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FIELD OF THE INVENTION 
       [0001]    This invention relates generally to the field of wastewater systems and in particular to a passive collector of fats, oils and grease of the type that is typically associated with a wastewater drainage system for a food service establishment. Most particularly this invention relates to a grease trap or collector which is used to collect such fats, oil and grease from a sink or drain from a commercial kitchen or the like to prevent the same from being discharged directly into a municipal wastewater system. 
       BACKGROUND OF THE INVENTION 
       [0002]    Grease traps or interceptors are well known and used extensively to collect fats, oil and grease (“F/O/G”) from the wastewater discharge streams from commercial food service establishments such as kitchens and restaurants. In many jurisdictions there are by-laws or other local rules which require the owners or operators to use such devices to prevent the F/O/G from being freely discharged and then fouling the downstream wastewater system. 
         [0003]    Typically in the past these grease interceptor devices have taken the form of steel containers or vessels which are positioned in the wastewater effluent stream downstream of the food preparation areas. Often they are large volume containers which are sunk into the floor with removable lids at or slightly above grade. They are typically immovable and plumbed into place. Water from the sinks or dishwashers flows, by gravity, into and then out of the devices, and is then carried away by the wastewater or sewer system. Baffles and the like are positioned inside of the container to trap the floating F/O/G within the container to prevent it from entering into the sewer system. However, even with a large container, over time the FOG builds up and then the grease interceptor needs to be emptied. 
         [0004]    Typically such devices are built with a removable lid so that the floating F/O/G can be periodically removed from the top of the container. There are several methods used to empty the F/O/G from the container. In some small volume devices an employee may be asked to remove the top of the container and then bail out the F/O/G into a ladle or bucket and then dump the removed material into a dumpster or other solid waste container. In other cases a service will be used to bring a pump out truck to pump out the F/O/G from the container, once the lid is taken off. In this case a long hose is threaded from the truck to the container and the F/O/G is sucked out through the hose. Various other means of emptying the container also exist. 
         [0005]    However, in all cases when the lid is taken off the smell is very strong and noxious. The smell can penetrate clothing, foul the air and typically will be located deep within the kitchen. Nasty smells within the kitchen can be very off putting for customers of the food service establishment, as well as the employees. Therefore the F/O/G removal operation is often scheduled for late at night or early in the morning when the facility is otherwise closed. However in some cases the food service facility may be open  24  hours per day making this scheduling more difficult. Furthermore, in some applications such as a shopping mall food court, the grease interceptor may be located at such a distance from an outside wall that it can be difficult to stretch the suction hose from the truck to the interceptor. What is desired is a way to accomplish the removal of the F/O/G without exposing the employees and customers to the foul smells associated with the accumulated F/O/G while improving the cost effectiveness and convenience of the F/O/G collection process. 
       SUMMARY OF THE INVENTION 
       [0006]    Accordingly the present invention provides a grease interceptor system which includes a grease trap that comprises a portable light weight container body, which can be easily connected and disconnected to the wastewater system for pick up and removal, without the need for the container to be opened during this removal step. The present invention provides for an above grade mounting for the container body of the grease interceptor in between opposed inflow and outflow portions of the wastewater drain pipes. The body includes inflow and outflow openings which are sized and positioned to be connectable to the drain pipes. The drain pipes are provided with shut off valves to permit the drain pipes to be closed when the grease interceptor is disconnected from the drain pipes. There is also provided easy to use pipe couplings to fluidly connect to the container body of the grease interceptor to the drain pipes. 
         [0007]    In one embodiment the present invention provides a method whereby a container body which is full of trapped F/O/G may be removed by means of a hand cart placed under the bottom of the grease interceptor container body. Plugs, such as screw thread caps, or valves are provided to permit the inflow and outflow openings of the full grease container to be sealed for transport once the container body is disconnected from the inflow and outflow lines. Means are provided on the body of the grease interceptor to temporarily displace the connecting elements laterally as the body is placed into or pulled out of position between the drain pipes, to protect the seals, o-rings and coupler stems that are present on the container body to provide the hydraulic connection to the wastewater drain. 
         [0008]    Thus according to the present invention a replaceable grease interceptor can be removably secured in place in a wastewater line to collect F/O/G. When full, a service is called and a clean, empty unit is wheeled into the kitchen on a hand cart. The wastewater flow line valves are shut both upstream and downstream of the container body and the couplers are disconnected. Then the full unit can be moved slightly, in a direction generally perpendicular to the axis of the pipe connections, by placing the hand cart under the unit and levering it up and pulling it out slightly, to permit closure members, such as the plugs, stoppers, caps or other sealing means to be threaded, or otherwise secured in place to seal the pipe openings in the body. Then the full unit can be fully removed from between the inlet and outlet drain pipes. It will be noted that this initial movement of the container body can be accomplished without tilting the body side to side thus reducing the chances of causing a spill out of the pipe coupler openings, before the drain plugs are secured in the openings. Once the full unit is removed from between the upstanding pipes the clean unit can be placed in position. 
         [0009]    The clean unit is positioned between the drain pipes and coupled to the drains. Once this is done the valves upstream and downstream on the wastewater lines can be re-opened to permit the water to drain through the unit whereby fresh F/O/G will be captured. The full unit can be wheeled away to a truck or the like for eventual disposal at a land fill site or the like or for recycling as appropriate. In this way the F/O/G remains substantially enclosed as the container is moved through the kitchen and then out through the commercial establishment and the bad smell is greatly reduced if not eliminated. A single service truck can be provided with multiple replacement containers and can follow a route to service many separate commercial restaurants by pulling the full units and replacing them with empty units as needed. Over time the route can be timed to co-ordinate with the frequency of the haul away need of the establishment. 
         [0010]    Thus according to a first aspect the present invention provides a grease trap system for wastewater systems, said grease trap system comprising: 
         [0011]    a ground engaging frame into which a replaceable container body may be inserted, 
         [0012]    an inlet pipe connector with shut off valve on an inlet side of said frame; 
         [0013]    an outlet pipe connector with a shut off valve on an outlet side of said frame; 
         [0014]    a grease interceptor comprising a replaceable container body including means to trap fats, oils and grease within said replaceable container body and further being sized and shaped to be positioned within said frame and connected to said inlet and outlet pipe connectors, said container body including inlet and outlet slide couplers through opposed walls of said body, said inlet and outlet slide couplers having associated connecting means to sealingly fluidly connect said inlet and outlet connectors to said container body, said inlet and outlet slide couplers being further configured to be sealed for transport of said container body by a closure member; 
         [0015]    wherein said slide couplers laterally displace away from said inlet and outlet connectors when said container body is being replaced. 
         [0016]    According to another aspect the present invention provides a method of collecting grease from a wastewater stream comprising the steps of: 
         [0017]    positioning a replaceable container body between a pair of inlet and outlet connectors mounted on a frame, wherein said connectors are connected to a wastewater drain and fluidly connecting inlet and outlet slide couplers on said body to said connectors so wastewater flows through said container body; 
         [0018]    capturing fats, oils and grease in said container body over time; 
         [0019]    shutting inflow and outflow pipe valves to stop the flow of wastewater through said body; 
         [0020]    displacing one or both of said inlet and outlet pipe connections and said inlet and outlet couplers laterally to permit said container to be removed from between said connectors without interference at said connectors; 
         [0021]    sealing inlet and outlet slide couplers on said container to ready said container body for transport; and 
         [0022]    transporting said sealed container to a remote location to be emptied and cleaned. 
     
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         [0023]    Reference will now be made to preferred embodiments of the invention by way of example only to the following illustrative figures in which: 
           [0024]      FIG. 1  is a front view of a container according to present invention in place and fluidly connected to a wastewater flow line; 
           [0025]      FIG. 2  is a close up of an inflow connection portion according to a preferred aspect of the present invention ready to connect to the wastewater flow line; 
           [0026]      FIG. 3  is the same view as in  FIG. 2  with the inflow connection portion connected to the wastewater flow line; 
           [0027]      FIG. 4  is a view of the inflow connection portion of  FIGS. 2 and 3  disconnected from the wastewater line and with a plug sealing the inflow connection portion so the container may be transported without spilling it contents; 
           [0028]      FIG. 5  is a view from behind showing a support frame according to a preferred aspect of the present invention; 
           [0029]      FIG. 5   a  is a close up view of a section through an orientation tab on the frame of the present invention; 
           [0030]      FIG. 6  is a cut away view of the full sealed container ready for transport. 
           [0031]      FIG. 7  is an exploded view of a further embodiment of an attachment assembly according to the present invention; 
           [0032]      FIG. 8  is a top view of the attachment assembly of  FIG. 7  in an attached position where wastewater can flow through the assembly; 
           [0033]      FIG. 9  is a top view of the attachment assembly of  FIG. 8  partially uncoupled from the fixed wastewater plumbing; 
           [0034]      FIG. 10  is a top view of the attachment assembly in a fully disconnected position; and 
           [0035]      FIG. 11  is a view of an alternate embodiment of a container according to the present invention. 
       
    
    
     DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS 
       [0036]      FIG. 1  shows a preferred embodiment of a grease trap system  10  according to the present invention from the front, having a grease collector or container body  11 . The system includes an inlet pipe connector  12  having a drain pipe receiving collar collar  14  to which a conventional drain pipe  15  from a sink or the like can be joined in the usual manner such as by solvent welding. The inlet pipe connector  12  is preferably carried on a frame  16 , which holds the connector  12  in position even when the connector  12  is not connected to a drain pipe  15  or a container  11 . As will be explained in more detail below the present invention requires the inlet connector be carefully positioned so that a connection can be made to the container  11 . Thus, the frame  16  is useful to position the inlet coupler in the right position for the installer, who merely has to connect the pipe  15  to the inlet connector, without having to worry about putting the connector in the right place in space. The inlet pipe connector  12  includes a shut off valve  18  and ends with a threaded pipe end  20  having a groove  21  with an o-ring seal  22 . A manually operated gate valve  18  with a twist lock feature to prevent accidental release has provided good results. Most preferably the grease trap system  10  is positioned below or close to a sink so the drain pipe  15  has a minimum run and does not form an obstruction to movement of employees within the kitchen. The threaded pipe end  20  can be molded in as part of the valve  18 , or can be as shown, namely, a separate sleeve that is threaded or solvent welded onto the valve  18 . 
         [0037]    The threaded pipe end  20  is sized and shaped to engage with and seal with a slide coupler  22  mounted in an inlet sleeve  24  of the container  11 . The slide coupler  22  defines an inlet opening  26  in an upstream side  28  of the container body  11 . The slide coupler  22  is comprised of an internally threaded collar  30  rotatably mounted on an outside stem portion  32 , in a channel  34 . The channel is formed by shoulders  33 ,  35  ( FIGS. 2 and 3 ) which trap the collar  30  in place relative to the slide coupler  22 . The threaded collar  30  can be manually turned onto and off of the threaded pipe end  20 . The outside stem portion  32  is secured to an internal stem portion  36  that includes a limit stop lip  38  and a pair of o-ring seals  40  and  42  ( FIG. 2 ) secured in channels  44  and  48  ( FIG. 2 ) respectively. The inside and outside stem portions  32 ,  36  may be threaded together as shown at  37 , solvent welded or joined in any other manner that ensures a secure liquid tight connection. 
         [0038]    The container body  11  is preferably made from molded plastic and sized and shaped to hold a reasonable amount of liquid inside. Plastic has the advantage of being reasonably light weight, easy to clean and inexpensive to manufacture, but the present invention comprehends that other materials may also be used without departing from the scope of the invention. The container body  11  includes a removable top or lid  50 , which can be secured to the container body  11  in a liquid tight manner, such as through the use of fasteners clips and seals or the like as is known in the art. Most preferable the container body  11  includes the usual baffles and grease separating structures (not shown) within to allow the container body  11  to trap grease oil and the like over time as wastewater flows through the body  11 . As will be understood wastewater will enter through an upstream side  28  and then exit the container body  11  through a downstream side  52  and then be carried away by an outlet drain pipe  54 . 
         [0039]    As well as the inlet pipe connector  12  there is provided an outlet pipe connector  60  on the frame  16  on the downstream side  52  of the container body  11 . As can now be better understood the frame holds both the inlet and outlet connectors in the correct position to accommodate a container  11  there-between and so greatly helps in installing the connectors in the correct position when they are first plumbed into the wastewater drain pipe. The outlet pipe connector  60  is preferably the same as the inlet pipe connector  12  previously described, only in reverse. There is an outlet sleeve  62  which most preferably is at a height relative to the inlet sleeve  24  that allows the wastewater flowing into the container body  11  to the flow out of the container  11  by gravity drainage with the F/O/G trapped inside. 
         [0040]    Located within the outlet sleeve  62  is an outlet slide coupler  64  which is comprised of an internal stem portion  66  and an external stem portion  68 . Again these may be joined together by threads, solvent welding or the like. The internal stem portion  66  includes a stop lip  70 , and a pair of o-ring seals  72 ,  74  located within channels  76 ,  78  respectively to seal against an inside surface of the outlet sleeve  62 . The external stem portion  68  includes a receiving channel  80  in which an internally threaded collar  82  is rotatably received. Once again the slide coupler  64  may move back and forth within the outlet sleeve  62 , by means of the difference in distance between the internal side of the collar  82  and the end of the sleeve  62 . 
         [0041]    Downstream of the outlet slide coupler  64  is the outlet pipe connector  60 . As with the inlet pipe connector  12  the outlet pipe connector  60  includes an externally threaded tube which forms an outlet pipe  86  onto which the threaded collar  82 , may be secured. Again an o-ring seal  88  may be used to seal the slide coupler  64  to the outlet pipe  86 . Also the outlet pipe connector  60  includes a manually operable shut off valve  90  to shut off the water flow through the pipe  86  when the valve is shut. 
         [0042]    As shown in  FIG. 1  both the inlet and outlet pipes  15 ,  54  are in the form of a gravity drainage wastewater pipes and need to be plumbed with the drainage slope as is required by code or the like to ensure good drainage of the wastewater through the pipes.  FIG. 1  also shows support rails or posts  65  which raise the bottom  67  of the container body  11  off the floor to permit lifting forks  69  of a dolly or lift truck (not shown) to fit underneath the bottom  67 . An orientation tab  214  is also shown which is explained in more detail below. 
         [0043]    Turning to  FIGS. 2 ,  3  and  4  there is shown a close up view of the inlet connector  12  and the slide coupler  22  according to the present invention in three different positions. Although showing only the inlet side, it will be understood that the outlet side will be substantially the same. In  FIG. 2  the slide coupler  22  is displaced inwardly towards the container  11  to permit the container  11  to be inserted or removed from between the inlet and outlet connectors  12 ,  60 . In  FIG. 3  the slide coupler  22  is extended outwardly and connected to the connector  12  to permit wastewater to flow through the connection to permit the collection of F/O/G within the container  11 . In  FIG. 4  the slide coupler  22  is shown with a seal or plug, which is used to contain the fluids inside of the container  11  when transporting a full container. 
         [0044]    It will be appreciated by those skilled in the art that although threaded engagements are shown between the slide couplers  22 ,  68  and the connectors  12 ,  60  and have been found to work well, other types of connection can also be used, such as a bayonet type mount or the like. All that is required is for the components to be manually coupled together in a manner that permits them to be easily connected and disconnected as and when required, preferably without the need for any tools or the like. As well, although there is reference to the sealing ring  21  being placed on the threaded pipe end  20  of the connector it will be understood that the sealing ring could also be placed on the other component as a matter of design choice without departing from the spirit of the present invention. 
         [0045]      FIG. 2  shows the present invention configured for insertion or removal of a container  11  into position between the connectors  12 ,  60  on the frame  16 , with only the inlet side being shown. In this view the slide coupler  22  is displaced inwardly towards the container  11  and a gap is shown at  100  between the stop lip  38  and an inside wall of the container  11 . This gap  100  permits there to be a smaller gap at  102  which allows the threaded collar  22  to be displaced away from the threaded pipe end  20 . As can now be more clearly understood the slide couplers of the present invention provide a certain amount of axial movement along a centerline axis of the wastewater pipe or generally orthogonal to the inlet and outlet sides  28  and  52  of the container  11 . The present invention comprehends a number of ways of providing this axial movement, such as by using flexible pipes or the like, but good results have been achieved through the slide couplers as described above. What is desired is to allow the inlet and outlet couplers to connect to the inlet and outlet sleeves of the container but to have enough space between the connecting elements to permit the connection elements to be out of contact with each other to permit the container  11  to be easily removed from between the connectors at both ends along an axis generally perpendicular to the direction of the axial movement of the slide couplers. In this way there is no interference between the inlet and outlet couplers and the container when the container is being moved. 
         [0046]    Most preferably the external ends of the slide couplers will be displaced away from the connectors (i.e. towards the container  11 ) when disconnected as described above. This will allow the container  11  to be lifted up, for example, on a lift cart or dolly with lifting forks  51  and moved back from between the pipes. Ideally the present invention allows the lifting and movement of the container to occur in a plane perpendicular to the plane of the pipes. This avoids a problem of the prior art where the lifting of one end of the container, while the other end was still partially engaged with the pipes might lead to tipping the container and accidental spilling before the container is fully disengaged from the pipe connections. 
         [0047]    In  FIG. 3  the slide coupler  22  has been slid out until the internal threads of the collar  30  can engage the threaded pipe end  20 , and then the collar  30  is turned to cause it to engage with the threaded pipe end  20 . As the collar  30  is turned on, the slide coupler  22  is moved along the inlet sleeve axis away from the container  11  by the turning action of the collar  30  on the threads  20  until the collar  30  is fully threaded on the pipe  20 . At this point the o-ring seal  21  is engaged with a sealing surface  104  on the slide coupler  22 . As can be seen the gap  106  is much smaller than the gap  100  shown in  FIG. 2  as the collar has pulled the slide collar out almost the full distance of the gap  100 . During this movement the two o-ring seals  40 ,  42  remain in contact with the inner surface of the inlet sleeve  24  and maintain a sliding sealing engagement therewith. 
         [0048]      FIG. 4  shows a view of the container  11  with a closure member, in this case a plug  130  in place in the slide coupler  22 . This occurs once the container  11  has been removed from between the inlet and outlet couplers as described above. The plug  130  is threaded and mates with the threads on the collar to form a liquid tight joint. An o-ring  140  is provided to seal against the sealing surface  104  of the slide coupler  22 . With the plug  130  in place the full container may be easily transported around without spilling or losing any of the contents of a full container  11 . It will be appreciated by those skilled in the art that while the drawings show plugs being used to close the openings on the grease interceptor, other closure members such as stoppers, caps, valves or the like are comprehended by the present invention. Further, such devices can be threaded, frictionally fit, bayonet mounted, or otherwise secured to the open ends without departing from the scope of the present invention. 
         [0049]    The frame  16  can now be understood in better detail. The frame  16  is shown from behind in  FIG. 5 . As shown the inlet and outlet connectors are held in position by the frame in the exact locations where they can be connected to the slide couplers of a container. Thus they have to be spaced and positioned in the correct locations so that a standard sized container  11  can be easily connected and disconnected to the couplers as described above. The frame  16  is configured to allow the container to slide into place between the connectors and is provided with a pair of support rails  65  upon which the container rests. This provides a space under the container into which the forks or edge of a lifting truck can be inserted. As well, the present invention comprehends that the frame will include an orientation tab  214 , which fits into an indentation  216  formed into the container  11  to ensure that the container  11  is inserted between the inlet and outlet connectors in only the correct orientation for the capturing of the F/O/G within the container  11 . The orientation tab is offset from the center of the container so that if the container is reversed the parts won&#39;t fit and the container cannot be connected to the slide couplers as required. As will be understood by those skilled in the art, the interceptor is designed to capture F/O/G that flows through in a preferred direction. If the unit was mounted in reverse orientation, this would affect the ability to collect and trap F/O/G. Thus the restricted orientation is believed desirable. 
         [0050]      FIG. 6  shows a sectional view of a container  11  which is full and being replaced. The inlet and outlet features are shown as  82  and  84  and the plugs are in place to seal the container. There is a layer of trapped F/O/G at  90  and a layer of water at  92  underneath. All that is required to clean the unit is to take it to a solid landfill site, remote the top, dump out the contents and wash with a pressure sprayer or the like. Since this can be done at a location remote from the food service establishment, there is no risk of the strong odours offending the customers. 
         [0051]    Having now described the various components of the invention the operation of the invention can now be more clearly understood. First a clean container is put into place between a pair of connectors as described above. The container will sit up slightly on supports that are positioned in such a way to permit conventional lift truck, or dolly forks, to be inserted under the container  11  to easily manipulate it when full. Various forms of lift truck are available so the present invention comprehends various forms of supports positioned and configured for the type of forks to be used. According to the present invention therefore the supports are positioned under the container to allow easy access for lifting forks under the container and to center the lifting to avoid tilting the container, which is important as explained below. 
         [0052]    Then both on both sides the wastewater drain pipes, inlet and outlet, are coupled to the container  11  by extending the slide couplers out of the containers until they are sealed with the connectors. Then the valves are opened and wastewater is allowed to flow into and then out of the grease trap in the usual hydraulic gravity feed fashion. Over time grease and oil will collect and at a certain point it will be necessary to empty the container  11 . In this case a service is called. The service will bring a fresh clean and empty container body to the site. They will then shut off the flow of wastewater through the pipes by turning off or closing the inlet and outlet valves. Next they will position a dolly under the full container and get ready to lift the same. Then they will unscrew the threaded sleeves, the action of which moves the slide couplers in towards the container  11  and then gently lift the container  11  up with the dolly, and back slightly, without tiling it so much that it spills. At this point it is only necessary to move the container  11  enough to provide access to the slide couplers to screw in a drain plug on either side of the container. The next step is to continue to guide the container from out between the inlet and outlet connectors and the frame  16  until the full container is clear. Since it is now sealed it will not be emitting any odours. Once the full container is out of the way, the fresh clean container can be positioned on the frame  16  between the threaded pipe ends and fluidly connected to the upstream and downstream pipes by means of the collar connectors. The next step is to open the valves to get the wastewater flowing again through the empty container body. Then the full container, which is sealed by reason of the plugs, is taken out to a waiting truck for transport. In this sealed state it can be easily wheeled out of the food service establishment without offending any staff or patrons. 
         [0053]    Now that the container is sealed and moveable it may be taken to a remote site, by truck for example to be emptied and cleaned. Alternatively, the restaurant staff may disconnect and remove the unit and take it to their grease collection bin usually located behind the restaurant where they will remove the grease manually. Then it can simply be reinstalled in place. A preferred form of cleaning includes using water such as a hose or pressure sprayer to clean out the container of any solids collected in the container. The plastic will easily wash clean. By providing a removable top or cover it will make the container easier to clean and empty and the container top need not be opened until the container is at a disposal site such as a land fill disposal site. Thus the bad odours that are emitted will not be in close proximity to the food service areas. 
         [0054]    It can now be appreciated that the present invention permits the replacement of full containers with empty containers without the need to expose the trapped fats oil and grease to the open air. Thus, by means of the dolly and the closure members or plugs, the present invention comprehends an easy, clean and smooth exchange of empty containers for full containers according to a service schedule that can be determined based on the usage and need of the food service establishment. Further the positioning of the inlet and outlet opening on opposite side walls of the device permits the initial lifting of the full container body to occur without tilting, ensuring that there is no spillage before the plugs can be put in place. 
         [0055]    A second embodiment of an attachment assembly for connecting the container  11  to the fixed wastewater piping  15 ,  54  is shown in exploded view in  FIG. 7 . The second embodiment permits the container to be sealed and disconnected from the fixed piping or conversely unsealed and connected to the fixed wastewater piping with a simple one handed motion as explained below. As shown an upper actuator plate  300  and a lower actuator plate  302  are connected together by, among other things, push/pull handles  304  and  306  at either end, which fit into holes  305  and  307  respectively. As described below, the handles may be used to push or pull the upper and lower actuator plates laterally between a first position forming liquid tight sealing connection between the container and the piping and a second unsealed position to allow the full container  11  to be replaced. In the sealed position the container  11  can be used to collect grease and the like and in the other position the container will be separated from the piping and sealed against spillage to allow the full container to be removed and replaced with an empty one. The handles  304  and  306  straddle the inlet/outlet pipe assembly portion  308 . Although the drawings only show one side of the container it will be understood by those skilled in the art that a similar assembly will be provided on each side of the container to permit the quick connect and disconnect method to be used at both the upstream and downstream connections for the container  11 . Further although the discussion focuses on the upper actuator plate  300 , it will be understood that the lower actuator plate  302  is the same and operates the same way. 
         [0056]    An outwardly extending sleeve  310  is formed on the container  11  onto which is surmounted an outer sleeve  312 . A guide pin  314  is positioned on the sleeve  312  and is retained in a slot  316  of the upper plate  300 . A similar guide pin  318  extends from the bottom of the sleeve  310  into a guide slot  320  of lower plate  302 . 
         [0057]    A slide coupling element  322  is slideably engaged in the outwardly extending sleeve  310 . The slide coupling element  322  has two o-rings  390  and  392  mounted thereon. As in the previous embodiments the element  322  slides in and out relative to the sleeve  310  to seal and unseal with an end of the fixed wastewater piping. The slide coupling element  322  slides within an inner sleeve member  321  which seals against an inside of the container by means of gasket  319  and is secured in place by nut  317 . The nut  317  also secures the outer sleeve  312  in place. 
         [0058]    Adjacent to the other end of the assembly  308  is a wastewater piping shut off valve  324  having a handle  323  for opening and closing the shut off valve  324 . The shut off valve  324  is attached to an end of the fixed wastewater pipe (not shown) such as  15 ,  54 , and is permanently fixed at that location. The valve  324  can be opened and closed by pulling or pushing of the handle  323 . As previously described the shut off valve  324  allows the pipes  15 ,  54  to be sealed during the replacement and removal of a full container with an empty one. On the container side of the valve  324  is located a sleeve  325  having upper and lower locking pins  326  which engage with locking arms  327  of the upper and lower pivoting locking plates  328  in a manner as described below. Because the locking pins  326  are located on the shut off valve, which is fixed in position, the locking pins  326  do not move during coupling and decoupling of the container to the fixed wastewater piping. 
         [0059]    A further pair of pins  330  are provided extending from the sliding coupling element  322 . The pivoting locking plates  328  have curved slots  336 , which interact with pins  330  to extend and retract slide coupler  322 , and a locking slot  338  which helps define the locking arm  327  to secure the slide coupler  322  into sealing engagement with shut off valve assembly  342  and in particular with the sleeve  325 . It will be understood that similar slots and pins exist with respect to both the upper and lower plates  300  and  302 , so that the slide coupler is secured in diametrically opposite positions about the pipe to ensure a good fit and seal. Also shown is pin  344  which extends into upper plate  300  and lower plate  302  through slots  346  which controls the movement of the pivoting locking plates  28  as described below. 
         [0060]    Also shown in top plate  300  is angled slot  350  which carries a pin  352  attached to a container shut off valve  354 . The actuation of the container shut off valve  354  is controlled by the movement of the pin  352  in the slot  350  as described below as well as the movement of the plates during the coupling or uncoupling steps. The slot  350  includes a bend as shown to accommodate the inward and outward motion of the slide coupler  322  during the coupling uncoupling steps as described below. 
         [0061]    Having described the elements the operation of the present embodiment can now be understood.  FIG. 8  is a view from above of the attachment assembly  308  attached to a container and a fixed wastewater piping system (not shown) such as  15 ,  54  ending is a shut off valve  324  and capable of having liquid flow through the attachment assembly  308  out of the container. As shown the handle  323  of the shut off valve  324  is pulled out permitting liquids to flow through the valve  324 . 
         [0062]    As shown the top plate  300  and the bottom plate  302  are positioned to the left which has a number of effects. The first is that the pin  352  has carried the container shut off valve  354  to an open position. The second is that pivoting locking plate  328  has pivoted about the guide pin  314  to a position where the locking arm  327  has engaged fixed locking pin  326  to help draw the slide coupler  322  into sealing engagement with the sleeve  325 . As well, the curved slot  336  has interacted with pin  330  to help draw the slide coupler out and into sealing engagement with the sleeve  325 . 
         [0063]    The following sequence is used to detach the assembly  308  from the valve  324  as shown in  FIGS. 9 and 10 . First the piping shut off valve  324  is closed in direction C by pushing in the handle  323  and closing the pipe  15  to the flow of liquid. Then a user grips the handle  300  and draws it towards the right as shown by arrow O in  FIG. 8  as shown in  FIG. 9 . As the handle is pulled and the top and bottom plates  302  and  304  are displaced to the right the following things happen: the pin  352  of the container shut off valve  354  moves along the angled slot  350  until it is at an end of the slot  350  and after that further movement of the top plate  300  to the right will cause the container shut off valve  354  to slide in valve housing  360  ( FIG. 7 ) until eventually it covers an open end of the sliding sleeve  322 . During this time, the pivoting locking plate  328  pivots about the fixed guide pin  314  to allow the locking arm  327  to disengage from fixed locking pin  326 . As well, the pin  330  on the slide coupler  322  is forced along the curved slot  336  whereby the slide coupler is forced to the present invention comprehends that other mechanical structures can be used to implement the desired functionality of an easy to use quick disconnect and quick connect design. What is most desired is a structure that translates a simple hand motion into causing the slide coupler to displace axially in a direction into or out of the container while at the same time forming a seal or plug against spillage out of the container  11  through the slide coupler during movement of the full container as it is replaced and taken away to be emptied. For example, instead of using a lateral motion as shown the present invention comprehends using a lever to cause a rotational motion about an axis defined by the centreline of the slide coupler. In this case a screw thread or the like can be used to advance and withdraw the slide coupler. Further, while the design shown includes a seal against spillage being formed on an outside of the container it is also comprehended that the seal against spillage can be formed within the container such as by overlapping slots in an inlet sleeve which can rotate open and closed. However, the lateral movement design described above is the most preferred at present. 
         [0064]      FIG. 11  shows a further embodiment of the container which includes a toe space  500  formed into the bottom edge  502  of the container  11 . The present invention needs to be placed in a position, for example in a kitchen, where there is easy access to it to permit the containers to be changed as needed. Convenient locations include under a sink or under a counter. However, in such a location the bottom edge of the container may represent an ergonomic issue to those needing to use or work in the sink or counter. As such a toe space formed in the container as shown permits ergonomic access to the sink or counter above by kitchen staff or the like by allowing the user to move closer and reducing the amount of bending over and reaching. In an alternative embodiment the present invention comprehends using the frame or other spacer elements to create a toe space under the container body where there is enough head room under the sink or counter to permit the same. 
         [0065]    While the foregoing description has been in respect of preferred embodiments of the invention it will be understood that many variations and alternations are possible without departing from the scope of the invention as defined by the appended claims. Some of these have been discussed above and others will be apparent to those skilled in the art. For example, although plastic is preferred for both the container and the pipes, these could be made from other materials that were light weight and flexible.

Summary:
The present invention relates to a grease trap system for wastewater systems, having an inlet pipe with a shut off valve, an outlet pipe with a shut off valve and a grease interceptor comprising a replaceable container body including means to trap fats, oils and grease within the body. The body has inlet and outlet slide couplers in opposed walls, and each coupler has an associated connecting means to sealingly fluidly connect the slide couplers to the inlet and outlet pipes. When the container body is disconnected from the pipes the slide couplers may also be sealed by a removable plug for transport. The slide couplers displace inwardly and outwardly relative to the container to give clearance between the pipes to remove the container. A method of replacing full containers with empty containers is also comprehended.