WASTE HANDLING CAPABILITIES

Cross Reference to Related Applications

[0001] This application claims the benefit, under 35 U.S.C. 119 (e), of US

Provisional Application 61/361,227, filed July 2, 2010, which is hereby incorporated by reference.

Background of the Invention

1. Field of the Invention

[0002] The present invention relates in general to a system for the handling and disinfection of medical waste with improved medical waste handling capabilities. The system allows users to safely, efficiently and legally dispose of large amounts of medical waste with minimal risk of aerosolizing the infectious agents or user interaction with the waste.

2. Description of the Background Art

[0003] Medical waste, including without limitation needles, syringes, bed linens, body parts and other objects that have contacted bodily fluids, must be disposed of properly by institutions such as hospitals. The proper disposal of medical waste, especially infectious medical waste, is a time consuming and costly endeavor. It is critical that the medical waste be decontaminated and disinfected so as to be free of microorganisms, especially pathogenic viruses, bacteria and fungi. In some aspects, it is also desirable that the medical waste components (such as syringes, needles and bandages) be rendered unrecognizable by resizing and re-characterizing so that the medical waste represents no continued handling hazards. Disinfection is primarily accomplished by attacking the infectious waste with either heat, chemicals or radiation.

[0004] The prior art has attempted to address the problem of disposing of medical waste by methods such as specialized land filling, incineration, steam autoclaving, chemical treatment, shredding, and/or radiation treatment. Environmental regulations have severely limited the use of incineration for infectious waste treatment due to the potential production of gaseous emissions that may contain high levels of heavy metals, volatile organic compounds, dioxins, furans, and acid gases.

[0005] Steam sterilization is a known method for treating medical waste. Steam sterilization is primarily performed in steam autoclaves. Steam autoclaves use a thermal process in which the medical wastes are sterilized by exposure to high-temperature steam in a pressurized environment. The high temperature and penetrability of steam are employed to destroy the infectious microorganisms, however, steam autoclaving is not efficient. For steam autoclaving to be an effective treatment method, the steam must fully penetrate the medical waste to ensure that all microorganisms are destroyed. This full penetration by the steam may take a prolonged period of time; however, some medical waste is processed in field containers such as sharps and other dense waste which resists steam penetration. Also, since autoclaved waste is neither mechanically destroyed nor significantly reduced in volume, it is still recognizable as medical waste. Accordingly, an additional step is sometimes utilized to render the waste unrecognizable.

[0006] Chemical bathing of medical waste is still another method for treating infectious waste. Hospitals and other health care facilities have used chemical agents routinely for decades in the treatment of medical waste. As in steam autoclaving, chemical treatment will not be effective unless there is adequate contact between the medical waste and the chemical agent. In addition, the chemical agent will need to be maintained at a sufficient concentration and there will need to be sufficient exposure time between the waste and chemical agent to achieve proper levels of disinfection. Accordingly, the concentration of the chemical agent will have to be periodically monitored and the residence time necessary for the chemical agent to effectively decontaminate the medical waste may limit throughput. It is desirable to avoid the use of chemicals in the treatment system of infectious waste due to the potential occupational exposure of workers to chemical concentrations in the air and through skin contact, the possibility of toxic byproducts in the wastewater, chemical hazards involved with the use and storage of the chemicals, chemical residue in the treated waste, offensive odors, and no significant volume reduction of waste material.

[0007] Still another method of disinfecting medical waste is to use radiation treatment. The radiation may be microwave, shortwave radio, and the like. It is desirable to avoid the use of radiation in disinfecting medical waste because: (i) radiation treatment by itself will not render the medical waste unrecognizable; (ii) the medical waste must have a significant moisture content to insure effective treatment with microwaves; and (iii) radiation treatment will not significantly reduce the volume of the medical waste.

[0008] Another particularly troublesome area is the efficient and safe opening of disposable medical waste containers such as "red bag" or infectious waste and sharps containers ("medical waste receptacles"). It is very desirable not to disturb or aerosolize the contents of medical waste receptacles to avoid the spread of infectious microorganisms to other machinery or people. As a result, feeding whole bags and containers of medical waste into a waste processing system has been more than a challenge. The apparatus should efficiently open the medical waste receptacles but not do so in an overly violent manner as to risk aerosolizing the contents thereof or ejecting the contents thereof risking contamination of the surrounding environment or the user. Whether the treatment technology requires batch or continuous feeding, it is desirable to separate the contents of the bags before treatment.

Historically, shredders have been used for this task, but some state laws prohibit the shredding of untreated medical waste. The ideal technology would ingest whole containers of medical waste and once inside the system, open the containers and separate the contents.

[0009] Prior to the subject invention, such a container processor did not exist.

Several commercial manufacturers make and sell technology utilizing one tapered auger to feed whole containers of refuse. There are two primary flaws with such systems. The first is that the bags of refuse do not always open and pass through the system in entirety. The second is the lack of feed control. The waste either fails to feed or pulses a big wad of waste. The bags of waste either get stuck between the flights of a single auger or the bag wraps itself around the single auger shaft. For the forgoing reasons, it is desirable to have a medical waste treatment system that is capable of safely, efficiently and thoroughly decontaminating medical waste that overcomes the problems cited above.

Summary of the Invention

[0010] The subject invention comprises a system for the re-characterizing and disinfection of medical waste with improved medical waste handling capabilities. The system allows users to safely, efficiently and effectively disinfect and dispose of large amounts of medical waste with minimal risk of aerosolizing the infectious agents or user interaction with the waste. To accomplish the foregoing, the waste treatment system includes a number of sub-systems. These include a whole-container medical waste (e.g. medical waste receptacles) feed apparatus which feeds unopened bags and boxes of medical waste into a container opener apparatus. The waste feed apparatus includes a feed hopper and first and second feed hopper rams which feed whole containers into the container opener apparatus. The container opener apparatus opens the containers containing the medical waste to be disinfected and injects the contents loosely into a thermal friction extruder apparatus without unduly disturbing the contents thereof. The thermal friction extruder apparatus disinfects the waste by heating the same using friction preferably generated by counter rotating worm gear augers to grind and heat the waste thereby creating a light density fibre (to triturate) to a disinfection temperature. Finally, the treated waste extruded from the thermal friction extruder apparatus is fed into a heated chamber along with a spore strip or the like for a preselected period of time for facilitating confirmation that the waste has been sterilized.

[0011] In a preferred embodiment, the waste feed apparatus is specifically designed to handle medical waste bags or containers. Generally, medical waste is generated in the operating rooms of a hospital. All infectious waste is, by law, placed in a specially designed and marked "red bag" plastic bag. The volume capacity of these bags is generally 3 cubic feet. The red bags are placed into wheeled carts which usually have a one cubic yard capacity and are then transported to the waste treatment system site. Once at the waste feed apparatus, the cart is placed inside of a lift device that can lift and dump the cart's contents into the hopper. The floor of the hopper contains the two movable rams which are controlled by any suitable means, preferably a computer based system controller, to move backwards and forwards inside the hopper. As the rams move forward they push containers of waste out of the hopper and into a pair of augers disposed in a barrel shaped chamber of the container opener apparatus. As the rams move backwards they open a corresponding section of a well into which a new container can fall down and allow the container to be pushed into the opener apparatus. The rams are sized and timed to avoid the bridging of containers piled inside the hopper. Bridging is to be avoided because it would require undesired manual handling of the waste containers. Controlled movement of the rams is critical to controlling the waste throughput. A consistent flow of waste material creates frictional heat and helps maintain the heat.

[0012] In the preferred embodiment of the container opening apparatus, which overcomes the previously noted drawbacks of single auger systems, at least one and preferably two or more counter rotating augers are provided along with a geometrically configured bulkhead. The number of augers in the container opener can be adapted based upon the material to be processed. A sensor, such as a high hydraulic-pressure sensing switch, can be employed which allows the augers to reverse direction in the case that medical waste "chokes" the opening apparatus. To retain the bags inside the apparatus longer to be acted upon by the augers, the bulkhead is fashioned and bolted to the end of the auger barrels. The bulkhead includes a specially designed aperture which facilitates smooth discharge of the waste material, prevents the waste from being wadded up into dense balls, and prevents too much material from being discharged.

[0013] In the preferred embodiment, the thermal friction extruder apparatus is designed so that the medical waste that is introduced therein will be heated, disinfected, dried, homogenized, made fibrous and rendered unrecognizable. A receiver chamber receives the waste stream leaving the container opener apparatus. An anti-bridging gate operates inside of the receiver chamber. The anti-bridging gate continuously operates by moving up and down vertically in a cycle that lasts approximately one minute. As the gate moves downwardly from the ceiling of the chamber, the bottom of the gate engages the waste material and forces the material into engagement with the worm gear augers, thereby keeping material feeding uniformly into the extruder.

[0014] Preferably, the worm gear augers having spirally threaded flights that extend through two or more compression chambers in series. The number of worm gear augers and compression chambers can be adapted to the waste material to be processed and/or to the desired throughput to be achieved. Preferably, the number of flights on the worm gear augers increases from compression chamber to compression chamber. In the preferred embodiment, a plurality of dams is provided, one for each chamber, each of which acts to prevent medical waste in a chamber from back flowing into a previous chamber. The dams are each preferably located on the inner surface of a corresponding compression chamber and are designed to fit around the worm gear augers. One of the dams in the final compression chamber is located approximately 1-6 inches from an extrusion die located at a terminal end of the thermal friction extruder apparatus. This dam prevents medical waste in the extrusion die from back flowing into the thermal friction extruder apparatus.

[0015] The extrusion die bolts to a terminal plate of the extruder apparatus and controls the backpressure of the extrudate leaving the thermal friction extruder apparatus. The longer the extrudate remains inside the thermal friction extruder apparatus the hotter it becomes. Under computer control, a hydraulic ram either opens or closes a valve piston located inside the extrusion die. In the preferred embodiment, the extrusion die acts to conform the geometric shape of the extrudate as well as slow down and possibly stop the flow of the extrudate material without leaking.

[0016] Preferably, all of the thermal energy required to decontaminate the infectious waste is introduced from the conversion of mechanical energy into thermal energy in the thermal friction extruder apparatus, however, there may be situations where an external source of heat is needed for a continuous operation, upon start-up of the machine, or to accommodate a special type of waste material. This external source of heat can be supplied by resistance heating, inductive heating, combustion heating, or other like sources of heat input. As waste is extruded out of the thermal friction extruder apparatus die it is injected into the heated chamber, which is an extended residence chamber. The disinfection of the waste must be demonstrated, by running through the process, microorganisms which are predetermined by state environmental agencies. These organisms must be recoverable in order to be lab tested for organism kill efficiency. If these organisms were introduced into the thermal friction extrusion apparatus they would be unrecognizable for recovery and therefore must be introduced into the system post-extrusion. The heated chamber does not further macerate the waste, but only holds and maintains the waste at extrusion temperatures for an extended time (e.g. 4 or more minutes) and allows for the insertion and recovery of the microorganism in the form of spore strips. The duration of time that the material is exposed to these high temperatures is controlled by the internal auger conveyor. The auger will turn at a speed (depending on the length of the chamber) to ensure that the exposure time at temperature is approximately 4 minutes.

Brief Description of Drawings

[0017] It should be noted that identical features in different drawings are shown with the same reference numeral.

[0018] FIG. 1 shows a preferred embodiment of a waste treatment system constructed in accordance with a preferred embodiment of the subject invention which includes: a waste container feed apparatus; a waste container opening apparatus; a thermal friction extrusion apparatus; and an induction heated chamber.

[0019] FIGs. 2-4 are diagrammatic cutaway illustrations of the waste treatment system of FIG. 1 showing the internals of the waste container opening apparatus; thermal friction extrusion apparatus; and the induction heated chamber.

[0020] FIG. 5 shows a cart lift that forms part of the waste container feed apparatus and is used to receive carts of medical waste as they are brought to the waste treatment system (e.g. from a hospital).

[0021] FIG. 6 shows the inside of a feed hopper that forms another part of the container feed apparatus and receives bags or containers of waste dumped from a cart by the cart lift of FIG. 5. [0022] FIG. 7 shows the waste container opening apparatus in greater detail. The apparatus employs two counter rotating augers located under a hood enclosure and inside an auger barrel which are driven by a hydraulic motor and transmission. The augers force the waste through a specially designed bulkhead.

[0023] FIG. 8 is an illustration showing the shape and configuration of the bulkhead formed adjacent the ends of the augers for the container opening apparatus of FIG. 7.

[0024] FIG. 9 shows the thermal friction extruder apparatus used in the preferred embodiment of the subject invention.

[0025] FIG. 10 shows an anti-bridging gate which forms part of the thermal friction extruder apparatus and forces waste onto and into a pair of extrusion worm gear augers.

[0026] FIG. 11 shows the extrusion worm gear augers and one of the internal dams that inhibit the movement of the waste through the thermal friction extrusion apparatus, thereby enhancing the resizing process.

[0027] FIG. 12 shows a die ram, die barrel and extruder end plate that form another part of the thermal friction extrusion apparatus.

[0028] FIG. 13 is a schematic block diagram of a computer based control system for the preferred embodiment of the subject waste treatment system.

Detailed Description of the Preferred Embodiments

[0029] A first preferred embodiment of a waste treatment system 10 for triturating and sterilizing medical waste with improved medical waste handling capabilities is shown in FIGs. 1-4. The system 10 allows users to safely, efficiently and effectively dispose of large amounts of medical waste with minimal risk of aerosolizing the infectious agents or user interaction with the waste. In this embodiment, the waste treatment system 10 is composed of four critical subsystems which must work in harmony to produce the desired waste sterilization. A waste feed apparatus 12 is provided which is capable of transferring medical waste (whether in bags, boxes or plastic containers) from one or more hospital bulk transfer carts 13 (typically 1 cubic yard) into a container opening apparatus 14 without necessitating human handling of containers or prematurely opening the containers and aerosolizing the infectious agents contained in the waste stream. The container opening apparatus 14 is capable of opening any form of medical waste container and conveying the container contents into a thermal friction extrusion apparatus 16 without wadding or compacting the contents. The thermal friction extrusion apparatus 16 is capable of triturating the waste and applying thermal friction heat which in turn disinfects, homogenizes and dries the waste. The extruder apparatus 16 includes a hydraulic motor driving a transmission which in turn drives two counter-rotating extrusion worm gear augers. Waste enters the extruder apparatus 16 inside a receiver chamber. The worm gears operate inside worm gear barrels and extrude the waste out of an extrusion die

[0030] The disinfected waste is then fed into a heated chamber 18 equipped with a source 20 of external heat (preferably induction heating) and a motor 22 to turn an internal auger 24 to convey the processed medical waste through and out of the heated chamber 18. The heated chamber 18 is employed to verify that the waste has been completely disinfected during passage through the thermal friction extrusion apparatus 16. This is preferably accomplished by injecting a spore test strip into the waste stream at an input end 26 of the chamber 18 and then retrieving the spore test strip at an exit end 28 of the chamber 18.

[0031] As illustrated in the cutaway views in FIGs. 2-4, the container opening apparatus 14 employs a pair of counter rotating augers 30 which convey the medical waste toward the thermal friction extrusion apparatus 16. A motor 32 drives the augers 30 through a drive transmission 34. Similarly, the thermal friction extrusion apparatus 16 preferably employs a pair of counter rotating worm gear augers 36 for grinding the waste material and thereby heating the same to a temperature sufficient to disinfect the waste. Another motor 38 drives the worm gear augers 36 through a drive transmission 40.

[0032] FIGs. 5 and 6 show the details of the waste feed apparatus 12. Generally, medical waste is generated in the operating rooms of a hospital. All infectious waste is, by law, placed in a specially designed and marked "red bag" plastic bag. The volume capacity of these bags is generally 3 cubic feet. Hospitals need to handle this infectious waste as little as possible to protect the staff and general public from germ transmission. Once the bag is closed, it should not be opened again until it is inside a treatment system for disinfection processing. Hospital staff place the red bags into one of the wheeled carts 13, which usually have a one cubic yard capacity, and transport the cart 13 outside the hospital to the waste treatment site. The cart 13 is placed inside of a lift device 42 that can lift and dump the cart's contents into a hopper 44. It should be noted that the cart 13 can be used as-is without re- handling of the waste.

[0033] A floor 46 of the hopper 44 contains two movable rams 48 that are engaged side by side with one another using a tongue and groove arrangement 50. The rams 48 are controlled by any suitable means, preferably a computer based system controller as discussed in greater detail in conjunction with FIG. 13 to move backwards and forwards inside the hopper 44. As the rams 48 move forward they push containers of waste out of the hopper 44 and into the pair of augers 30 disposed in a barrel shaped chamber 52 of the container opener apparatus 14. As the rams 48 move backwards they open a corresponding section of a well 54 into which a new container can fall down and allow the container to be pushed into the opener apparatus 14. The rams 48 are sized and timed to avoid the bridging of containers piled inside the hopper 44. Bridging is to be avoided because it would require undesired manual handling of the waste containers. Controlled movement of the rams 48 is critical to controlling the waste throughput. A consistent flow of waste material creates frictional heat and helps maintain the heat.

[0034] In the preferred embodiment designed to be used with 3 cubic foot bags, these rams 48 need to be between 29" to 31" wide and 32" to 34" long and are arranged side-by- side so as to form an opening sized large enough to accommodate 3 full (but not 4) medical waste bags (as well as standard cardboard/plastic containers) laid in side-by-side. This is important (when trying to feed only one container at a time because the apparatus can only process one container at a time) because a smaller (narrower) or wider arrangement would facilitate bridging of the containers and thus impede the feeding process. Three containers laid side-by-side will not normally bridge, but 2 or 4 will have a tendency to bridge.

[0035] FIGs. 7 and 8 show the preferred embodiment of the container opening apparatus 14 which overcomes the previously noted drawbacks of single auger systems. In this embodiment the container opening apparatus 14 includes the two or more augers 30, a container diverter/hood 56, the barrel shaped chamber 52 conforming to the outside diameter of the augers 30, the hydraulic drive motor 32, the transmission 34, and a geometrically configured bulkhead 58 as best illustrated in FIG. 8. The bulkhead 58 will be discussed in greater detail later.

[0036] Generally, in the preferred embodiment, the container opener apparatus 14 includes two of the augers 30. Preferably, the augers 30 are cantilevered and counter-rotate relative to one another. The number of augers in the container opener apparatus 14 can be adapted based upon the material to be processed. The augers 30 each generally include a driver shaft 60, a blade/propeller (flights) 62, and a terminus 64 as best illustrated in FIG. 8. The augers 30 are driven by the motor 32, which provides the energy necessary to cause the augers 30 to rotate. In the preferred embodiment, the motor 32 is hydraulic. The auger shafts 60 are coupled to the transmission 34. A sensor (see FIG. 13), such as a high hydraulic- pressure sensing switch, can be present which allows the augers 30 to reverse direction in the case that medical waste "chokes" the apparatus. In the preferred embodiment the hood 56 is angled to vector the waste containers being forced out of the feed hopper 44 by the feed rams 48 down and into the container opener augers 30. The hood 56, also serves to ensure that the contents of the containers 13 stay confined within the opening apparatus 14. It is preferred that the hood 56 be hinged to facilitate any container jamming that might occur. A hydraulic or other type of actuator 65 is provided for adjusting the position of the hood 56.

[0037] The selection of the augers 30 and design of the bulkhead 58 are the result of evaluation of a number of trial and error experiments. As discussed previously, several commercial manufacturers manufacture and sell technology utilizing one tapered auger to feed whole containers of refuse. One such device was purchased and employed during development of the container opening apparatus 14. There were two primary flaws. The first flaw was that the bags of refuse would not always open and pass through the opening apparatus in entirety. The second was the lack of feed control. The waste would either fail to feed or pulse a big wad of waste. Other single auger systems were tried and failed. The bags of waste either get stuck between the flights of a single auger or the bag wraps itself around the single auger shaft. It was apparent that one auger would not work.

[0038] Experimentation was then undertaken to utilize two 18" (12" pitch), counter rotating interlocking augers. These dimensions were used because the volume between an 18" diameter/12" pitch auger flight accommodates a whole waste container. The theory was that each auger would in turn clean between the flights and shaft of the opposing auger. The augers were enclosed in the barrel, conforming to the outside diameter of the interlocking augers leaving about a 1" clearance between the auger flights and the barrel walls. The discharge end of the apparatus was left open. Upon experimentation, bags would consistently be ingested into the augers and pushed out the discharge end. Nothing wrapped around the augers that was not self cleaned by the opposing auger. The bags, however, were not opened in the process.

[0039] It became apparent that the bags needed to be retained inside the apparatus longer to be acted upon by the augers 30. To do this, a bulkhead was fashioned and bolted to the end of the auger barrels. In one test design, a single 6" circular opening was cut into the bulkhead to match the apex of the interlocking augers. This location was chosen because it matched the die proximity to the extruder shafts. This did not work because the waste would not discharge. Different diameter circular openings were experimented with, but the results did not improve. Two 6" circular openings were then cut into the bulkhead centered on the auger shafts 6. Again the waste discharge did not improve. When waste was discharged, it was wadded up into dense balls. There was no consistent feeding. The circular openings were increased from 6" to 10" with little improvement in feeding. When increased to 12" diameter openings, too much material was discharged. When decreased to 11", waste material started to move, but not smoothly.

[0040] FIG. 8 illustrates the final design of the bulkhead 58 that proved to provide the desired performance. In this design, first and second circular openings 66 and 68 are first formed in the bulkhead 58 which are each concentric with a corresponding one of the auger shafts 60. In addition, an additional opening 70 is formed between the circular openings 66 and 68 which connects the two and combines to form one large opening that is specifically designed to provide the desired performance. The shape of the additional opening 70 was arrived at by first extending two downwardly arched lines commencing at a 30° tangent 72 on the first, left circular opening 66, and a 330° tangent 74, on the second, right circular opening 68, and intersecting the curved lines at a point 76 on the vertical construction line 78, that is 2" above the horizontal construction line 80. The lower portion of the additional opening 70 is defined by a connecting line 82, drawn between the 110° tangent point 84, on circle 66, and the 250° tangent point 86, on circle 68. The resulting line 88 is then radiused to keep waste material from hanging up on the surface. The additional opening 70 is therefore defined by a top shaped piece comprising two concave curved arches extending downwardly and intersecting each other at a downwardly projecting point 76, while the bottom of the opening 70 is defined by a convex curved hump shape intersecting upwardly concave curved shapes on either side of the hump.

[0041] With the additional opening 70 in the bulkhead 58, the discharging of the waste material was greatly improved, but again it was not a smooth consistent discharge. The spacing between the terminus 64, and the bulkhead 58, was next addressed. The gap was originally set at 4". When the gap was reduced to 1" the material flow deteriorated. The gap was increased in .5" increments with improved results at each setting until the gap was 2". With this gap setting and the geometry of the bulkhead 58 as shown in FIG. 8 the waste material came out of the bags and the contents discharged in a smooth consistent rate. The material was not wadded up or densified in any manner. Whole bags went into the apparatus and the individual contents of the bags were discharged in a smooth continuous fashion. The apparatus worked admirably. It should be understood that the terminal bulkhead 58 represented in FIG. 8 can be made of any type of rigid material that can withstand the force caused by the counter-rotating augers 30 conveying the medical waste through the apparatus.

[0042] In summary, the terminal bulkhead 58 is configured with regard to the geometric design of the exit hole and the distance between the bulkhead and the terminal end of the auger shaft 60 ("the delta"). The delta between the bulkhead 58 and the terminal end of the auger shaft can be adjusted to fit the particular needs of the type of waste that is being processed. In the preferred embodiment, the container opening apparatus has a delta of between 1.5 to 4.5 inches when opening typical medical waste containers. It is also preferable to have a diameter of about 11 inches for each of the circles that are cut out of the bulkhead 58. Of course, all of these parameters can be adjusted to optimize the container opener according to the type of material that is to be processed.

[0043] With reference to FIGs. 9-12, the thermal friction extruder apparatus 16 is shown in greater detail. In this apparatus, medical waste or potentially infectious medical waste that is introduced therein will be heated, disinfected, dried, homogenized, made fibrous and rendered unrecognizable. The preferred embodiment employs at least two of the interleaved counter-rotatable worm gear augers 36, however, it will be understood that any number of worm gear augers in any number of configurations can be employed. Each of the worm gear augers 36 has spirally threaded flights 90 as illustrated in FIGs. 2-4 and 10. In the preferred embodiment, the thermal friction extruder apparatus 16 includes two compression chambers 92 in series, however, any number of chambers can be employed so long as there is at least one compression chamber. A receiver chamber 94 receives the waste stream leaving the container opener apparatus 14. An anti-bridging gate 96 operates inside of the receiver chamber 94 by means of a hydraulic actuator 97. An extrusion die 98 is disposed at the exit end of the extruder apparatus 16 and extends from a terminal plate 100 (see FIG. 12).

[0044] The number of worm gear augers and compression chambers can be adapted to the waste material to be processed and/or to the desired throughput to be achieved. In the preferred embodiment, a plurality of dams 102 is provided, one at an exit end of each compression chamber 92 and the receiver chamber 94. With respect to the compression chamber 92 adjacent the extrusion die 98, the dam 102 is located approximately 1-6 inches from the extrusion die 98, most preferably about 4 inches from the extrusion die 98. The dam 102 can be located on the inner surface of the compression chamber 92 and be designed to fit around the worm gear augers 36. The dam 102 prevents medical waste in the extrusion die 98 from back flowing into the thermal friction extruder apparatus 16. [0045] FIG. 10 shows a preferred embodiment of the thermal friction extruder apparatus's receiver chamber 94. The anti-bridging gate 96 continuously operates by moving up and down vertically in a cycle that lasts approximately one minute. As the gate 96 moves downwardly from the ceiling 103 of the chamber 94, the bottom of the gate 96 engages the waste material and forces the material into engagement with the worm gear augers 36, thereby keeping material feeding uniformly into the thermal friction extruder apparatus 16.

[0046] FIG. 11 shows a preferred embodiment of the thermal friction extruder apparatus's extruder worm gear augers 36 and dams 102. In one embodiment of the thermal friction extruder apparatus, waste is conveyed through the apparatus using extrusion shafts fitted with multiple flights. As the waste is forced further and further into the compression chambers 92 the number of flights increases (see FIGs. 2-4). Inside of the receiver chamber 94 the worm gear augers 36 are fitted with two of the flights 90 each. As waste is forced beneath the built-in dam 102, it enters the first compression chamber 92 where the worm gear augers 36 are fitted with 5 flights each.

[0047] FIG. 12 shows a preferred embodiment of the extrusion die 98. The die 98 bolts to the terminal plate 100 of the thermal friction extruder apparatus 16, and controls the backpressure of the extrudate leaving the thermal friction extruder apparatus 16. The longer the extrudate remains inside the thermal friction extruder apparatus 16, the hotter it becomes. Using the temperature input from a thermocouple, the system controller (see FIG. 13) controls the hydraulic ram 104, and moves a valve piston 106 located inside the die 98 either towards a fully opened or a fully closed position, thereby adjusting the size of the die aperture to provide a desired residence time of the extrudate in the thermal friction extruder apparatus 16. The piston 106 is preferably fitted with two compression rings that contain any moisture and or vapor leaving the apparatus. The extrudate and moisture are under extreme pressures and the die 98 must contain the vapor and extrudate until they are clear of the die 98, discharge end. In this embodiment, the die 98 acts to conform the geometric shape of the extrudate as well as slow down and possibly stop the flow of the extrudate material without leaking.

[0048] The thermal friction extruder apparatus 16 thus heats, mixes, grinds, crushes, and compresses the infectious waste as the waste moves there through. The resulting extrudate is a hot, fluff material that is unrecognizable and is suitable for disposal in a landfill. Depending on the operating conditions of the extrusion process and the type of waste fed into the thermal friction extruder apparatus 16, the extrudate can be substantially homogeneous in a brickquette form wherein the extrudate can be bonded and compressed so that there is volume reduction of about 95%. In addition, the resultant extrudate can be substantially free from leachate and extrudate can have diminished leachability such as when extrudate is placed in a landfill. The percentage of volume reduction can be variable depending on the type of waste, operating conditions, temperature, and rotational speed of the screw members.

[0049] At least a portion of the mechanical energy of the worm gear augers 36 is converted into thermal energy in the thermal friction extruder apparatus 16 by way of the friction imparted on the waste material due to the rotation of the worm gear augers 36 wherein the waste material will grind against itself and the components of the thermal friction extruder apparatus 16. Mechanical energy of motion can be converted into thermal energy when surfaces grind together, producing friction between the surfaces. This conversion of mechanical energy to thermal energy occurs in the thermal friction extruder apparatus 16 when the waste material is compressed and grinds against other waste material and the internal components of the thermal friction extruder apparatus 16. Preferably, all of the thermal energy required to decontaminate the infectious waste in the thermal friction extruder apparatus 16 is introduced from this conversion of mechanical energy into thermal energy; however, there may be situations where an external source of heat is needed for a continuous operation, upon start-up of the machine, or to accommodate a special type of waste material. This external source of heat can be supplied by resistance heating, inductive, heating, combustion heating, or other like sources of heat input.

[0050] It is known throughout the industry that subjecting infectious waste to temperatures greater than 271° F for a minimum of 6 seconds will disinfect the waste. With few exceptions, medical waste passed through the thermal friction extruder apparatus is subjected to temperatures greater than 271° F for more than 6 seconds.

[0051] As waste is extruded out of the thermal friction extruder apparatus die 98 it is injected into the heated chamber 18. The heated chamber 18 is an extended residence chamber. The disinfection of the waste must be demonstrated, by running through the process, microorganisms which are predetermined by state environmental agencies. These organisms must be recoverable in order to be lab tested for organism kill efficiency. If these organisms are introduced into the extrusion apparatus 16 they would be unrecognizable for recovery and therefore must be introduced into the system post-extrusion. Heated chamber 18 does not further macerate the waste, but only holds and maintains the waste at extrusion temperatures for an additional extended period of time and allows for the insertion and recovery of the microorganism in the form of a spore test strip.

[0052] The temperature of the heated chamber 18 and of the waste material can be measured at any point or multiple points either directly or indirectly inside of the chamber 18. The pre-set temperature range is preferably between 325°F and 350°F although the temperature can be pre-set to any temperature that matches the exit temperature of the waste exiting the extruder die 98. The pre-set temperature is preferably over about 250°F, more preferably 271°F, and most preferably over 325°F. The duration of time that the material is exposed to these high temperatures is controlled by the internal auger conveyor 24. The auger 24 will turn at a speed (depending on the length of the chamber) to ensure that the exposure time at temperature is approximately 4 minutes or more (e.g. 3-6 minutes).

[0053] The extrudate can be collected and disposed of in a landfill or other similar location. Alternatively, the extrudate can be collected and processed in an incinerator or similar combustion processor wherein the extrudate is used as a fuel and wherein the extrudate is converted into a usable energy source. The incinerator can be located at the thermal friction extruder apparatus 16 site or off-site in order to recover the BTU value of the extrudate. Furthermore, the extrudate can be collected and further transformed in a steam reformation process wherein the extrudate will be at least partially converted into syngas comprised primarily of hydrogen, carbon monoxide, methane and carbon dioxide.

[0054] As mentioned in the foregoing description of the invention, the thermal friction extruder apparatus 16 can be operated wherein substantially all of the mechanical energy input to the rotation of the worm gear augers 36 is converted into thermal energy. The thermal friction extruder apparatus 16 can also be operated without the addition of disinfectant chemicals. The temperature within the extrudate can drive the thermal friction extruder apparatus 16 process without the need of these disinfecting chemicals. In addition, the thermal friction extruder apparatus 16 can be operated without the need of any type of radiation source such as microwaves or radio waves. Furthermore, the thermal friction extruder apparatus 16 can be operated without the addition of steam from an external source with the understanding that some steam can be generated within the thermal friction extruder apparatus 16 due to the operating temperature.

[0055] The thermal friction extruder apparatus 16 will be preferably operated between

250° F and 300° F, which is a temperature range that will prevent the incineration, combustion, and/or the thermal oxidation of the waste material. However, all of the methods disclosed can be incorporated into the thermal friction extruder apparatus 16 if the operator so chooses.

[0056] With reference now to FIG. 13, a system controller 120 regulates the operation of the entire waste system 10, including the various sub-system apparatus. The system controller 120 is preferably a conventional, microprocessor-based process controller, a process logic controller, or similar process controller. The system controller 120 receives as input and responds to signals from a container opener high pressure sensor 121, one or more temperature sensors 122 located in the thermal friction extruder apparatus 16 and the heated chamber 18, and a level sensor 124 in the feed hopper 44. The system controller 120 monitors the start-up and shut-down of the waste system 10 by monitoring a signal generated by the level sensor 124 in the hopper 44.

[0057] In response to these inputs, the system controller 120 controls a number of motor controllers 126 and thereby controls the speed and direction of the augers 30 in the container opener apparatus 14, the speed of the worm gear augers 36 in the thermal friction extruder apparatus 16 and the speed of the auger 24 in the chamber 18 by controlling operation of their drive motors. The system controller 120 also control operation of the anti- bridging gate 96 through the actuator 97 and by means of the die piston actuator 104 prevents the output of waste from the thermal friction extruder apparatus 16 until the temperature of the thermal friction extruder apparatus 16 material flow passage is at least at the required minimum temperature that is pre-set into the system controller 120. Finally, the system controller 120 also regulates the feed rate of the feed hopper 44 by controlling the forward and reversing motions of the feed rams 48.

[0058] While the invention has been described with respect to a limited number of embodiments, those skilled in the art, having benefit of this disclosure, will appreciate that other embodiments can be devised which do not depart from the scope of the invention as disclosed here.