Method for reprocessing animal bedding

Abstract

A process for reprocessing soiled animal bedding material commingled with animal manure to form a compact product. The soiled animal bedding material is separated in a shaker to send at least a preponderance of the manure to a holding tank. The bedding material is subsequently dried and compacted to form a compacted product. Alternatively, the bedding material is dried (without a compacting step) to form a product.

Claims

1. A process for reprocessing soiled animal bedding material commingled with manure to form a compacted product, comprising in sequence the steps of: separating said soiled bedding material in a shaker to send at least a preponderance of said manure to a holding tank; omitting cleaning said separated bedding material with cleaning agents and/or washing and rinsing thereof; decontaminating said bedding material by heating and drying said separated bedding material, wherein said bedding material is held at a temperature for a time sufficient to attain a required moisture level ranging from about 8 to 9% and ensure that any of said manure remaining breaks down and any pathogens are killed; and compacting said dried bedding material to form a compacted product.

2. A system as recited by claim 1, wherein said compacting is carried out by a press.

3. A process as recited by claim 1, further comprising the step of packaging said compacted product.

4. A process as recited by claim 3, wherein said packaging is carried out by a bagging system configured to receive said compacted product and package it into bags.

5. A process as recited by claim 3, wherein said compacted product is formed as pellets.

6. A process as recited by claim 3, wherein said compacted product is formed as briquettes.

7. A process as recited by claim 3, wherein said compacted product is a manufactured log.

8. A process as recited by claim 1, further comprising the step of composting said separated manure.

9. A process as recited by claim 1, wherein said bedding material comprises wood shavings.

10. A process as recited by claim 1, wherein additives are added to said bedding material.

11. A process as recited by claim 10, wherein said additives are provided for imparting an aroma.

12. A process for reprocessing soiled animal bedding material commingled with manure to form a product, comprising in sequence the steps of: separating said soiled bedding material in a shaker to send at least a preponderance of said manure to a holding tank; omitting cleaning said separated bedding material with cleaning agents and/or washing and rinsing thereof; decontaminating, said bedding material by heating and drying said separated bedding material, wherein said bedding material is held at a temperature for a time sufficient to attain a required moisture level ranging from about 12 to 17% and ensure that any said manure remaining breaks down and any pathogens are killed.

13. A process as recited by claim 12, further comprising the step of packaging said product.

14. A process as recited by claim 13, wherein said packaging is carried out by a bagging system configured to receive said product and package it into bags.

15. A process as recited by claim 12, further comprising the step of composting said separated manure.

16. A process as recited by claim 12, wherein said bedding material comprises wood shavings.

17. A process for reprocessing soiled animal bedding material commingled with manure to form a compacted product for use as fuel and kindling for a fire, comprising the steps of: a. separating said soiled bedding material in a shaker to send at least a preponderance of said manure to a holding tank, omitting cleaning said separated bedding material with cleaning agents and/or washing and rinsing thereof; b. decontaminating said bedding material by heating and drying said separated bedding material; c. adding an additive to said bedding material; d. compacting said dried bedding material to form a compacted product for use as fuel and kindling.

18. A process for reprocessing soiled animal bedding material commingled with manure to form a compacted product, consisting of in sequence the steps of: separating said soiled bedding material in a shaker to remove at least a preponderance of said manure; decontaminating said bedding material by heating and drying said separated bedding material; and compacting said dried bedding material to form a compacted product.

19. A process for reprocessing soiled animal bedding material commingled with manure to form a compacted product, consisting in sequence the steps of: decontaminating said soiled animal bedding material commingled with manure by heating and drying said soiled animal bedding material commingled with manure; and compacting said dried bedding material to form a compacted product.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

(1) The invention will be more fully understood and further advantages will become apparent when reference is had to the following detailed description of the preferred embodiments of the invention and the accompanying drawings, wherein like reference numeral denote similar elements throughout the several views and in which:

(2) FIG. 1 is a schematic depiction of a process for recycling animal bedding material.

DESCRIPTION OF THE PREFERRED EMBODIMENTS

(3) FIG. 1 illustrates one possible implementation of the present animal bedding reprocessing process, shown generally at 10. The process first involves separating soiled bedding and manure in a shaker device 11. Preferably, separation is achieved by shaking the soiled bedding to remove the fecal debris, and the shaker employs a leaf-type vibrating screener. Upon separation, the manure is removed to manure holding tank 12. The removal can be done by any suitable mechanism, including a gravity feed, a pneumatic system, or a conveyor belt arrangement. The removed manure can be composted to produce fertilizer or potting soil using known techniques.

(4) The shaker usually employed in the first step of the present process operates by sifting the bedding to separate solid manure droppings from the soiled bedding. The incoming bedding passes through one or more screens of the shaker device with the manure sent to a holding tank 12. The manure may be allowed to fall by gravity, or a conveyor or other transport means may be used. Soiled bedding with at least a preponderance of the manure removed, then travels, e.g. using a conveyor, to cleaning tank 13.

(5) One form of shaker useful in carrying out the separation of manure from bedding comprises a plurality of vibrating, parallel bars, rods, or tines inclined at a slight angle to the horizontal. Bedding to be separated is placed atop the bars, which are spaced apart by a distance that permits shavings or the like, but not pieces of the animal excrement, to fall between them into a collection system. The inclination and vibrating action of the bars urges the manure to migrate downward into a holding bin, yielding an efficient separation with minimal loss of soiled bedding. One useful configuration of such a separator is disclosed in U.S. Pat. No. 5,927,513 to Hart.

(6) The present shaker is readily assembled using components such as sifters, vibrating screeners, shakers, linear screeners, separators and processing equipment available from vendors such as Smico and Triflo, that currently serve the bulk material handling industries.

(7) Soiled bedding is transferred from the shaker system into cleaning tank 13, wherein it is treated with cleaning products and rinsed with water, preferable while undergoing slow agitation. For example, the agitation may be provided by an overhead rotary impeller. When used to process bedding material that is appointed for reuse, a relatively gentle agitation should be used to prevent overmanipulation and breakage of the bedding material. Preferably, the washing is carried out with a ratio of a volume of water used to a volume of soiled bedding being at least 1:1. More preferably the ratio is at least 2:1, and even more preferably, at least 3:1. It is preferred that the water further include a detergent, soap, or other cleaning agent, such as at least one tablespoon of a domestic laundry detergent per gallon of soiled bedding, and more preferably at least two tablespoons per gallon. The present system preferably includes a cleaning agent dispenser adapted to dispense a preselected amount of a cleaning agent into the first cleaning tank. Rinsing is preferably carried out with a ratio of a volume of water used to a volume of soiled bedding of at least 1:1 and, more preferably, at least 2:1. Tank 13, as well as all other tanks in the system, preferably includes one or more drains from which liquid can be removed as needed, either by gravity or by active means such as pumps. Preferably, tank 13 is cylindrical or frustoconical in shape to permit it to act in the manner of a large washing machine vat. Tank 13 can be oriented with its cylindrical axis either vertical or horizontal. In some implementations, tank 13 can be spun rapidly to facilitate centrifugal extraction of liquid at the end of each liquid cycle. In other implementations, a compression device is present and used to squeeze the contents for tank 13 to remove liquids. As another alternative, the bedding being cleaned is transferred after draining from the cleaning tank to a separate dewatering apparatus, which extracts more liquid by centrifugal or compressive action. Suitable systems for carrying out the dewatering include those sold by The Schlueter Company, Janesville, Wis.

(8) Preferably, all the used liquids from the cleaning, rinsing, and bleaching cycles of the present process are collected in one or more wastewater holding tanks. Although the water may be discharged, possibly after remediation needed to comply with environmental requirements, preferably it is recycled to be used in one or more steps of the present process.

(9) Tank 13 further includes an optional hatch at its bottom that can be opened at the end of the cleaning and rinse cycles to allow the material to be removed for drying. For example, material may be directed onto conveyors carrying the material to the drying apparatus 16.

(10) Preferably, a rotary drum drying machine is used to dry the bedding material after it is cleaned and decontaminated, but any suitable dryer capable of reaching the temperature needed to remove moisture and assure that any remaining pathogens are destroyed may also be used, for example, a grain bin with augers. At least part of the fuel for the drum or other type dryer can be provided from the bedding itself, including fines collected during the processing of the bedding. As another alternative, a continuous belt-type dryer carrying the material through a heated zone may be used. The heat source may be of any type, including heat from combustion of a fuel, resistive heating, or infrared lamps. Microwave heating may also be used. Suitable rotary drum dryers include those sold by Energy Unlimited Inc. for manufacturing wood shavings. Fuel feeder units and burners/solid fuel combustion systems/bio mass burners may be used, such as those sold by Jackson Lumber Harvester, Mondovi, Wis., under the trade name Webb Burner, or by Energy Unlimited, Inc, Dodgeville, Wis.

(11) The drying is typically carried out by placing the cleaned bedding material in a dryer held at temperatures of at least about 300-350 F., and preferably at about 600-800 F. The material is held at temperature in the dryer for a time sufficient to attain a required moisture level and to kill any remaining pathogens. At 600-800 F., the drying can often be accomplished in a matter of two to four minutes. After the reprocessed bedding is dried to a desired moisture level, the reprocessed, clean bedding is bagged or otherwise packaged at 17. Typically, wood shavings are dried to a moisture level ranging from about 12 to 17% for reuse as bedding to inhibit formation of mold or mildew. The bagging step at 17 is optionally omitted if the reprocessed bedding is to be sold in bulk form.

(12) As previously noted, the present system and method are primarily intended for reprocessing bedding material so it can be reused for the same purpose. However, other end uses are also possible. For example, after a number of reprocessing cycles, the physical character and appearance bedding may deteriorate. However, such clean reprocessed bedding material is still useful for other applications. It may be compacted using a suitable press or like apparatus into the form of pellets, briquettes, or other articles such as manufactured logs. The pellet form can be also used as bedding, or it can be directly burned as fuel. Shavings intended to be compacted are typically dried to a moisture level ranging from about 8 to 9% to promote good coherence of the material in the compacted form. Presses suitable for producing briquettes from cleaned bedding include those manufactured by Biomass Briquette Systems, LLC, Chico, Calif.

(13) Separation of the manure and debris from the soiled bedding prior to washing can optionally be skipped and the soiled bedding with fecal matter and debris can go directly to cleaning tank 13 for processing. However, separation of the fecal matter mitigates contamination of the process water and allows for a marketable byproduct, e.g. as fertilizer or compost.

(14) In some instances, multiple cleaning cycles are optionally employed. They may be carried out serially in a single tank or, alternatively, in a semi-continuous process using separate cleaning tanks for different cycles, with material being transferred from one tank to the next after each step. The cleaning products and water rinse beneficially improve the cleaning of the soiled bedding, substantially eliminate smell, and restore color.

(15) It is preferred that the soiled bedding not be packed too tightly in the cleaning tank 13, lest the cleaning of the bedding is compromised. Instead, cleaning is best achieved if the bedding material is able to move around and circulate in the cleaning tank 13 during the washing, rinsing, and optional bleaching operations. Whatever material remains in the bedding after the cleaning operation is substantially non-toxic and clean. Too much material in the dryer makes it is difficult to achieve uniform drying in a reasonable time. The temperature actually attained in the bedding during the cleaning and drying steps is preferably sufficient to ensure that any feces remaining in the bedding breaks down and any pathogens are killed, without charring, discoloring, or otherwise damaging the bedding.

(16) The cleaning agents used in the one or more washing steps may include one or more of conventional soaps, detergents (such as those used for domestic laundering), or other suitable surfactants. Further additives may be used, such as alcohol, sodium bicarbonate, or sodium carbonate. Green soaps may be used as the cleaning products to provide even more enhanced environmental benefits to the process as waste from the process itself would be minimized and/or environmentally friendly. The washing and cleaning equipment may include tanks having capacities ranging from small quantities up to over 50,000 gallons of materials, such as those offered for sale by Pittsburgh Tank & Power Company. Preferably, the tank 13 is implemented with an agitator and centrifuge machinery to clean and dewater the solid material. The agitating equipment aids in the cleaning process. Suitable impeller systems and blades are available in various RPM motor speeds, and are offered for sale, e.g. by Triflo. The cleaning tank 13 preferably acts as a large washing machine with material being transferred into and out of the tanks by conveyor belts, pneumatic systems, loading equipment, or the like. A conveyer with sides is preferred to be used in the process to avoid spillage of the bedding material or loss of bedding material during conveying.

(17) One particularly efficacious cleaning detergent that may be used is sold under the trade name SA8 Bio Quest laundry detergent. Other chemicals can be used, such as alcohol, hydrogen peroxide, PineSol cleaner, OxyClean powder, and any laundering, dishwashing detergent, soap nuts or magnetic laundering device. The washing, rinsing, and bleaching process steps may be carried out in vats or laundering machines, textile laundering machines. Drying may be accomplished using any suitable source of heat, such as a bin with a device such as an auger system to turn the contents during the heat drying.

(18) The preferred duration of the washing cycle and whether a second washing cycle is needed, depends, in part, on the intended use of the cleaned bedding. For material appointed to be recycled as bedding, a second cycle and longer duration are preferred to provide material with substantially the same color and appearance as raw bedding. Inclusion of a bleaching cycle is also preferred to further enhance appearance. On the other hand, color and appearance are less critical for material to be formed into pellets, briquettes, or logs for fuel, so that only a single short cycle is needed to substantially remove all vestiges of the animal waste.

(19) A bleaching operation is optionally included in the process, either as a discrete step or as part of at least one of the washing steps. For the latter, the washing or rinsing solution may include a bleaching agent in addition to water and some surfactant. Preferred bleaching agents include chlorine-containing agents, such as chlorine gas, chlorine dioxide, or sodium hypochlorite. The present system may include a system for on-site generation of chlorine gas as it is needed. Such a system is economically beneficial and eliminates the hazards involved in transporting and storing chlorine (either as a gas or liquid) or other chlorine-containing agent. Sodium hydroxide, a known byproduct of most industrial processes for producing chlorine gas, may be used as part of the present process or sold for other uses. Preferably, bleaching is carried out in a separate bleaching step by soaking the bedding in a chlorine-containing bleaching solution, and thereafter rinsing the bedding with water. Preferably, bleaching is carried out after at least one washing cycle, and most preferably after all washing steps are completed. The concentration and type of bleaching agent used are selected to achieve the desired level of restored coloration to the bedding, without causing breakdown of the structural integrity of the shavings or like bedding material. The present system preferably comprises a bleaching agent dispenser adapted to dispense a preselected amount of a bleaching agent into the first cleaning tank.

(20) If a chlorine bleaching agent is used, both the waste water and bedding are beneficially dechlorinated using a sulfur-based dechlorinating agent. A preferred agent is sodium thiosulfate, which is relatively benign and non-toxic. Alternative agents include other thiosulfate salts or sulfite, bisulfite, and metabisulfite metal salts, preferably of the alkali or alkali earth metals. These agents may be introduced either from aqueous solution or as solids. The waste water is treated with an amount of dechlorinating agent sufficient to reduce the chlorine or chlorine-containing compounds, including halogenated alkanes, in the waste stream to environmentally acceptable levels. Preferably, enough dechlorinating agent is used to substantially neutralize the chlorine content. It is also preferred that any residual chlorine bleaching agent in the cleaned bedding material be neutralized to prevent any harm or discomfort to animals for whom the recycled bedding is provided.

(21) It is preferred that waste water from the various washing, bleaching, and rinsing steps be collected in one or more waste water holding tanks. The waste water is preferably recycled in a closed loop system to minimize consumption. If needed, the recycled water can be remediated as part of the process. Some waste water can also be mixed with the manure to create a liquid fertilizer product. Alternatively, the water can be disposed after any remediation necessary for environmental compliance.

(22) Used chemical tank 14 and used liquid tank provide storage for used process liquids. Suitable processing and remediation may be given these liquids, to permit them either to be recycled in the continued operation of the present system, used as input for liquefying the removed manure to form fertilizer, or discharged as acceptable effluent.

(23) While the animal waste separated from bedding may be disposed of, burned, or otherwise discarded, it is preferred that it be recycled for secondary use by processing it into liquid fertilizer or composting. Some or all of the process water used in the present method may be blended with the manure to make liquid fertilizer. Alternatively, composting may be carried out by any suitable technique, including windrowing or with in-vessel techniques. In the present process, use of a mechanical separator to segregate the manure is beneficial for composting, as removal of the carbon-rich shavings reduces the ratio of carbon to nitrogen in the incoming material, yielding a superior output composted material that does not degrade agricultural soils. The presence of the shavings also markedly slows the composting. It is generally found that manure by itself will compost in one to two months, whereas mixed material requires three months or more to be fully composted. In-vessel techniques are also generally more efficient in promoting rapid composting than windrowing, and they beneficially reduce the emission of noxious odors. Careful control of temperature and aeration in an in-vessel composting process also reduces the emission of certain greenhouse gasses, including methane and other volatile organic compounds.

(24) The present system can be mounted in a fixed installation. It is also possible to dispose the equipment on a trailer or like conveyance, permitting it to be moved to different sites. By moving the equipment closer to barns in which the bedding is used, the cost and difficulty of transporting used bedding is eliminated, and the now-cleaned bedding can be reused, again without incurring any need to transport it. In addition, the need for packaging can often be eliminated, as the cleaned material can be conveniently stockpiled pending use.

(25) The following examples are provided to more completely describe the system and method described herein. The specific techniques, conditions, materials, proportions and reported data set forth to illustrate the principles and practice of the invention are exemplary only and should not be construed as limiting the scope of the invention.

EXAMPLE

(26) Soiled bedding in the form of wood shavings used in a horse stall and containing horse manure is cleaned using a series of washing, rinsing, and bleaching steps. A bag containing approximately 50 gallons of used bedding is first run through a shaking operation to separate most of the manure from the remaining bedding. A gallon of the soiled bedding from which the manure is substantially removed is then placed in a cleaning vessel having a capacity of about five gallons and there washed in about three gallons of a washing solution comprising water to which a quarter-cup of liquid domestic laundry detergent is added per gallon of bedding. The soiled bedding is agitated in the solution for 20 minutes. Then the vessel is drained and refilled with two gallons of rinse water. The soiled bedding agitated periodically during a 20 minute rinse cycle. Thereafter, three-quarters of a cup of 12.5% sodium hypochlorite bleach is added to bleach the shavings to substantially restore their original color and appearance and kill pathogens remaining. Alternatively, chlorine gas (about twenty grams per gallon soiled bedding processed) is used as the bleaching agent. After about ten minutes, the bleaching operation has restored the color of the shavings. Then, sufficient neutralizer in the form of a solution of 3 grams of sodium thiosulfate per gallon of water is added to neutralize the residual chlorine present from the bleach. After neutralization, the characteristic smell of chlorine is no longer perceptible. Conventional chlorine test strips are used to confirm complete neutralization. The now cleaned and sanitized bedding is dewatered and heated in an oven held at 350 F. for about one hour to dry it and kill any remaining pathogens. Alternatively, the drying is carried out for about 2-4 minutes in a rotary drum dryer held at 600-800 F. for 2-4 minutes.

(27) The resulting bedding material has substantially the same texture, color, and appearance as fresh wood shaving bedding, demonstrating that it is suitable for reuse as bedding.

(28) Having thus described the invention in rather full detail, it will be understood that such detail need not be strictly adhered to, but that additional changes and modifications may suggest themselves to one skilled in the art. It is to be understood that the present system and process may be implemented in various ways, using different equipment and carrying out the steps described herein in different orders. For example, the bleaching operation might be accomplished between two washing cycles. All these changes and modifications are to be understood as falling within the scope of the invention as defined by the subjoined claims.