIG. 5, each channel cover plate 26 may include openings 26a that allow the percolate and fluid from the pile 16 to flow into each conduit 18. The channel cover plate 26 may be made of various materials, preferably configured to withstand the forces of the pile and a machine, such as an excavator, that may be placed on the bottom surface 12a of the enclosure 12 when the digester batch is being removed. The conduits 18 may be spaced any distance apart from one another, e.g., about 8 feet apart, and may be formed of various materials, e.g., constructed of cast in place concrete. For example, each channel cover plate 26 may be about 48″×75″ and the openings 26a may be about 1.5″×3″ with 3″ spacing and 6″ spacing between openings. Alternatively, a layer of porous material designed to withstand the forces of the pile and a machine 64, such as an excavator, that may be placed on the bottom surface 12a of the enclosure 12 when the digester batch is being removed may be used to convey the liquid at the bottom of the enclosure.
As shown in FIGS. 1 and 2, the conduits 18 collect the percolate and fluid from the pile 16 and a submersible pump 28 pumps the liquid through a vertical manifold 30 to a liquid digester 32 adjacent to the digester system 10. The irrigation system 24 is in fluid communication with the liquid digester 32. The vertical manifold 30 may be formed of various materials, e.g., concrete, steel, or HDPE pipe. The liquid stored in the liquid digester 32 may consist of hydrolyzed liquids from the pile and make up water. The liquid is provided to the pile 16 and is collected through the conduits 18 such that a continuous production of biomethane occurs. The liquid in the irrigation system 24 may be maintained at a desired temperature to control the interior temperature in the digester enclosure 12. For example, the liquid may be heated in the liquid digester 32 or in the pipes in the irrigation system 22. When the percolate recovery and return system is operating and temperatures in the liquid and digester enclosure 12 are maintained in the optimum range, the production of biomethane increases significantly.
The biomethane production rate is measured for methane content and gross volumetric biogas production. Longer residence time, higher temperatures, and efficient liquid to organic matter contact (during percolation) are factors that increase actual biomethane yield. An example of this embodiment would be 6 months of residence time, a uniform 100° F. digester temperature, and an initial bulk density of 600-700 lbs per cubic yard. The biogas produced may be recovered from the top portion of the enclosure 12 and captured for later use.
As shown in FIGS. 2 and 4, the digester system 10 may also include a lower surface 10a formed on the native soil 34 and beneath the conduits 18. For example, the bottom surface 12a of the enclosure 12 and lower surface 10a of the system 10 may be constructed of concrete. The lower surface 10a of the system may be installed underwater as a tremie concrete plug to exclude groundwater and facilitate construction of the digester system 10 in areas of high groundwater. Between the bottom surface 12a and the lower surface 10a, a coarse (porous) mineral aggregate layer or other porous material 36 may be used between the surfaces, creating a leak detection zone. The leak detection zone may include a submersible pump 38 that pumps any recovered liquid to a liquid storage tank 40 adjacent to the digester system 10, as shown in FIG. 1. The recovered liquid may be groundwater that leaks upward from below the lower surface 10a or digester liquid that leaks downward from the digester enclosure 12, or a combination of both. After characterizing the liquid, the liquid can be either reused or disposed of depending upon its quality.
Referring again to FIG. 3, in step 140, the process then alternates to an aerobic environment for subsequent aerobic composting when the desired biomethane yield has been achieved. This is accomplished by turning the liquid irrigation system 24 off and removing all excess liquid from the system 10. Then, air is forced into the digester enclosure 12 using one or more pressure blowers or fans 42. The pressure fan 42 is configured to provide air flow through the conduits 18 such that a positive air pressure is formed at the bottom of the pile 16 forcing air through the pile and causing heat and moisture to exhaust out of the top of the pile 16. FIGS. 6 and 7 schematically show the flow of liquids and air in the anaerobic phase and the aerobic phase of the process. The airflow rate may vary from about 0.5 cfm per cubic yard to about 3.0 cfm per cubic yard. The exhaust air escaping from the top of the pile is hot (around 120-175° F.), odorous, and saturated.
The digester system 10 may further include a biofilter system 50 in fluid communication with the top portion of the enclosure 12 such that the air and moisture withdrawn from the pile is transported to the biofilter 50 for exhaust treatment. For example, as shown in FIG. 1, the exhaust may be captured and collected by one or more exhaust fans 44 and discharged through an air manifold 46 in fluid communication with the top portion of the enclosure 12. The air manifold 46 is in fluid communication with a biofilter manifold 48, which transports the exhaust to the biofilter 50 which is used for emission or odor control. One or more ventilation fans 51 may also be in fluid communication with the biofilter manifold 48, which may allow ambient air to be blended in with the exhaust before going to the biofilter 50, to help with the temperature and moisture control of the biofilter air entering the biofilter system 50. The biofilter manifold 48 is also in fluid communication with a series of biofilter pipes 52, which are disposed on or in a biofilter surface 54 surrounded by a biofilter enclosure 56. The biofilter manifold 48 may run through an opening formed in the biofilter enclosure 56. The biofilter enclosure 56 is configured to hold biofilter media 58 formed around and on top of the biofilter pipes 52. FIGS. 8A and 8B schematically show a side-view and cross-sectional view, respectively, of one illustrative biofilter pipe 52. As shown, each of the biofilter pipes 52 has holes 60 that allow fluid to flow from within the biofilter pipe 52 to an area outside of the pipe which contains the biofilter media 58. Each of the biofilter pipes 52 may be placed on top of the biofilter surface 54, such as shown in FIG. 9, or may be placed within channels (not shown) formed within the biofilter surface 54.
As known by those skilled in the art, the biofilter media 58 may be composed of various materials and layers, such as shown in FIG. 10. For example, the biofilter media 58 may include shredded wood and bark, preferably about 75% wood and about 25% bark. Other acceptable green materials may include plant leaves, needles, and grass, although preferably these are no more than about 2% by wet weight of the biofilter media. Dimensional wood, stumps, trees, clean plywood, and clean particle board or other materials may also be used. Preferably, the biofilter media 58 includes at least about 60% organic matter, a maximum TKN nitrogen of no more than 0.35%, a moisture content of between about 35 to about 60%, and combined nitrate and ammonium concentrations that are less than about 100 ppm. The biofilter media 58 also preferably includes at least about 90% by weight of particle sizes ranging from about 1.0 to about 4.0 inches, with less than about 10% by weight of particle sizes ranging less than about 1.0 inch and less than about 5% by weight of particle sizes ranging greater than about 4.0 inches.
Referring again to FIG. 3, in step 150, the process further includes temporarily removing the membrane cover 14 after aerobic composting has been started and inserting a pile restructuring apparatus or spike 62 in the pile 16 at designated areas and times in order to form air shafts in the pile. The air shafts repair uneven airflow allowing substantially uniform aerobic conditions in the pile. As shown in FIGS. 11 and 12, the spike 62 may be mounted on a machine 64, such as an excavator or loader, which may be positioned around the enclosure 12. The spike 62 has a long shaft and may include a sampling corbel 66 attached on a side of the spike toward its end.
In operation, the machine moves around the top of the enclosure 12 and punctures the pile with the spike 62 at designated areas leaving vertical air shafts throughout the pile. The air shafts may be formed in a uniform array of shafts across the pile or in an uneven pattern, e.g., in designated areas where more aerobic conditions are needed. For example, the air shafts may be spaced about 6 feet apart from the center of one shaft to the center of another. Preferably, the spike 62 is long enough so that the air shafts are formed through at least half the height of the pile. For example, for a pile having an initial height of about 25 feet, the spike may be about 13 feet long and have about an 8 inch diameter. The sampling corbel 66 allows a small sample of the lower horizon of the pile to be brought to the surface for observation and mapping of the lower horizon. The inspection of the sample may include a visual inspection of the moisture, color, texture, odor, and/or temperature of the organic matter. The observations and mapping may be recorded. This information may then be used to adjust airflow through the pile. Forming the array of air shafts across the pile 16 with the spike 62 may be done one or more times during the composting phase of the process, preferably about once for a pile having a composting process of about one month.
The use of the spike 62 allows the organic matter in the pile 16 to have sufficient aerobic conditions for the composting process without the need for turning (tearing down and rebuilding) the pile. Higher porosity, volatile solids, nitrogen, and airflow are factors that increase the rate of composting. An example is about 1 month of residence time, an initial 160° F. digester temperature declining to 120° F., and an initial bulk density of 700-800 lbs per cubic yard at the beginning of composting.
When a desired temperature drop has been achieved or a desired amount of biomethane has been produced, the digestion process is complete and the digester batch can be removed. FIG. 15 schematically shows various locations of a machine 64, such as a track styled hydraulic excavator or loader, during pile restructuring or removing of the organic matter at the end of the alternating subterranean digesting process. For example, a hydraulic excavator with approximately 30,000 lbs operating weight and approximately 100 hp may be used. After removal, the batch can be aged and then screened for sale as a compost or soil product. After removal of the batch, the bottom surface 12a of the enclosure 12 and pumps may be cleaned and serviced.
The alternating digester system 210 may produce heat, electricity, compressed natural gas, biomethane, and compost. Preferably, the compost is further finished and/or improved in an enclosed ventilated composting system 240 or digestate drying or pelleting process 230. Preferably, odor is controlled in a four-stage, series system of enclosures: biofilter, carbon filter, and counteractant misting system in an exhaust stack 240.
Referring to FIG. 17, in another embodiment, food waste and paper 250 from agricultural, institutional, commercial, urban, and suburban settings may be processed in an above grade anaerobic digestion system 260. The above grade anaerobic digestion system 260 may produce heat, electricity, compressed natural gas, biomethane, and digestate. Preferably, the by-product digestate 270 is further finished and/or improved in an enclosed ventilated composting system 240 or digestate drying, pelleting, or prilling process 260. Preferably, odor is controlled in a four-stage, series system of enclosures: biofilter, carbon filter, and counteractant misting system in an exhaust stack.
Referring for FIG. 18, in another embodiment seasonal landscape waste can be processed in an enclosed ventilated composting system 240. The enclosed ventilated composting system 240 may produce heat, compost, mulch, and wood waste. Preferably, the by-product wood waste 320 is further finished and/or improved in a wood gasification system 330. Preferably, the mulch 440 is further finished and/or improved in the alternating digester system 210 and/or the drying, pelleting, and prilling system 230. Preferably, the remaining compost 280 is finished and/or improved in the enclosed ventilation composting system 240 and/or the drying, pelleting, prilling system 230. Preferably, odor is controlled in a four-stage, series system of enclosures: biofilter, carbon filter, and counteractant misting system in an exhaust stack.
Referring to FIG. 19, in another embodiment, biosolids, manure, and animal bedding (soiled with manure) 300 may be processed in an enclosed ventilated composting system 240. The enclosed ventilated composting system 240 can produce heat, compost 280, mulch 440, and/or wood waste 320. The by-product wood waste 320 may be further finished and/or improved in a wood gasification system 330. Preferably, the remaining compost 280 is finished and/or improved in the enclosed ventilation composting system 240 and/or the drying, pelleting, prilling system 230. Preferably, the mulch 440 is further finished and/or improved in the alternating digester system 210 and/or the drying, pelleting, and prilling system 230. Preferably, odor is controlled in a four-stage, series system of enclosures: biofilter, carbon filter, and counteractant misting system in an exhaust stack.
Referring to FIG. 20, in another embodiment, green tree and branch sections, and dimensional kiln-dried wood waste 320 may be processed in a wood gasification system 330. The wood gasification system 330 may produce heat, electricity, syngas, biohydrogen, and biochar 440. The biochar 440 may be beneficially used in anaerobic digestion 260 to boost biogas production and can be used in odor control devices to remove odor from odorous exhaust airstreams. The Biochar may also be further finished and/or improved in the alternating digester system 210, the above grade anaerobic digestion system 260, the drying, pelleting, prilling system 230, and/or the enclosed ventilated composting system 240.
Referring to FIG. 21, in another embodiment packaged un-salable food 400 may be processed in a product-package separation system 410. The product-package separation system 410 can produce separate outputs of food waste, plastic packaging, metal packaging, glass packaging, and digestible or compostable paper packaging. The food waste and paper packaging 200 may be further finished and/or improved in a subterranean alternating digester 210, above grade anaerobic digestion system 260, and/or enclosed ventilated composting system 240. Preferably, odor is controlled in a four-stage, series system of enclosures: biofilter, carbon filter, and counteractant misting system in an exhaust stack.
Referring to FIG. 22, in another embodiment fats, oils, and grease from cooking operations 420 can be processed in a trans-esterification system 430. The trans-esterification system 430 can produce biodiesel fuel and glycerin. Preferably, the by-product glycerin 450 can be further finished and/or improved in a subterranean alternating digester 210, above grade anaerobic digestion system 260, or enclosed ventilated composting system 240. Preferably, odor is controlled in a four-stage, series system of enclosures: biofilter, carbon filter, and counteractant misting system in an exhaust stack.
Referring to FIG. 23, in another embodiment digestate, compost, or biochar 440 may be processed in a drying, pelleting, prilling system 230. The drying, pelleting, prilling system 230 may produce powdered fertilizer, pellets for soil amendment, filtration, or fuel, or prill for soil amendment. Preferably, the pellets are used in odor control devices to remove odor from odorous exhaust airstreams. Preferably, odor is controlled in a four-stage, series system of enclosures: biofilter, carbon filter, and counteractant misting system in an exhaust stack.
A person having ordinary skill in the art will understand that, in any of the embodiments described above and any obvious variation thereof, any non-saleable or by-products can be reused in an appropriate system until saleable material has been obtained and/or by-product can no longer be used in a subsequent mode.
