Abstract:
Infectious wastes originating in hospitals or other locations are deposited into a sealable, pressure resistant, portable sterilizer vessel at the source of the wastes. The sterilizer vessel rides on wheels enabling travel of the filled vessel to a sterilization station at another location where steam is directed into the vessel to perform the sterilization. Operators need not transfer unprocessed infectious waste from a collection cart to a fixed sterilization vessel at the sterilization site. In the preferred form, handler exposure to unprocessed wastes is further reduced by creating an airflow from the vessel opening to a filter while the vessel is opened for deposit of wastes.

Description:
TECHNICAL FIELD 
     This invention relates to the processing of infectious wastes at medical facilities or other locations and more particularly to apparatus and methods for collecting and sterilizing such wastes. 
     BACKGROUND OF THE INVENTION 
     Potentially infectious wastes which originate in hospitals, medical clinics or other locations must be sterilized prior to being disposed of at landfills or other garbage disposal sites. Such wastes may be of various types of which used bandages, specimen containers and used hypodermic needles are examples. 
     In the typical practice medical personnel or others deposit such wastes in temporary containers which are situated in the hospital or the like at the locations where the wastes originate. The containers are lined with disposable plastic bags. The filled bags of unprocessed waste are transferred to a wheeled collection cart which is traveled to a sterilization station that is usually located some distance away from the locations at which the wastes originate. The bags are then transferred to a sealable pressure resistant sterilizer vessel which is a built in component of the sterilization station. Sterilization is typically effected by directing high temperature steam into the sealed sterilizer vessel for a period of time sufficient to destroy infectious organisms in the waste. 
     Collection of the bags of unprocessed waste at the source and subsequent transfer of the bags from the collection cart to the sterilizer can cause spatter and air flow towards the persons who perform the operations. This has necessitated sanitation procedures which complicate the processing of the wastes and add significantly to operating costs. It would be advantageous if this repeated handling of unsterilized wastes were minimized or eliminated. 
     The present invention is directed to overcoming one or more of the problems discussed above. 
     SUMMARY OF THE INVENTION 
     In one aspect, this invention provides biohazardous waste processing apparatus having a waste sterilizer vessel forming a chamber with an opening for receiving the wastes. The opening is sealable by a sealing closure to enable sterilization of the contents of the vessel by admission of steam into the chamber. The sterilizer vessel is also a portable waste collection cart which rides on support wheels enabling travel of the sterilizer vessel between a first location at which the waste is collected and a second location at which sterilization is performed. 
     In another aspect of the invention, biohazardous waste collection and processing apparatus includes a portable sealable waste collection vessel formed of pressure resistant and thermally insulative material and having an opening through which biohazardous waste is deposited in the vessel. The waste collection vessel is supported on wheels which enable travel of the vessel between a first location at which the waste originates and a second location at which the wastes within the vessel are sterilized by direction of steam into the vessel. The apparatus further includes an openable lid for closing the opening at the first location, the lid being temporarily replaceable by a sealing closure at the second location. The sealing closure seals the vessel at the second location during direction of steam into the vessel. 
     In still another aspect, the invention provides a method for processing biohazardous wastes which originate at a first location and which are sterilized at a second location. Steps in the method include utilizing a wheeled sealable pressure resistant sterilizer vessel at the first location for receiving said wastes thereat, wheeling the vessel to the second location, temporarily sealing the vessel at the second location while the wastes remain therein, and sterilizing the wastes at the second location by injecting steam into the vessel prior to removal of the wastes from the vessel. 
     The invention reduces exposure of handlers to infectious wastes by utilizing a portable sterilizer chamber as a waste receiving or collection cart at the source of the wastes. The cart may then be wheeled to another location where the sterilization is performed without requiring any transfer of the wastes from the cart to a sterilizer. Optionally, the still unemptied cart may be used to transport the now sterilized waste to still another location where the waste is dumped into a compactor and transferred to a transportable processed waste receiving bin. This enables the waste processing system as a whole to be compact and flexible with regard to the location of system components. In the preferred form of the invention, medical staff or others who first deposit infectious wastes in the portable sterilizer chamber are protected by creating an air flow from the chamber opening to a filter at times when the chamber lid is open. 
     The invention, together with further aspects and advantages thereof, may be further understood by reference to the following description of the preferred embodiment and by reference to the accompanying drawings. 
    
    
     BRIEF DESCRIPTION OF THE DRAWINGS 
     FIG. 1 is a side view of a combined sterilizer and waste collection cart embodying the invention. 
     FIG. 2 is a frontal view of the sterilizer and waste collection cart of FIG. 1 
     FIG. 3 is a top view of the sterilizer and waste collection cart of the preceding figures. 
     FIG. 4 is a section view taken along line  4 — 4  of FIG.  3 . 
     FIG. 5 is an elevation section view of the sterilizer and waste collection cart of the preceding figures. 
     FIG. 6 is a block diagram depicting a typical route of travel of the sterilizer and waste collection cart during usage thereof. 
     FIG. 7 is a frontal view of a sterilizing station at which the contents of sterilizer and waste collection carts are sterilized. 
     FIG. 8 is a plan section view of portion of the sterilizing station taken along line  8 — 8  of FIG.  7 . 
     FIG. 9 is a section view taken along line  9 — 9  of FIG.  8 . 
     FIG. 10 is an elevation view of a dumping and compaction station at which the sterilized contents of the sterilizer and waste collection carts are transferred to transportable bins for disposal. 
     FIG. 11 is a side view of an air evacuation system for protecting persons who deposit wastes in the cart from airborne contamination. 
    
    
     DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS 
     Referring initially to FIGS. 1,  2  and  3  of the drawings, a sealable pressure resistant sterilizer vessel is provided with ground wheels  12  which enable the sterilizer vessel to also be used as a portable waste collection cart  11 . The combined sterilizer vessel and collection cart  11  eliminates any need for transferring untreated infectious wastes from a collection cart to a sterilizer vessel. 
     With reference jointly to FIGS. 1,  3  and  4 , the sterilizer vessel and collection cart  11  of this example includes a pressure resistant metal drum  13  with an opening  14  at the top and which forms a chamber  16  in which wastes are deposited and later sterilized. An outer shell  17  of thermal insulation encases the drum  13  except at the opening  14 . The wheels  12  which support the sterilizer vessel and collection cart  11  are attached to the base of the cart by brackets  18  and are preferably of the swiveling type. A U-shaped push handle  19  extends outward from the back of the cart  11  preferably at an elevation corresponding approximately to the waist level of an adult person of average size. Two vertically spaced U-shaped lifting handles  21  extend outward at the front of the cart  11  to enable lifting and tilting of the cart by dumping mechanism as will hereinafter be described. 
     An annular flange  22  of angled cross section at the top of drum  13  enables sealing of the chamber  16  during the sterilization step. The flange  22  forms an annular step  23 , encircling the chamber opening  14 , against which a seal can be compressed. The flange  22  is penetrated by angularly spaced apart apertures  24  for purposes to be hereinafter described. 
     The cart  11  is provided with a removable circular lid  26  which is seated against step  23  within flange  22  during periods when the cart is being used for waste collection and storage at the source of the wastes. Lid  26  has a first section  27  which is held in place by a pair of clips  28  which extend upward and outward from the first section and which may be integral portions of the lid section  27  provided that it is formed of slightly resilient material. Clips  28  are shaped and positioned to snap engage in the pair of flange apertures  24  which are closest to the front of the cart  11 . 
     The removable lid  26  has a second larger section  29 , provided with an upward extending handle  31 , which is hinged to the first section  27  by a pair of hinges  32 . Thus the chamber  16  may be opened for deposit of wastes therein by grasping handle  31  and pivoting the second lid section  29  upward. 
     Further components of the cart  11  include a pair of closure positioning pin guides  33  which are secured to flange  22  at diametrically opposite locations therearound. Each such guide  33  has a tapered vertically extending passage  34  which is of progressively diminishing diameter in the downward direction. The guides  33  serve to assure correct registry of the cart  11  with a sealing closure during the sterilization stage of operation in a manner which will be hereinafter described. 
     Referring to FIGS. 3 and 5, the base  36  of the drum  13  and outer shell  17  has an inverted dome shape and a horizontally oriented perforated circular plate  37  extends across the lowermost region of chamber  16  within the base. This forms a steam condense collection sump  38  at the bottom of the chamber. A condensate extraction tube  39  extends upward, along the inside surface of drum  13 , from the center of the bottom of sump  38  to the level of the previously described step  23  that is formed by the drum flange  22 . A circular resilient seal  41  seats in an enlargement  42  at the top of the extraction tube  39  and provides for connection to a condensate pump in a manner which will be hereinafter described. A second tube  43  extends upward along the inside surface of drum  13  from the sump  38  to a location which is slightly below the step  23 . During the sterilization step, tube  43  assures that steam directed into the top region of chamber  16  is not blocked from the bottom region by material contained within the chamber. The tube  43  also assures equalization of pressure at the top and bottom regions of the chamber  16  during the sterilization step. 
     Referring jointly to FIGS. 1 and 4, the drum  13  is provided with a disposable liner  44  prior to deposit of wastes in the cart  11 . The liner  44  may be a bag formed of thin flexible plastic and extends over the drum flange  22  and downward for a distance along the outer surface of the flange. The liner  44  is formed of one of the heat resistant plastics, such as polypropylene for example, which remains intact at the high temperatures to which the contents of the cart  11  are subjected during the sterilization step. This protects the inner surface of drum  13  from fouling by other plastics or substances in the waste that melt at the high temperature and which might adhere to the drum wall in the absence of the liner  44 . Referring jointly to FIGS. 3 and 4, a disposable cover  46  encases the lid  26  during the waste collection step to prevent contamination of the lid. Cover  46  is also formed of flexible plastic. Lid  26  is detached from the cart  11  just prior to the sterilization step and the disposable lid cover  46  is added to the collected wastes within the cart  11 . 
     In a typical usage of the portable sterilizer vessel and collection cart  11 , with reference to FIG. 6, the cart is initially situated at or close to a location at which infectious wastes originate. The source location  47  may typically be within a hospital, medical clinic or the like although there are other types of facilities at which such wastes may be produced. A number of the sterilizer vessel and collection carts  11  may be stationed within large facilities where infectious wastes are produced at a number of different locations. 
     When a cart  11  has been filled with wastes it is manually pushed or pulled to a sterilization station  48  where steam sterilization of the contents is effected prior to emptying of the cart. The cart  11  still containing its original contents is then pushed or pulled to a dumping and compaction station  49  where the sterilized contents of the cart are loaded into transportable bins  51  which may be hauled to a landfill or other disposal site. 
     In one mode of operation, this waste collection and sterilization procedure eliminates any need to transfer infectious wastes from one receptacle to another after the initial depositing of the wastes in a collection receptacle. In another mode of operation, the wastes may be initially deposited in conventional plastic bag lined collection receptacles. The combined sterilizer vessel and collection cart  11  may then be used to collect filled bags from a number of such receptacles. While this requires a transfer of filled bags from one receptacle to another, it is still advantageous as only a single such transfer is needed. An additional transfer of the infectious wastes into a sterilizer vessel is not needed as in the conventional practice. 
     The process has advantages additional to that of reducing handling of untreated wastes. Greater flexibility in the location of components of a waste processing system is made possible. For example, portability of the waste sterilizing vessel allows the dumping and compaction components to be located away from the sterilizing station in instances where that is desirable because of space limitations or for other reasons. The waste processing system as a whole can be more compact as the functions of a collection cart and a waste sterilizer vessel are combined into one unit. 
     Referring to FIGS. 7 and 8 in conjunction, this example of the invention utilizes three sterilization stations  48  to enable simultaneous processing of more than one cart. A single sterilization station  48  or a larger number of sterilization stations may be appropriate depending on the amount of waste which needs to be processed at the particular facility. 
     The sterilization stations  48  of this example are disposed in side-by-side relationship within framing  52 . Linear frame members  53  extend along the floor or pavement which underlies each station  48  to define a rectangular cart parking site  54 . Frame members  53  are positioned to locate the cart  11  directly below a sealing closure  56  which replaces the previously described lid of the cart and which seals the sterilization chamber of the cart during the sterilization step. 
     The sealing closure  56  of this example is supported by a pair of vertically oriented linear hydraulic actuators  57  which extend downward at opposite sides of the cart  11  from brackets  58  attached to framing  42 . Support arms  59  extend laterally from opposite sides of the top of closure  56  and are secured to the lower ends of the extendible and retractable rods  61  of the hydraulic actuators  57 . Thus extension of the actuator rods  61  lowers the closure  56  into the flange  22  at the top of the cart  11  and retraction of the rods raises the closure out of the cart. Pressurized hydraulic fluid for operating the actuators  57  is provided by a hydraulic fluid supply  62  situated at the base of the sterilization station  48  at one side of the cart parking site  54 . The hydraulic fluid supply  62  includes a fluid reservoir  63  and motor driven pump  64  which may be of conventional design. A solenoid controlled valve  66  for selectively supplying hydraulic fluid to opposite ends of the actuators  57  is situated within an overhead portion  67  of the station framing  52 . 
     Referring jointly to FIGS. 8 and 9, an annular heat resistant resilient seal  68  is disposed within an annular groove  69  at the underside of the peripheral region of closure  56 . The seal  68  protrudes downward from the closure  56  and is proportioned and positioned to seat against the previously described step  23  formed by the flange  22  at the top of the cart  11 . Thus downward pressure on the closure  56  compresses the seal.  68  and hermetically seals the sterilization chamber  16 . The downward pressure can be exerted by the previously described fluid actuators but the resulting force is exerted on the entire cart including the support wheels and may unevenly compress different portions of the seal  68 . It is preferable that the closure  56  be of the known form having radially directed crimp arms  71  which extend and pivot in response to turning of a control wheel  72  in a manner which causes the arms to enter the apertures  24  in flange  22  and to crimp the closure and flange together. The detailed construction of such closures, used for such purposes as sealing bulkhead openings in ships, is known to the art. 
     The control wheel  72  may be turned manually if desired but in this example is turned by a reversible electrical motor  73  carried by the closure  56 . Alternately, motor  73  may be a hydraulic motor. 
     One of pair of vertically directed positioning pins  74  extends downward from each of the closure support arms  59 . Referring to FIGS. 3 and 7 in conjunction, pins  74  are positioned to enter the previously described pin guides  33  at each side of the cart  11  and act to assure that the step  23  at the chamber opening is in precise register with the closure  56  in order to effect the sealing operation. As the guide passages  34  in the guides  33  are tapered, downward travel of the pins  74  can shift the cart  11  laterally if necessary to assure registry. 
     Air is evacuated from the sealed sterilization chamber  16  at the start of a sterilization step and high temperature pressurized steam is directed into the chamber for a period of time sufficient to destroy infectious organisms. Steam condensate is evacuated from the chamber during this period. The initial evacuation of air is desirable as pockets of air within plastic bags and the waste itself constitute thermal insulation which can slow the transfer of heat to the wastes. 
     Referring to FIGS. 5 and 7, the evacuation pump  76  of this example is situated in the overhead portion  67  of framing  52  and is coupled to the sterilization chamber  16  through a flexible hose  77  which connects with the closure  56  and which has sufficient slack to accommodate to the vertical movement of the closure. Hose  77  communicates with a passage  78  in closure  56  located to seat over the previously described enlargement  42  and seal  41  at the top of extraction tube  39 . Pump  76  is preferably of the known steam jet operated aspirator type and receives steam from the steam supply  79  through solenoid operated control valve  81 . Steam condensate extracted from the sterilization chamber  16  is temporarily stored in a condensate tank  82  at the back of the sterilization station. 
     Many hospitals and the like have a pre-existing source of steam which is used for heating and/or other purposes. The steam supply  79  of this sterilization station  48  is simply a conduit  83  which is connectable to a pre-existing steam source. A boiler for generating steam can be provided in instances where a pre-existing steam source is not available. Steam from the supply  79  is directed into the sterilzation chamber  16  through a solenoid operated control valve  84  and another flexible tube  86  which connects with a passage  87  in closure  56 . 
     A housing  88  at one side of the sterilization station framing  52  contains switches  89  for selectively energizing and operating the electrically controlled devices such as solenoid operated valves  66 ,  81  and  84 , closure motor  73  and the motor driven hydraulic fluid pump  84 . Automatic cycling of these devices can be provided for if desired. 
     Referring to FIG. 10, the dumping and compaction station  49  has a compactor  91  which may of the known type in which a elongated housing  92  extends a short distance into a conforming opening  93  at the base of a transportable bin  51  which can be loaded onto a truck and hauled to a landfill or the like for disposal of wastes. Wastes deposited through a door  94  at the top of the compactor housing  92  are forced into the bin  51  and compacted in the process by a translatable ram plate  96  within the housing that is driven by extendible hydraulic actuators  97 . The station  49  also includes a dumper  98  which may be of one of the known types. The dumper  98 , operated by a rotary hydraulic actuator  99  in this example, engages the lifting handles  21  of cart  11  and lifts and tilts the cart to deposit the contents in compactor  91 . The cart  11  is then returned to the source of the infectious wastes for reuse in the manner which has been previously described. 
     Referring again to FIGS. 1,  2  and  3 , a detachable air evacuation unit  101  can protect personnel from airborne contamination during the initial deposit of wastes in the cart  11 . The unit  101  of this example has a casing  102  shaped to rest against the exterior side surface of cart  11 . Casing  102  is suspended from the drum flange  22  by two air intake tubes  103  which have air intake fittings  104  at their upper ends that are also clips that fit onto the top of the flange  22 . Air intake openings  106  in the fittings  104  face the region that is immediately above the waste receiving chamber  16 . 
     Casing  102  contains an air filter  107  preferably of the dual process HEPA type which is disposed against a slotted outer wall  108  of the casing that allows air which has been directed through the filter to escape from the casing. An air pump  109  within casing  102  draws air into intake fittings  104  through tubes  103  and discharges the air through filter  107 . Pump  109  is driven by an electrical motor  111  in casing  102  that is energized by a rechargeable battery  112 . A control switch  113  on casing  102  enables a person who is about to deposit wastes in the cart  11  to turn the motor  111  on prior to opening the lid  29  of the cart  11 . Consequently, air flow from the opened chamber  16  is drawn into fittings  104  and is filtered rather than traveling towards the person who is depositing waste. The air evacuation unit  101  preferably includes a timer  114 , which may be adjustable, that automatically shuts motor  111  off after a period of time sufficient to accomplish the deposit of wastes. The air evacuation unit  101  may be detached from cart  11  during sterilization step. 
     The direct attachment of the air evacuation unit  101  to the cart  11  for travel therewith is particularly advantageous when the cart is used as a collection cart to pick up wastes which have been initially deposited in a series of receptacles situated at different locations. Referring now to FIG. 11, a different arrangement of the unit  102  can be advantageous where the cart  11  remains at one location during the waste collection step and is itself the receptacle into which wastes are initially deposited. In this mode of operation, the cart  11  may be partially entered into an open fronted fixed housing  116  which has a hood  117  at the top that partially encloses the region above the cart  11 . An air evacuation unit  101 , essentially similar to that previously described, is secured to the back of the hood  117 . The relatively long air intake tubes of the previously described embodiment may be replaced with shorter tubes  118  which draw air through the hood from the region which is above cart  11  during periods when the cart is opened for deposit of wastes. 
     While the invention has been described with reference to certain specific embodiments for purposes of example, many modifications and variations are possible and it is not intended to limit the invention except as defined in the following claims.