Abstract:
A grease trap ( 1 ) device for trapping waste material including water and fats, oils and/or greases (FOGs), and for removing at least some of the FOGs from the water. The device includes a first receptacle ( 3 ) having a storage volume ( 31 ) for storing waste material in a manner that enables FOGs to float on the surface of the water; an inlet ( 9 ) for receiving waste material into the first receptacle; a drain ( 49 ) having an inlet ( 47 ) positioned to capture FOGs floating at and/or near the surface of the water, and an outlet ( 51 ) positioned for transferring waste material out of the storage volume; a valve ( 53 ) for controlling the flow of waste material through the drain; an outlet ( 15 ) enabling cleaned water to exit the first receptacle; and at least one heat exchanger unit ( 57,59 ) arranged to remove heat from the waste material stored in the first receptacle.

Description:
CROSS-REFERENCE TO RELATED APPLICATION 
       [0001]    This application claims foreign priority under 35 USC 119 to British application no. GB 1502432.6 filed Feb. 13, 2015. 
       FIELD 
       [0002]    The present invention relates to a grease trap device, and a water system including the grease trap device. 
       BACKGROUND 
       [0003]    Traditional grease traps are commonly used to capture fats, oils and/or greases (FOGs) from waste water generated by cooking and cleaning processes carried out in commercial kitchens. The FOGs are often generate in sinks, dishwashers and cooking appliances and are discharged directly into the kitchen&#39;s drainage system. Grease traps are installed in-line in the waste pipework leading from the kitchen, in order to mechanically trap the FOGs and facilitate their removal before the FOGs can reach the main sewer, where they can build up over time and cause damage to the sewage infrastructure by creating blockages. 
         [0004]    Grease trap technology is well-known and proven. A grease trap slows and temporarily captures FOGs laden water between baffles and allows the water time to cool. As the water cools, the FOGs congeal within the trapped water and naturally float to the surface of the water where they can be collected for removal for disposal or recycling. 
         [0005]    Ideally grease traps should be located outside of the kitchen area because they require opening on a regular basis in order to facilitate the removal and disposal of the captured FOGs. FOGs are usually removed from the grease trap by a specialist worker, who is equipped with specialist vacuum equipment required to suck out waste materials from the grease trap. 
         [0006]    By its nature, this work is messy, noisy and disruptive, and it is highly undesirable to open a grease trap in a commercial kitchen environment and expose the kitchen to the bad smells and the risk of contamination that this causes. In addition, calling in specialist contractors to empty grease traps on a regular basis is expensive. 
         [0007]    However, it is not always possible to locate a grease trap outside of the commercial kitchen due to space or access restrictions, and as a result, many kitchens are forced to endure the disruption and potential for contamination caused by opening the grease trap. In extreme cases, commercial kitchens are forced to close while the work is carried out, further adding to the disruption and cost. 
         [0008]    Commercial kitchens use a great deal of hot water for their cooking and cleaning operations, and the demand for hot water naturally coincides with times when the maximum volumes of waste water are likely to be discharged into the grease trap. In traditional grease traps, the heat energy is naturally dissipated through the outer walls and lid of the grease trap and is lost to the atmosphere. This is unsatisfactory. 
         [0009]    Traditional grease traps are manufactured from stainless steel or cast iron. This provides a structure having sharp edges and corners, which are extremely difficult to keep clean. This is unsatisfactory for a commercial kitchen. 
       SUMMARY 
       [0010]    Accordingly the present invention seeks to provide a grease trap device, and a water system, that mitigates at least one of the aforementioned problems, or at least provides an alternative to existing systems. In particular, the invention seeks to provide a grease trap device that achieves at least one of the following: removes the requirement for visits to the kitchen by specialist workers to carry out the grease trap emptying work; recovers and utilises heat energy from the waste water; provides a structure that is easier to clean than traditional grease traps. 
         [0011]    According to one aspect of the invention there is provided a grease trap device for trapping waste material, said waste material including water and FOGs, and for removing at least some of the FOGs from the water; said grease trap device including: a first receptacle having a storage volume for storing waste material in a manner that enables FOGs to float on the surface of the water; an inlet for receiving waste material into the first receptacle; a drain having an inlet positioned and arranged to capture FOGs floating at and/or near the surface of the water, and an outlet positioned and arranged for transferring waste material out of the storage volume; a valve for controlling the flow of waste material through the drain; and an outlet enabling cleaned water to exit the first receptacle. 
         [0012]    The present invention facilitates removal of FOGs from the grease trap by means of a drain-off valve which, when opened, automatically skims the correct level of fluid and FOGs from the surface of the water held in the grease trap. Removal of the FOGs by use of the drain-off valve means that there is no requirement to open or remove a grease trap lid, which remains sealed at all times, therefore greatly reducing the risk of bad odours or contamination in the kitchen from the contents of the grease trap. 
         [0013]    The invention provides a grease trap device which is designed to facilitate the safe, hygienic, and easy removal of grease from the grease trap on a regular basis by kitchen staff, thereby removing the requirement for visits to the kitchen by specialist workers to carry out the grease trap emptying work. By providing the means for kitchen staff to empty the grease trap themselves, the kitchen staff can decide on the most appropriate time to carry out the work and thereby reduce or eliminate disruption to the kitchen operation, as well as making a substantial saving on cost. 
         [0014]    Advantageous features of preferred embodiments are disclosed in the dependent claims and in the statements of invention below. 
         [0015]    The drain inlet is positioned below a maximum water level. The valve is located within the first receptacle. The waste material flows through the drain, when the valve is in an opened condition, under the action of gravity. The drain outlet is positioned and arranged to drain waste material out of the first receptacle. 
         [0016]    Advantageously the device includes a second receptacle for capturing the FOGs removed from the first receptacle via the drain. When the valve is opened, waste material is drained from the first receptacle and is deposited into the second receptacle. The waste material drained from the first receptacle includes FOGs, and typically includes a quantity of water. The contents of the second receptacle can be safely and hygienically removed for disposal into a suitable container. The drain outlet is positioned adjacent the second receptacle, and preferably above the second receptacle when the device is in its normal operating orientation. 
         [0017]    The second receptacle is movably mounted, and preferably slidably mounted, with respect to the first receptacle. In preferred embodiments the second receptacle is a separate component from the first receptacle and is removably mounted to the first receptacle. 
         [0018]    The first receptacle includes a base and at least one side wall. In preferred embodiments the first receptacle has a substantially cuboid form, and therefore includes four side walls. In preferred embodiments the second receptacle is located towards the base of the first receptacle. For example, a recess can be formed in a lower portion of the first receptacle and the second receptacle can be stored within the recess. 
         [0019]    Advantageously the device includes a locking mechanism for selectively locking the position of the second receptacle with respect to the first receptacle. 
         [0020]    Advantageously the device includes including a manually operable control for controlling operation of the valve. The manually operable control allows a user to open the valve to drain FOGs from the first receptacle. The manually operable control allows a user to close the valve to prevent further waste from draining from the first receptacle. 
         [0021]    In preferred embodiments the manually operable control controls operation of the locking mechanism. 
         [0022]    The manually operable control and the locking mechanism are arranged such that: the locking mechanism is in the locked condition when the valve is open, thereby locking the second receptacle to the first receptacle; and/or the locking mechanism is in the unlocked condition when the valve is closed, thereby unlocking the second receptacle with respect to the first receptacle. Thus it is not possible to remove the second receptacle from the first receptacle when the valve is open. It is only possible to remove the second receptacle with respect to the first receptacle when valve is closed. This prevents spillages from occurring. 
         [0023]    The first receptacle includes a reception volume adjacent the waste material inlet for receiving incoming waste material; a central volume for storing waste material; and an outgoing volume adjacent the outlet, through which the cleaned water passes on route to the cleaned outlet. 
         [0024]    Advantageously the device includes a first baffle located within the first receptacle adjacent the waste material inlet. The reception volume is partially separated from the central volume by the first baffle. The arrangement is such that waste material flowing into the first receptacle via the water inlet flows into the reception volume and around the first baffle into the central volume. The incoming waste material is directed towards the base of the first receptacle. The waste material flows under the first baffle into the central volume of the first receptacle, there being a gap between the base and a lower portion of the first baffle. Thus the central volume is contiguous with the reception volume. 
         [0025]    The waste material inlet is arranged substantially orthogonally to a surface of the first baffle which faces the inlet. The first baffle has a substantially rectangular cross-section, albeit with convex upper and lower surfaces. The waste material flowing into first receptacle follows a tortuous path. It is turned through approximately 90 degrees when it meets the first baffle. The water is turned through approximately 180 degrees when it meets the base. 
         [0026]    Advantageously the device includes a second baffle located within the first receptacle adjacent the cleaned water outlet. The outgoing volume is partially separated from the central volume by the second baffle. The arrangement is such that water flowing out of the first receptacle flows from the central portion around the second baffle, into the outgoing volume, and then into the cleaned water outlet. The outgoing water flows under the second baffle, there being a gap between the base and a lower portion of the second baffle. Thus the outgoing volume is contiguous with the central volume. 
         [0027]    The cleaned water outlet is arranged substantially orthogonally to a surface of the second baffle which faces the water outlet. The water flowing out of the first receptacle follows a tortuous path. It is turned through approximately 180 degrees, directed by the base and second baffle. When exiting the receptacle via the outlet, the water is turned through approximately 90 degrees. 
         [0028]    Advantageously the device includes at least one heat exchanger. 
         [0029]    The or each heat exchanger unit is arranged to remove heat from the waste material stored in the first receptacle. This feature enables the invention to recover and utilise heat energy from the waste material. It also promotes FOG congealing since the water stored in the first receptacle cools more quickly, which speeds up the congealing process. Therefore the waste material can have a shorter residence time within the grease trap. 
         [0030]    The or each heat exchanger unit includes an arrangement of piping. The piping is arranged in a tortuous fashion, typically in a coiled or raster pattern. The piping includes an inlet, which is connectable to a source of a heat transfer medium, for example a cold water supply. By feeding the heat transfer medium through the heat exchanger piping at a temperature that is lower than the temperature of the waste material in the first receptacle, heat is transferred from the warmer waste material into the heat transfer medium. The piping includes an outlet, which is connectable to, for example additional apparatus, such as a boiler or a storage receptacle such as a water tank. The heated heat transfer medium is fed to the additional apparatus, where the energy required to heat the heat transfer medium to an operating temperature is reduced because of the heat supplied from the grease trap. 
         [0031]    In preferred embodiments at least one of heat exchangers is removably mounted in the first receptacle. 
         [0032]    The first receptacle includes a first compartment and a first heat exchanger unit is mounted in the first compartment. The first compartment is sealed from the waste material storage volume. The first heat exchanger unit is removably mounted in the first compartment. The first heat exchanger unit is in the form of a first cassette that is arranged to be inserted into, and removed from, the first compartment. Since the first heat exchanger unit is separated from the waste material, it does not become caked with oil, grease or fat. 
         [0033]    The first compartment includes a first opening and the first heat exchanger unit is insertable into the first compartment, and removable therefrom, via the first opening. In preferred embodiments, the first opening is located in a wall of the first receptacle, such as a side wall. The first opening is accessible from an outer side of the first receptacle. This enables the first heat exchanger unit to be inserted into, and/or be removed from, the first compartment without any waste material stored in the storage volume leaking from the first receptacle. 
         [0034]    The first compartment is at least partly located within the first baffle. It will be appreciated that the warm waste material heats the walls of the first receptacle including the first baffle, and that heat can be transferred from the warm waste material to the first heat exchanger through the first baffle. 
         [0035]    The first receptacle includes a second compartment and a second heat exchanger unit is mounted in the second compartment. The second compartment is sealed from the waste material storage volume. The second heat exchanger unit is removably mountable in the second compartment. Since the second heat exchanger unit is separated from the waste material, it does not become caked with oil, grease or fat. 
         [0036]    The second compartment includes a second opening and the second heat exchanger unit is insertable into the second compartment, and removable therefrom, via the second opening. In preferred embodiments, the second opening is located in a wall of the second receptacle, such as a side wall. The second opening is accessible from an outer side of the first receptacle. This enables the second heat exchanger unit to be inserted into, and/or be removed from, the second compartment without any waste material stored in the storage volume leaking from the first receptacle. The second heat exchanger unit is in the form of a second cassette that is arranged to be inserted into, and removed from, the second compartment. 
         [0037]    Optionally, an interconnecting pipe can be provided between the first and second heat exchangers. Preferably the interconnecting pipe connects the outlet from the first heat exchanger unit to the inlet of the second heat exchanger. Thus the first and second heat exchangers can be connected in series, with only one of the first and second heat exchangers being connected to the cold water source, and the other of the first and second heat exchangers being connected to the further piping and additional apparatus. 
         [0038]    The second compartment is at least partly located within the second baffle. It will be appreciated that the warm waste material heats the walls of the first receptacle including the second baffle, and that heat can be transferred from the warm waste material to the heat exchangers through the baffles. As warm waste material passes into the grease trap from the kitchen&#39;s drainage system, the baffles become immersed in a continuous supply of warm water and become heated. 
         [0039]    In preferred embodiments at least one of the first and second compartments includes a second heat transfer medium, such as a heat transfer gel, which is arranged to promote heat transfer between the first receptacle and the heat exchanger(s). 
         [0040]    Advantageously the device includes an alert system arranged to alert a user to drain FOGs from the first receptacle. 
         [0041]    The alert system includes a timing device, and the alert system is arranged to issue an alert according to inputs received from the timing device. The timing device is programmable. This enables the user to set the alert period to suitable period of time, for example to issue an alert every day, every two days, every three days, etc. 
         [0042]    The alert system includes at least one of a visual display unit (VDU), an indicator lamp, and a speaker; and the alert system is arranged to issue at least one of visual and audio alerts. In preferred embodiments the grease trap device includes a power source, such as at least one cell. 
         [0043]    The alert system receives an input signal from the manually operable control. In preferred embodiments, the alert issued, for example an audible sound, continues until the user operates the manually operable control. Operating the manually operable control cancels the alert. 
         [0044]    Advantageously the grease trap device can include an electric generator device, for example a thermoelectric generator device. The generator device is arranged to supply electricity to the alert system. In preferred embodiments the alert system includes at least one rechargeable cell, and the generator device is arranged to recharge the at least one rechargeable cell. 
         [0045]    Advantageously the drain includes a funnel formation at the receptacle inlet, which collects FOGs floating at and/or near the surface of the water. The funnel formation has an opening area, which is sized as a significant proportion of the surface area of the water, typically around at least 20% of the surface area of the water. The funnel formation increases the proportion of congealed FOGs that is drawn from the surface of the water when the valve is opened. Because any FOGs trapped in the grease trap will naturally float to the surface of the trapped fluid, the skimmer funnel increases the efficiency of the drain-off valve in collecting the FOGs and depositing them in the second receptacle. 
         [0046]    In a condition where the first receptacle is mounted in its normal operating orientation, the drain inlet is positioned at a height, which is below the height of the cleaned water outlet. In a condition where the first receptacle is mounted in its normal operating orientation, the drain inlet is positioned at a height, which is below the height of the waste material inlet. 
         [0047]    Advantageously the first receptacle includes a removable lid. The lid seals the first receptacle when closed. 
         [0048]    Advantageously the first receptacle is moulded from a plastics material. This provides smooth rounded corners, which are easy to clean. In preferred embodiments the first receptacle is formed by a rotary moulding process. The inventors have found that rotary moulding provides a good liquid tight arrangement that is easy to clean. In preferred embodiments the first receptacle is formed from a high-density polyethylene (HDPE) material. 
         [0049]    According to another aspect of the invention there is provided a water system including a waste material source, said waste material including water and FOGs, a grease trap device according to any one of the preceding claims, a first line connecting the waste material source to the grease trap device waste material inlet, and a drain connected to the grease trap device cleaned water outlet. 
         [0050]    The water system includes a cold water source and a line connecting the cold water source to a heat exchanger unit inlet. 
         [0051]    The water system includes an appliance, such as a heating system boiler, and a line connecting the appliance to a heat exchanger unit outlet. 
         [0052]    According to another aspect of the invention there is provided a grease trap device for trapping waste material, said waste material including water and FOGs, and for removing at least some of the FOGs from the water; said grease trap device including: a first receptacle having an inlet for receiving the waste material; an outlet for cleaned water; and at least one heat exchanger unit arranged to remove heat from the waste material stored in the first receptacle. The heat exchanger is arranged to cool the waste water, thereby promoting congealing of the FOGs. Advantageously this aspect of the invention can include any feature, or any combination of features, from any other aspect of the invention. 
         [0053]    According to another aspect of the invention there is provided a grease trap device for trapping waste material, said waste material including water and FOGs, and for removing at least some of the FOGs from the water; said grease trap device including: a first receptacle having an inlet for receiving the waste material, and an outlet for cleaned water; wherein the first receptacle is manufactured by a rotary moulding process. Advantageously this aspect of the invention can include any feature, or any combination of features, from any other aspect of the invention. 
     
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         [0054]    An embodiment of the present invention will now be described, by way of example only, with reference to the accompanying drawings in which: 
           [0055]      FIG. 1  is an isometric view of a grease trap device in accordance with the invention, in the context of plumbed water system; 
           [0056]      FIG. 2  is an isometric view of the grease trap device of  FIG. 1 , showing a front view of the device with a FOGs collection tray in a withdrawn state; 
           [0057]      FIG. 3  is an isometric view of the grease trap device of  FIG. 1  with a lid removed to show the interior thereof; 
           [0058]      FIGS. 4A &amp; 4B  are isometric views of the grease trap device of  FIG. 1 , showing rear views, and illustrating insertion and removal of first and second heat exchangers; 
           [0059]      FIG. 5  is a diagrammatic cross-sectional view of a rear portion of the grease trap device of  FIG. 1 , illustrating the positions of the first and second heat exchangers within first and second baffles respectively; and 
           [0060]      FIGS. 6A and 6B  are diagrammatic cross-sectional views of a front portion of the grease trap device of  FIG. 1 , illustrating the way in which FOGs and some waste water are drained from the device. 
       
    
    
     DETAILED DESCRIPTION 
       [0061]      FIG. 1  shows a grease trap unit  1  plumbed into a waste water system  100  and a heating system  200 . 
         [0062]    The grease trap unit  1  includes first and second receptacles  3 , 5 . 
         [0063]    The second receptacle  5  is in the form of a tray, which is removably attachable to a lower portion of the first receptacle  3 . The first receptacle  3  includes a recessed portion  7  and the tray  5  is stored in the recessed portion  7  and is removable therefrom. 
         [0064]    The first receptacle  3  is substantially cuboid in shape, and includes a front wall  17 , a rear wall  19 , first and second side walls  21 , 23 , a base  25  and a lid  27 . The first receptacle  3  is made from a moulded plastics material, and is preferably rotary-moulded to produce smooth rounded edges and corners for ease of cleaning. 
         [0065]    The first receptacle  3  includes a waste material inlet  9 , and a cleaned water outlet  15 . The waste material is mainly in the form of waste water, which includes water and FOGs. The receptacle  3  includes first and second baffles  11 , 13 . The first baffle  11  is located adjacent the inlet  9 . The second baffle  13  is located adjacent the outlet  15 . The arrangement provides a reception storage volume  29 , a main storage volume  31  and an outgoing storage volume  33 . 
         [0066]    The reception storage volume  29  is defined by the first side wall  21 , front and rear walls  17 , 19 , base  25  and first baffle  11 . Waste water entering the first receptacle  3  via the waste material inlet  9  flows initially into the reception storage volume  29 . A first aperture or gap  37  is provided between a lower portion of the first baffle and the base  25  of the first receptacle. Thus the reception storage volume  29  is contiguous with the main storage volume  31 , which enables water flowing into the reception storage volume  29  to flow into the main storage volume  31 . 
         [0067]    The main storage volume  31  is defined by the front and rear walls  17 , 19 , base  25  and first and second baffles  11 , 13 . Waste water resides in the main storage volume  31  for a period of time. This enables FOGs to congeal and float to the surface of the waste material. 
         [0068]    A second aperture or gap  39  is located at or near the base of the second baffle, thus the outgoing storage volume  33  is contiguous with the main storage volume  31 . This enables water to flow from the main storage volume  31  into the outgoing storage volume  33 , and from there into the cleaned water outlet  15 . 
         [0069]    The outgoing storage volume is defined by the second side wall  23 , front and rear walls  17 , 19  and second baffle  13 . 
         [0070]    A drainage system  41  is located in the main storage volume  31  and is arranged for removing at least some of the FOGs floating at or near the surface of the waste material, from the first receptacle  3 . The drainage system  41  includes a funnel  43  mounted adjacent a conduit inlet  47 , a conduit  49 , a conduit outlet  51  and a valve  53 . The valve  53  controls the flow of material through the conduit  49 . In a closed condition, material is blocked from reaching the outlet  51 . In an open condition, material flows through the conduit  49  to the outlet  51 , which is arranged to deposit the material drained from the first receptacle  3  into the tray  5 . 
         [0071]    The funnel  43  is located below the surface of the water. It is positioned at predetermined distance below the surface of the water, when the surface water is at its maximum depth. This is typically at a depth when the water surface is substantially level with at least one of the inlet  9  and outlet  15 . 
         [0072]    The funnel  43  has a large surface area at its entrance and is arranged to capture waste material and FOGs from the surface of the water, and direct them into the conduit inlet  47 . 
         [0073]    When the valve  53  is open, and waste material is draining from the first receptacle  3  into the tray  5 , the level of the water within the first receptacle drops to a height that is substantially level with the entrance of the funnel  43 . This effectively limits the volume of waste material that can be drained from the first receptacle  3  in one operation. Since the maximum and minimum water heights are known, the tray  5  is sized to have a sufficient volume to accommodate the maximum volume of waste material that can be drained from the receptacle in an operation, thereby preventing spillages from occurring. 
         [0074]    The grease trap unit  1  includes a manually operable control  93 , and preferably a rotatable manually operable control, such as a knob or handle. The control  93  actuates the valve  53  in response to a manual input. This enables a user to open and close the valve  53 , as required. Preferably the control  93  is located on the front wall  17  of the receptacle for ease of access. 
         [0075]    The grease trap unit  1  further includes a locking mechanism  97 , which is arranged to selectively lock and unlock the tray  5  within the recessed portion  7 . The locking mechanism  97  is operated by the control  93 . The locking mechanism includes a locking member  99  which is actuated by rotating the control  93 . The arrangement is such that when the valve  53  is in the closed condition, the locking member  99  is in the “unlocked” position thereby enabling the tray  5  to be removed from the recessed portion  7 ; and when the valve  53  is in the open condition, the locking member  99  is in the “locked” position thereby locking the tray  5  within the recessed portion  7 . This prevents a user from withdrawing the tray  5  from the recessed portion  7  while waste material is draining from the first receptacle  3 . 
         [0076]    The grease trap unit  1  further includes first and second heat exchangers  57 , 59 . The first heat exchanger  57  is located in a first cavity  61  within the first baffle  11 . The second heat exchanger  59  is located within a second cavity  63  within the second baffle  13 . Each of the first and second heat exchangers  57 , 59  is a self-contained unit which is removably mounted within its respective cavity  61 , 63 . Each heat exchanger  57 , 59  comprises an arrangement of pipes, preferably in a coiled or raster-like pattern. Each heat exchanger  57 , 59  includes a mounting plate  67 , 69  which is arranged to close off the respective cavity  61 , 63  when the heat exchanger  57 , 59  is located in-situ. Each heat exchanger  57 , 59  includes an inlet  71 , 72  and an outlet  73 , 74 . Optionally, each of the cavities  61 , 63  may include a gel or other substance for promoting thermal transfer between the piping and the respective baffle  11 , 13 . Additionally, or alternatively, the heat exchanger piping may include fins  76  to promote heat transfer. 
         [0077]    The heat exchangers  57 , 59  are arranged to extract heat from the waste material and to use the heat extracted in a beneficial manner, for example by circulating a heat transfer medium such as cold water within the heat exchanger piping. The water circulated within the piping is at a lower temperature than the waste water within the receptacle  3 . The main purpose of extracting heat from the waste material is to cool the FOGs trapped within the waste material thereby promoting congealing of the FOGs. This enables the FOGs to be removed from the waste material more quickly. The heat extracted from the waste material can be provided to another system, for example it can be provided to an input side of a water boiler  206 . The boiler  206  would use less energy to heat the water to a target temperature, since the water supplied to it is warmer than would normally be supplied. 
         [0078]    An electronic unit  77  is mounted on at least one of the lid  27  and a receptacle wall  17 , 19 , 21 , 22 . Preferably the electronic unit  77  is mounted on or to the front wall  17 . The electronic unit  77  includes a timing device  79 , visual display  81 , speaker  83 , controls  87 , 89 , 91  and a battery (not shown). The purpose of the electronic unit  77  is to issue an alert to the user to have the user actuate the control  93  to drain waste products from the first receptacle  3 . For example, the timing device  79  can be programmed using at least one of the controls  87 , 89 , 91  to remind the user to undertake the draining action periodically, such as each day, two days, three days, etc. The alert can be provided by at least one of the visual display device  81 , an indicator lamp (not shown) and the speaker  83 . 
         [0079]    Optionally, the electronic unit  77  can include an electricity generator (not shown). For example, the electronic unit  77  can include a thermoelectric generator, which generates electricity by means of a temperature difference. A temperature difference can be obtained, for example between the temperature of the waste material within the first receptacle and the temperature outside the first receptacle. The battery can be of the rechargeable type and the electricity generated is preferably used to recharge the battery. Of course, it may be possible in some circumstances to power the alert system directly from the electricity generator as an alternative to the battery or in addition to the battery. 
         [0080]    In use, the grease trap unit  1  is plumbed into the waste material system  100 . The waste water system  100  includes an appliance such as a dishwasher, sink, or drain, etc, which generates or receives waste water. The waste water system  100  includes a first pipe  102 , which connects the receptacle inlet  9  to the appliance; and a second pipe  104 , which connects the receptacle outlet  9  to a drain. 
         [0081]    The heat exchanger inlet  71  of the first heat exchanger is connected to a cold water source (not shown) via a pipe  202 . The outlet  73  of the first heat exchanger is connected to the inlet  72  of the second heat exchanger by a pipe  204 . The outlet  74  of the second heat exchanger is connected to apparatus requiring warmed water, such as the boiler  206 , via a pipe  208 . While this is the preferred arrangement, it is possible to connect the cold water source to the second heat exchanger  59  and the appliance requiring warmed water to the first heat exchanger  57 . 
         [0082]    The valve  53  is normally in the closed condition. 
         [0083]    Waste water carrying FOGs enters the receptacle  3  via the inlet  9 . The water enters the reception storage volume  29 . The first baffle  11  directs the water downwards, turning the waste water through approximately 90 degrees, towards the base  25  of the receptacle. Waste water passes from the reception storage volume  29  into the main storage volume  31  via the first aperture or gap  37 , turning approximately 180 degrees. The waste material resides within the storage volume  31  for a period of time, thereby enabling FOGs to solidify/congeal and float to the surface of the waste water as illustrated in  FIG. 6A . 
         [0084]    When the user receives an alert from the electronic unit  77 , the user operates the control  93  to open the valve  53 , which also locks the tray  5  in the recess  7 . 
         [0085]    When the valve  53  opens, waste material (FOGs and water) above the funnel  43  flows into the tray  5  via the funnel  43  and conduit  49 . When the waste water level falls to approximately the level of the funnel  43 , no further waste material is drained from the receptacle  3 . The user then turns the control  93  to close off the valve  53 . This also unlocks the tray  5 . The user removes the tray from the recessed portion  7  and the waste material is disposed of. The tray  5  is then returned to the recessed portion  7 . 
         [0086]    The process is repeated when the next alert is received from the electronic unit  77 . 
         [0087]    Of course, it will be appreciated that the user can drain waste material from the first receptacle  3  at any time. The electronic unit  77  enables a schedule to be preprogramed to ensure that the receptacle is drained on a periodic basis, to prevent an excessive accumulation of FOGs. 
         [0088]    When there is a surge of waste water into the first receptacle  3  via the inlet  9 , and the waste water is already at or near its maximum level, the incoming waste water pushes cleaned water from the main storage volume  31  into the outgoing storage volume  33  via the second aperture or gap  39 . The cleaned water turns through approximately 180 degrees. This in turn pushes water from the outgoing storage volume  33  into the outlet  15 , turning through approximately 90 degrees. The cleaned water exiting the first receptacle  3  is not necessarily pure water, since it may still contain some FOGs, however the water is cleaner than the waste water that entered the unit. 
         [0089]    Although the present invention has been described in connection with specific preferred embodiments, it should be understood that the invention as claimed should not be unduly limited to such specific embodiments. Furthermore, it will be apparent to the skilled person that modifications can be made to the above embodiment that fall within the scope of the invention.