Abstract:
A continuously operational biological reactor for the aerobic processing of animal waste into chemically free fertilizer includes an inner drum and an outer drum coaxially mounted on a horizontal center shaft with the inner annular surface of each drum including conveyor threads with the angularity of the conveyor threads being opposite each other so that the animal waste material can be conveyed down the inner drum and then back up the outer drum for processing into chemically free fertilizer. The biological reactor will include a hopper for receiving the material, a dewatering unit for material compression and preheater, and a mixer for introducing air and microbes to facilitate the processing. The center shaft includes instrumentation passageways for monitoring and control of the process and air flow passageways for diluting and discharging volatile substances such as methane.

Description:
FIELD OF THE INVENTION  
       [0001]     The present invention pertains to digester tanks and reactors, and, more particularly pertains to a continuously operational double drum biological reactor for environmentally safe aerobic decomposition of bulk animal and livestock waste.  
       BACKGROUND OF THE INVENTION  
       [0002]     Farm animals and farm livestock, such as cattle, sheep, goats, and pigs, produce tens of millions of tons of waste each year. The disposal of such waste presents both problems and opportunities for farms and farmers ranging from the small family owned generational farm to the large corporate farms and for the feed livestock yards and food processing plants. The opportunity that presents itself is that if properly treated such waste can be transformed into valuable fertilizer for enhancing crop productivity and yields for that particular farm; or as a commodity that can be sold for profit. The ability to transform livestock waste into a salable commodity is of particular importance for small family-type farms whose profit margin is slight and tenuous. The problem faced by farms of all types is that local, state and federal laws, from township zoning ordinances to federal EPA and USDA regulations regulate and control the treatment, removal, disposal, reuse and recycling of animal waste. Numerous regulations and standards must be adhered to before, for example, livestock manure can be reprocessed for sale and use as natural fertilizer.  
         [0003]     The prior art discloses a number of different tanks and drums for decomposing and processing waste and refuse material into useful soil fertilizer.  
         [0004]     For example, the Emmet patent (U.S. Pat. No. 3,248,175) discloses a rotatable drum for manufacturing compost that includes a plurality of spaced openings at one end surface of the drum that can be selectively opened or closed to allow the discharge of the warm moist air or the air-steam mixture being piped through the drum. The conduit for the air extends in a u-shaped manner within the drum.  
         [0005]     The Chester patent (U.S. Pat. No. 3,890,129) discloses a composting device that has open mesh side and end panels. For aerobic treatment, removable covers are placed over the open mesh side panels and when composting is completed, the covers are removed so that the composted material can be discharged through the mesh panels. For anaerobic treatment, both the mesh side panels and ends are covered to restrict airflow for such anaerobic treatment.  
         [0006]     The Kaelin patent (U.S. Pat. No. 3,960,537) discloses a method and device for treating refuse and sludge and includes a chamber having an upper inlet aperture for receiving the material to be treated and a lower outlet aperture for discharge of the material. Sets of gas distributor blades are axially disposed along a vertical shaft for introducing a gas mixture into the chamber for treating the material.  
         [0007]     The Terry patent (U.S. Pat. No. 4,024,219) discloses a drum for aerobic processing of waste material and includes a chamber through which a horizontal shaft extends, and projecting from the shaft are three vanes for effecting mixing and processing of the material.  
         [0008]     The Cook patent (U.S. design Pat. No. 352,580) discloses a double drum design wherein two drums are mounted on a stand side-by-side for composting material.  
         [0009]     The Kakuk et al. patent (U.S. Pat. No. 5,432,088) discloses a bin for aerobic composting that includes a plurality of horizontal mixing and aeration slots through which an implement, such as a garden tool, can be inserted for effecting the mixing of the material held within the bin.  
         [0010]     Despite the ingenuity of the above devices, there remains a need for a continuously operable aerobic digester that can expedite the process of transforming waste material continually fed therein to safe and useful fertilizer.  
       SUMMARY OF THE INVENTION  
       [0011]     The present invention comprehends a continuously operable biological reactor for processing animal waste material into environmentally safe, chemically free natural fertilizer and includes a pair of drums, specifically an inner drum and an outer drum coaxially mounted on a horizontally extending center shaft for aerobic processing of animal waste material by continually moving animal waste material through the inner drum in one direction and then through the outer drum in the opposite direction. Each drum includes a series of conveyor threads or flights for turning over and moving the material therethrough, with the conveyor threads of each drum being angled in the opposite direction so that the waste material can move down the inner drum and then back up the outer drum in the opposite direction. The biological reactor also includes a dewatering press for removing excess water from the material received from a hopper, a mixer wherein microbes are introduced to facilitate material processing and a heater for directing a continuous airflow into both drums while the center shaft includes passageways for control and monitoring instrumentation and airflow passageways.  
         [0012]     It is an objective of the present invention to provide a continuously operational reactor for digesting animal waste matter using a screw-type conveyance design.  
         [0013]     It is another objective of the present invention to provide a continuously operational reactor wherein the animal waste matter is quickly brought to the aerobic state for processing by a pair of coaxially mounted rotatable drums.  
         [0014]     It is yet another objective of the present invention to provide a continuously operational biological reactor having a center shaft on which processing drums are mounted and through which instrumentation and airflow can be directed.  
         [0015]     It is still another objective of the present invention to provide a continuously operational biological reactor wherein animal waste material is input and environmentally safe fertilizer is output that meets all state and federal guidelines and regulations.  
         [0016]     It is still yet another objective of the present invention to provide a continuously operational biological reactor that processes animal waste into chemically-free fertilizer thereby decreasing the pollution of ponds, rivers, and water tables from the uncontrolled runoff, decay and degeneration of animal waste.  
         [0017]     Still another objective of the present invention is to provide a continuously operational biological reactor that is able to process canning factory waste into chemically free, environmentally safe fertilizer for sale or farm use.  
         [0018]     Still yet another objective of the present invention is to provide a continuously operational biological reactor capable of processing the waste product generated in the milking area of a diary farm into useful, environmentally safe fertilizer.  
         [0019]     Still yet a further objective of the present invention is to provide a continuously operational biological reactor that is transportable within a container to different sites, and is capable of processing one ton of animal waste an hour and up to  24  tons of animal waste daily.  
         [0020]     A yet further objective of the present invention is to provide a continuously operational biological reactor that allows for on site processing and treatment of waste material thereby avoiding the cost and time of transporting such waste to a dump site or landfill.  
         [0021]     These and other objects, features and advantages will become apparent upon a perusal of the following detailed description when read in conjunction with the drawings and appended claims. 
     
    
     BRIEF DESCRIPTION OF THE DRAWINGS  
       [0022]      FIG. 1  is a sectioned elevational view of the continuously operational biological reactor of the present invention illustrating the movement of animal waste material through the inner drum and then the outer drum;  
         [0023]      FIG. 2  is a top plan view of the continuously operational biological reactor of the present invention illustrating the location of the hopper, the chute and the inner an outer drum;  
         [0024]      FIG. 3  is a sectioned elevational view of the continuously operational biological reactor taken along line  3 - 3  of  FIG. 1  illustrating the coaxial alignment of the inner and outer drums on the center shaft;  
         [0025]      FIG. 4  is a bottom plan view of the continuously operational biological reactor illustrating the air flow pattern through the inner drum, the outer drum, and the center shaft;  
         [0026]      FIG. 5  is a sectioned elevational view taken along lines  5 - 5  of  FIG. 3  illustrating the instrumentation and air flow passageways extending through the center shaft; and  
         [0027]      FIG. 6  is a basic flow chart illustrating the control and monitoring events that occur concomitant with the movement of the waste material through the biological reactor. 
     
    
     DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT  
       [0028]     Illustrated in  FIGS. 1-6  is a continuously operable biological digester or reactor  10  for treating and processing animal waste, primarily from farm and livestock animals, into a natural fertilizer that is chemical free and environmentally safe and approved by the relevant government agencies. By treating and processing the animal waste (predominantly animal excrement) on site, the pollution of soil, streams, lakes, rivers and aquifers from seepage and runoff of the animal waste is prevented; and a salable commodity is produced for the farmer or other user of the reactor  10 .  
         [0029]     As shown in  FIGS. 1-6 , the biological reactor  10  includes an external housing or frame  12  preferably of black iron. Mounted at a first end of the frame  12 , and extending into the frame  12 , is a hopper  14  into which the animal waste is dumped from a conveyor or other piece of machinery such as a back hoe or ditch digger. The hopper  14  can include some type of screen or scrubber for removing or breaking down sticks, rocks and other non-digestible material intermingled with the animal waste. The hopper  14  is connected to a dewatering device  16  that is preferably an agricultural press operating at 120 psi; the dewatering device  16  compresses the animal waste for removing excess water from the waste and it is also where the preheating of the animal waste occurs. A worm conveyor (not shown) extends through the dewatering device  16  and acts on the animal waste passing through the dewatering device  16 .  
         [0030]     Illustrated in  FIGS. 1 and 4  is a furnace  18  that is preferably a 100 BTU heater with a three-speed fan or blower. The furnace  18  is mounted to the inside of the frame  12  by means of struts or support members  20 . Attached to the furnace  18  is a plenum chamber  22  for directing the flow of air from the furnace  18  into air ducts  24  extending outwardly from the plenum chamber  22 . The purpose of the airflow (shown by the directional arrows of  FIG. 4 ) is to dilute and discharge the methane that is a constituent and by-product of the animal waste, and to keep the methane—and other gasses—moving through the reactor  10  as will be hereinafter further explained. Adjoined to the dewatering device  16  is a mixer  26 , and as the animal waste is conveyed through the mixer  26 , microbes are introduced to facilitate the breakdown and decomposition of the animal waste. In addition, air is introduced into the mixer  26  for intermixing with the animal waste and for providing the aerobic processing conditions.  
         [0031]     As illustrated in  FIGS. 1 and 2 , attached to the mixer  26  and angled downwardly therefrom is a double-chambered chute  28 . The animal waste downwardly descends within both chambers of the chute  28 , and the chute  28  will include a back pressure plate that will operate as a safety valve if excessive pressure differentials occur within the reactor  10 . The chute  28  communicates with the two primary components of the reactor  10 : an inner reactor drum  30  and an outer reactor drum  32 . Both the inner drum  30  and the outer drum  32  are coaxially mounted to a center shaft  34 , and air ducts  24  interconnect the center shaft  34  to the furnace  18  so that airflow can be directed through the center shaft  34  and to the drums  30  and  32 . The drums  30  and  32  can be manufactured from stainless steel or from fiberglass and each drum  30  and  32  includes an inner annular surface  36 . The inner drum  30  and the outer drum  32  include a plurality of conveyor flights or threads  38  secured, preferably by welding, to their respective inner annular surfaces  36 ; and the conveyor threads  38  extend along the entire inside annular surface  36  of each respective drum  30  and  32 . The conveyor threads  38  for each drum  30  and  32  project inwardly from each respective inner surface  36  at least 12 inches and to facilitate the movement of the animal waste through, first, the inner drum  30 , and then the outer drum  32 , the conveyor threads  38  for the inner drum  30  are set at an angle that is opposite of the conveyor threads  38  of the outer drum  32 . The inner drum  30  has a first ingress end that registers with the double-chambered chute  28  for receiving the animal waste, and an opposite egress end having at least one discharge aperture  40  through which animal waste flows for processing within the outer drum  32 . In addition, air ducts  24  register with the outer drum  32  to maintain the flow of air therethrough. When the treatment and processing of the animal waste is completed, the treated waste flows through an outlet  42  for discharging and transferring to, for example, a waiting conveyor, bagging unit or dump truck. In addition, an air vent  44  for externally venting air, and especially the methane gas, can be included as shown in  FIG. 4 .  
         [0032]     As shown in  FIGS. 1-5 , the center shaft  34  is mounted to the inside of the frame  12  by shaft mounting members  46 , and the center shaft  34  extends through both the inner and outer drums  30  and  32  so that both drums  30  and  32  can rotate simultaneously and continuously thereon. The center shaft  34  includes bearing housings  48  located at opposed ends of the shaft  34 , and enclosed within the respective bearing housings  48  are machined bearing plates  50  and associated roller bearings  52 ;  FIG. 5  shows the bearings  52  and bearing blocks  54 . In addition, as shown in  FIGS. 3 and 5 , the center shaft  34  (preferably manufactured from steel tubing) includes passageways  56  for accommodating instrumentation and airflow, and the passageways  56  are coextensive with the shaft  34 . The center shaft  34  of the present invention includes four passageways  56 , two upper passageways for carrying instrumentation  57  and two lower passageways serving as airflow conduits. Also, instrumentation probes  58  are mounted to the center shaft  34  and extend into the interior of at least the inner drum  30  for monitoring such physical variables as temperature, ph levels, and gas content within the reactor  10 . At least six instrumentation probes  58  will be mounted to the center shaft  34  in the present embodiment of the invention. The center shaft  34  also includes a small space for accommodating a high pressure water conduit having spray nozzles spaced along the length of the conduit for discharging cleaning water through the nozzles and into the drums  30  and  32  for cleaning out the drums  30  and  32 . Moreover, the center shaft  34  is interconnected to the furnace  18  and plenum chamber  22  by air ducts  24 , as shown in  FIG. 4 , and spaced along the center shaft  34  are air shaft vents  60  for directing airflow from the center shaft  34  into the inner drum  30 .  
         [0033]     Various drive or drum rotation means can be used with the reactor  10 , and a preferred drive means includes 20 hp variable speed motor appropriately geared down for rotating both drums  30  and  32  at the rate of three revolutions per hour for continuously turning the animal waste and moving the animal waste through both drums  30  and  32 . Power for the motor can be supplied from an appropriately rated electrical outlet or from an optional generator. A PLC controller  62  will monitor and control the various functions and parameters of the reactor  10 , such as the ph balance, the temperature, and the gas levels, throughout the processing steps shown in the processing flowchart  64  of  FIG. 6 .  
         [0034]     In operation animal waste would be dumped into the hopper  14  where sticks and rocks would be screened for removal or broken up for digesting by screeners and/or scrubbers. For maximum digesting efficiency material should not exceed two inches in length or diameter. The animal waste is then compressed and preheated by the dewatering device  16  and then the animal waste enters the mixer  26  where the microbes are introduced for decomposing the animal waste by natural means. Air is also injected in the mixer  26  for providing the aerobic element to the processing of the animal waste. Thus, the animal waste is preheated and brought up quickly to the aerobic state whereby the ph and temperature are monitored and controlled by the PLC controller  62  (which can be from an external manually operable panel of known construction) to maintain the preheated aerobic state before the animal waste descends through the chute  28  and into the inner drum  30 . The flow of air from the furnace  18  and plenum chamber  22 , through the air ducts  24 , and then through the inner drum  30  and the outer drum  32  dilutes and discharges the methane so that the methane&#39;s flammability is nullified. The flow of air through the center shaft  34  occurs simultaneous with the airflow through the inner and outer drums  30  and  32 . The animal waste moves through the inner drum  30  by the rotatable action of the conveyor threads  38 , and as the animal waste moves through the inner drum  30 , the PLC controller  62  monitors events in the dewatering device  16 , the furnace  18  and the mixer  26  so that the proper temperature and ph balance is maintained before the animal waste enters the inner drum  30 .  
         [0035]     The movement of animal waste from the hopper  14  and through the inner drum  30  and then in the reverse direction through the outer drum  32  is shown by the directional arrows of  FIG. 1 . The outer drum  32  is the slower digesting drum and thus the animal waste has a longer dwell time while going through the outer drum  32 . The slower digesting of the outer drum  32  allows for a cooling down of the waste as the temperature is carefully monitored to allow for the gradual cooling of the animal waste before discharge from the outer drum  32 . Both the inner and outer drums  30  and  32  turn the animal waste at three revolutions per hour, and generally more solid material moves into the outer drum  32  from the inner drum  30 : for example, if 10% of the material is solid entering the inner drum  30 , the material is approximately 38-45% solid as it is discharged from the inner drum  30  to the outer drum  32 . The approximate weight of the animal waste is 66 pounds per cubic foot, and the configuration of the drums  30  and  32  provides for a discharge of 30 cubic feet of material from each drum  30  and  32  per hour thereby providing for the production of one ton of natural fertilizer per hour. It should be note that the biological reactor  10  of the present invention will not work with any material that will kill the biological microbes such as material from the family of hydrocarbon compounds. Thus, the present invention is a continuously operable biological reactor  10  in contrast to batch processors that go from anaerobic to aerobic and then back to anaerobic processing states.  
         [0036]     It will be seen that a preferred embodiment of the invention is disclosed, and that those skilled in the art will recognize that numerous alterations, modifications, and variations can be made that will still fall within the scope of the above detailed description and the following appended claims.