A device for removing fats, oils and / or grease (FOGs) from waste water

Abstract

A device 1 for removing fats, oils and / or grease (FOGs) from wastewater, comprises: a wastewater inlet 16, 18; a separator chamber (9, Fig. 6) for gravity separating FOGs from the wastewater; and a wa

Description

Field of the invention The present invention relates to a device for removing fats, oils and / or grease ("FOGs") from waste water. Background of the invention Commercial and industrial kitchens and catering establishments such as restaurants, fast food outlets, work canteens and food processing facilities often produce large volumes of waste water that is contaminated by fats, oils and / or grease ("FOGs"), silt and food debris. Kitchens in residential properties such as houses and apartments may also produce volumes of waste water contaminated by FOGs, silt and food debris. A large proportion of FOGs in waste water are produced as a result of cooking or otherwise breaking down of food stuffs, in particular vegetable and / or animal products. When cooking equipment, food preparation equipment, food preparation surfaces, eating utensils and certain fabrics (e.g. tea towels, table cloths, napkins) contaminated by FOGs are washed, these FOGs end up contaminating water. Catering FOGs include e.g. chicken fats, beef fats, duck fats, lamb fats, pork fats, fish oils, butter, margarines, spreads, mayonnaise, palm oils, corn oils, rape seed oils, sunflower oils, olive oils, cooking oils, vegetable oils, ice cream and milkshakes. If waste water contaminated by FOGs is allowed to enter drainage and sewerage systems this can lead to serious problems. For example, the presence of FOGs in drainage and sewerage systems can result in the formation of "fatbergs", which are large conglomerates of FOGs and other waste matter which block sewers and often have to be manually broken down to be removed from the sewers. Waste water contaminated by FOGs may also cause problems in sewage treatment systems. For example, if FOGs reach the bacteria or biomass that is present in sewage treatment systems to digest the sewerage, the biomass can be suffocated by the FOGs and the necessary treatment does not take place. The addition of chemicals and / or enzymes can also create a chemical oxygen demand that can asphyxiate active microbes. With the evolution of commercial kitchens and processes, larger volumes of waste water are being created. In addition, there are ever increasing demands from environmentally conscious and environmentally responsible businesses and business owners who desire "near zero" FOG pollution from their commercial kitchens and catering establishments. In recent years, the international media have also begun to highlight the large amounts of FOGs that end up in the drainage and sewerage systems, and in many cases the polluters are being held accountable. This has resulted in many larger national and international food and catering chains actively insisting on a near zero FOG discharge in order to avoid association with environmental pollution and the creation of fatbergs. Food service establishments are also increasingly being required by legislation to clean their waste streams on site in order to meet strict limits on the content of the waste that is discharged from their premises, for example to a maximum FOG content of 100 parts per million. FOGs and water are immiscible liquids, meaning that they do not form a homogenous mixture when mixed together. FOG droplets having a droplet size of >150 pm are categorised as a micro-emulsion weak and are able to separate from water under gravity with a separation time of <10 minutes. Such FOG droplets are reasonably easy to separate and remove from contaminated water. Kitchens and catering establishments may be provided with a device for removing FOGs from waste water before the waste water enters the drainage and sewerage systems. These devices, also referred to as grease removal units or "GRUs" typically include a separator chamber that is configured to allow low-density FOGs (that is FOGs having a lower density than water) to separate from waste water under the action of gravity, and a FOG removal system that is configured to allow FOGs that have separated from the waste water in the separator chamber to be removed from the device. Extracted FOGs can then be disposed of safely without contaminating the drainage and sewerage systems, and may be recycled, for example by being converted into biofuels. Examples of known FOG removal devices or GRUs are disclosed in EP0890381A1, US2005 / 211620A1 and US2012 / 152864A1. Some GRUs use a scraper to scrape FOGs that have separated from the waste water in the separator chamber off the water and into a FOG collection receptacle. However, controlling operation of the scraper system can be challenging. Operating the scraper system too often can result in waste water being scraped into the FOG collection receptacle together with the separated FOGs. On the other hand, operating the scraper system too infrequently can result in FOGs building up within the separator chamber, thereby increasing the risk of FOGs flowing through the GRU into a drainage or sewerage system. Other GRUs include a FOG outlet with a FOG outlet valve that is configured to open and close automatically in dependence on the level of the water / FOG interface in the separator chamber in order to allow FOGs that have separated from the waste water to exit the separator chamber. The FOG outlet valve may, for example, be a ball valve or float valve including a ball or float that is configured to float on water but to sink in liquid FOG. FOG removal systems including a valve that is configured to open and close automatically in dependence on the level of the water / FOG interface in the separator chamber are generally simpler than FOG removal systems including a scraper system, and may be more reliable. However, if the GRU cools then there is a risk that FOGs may congeal around the FOG outlet valve and prevent the FOG outlet valve from opening, which can result in FOGs building up within the separator chamber, thereby increasing the risk of FOGs washing through the GRU. Some GRUs include a heater that is configured heat the waste water passing through the device. Heating waste water passing through a GRU can speed up the separation of FOGs from waste water, thereby increasing the effectiveness of the separator chamber and allowing the GRU to handle higher flow rates of waste water. Heating waste water passing through a GRU also reduces the probability of FOGs congealing inside the separator chamber, which can interfere with the extraction of FOGs from the separator chamber. However, GRUs including a heater can suffer from increased risk of smoke or fire if FOGs are able to come into direct contact with the heater, and so the heater is generally located either upstream of the separator chamber or in an upstream portion of the separator chamber away from any FOG outlets. Known GRUs also struggle with the build-up of silt and food debris, especially at the base of the separator chamber. Silt and debris must be removed from GRUs periodically in order to prevent the silt and debris from interfering with the separation of FOGs from waste water in the separator chamber, and to prevent the silt and debris from flowing through the GRU into a drainage or sewerage system or blocking the GRU. Some GRUs require silt and debris to be removed from the separator chamber manually, which is time consuming and generally leads to incomplete removal of silt and debris. Other GRUs include a silt outlet via which silt and debris can be drained from the separator chamber. However, removing silt and debris via a silt outlet can also lead to incomplete de-silting, and also causes the water level within the separator chamber to drop, which can increase the probability of FOGs coming into direct contact with a heater, if present. The disposal of silt can also present challenges in known GRUs because FOG-laden silt is not allowed to be discharged to drainage and sewerage systems. GRUs may also have to deal with waste water that is contaminated by chemicals which interfere with the separation of FOGs from water, such as floor cleaning chemicals and de-greasing agents. Waste water that is contaminated with these chemicals can disrupt the separation of FOGs from waste water in the separator chamber, thereby reducing the effectiveness of the GRU. The separation of FOGs from waste water may also be made more challenging by mechanical processes such as whisking and blending, and by the use of detergents, both of which can cause emulsification of FOGs in a waste water stream. A FOG / water emulsion may also form when a FOG / water mixture is above a certain temperature. Mechanically emulsified FOG droplets tend to have a droplet size of between 20 pm and 150 pm and are defined as a "micro-emulsion moderate". These micro-emulsion moderate FOGs have a separation time in the region of hours. Similarly, chemically emulsified FOG droplets tend to have a droplet size of between 1 pm and 20 pm are defined as "micro-emulsion strong". These micro-emulsion FOGs and have a separation time in the region of days. FOG droplets having a droplet size of <1 pm are defined as "micro-emulsion very strong" and are almost impossible to separate from water using gravity alone. The addition of detergent to a waste water stream may result in the generation of a mixture of FOG types having a range of densities, including high-density FOGs (that is FOGs having a higher density than water). High-density FOGs may be created, for example, when FOGs join with detergent molecules. High-density FOGs will not generally float on water and will instead sink in the water. As such, high-density FOGs cannot be removed from the water using conventional FOG / water separators which primarily rely on the FOGs floating on top of the water. Water has an approximate density of 1000 kg / m3, although the density of water can be higher or lower than this depending on its temperature. Relative density is the ratio of the density of a substance to the density of a given reference material. Specific gravity is the relative density measured with respect to water. Low-density FOGs are considered to have an average density of less than 1000 kg / m3 and a specific gravity of less than 1, in contrast to high-density FOGs which have an average density of more than 1000 kg / m3 and a specific gravity of more than 1. WO2021 / 001352A1 discloses a GRU comprising a FOG filter located inside a filter chamber that is provided downstream of the separator chamber. The FOG filter is designed to remove FOGs that still remain in a waste water stream after the waste water has passed through the separator chamber, including high-density FOGs and FOGs with a droplet size of less than 150 pm. The present invention aims to improve upon existing FOG removal devices / GRUs. Summary of the invention GRU comprising a heater located inside a housing According to an aspect of the present invention there is provided a device for removing FOGs from waste water, the device comprising: a waste water inlet that is configured to receive waste water contaminated by FOGs into the device; a separator chamber that is configured to receive waste water from the inlet and to separate FOGs from the waste water under the action of gravity; a waste water outlet that is configured to emit waste water that has passed through the separator chamber from the device; a FOG outlet that is configured to emit FOGs that have been separated from the waste water in the separator chamber from the separator chamber; and a heating system located in the separator chamber, the heating system comprising a heater that is configured to heat waste water in the separator chamber, and a housing that at least partially surrounds the heater. The heater is able to heat waste water as it passes through the separator chamber, thereby reducing the probability of FOGs congealing in the separator chamber. The housing reduces the probability of FOGs coming into direct contact with the heater even if the water level in the separator chamber drops, for example during extended periods of low waste water flow and during de-silting operations. The device may further comprise a FOG outlet valve that is movable between an open configuration and a closed configuration, the FOG outlet valve being configured to allow fluid flow out of the separator chamber via the FOG outlet when in the open configuration and to prevent fluid flow out of the separator chamber via the FOG outlet when in the closed configuration. By heating heat waste water as it passes through the separator chamber, the heater is able to reduce the probability of FOGs congealing around the FOG outlet valve, which could prevent FOGs from being able to exit the device via the FOG outlet. The FOG outlet valve may comprise a ball valve or float valve that is configured to open and close automatically in dependence on the level of a FOG / water interface within the separator chamber. The ball valve or float valve may, for example, be configured to open automatically in response to a FOG / water interface in the separator chamber falling below a predetermined level and / or to close automatically in response to the FOG / water interface exceeding a predetermined level. The ball valve or float valve may include a ball or float that is configured to float on water but to sink in liquid FOG. The FOG outlet may be connected to the separator chamber at a location at or close to an upper wall of the separator chamber. The upper wall of the separator chamber may be angled upwardly in a direction towards the FOG outlet. The FOG outlet may be connected to the separator chamber in a downstream portion of the separator chamber, for example at a location that is closer to a downstream end of the separator chamber via which waste water exits the separator chamber than an upstream end of the separator chamber via which waste water enters the separator chamber during normal use of the device. The FOG outlet may be connected to the separator chamber at a location towards a mid-point of the separator chamber in a lateral direction, or alternatively towards a lateral side of the separator chamber. The FOG outlet may comprise a conduit that is configured to convey FOGs from the separator chamber to a FOG collection receptacle when the FOG outlet valve is opened. The FOG collection receptacle may be located outside the device, and may be configured to be emptied either manually or alternatively by an automated system according to a predetermined schedule, at a predetermined time interval and / or in response to the FOG collection receptacle being filled to a predetermined level. The device may comprise a FOG receptacle station that is configured to receive the FOG collection receptacle and hold the FOG collection receptacle in a position in which FOGs can be emitted from the FOG outlet into the FOG collection receptacle. The FOG receptacle station may be configured to mount the FOG collection receptacle to the device. The FOG collection receptacle station may be configured to receive the FOG collection receptacle with a sliding interface, for example on rails provided on the FOG receptacle station, such that the FOG collection receptacle can be slid into and out of the FOG receptacle station. The heater may be located in a downstream portion of the separator chamber, at least substantially directly below the FOG outlet valve and / or in proximity to the FOG outlet valve, for example within 200mm of the FOG outlet valve. This is in contrast to existing FOG removal devices in which the heater, if present, is generally located away from the FOG outlet valve in an upstream portion of the separator chamber in order to reduce the probability of FOGs coming into direct contact with the heater. Location of the heater in a downstream portion of the separator chamber, directly below the FOG outlet valve and / or in proximity to the FOG outlet valve is facilitated by the housing in which the heater is located, which helps to reduce the probability of FOGs coming into direct contact with the heater. The heater may comprise a single heating element or alternatively a plurality of discrete heating elements. The heater may, for example, comprise an electric immersion heater or heating cartridge. The heater may be elongate, and may extend in a direction perpendicular to a flow direction in which waste water travels through the separator chamber during normal use of the device. The heater may extend across at least a majority of a width of the separator chamber. The heater may be located in proximity to the base of the separator chamber, for example within 50mm of the base of the separator chamber. Locating the heater in proximity to the base of the separator chamber may reduce the tendency for waste water to pass under the heater without being heated. The device may further comprise a temperature sensor or thermostat, which may be located in the separator chamber. The heater may be configured to be switched on automatically in response to the temperature in the separator chamber as measured by the temperature sensor or thermostat falling below a predetermined level. The heater may further be configured to be switched off after a predetermined time period and / or in response to the temperature in the separator chamber as measured by the temperature sensor or thermostat rising above a predetermined level. The temperature at which the heater is switched off may optionally be different to the temperature at which the heater is switched on. The temperature sensor or thermostat may be provided at a different location to the heater, for example outside the housing in which the heater is located. Locating the temperature sensor or thermostat away from the heater may allow the position of the heater to be optimised to provide the most effective heating of the FOG outlet valve while also allowing the position of the temperature sensor or thermostat to be optimised to accurately measure the temperature of waste water entering the separator chamber (without being distorted by the higher local temperatures around the heater). Separating the temperature sensor or thermostat from the heater may also enable the heater to be mounted closer to the base of the separator chamber. The temperature sensor or thermostat may be provided upstream of the heater, preferably at least 200mm upstream of the heater. The temperature sensor or thermostat may, for example, be provided around a mid-point of the separator chamber between an upstream end via which waste water enters the separator chamber and a downstream end via which waste water exits the separator chamber during normal use of the device. The temperature sensor or thermostat may also be provided at a higher position than the heater (at a greater distance above a base of the separator chamber than the heater), in an upper portion of the separator chamber (closer to an upper wall of the separator chamber than to a base of the separator chamber) and / or at a location that is at least 50mm above a base of the separator chamber. The device may further comprise a filter chamber located downstream of the separator chamber that is configured to receive a FOG filter for removing FOGs that remain in waste water that has passed through the separator chamber before the waste water exits the device via the waste water outlet. The filter chamber may include a FOG filter, for example a FOG filter as disclosed in WO2021001352A1. The filter chamber may comprise a filter holder that is configured to receive and retain the FOG filter. The filter holder may comprise a pair of guide rails or tracks that are provided on opposed side walls of the filter chamber and configured to receive and retain side edges of the FOG filter, or a perforated enclosure or basket that is configured to receive the FOG filter therein. The filter chamber may be configured to prevent waste water flowing therethrough from bypassing the FOG filter during normal use of the device. For example, the FOG filter, once installed in the filter chamber, may extend between opposed sidewalls of the filter chamber and down to a base of the filter chamber such that waste water flowing through the filter chamber will not be able to bypass the FOG filter during normal use of the device. However, a gap may be present between a top of the FOG filter and a top of the filter chamber such that if the flow rate of waste water entering the filter chamber exceeds a maximum flow rate capacity of the FOG filter then a portion of the waste water will be able to flow over the top of the FOG filter in order to prevent the water level within the device from rising above an intended working level. The device may comprise a weir located between the separator chamber and the filter chamber. The weir may define a gap at its lower edge that is configured to allow waste water to pass therethrough in order to move from the separator chamber into the filter chamber. The gap may extend between the lower edge of the weir and a base of the separator chamber. The weir may be configured to prevent FOGs that have separated from the waste water in the separator chamber from passing into the filter chamber together with the waste water. The housing in which the heater is located may be located in proximity to the weir, for example within 100mm of the weir. Locating the housing in proximity to the weir may facilitate the targeting of FOGs that remain in waste water that has passed over the housing by plumes of heated water, as described in more detail below. The device may further comprise a second weir, which may be located downstream of the first weir. The second weir may extend down to a base of the filter chamber, and may define a gap at its upper edge that is configured to allow waste water to flow over the second weir in order to progress through the filter chamber towards a FOG filter located in the filter chamber. The upper edge of the second weir may govern the working water level of the separator chamber. The housing in which the heater is located may comprise a wall with an inverted U-shape that at least partially surrounds the heater. The housing may extend in a direction perpendicular to the flow direction of the separator chamber, and may extend continuously between opposed sidewalls of the separator chamber. The housing may have an at least substantially constant cross-section along its length when viewed in a plane perpendicular to the flow direction of the separator chamber. The housing may be formed of sheet metal, for example sheet stainless steel. The sheet metal may be bent to form the shape of the housing. The housing may be connected to a base of the separator chamber and configured to act as a barrier in order to prevent silt and / or debris that has collected on the base of the separator chamber from moving from the separator chamber in a direction towards the waste water outlet. The housing may, for example, be configured to prevent silt and / or debris from moving from the separator chamber into the filter chamber. The housing may include at least one heated water outlet that is configured to direct a jet of water that has been heated by the heater in a direction towards the FOG outlet valve. The heated water outlet of the housing may enhance the effectiveness of the heater by enabling a jet of heated water to be directed towards the FOG outlet valve, thereby providing more targeted heating of this section of the separator chamber and facilitating placement of the heater in closer proximity to the FOG outlet valve. The heated water outlet may comprise a tube that is connected to a body of the housing and extends outwardly therefrom in a direction towards the FOG outlet valve. The tube may extend in a substantially vertical direction, and may have a distal end that is located in proximity to the FOG outlet valve, for example within 100mm of the FOG outlet valve. The tube may have a constant cross section, or may alternatively taper inwardly in a direction towards the FOG outlet valve. The housing may also be provided with a plurality of apertures (in addition to the above-mentioned heated water outlet) that are configured to direct plumes or "hydroblades" of water that has been heated by the heater outwardly from the housing. The plumes of heated water may increase the effectiveness of the separation of FOGs from the waste water in the separator chamber. The apertures may comprise elongate slots, and may be provided in an upper portion of the housing and / or on a downstream side of the housing. The apertures may be configured to direct plumes of heated water in multiple different directions. At least some of the plumes may be directed in substantially vertical directions and other plumes may be directed in substantially horizontal directions. At least some of the apertures may be configured to direct plumes of water towards the weir separating the separator chamber from the filter chamber. Directing plumes of heated water into waste water as it passes between the housing and the weir separating the separator chamber from the filter chamber has been found to be particularly effective because this helps to separate FOGs that still remain in waste water that has already passed over the housing. An upstream side of the housing may be free of any such apertures. Water may be expelled from the housing via the heated water outlet and the additional apertures due to heating from the heater without the need for any additional propulsion mechanism. The water that is expelled from the housing may be boiling, in which case the jet of water that is expelled from the heated water outlet and the plumes or "hydroblades" that are expelled from the additional apertures may comprise steam. Alternatively, the water that is expelled from the housing may be superheated. The housing may further comprise at least one inlet aperture for allowing water to enter the housing in order to be heated by the heater. The inlet aperture(s) may be provided at or adjacent to a lower edge of the housing, and may be located on a downstream side of the housing in order to prevent silt and / or debris that have collected on an upstream side of the housing from entering the housing. The waste water inlet may comprise an inlet pipe or port that is configured to receive waste water from one or more sinks or appliances external to the device. Alternatively, the waste water inlet may comprise a sink forming part of the device. The device may include a plurality of waste water inlets, for example an inlet pipe or port that is configured to receive waste water from one or more sinks or appliances external to the device, and a sink forming part of the device. In this case the separator chamber may be configured to receive waste water from multiple different waste water inlets. The device may be configured to retain waste water in the separator chamber for a target dwell time in the range 20 seconds to 1 minute when operating at its maximum intended flow rate. GRU comprising a silt removal system According to another aspect of the present invention there is provided a device for removing FOGs from waste water, the device comprising: a waste water inlet that is configured to receive waste water contaminated by FOGs into the device; a separator chamber that is configured to receive waste water from the inlet and to separate FOGs from the waste water under the action of gravity; a waste water outlet that is configured to emit waste water that has passed through the separator chamber from the device; a silt outlet that is configured to emit silt and / or debris from the separator chamber; a silt outlet valve that is movable between an open configuration and a closed configuration, the silt outlet valve being configured to allow fluid flow out of the separator chamber via the silt outlet when in the open configuration and to prevent fluid flow out of the separator chamber via the silt outlet when in the closed configuration; and a flushing water inlet separate to the waste water inlet that is configured to allow flushing water to enter the separator chamber when the silt outlet valve is opened. Allowing flushing water to flow into the separator chamber via the flushing water inlet when the silt outlet valve is opened increases the efficiency with which silt and debris can be drained from the separator chamber as the flushing water is able to wash silt and debris that have collected in the separator chamber towards the silt outlet. This reduces the need for manual intervention in order to clear silt and debris out of the separator chamber, and maximises the effectiveness of the separator chamber, which functions less efficiently when silt and debris are allowed to build up therein. The flushing water that flows into the separator chamber when the silt outlet valve is opened also prevents the water level in the separator chamber from dropping when the silt outlet valve is opened, or at least reduces the extent to which the water level in the separator chamber drops, thereby reducing the likelihood of any heating elements located inside the separator chamber coming into direct contact with FOGs. The silt outlet valve may be controlled by a motor or actuator that is configured to control the position of the silt outlet valve. The silt outlet valve may be configured to be opened automatically, for example according to a predetermined schedule, at a predetermined time interval, or in response to the detection of a build-up of silt or debris in the separator chamber. Alternatively, or in addition, the silt outlet valve may be configured to be opened upon receipt of a user-generated control signal. The silt outlet valve may further be configured to be closed automatically after a predetermined time period and / or after the predetermined volume of water has passed into or out of the separator chamber. The silt outlet may be connected to the separator chamber at a location at or close to a base of the separator chamber. The base of the separator chamber may be angled downwardly in a direction towards the silt outlet. The silt outlet may be connected to the separator chamber at an upstream end of the separator chamber, that is at an end of the separator chamber via which waste water enters the separator chamber and opposite an end of the separator chamber via which waste water exits the separator chamber during normal use of the device. The flushing water inlet may be located downstream of the separator chamber between the separator chamber and the waste water outlet. The flushing water inlet may, for example, be located in a filter chamber that is located downstream of the separator chamber, or between the separator chamber and a filter chamber that is located downstream of the separator chamber. The filter chamber may be separated from the separator chamber by a weir. The filter chamber may be configured to receive a FOG filter for removing FOGs that remain in waste water that has passed through the separator chamber before the waste water exits the device via the waste water outlet. The filter chamber may include a FOG filter, for example a FOG filter as disclosed in WO20210Q1352A1. The flushing water inlet may be provided with a valve that is configured to open and close automatically in response to changes in the water level within the device. The flushing water inlet valve may, for example, be a float valve that is configured to open automatically in response to the water level in the device falling below a predetermined threshold level. The flushing water inlet may be a fresh water inlet that is configured to deliver fresh water to the separator chamber when the silt outlet valve is opened. The device may further comprise a flushing water tank that is configured to store flushing water prior to delivery to the separator chamber. The flushing water tank may be configured to be placed in fluid communication with the separator chamber when the silt outlet valve is opened. The flushing water tank may have a capacity of at least 10 litres and / or a capacity that is at least 20% that of the separator chamber in order to ensure that a sufficient quantity of flushing water can be delivered to the separator chamber when the silt outlet valve is opened. The flushing water tank may be connected to and configured to receive fresh water from a mains water supply. The flushing water tank may ensure that a sufficient quantity of flushing water can be delivered to the separator chamber when the silt outlet valve is opened without requiring a direct connection between the separator tank and the mains water supply. The flushing water tank may be provided with a supply water inlet valve, for example a float valve, that is configured to regulate the supply of water into the flushing water tank in dependence on the water level within the flushing water tank. The device may further comprise a silt outlet chamber that is configured to receive silt and / or debrisladen water from the separator chamber via the silt outlet when the silt outlet valve is opened. The silt outlet chamber may be provided with a removable perforated basket that is configured to filter silt and / or debris out from water that enters the silt outlet chamber via the silt outlet when the silt outlet valve is opened. The removable perforated basket in the silt outlet chamber may be formed of a stainless steel mesh, and may have perforations with a size in the range 0.75-2mm. The removable perforated basket in the silt outlet chamber may have un upstream side and a downstream side. The upstream side of the basket may include an aperture for allowing water entering the silt outlet chamber via the silt outlet to enter the basket. The aperture may have a width or diameter that is greater than that of the perforations, for example a width or diameter of at least 25mm. The silt outlet chamber may comprise a port via which water from the separator chamber enters the silt outlet chamber when the silt outlet valve is opened. The aperture in the upstream side of the basket may be aligned with the port. The downstream side of the basket may be free of any such apertures. The silt outlet chamber may be configured to receive a FOG filter for removing FOGs from water that enters the silt outlet chamber via the silt outlet when the silt outlet valve is opened. The filter chamber may include a FOG filter, for example a FOG filter as disclosed in WO2021001352A1. The silt outlet chamber may comprise a filter holder that is configured to receive and retain the FOG filter. The filter holder may comprise a pair of guide rails or tracks that are provided on opposed side walls of the silt outlet chamber and configured to receive and retain side edges of the FOG filter, or a perforated enclosure or basket that is configured to receive the FOG filter therein. The filter holder may be located downstream of the removable perforated basket. The silt outlet chamber may comprise a waste water outlet that is configured to emit waste water from the silt outlet chamber. The waste water outlet may be located downstream of the removable perforated basket and the FOG filter. The removable perforated basket and FOG filter may ensure that the water that is discharged from the silt outlet chamber via the waste water outlet is substantially free of silt and FOGs, thereby enabling water from the silt outlet chamber to be discharged to a main drain. According to another aspect of the present invention there is provided a device for removing FOGs from waste water, the device comprising: a waste water inlet that is configured to receive waste water contaminated by FOGs into the device; a separator chamber that is configured to receive waste water from the inlet and to separate FOGs from the waste water under the action of gravity; a waste water outlet that is configured to emit waste water that has passed through the separator chamber from the device; a silt outlet that is configured to emit silt and / or debris from the separator chamber; a silt outlet valve that is movable between an open configuration and a closed configuration, the silt outlet valve being configured to allow fluid flow out of the separator chamber via the silt outlet when in the open configuration and to prevent fluid flow out of the separator chamber via the silt outlet when in the closed configuration; a silt outlet chamber that is configured to receive silt and / or debris-laden water from the separator chamber via the silt outlet when the silt outlet valve is opened, the silt outlet chamber comprising a removable perforated basket that is configured to filter silt and / or debris out from water that enters the silt outlet chamber via the silt outlet when the silt outlet valve is opened, the silt outlet chamber being configured to receive a FOG filter for removing FOGs from water that enters the silt outlet chamber via the silt outlet when the silt outlet valve is opened, and a waste water outlet that is located downstream of the removable perforated basket and the FOG filter and configured to emit waste water from the silt outlet chamber. The device may further include any of the features described above in connection with the preceding aspect of the present invention. GRU comprising a removable perforated basket According to another aspect of the present invention there is provided a device for removing FOGs from waste water, the device comprising: a waste water inlet that is configured to receive waste water contaminated by FOGs into the device; a separator chamber that is configured to receive waste water from the inlet and to separate FOGs from the waste water under the action of gravity; a waste water outlet that is configured to emit waste water that has passed through the separator chamber from the device; and a removable perforated basket that is located between the waste water inlet and the separator chamber such that waste water entering the device through the waste water inlet passes through the removable perforated basket before entering the separator chamber, the removable perforated basket being configured to filter silt and / or debris out of the waste water before it reaches the separator chamber. The removable perforated basket prevents large quantities of silt and debris from building up quickly in the separator chamber during use of the device, thereby increasing the effectiveness of the separator chamber, which functions less efficiently when silt and debris are allowed to build up therein, and reducing the frequency with which silt and debris need to be cleared out of the separator chamber. The removable perforated basket may be formed of a stainless steel mesh, and may have perforations with a size in the range 1-2.5mm. The removable perforated basket may comprise an upper opening, and may be located below an outlet of the waste water inlet such that waste water that enters the device via the waste water inlet is able to fall from the waste water inlet into the basket through the upper opening thereof. The waste water inlet may comprise an inlet pipe or port that is configured to receive waste water from one or more sinks or appliances external to the device. Alternatively, the waste water inlet may comprise a sink forming part of the device. The device may include a plurality of waste water inlets, for example an inlet pipe or port that is configured to receive waste water from one or more sinks or appliances external to the device, and a sink forming part of the device. In this case the removable perforated basket may be configured to receive waste water entering the device from multiple different waste water inlets. The removable perforated basket may comprise at least two compartments. Where the device includes a plurality of waste water inlets the removable perforated basket may be configured to receive waste water from one of the waste water inlets (for example from an inlet pipe or port) into a first one of the compartments and waste water from another one of the waste water inlets (for example from an integrated sink) into a second one of the compartments. The compartments may have different widths and / or capacities. The compartments may also have different perforation sizes. In one example a first one of the compartments may have a perforation size of approximately 2mm and a second one of the compartments may have a perforation size of approximately 1.5mm. The compartments may be separated from each other by a dividing wall. The dividing wall may be perforated, may be formed of a stainless still mesh, and may have perforations with a size in the range 1-2.5mm. The dividing wall may reduce the velocity of waste water entering the removable perforated basket from the waste water inlet(s) before the waste water moves out of the basket and progresses towards the separator chamber. Reducing the velocity of the waste water before it reaches the separator chamber may provide a calmer and less turbulent environment in the separator chamber, thereby enhancing the efficiency with which FOGs can be separated from waste water in the separator chamber. Reducing the velocity of waste water before it enters the separator chamber may also reduce the tendency for incoming waste water to disrupt any silt and debris that may have collected at the base of the separator chamber, thereby preventing the separation of FOGs from being interrupted by re-entrained silt and debris. The removable perforated basket may have a curved base. Where the basket includes at least two compartments each of the compartments may have a curved base. Providing the basket with a curved base (or curved bases in the case of a basket including multiple compartments) may facilitate cleaning and emptying of the basket and reduce the tendency for silt and debris to collect in corners of the basket. The removable perforated basket may be located above the working water level of the separator chamber such that the basket remains clear of the waste water in the separator chamber during normal use of the device. The removable perforated basket may be housed within a drawer that is configured to be pulled out from the device in order to facilitate removal and replacement of the perforated basket. The drawer may include a handle to facilitate movement of the drawer with respect to the device. The drawer may be provided with a plurality of rollers along its base. The removable perforated basket may be configured to sit on the rollers in order to facilitate movement of the basket with respect to the drawer. The ability of the basket to slide with respect to the drawer may facilitate removal of the basket from the drawer without requiring the drawer to be fully opened. The removable perforated basket may be provided with at least one handle to facilitate manual removal of the basket from the drawer. The device may further comprise a velocity reducing weir located below the removable perforated basket that is configured to reduce the velocity of waste water falling from the removable perforated basket before the waste water reaches the separator chamber. As discussed above, reducing the velocity of waste water before it reaches the separator chamber may enhance the efficiency with which FOGs can be separated from waste water in the separator chamber by providing a calmer environment and preventing re-entrainment of silt and debris from the base of the separator chamber. The velocity reducing weir may comprise a wall that extends in a plane that is angled relative to a horizontal plane when the device is in its normal orientation. The velocity reducing weir may, for example, be angled downwardly in a direction towards an upstream end of the separator chamber at an angle of 10-30 degrees to the horizontal plane. A distal end of the velocity reducing weir may be spaced apart from a proximal end wall of the separator chamber in order to allow waste water that has fallen out of the removable perforated basket and been slowed down by the velocity reducing weir to enter the separator chamber. GRU comprising a separator chamber and a flow path that bypasses the separator chamber According to another aspect of the present invention there is provided a device for removing FOGs from waste water, the device comprising: a waste water inlet that is configured to receive waste water contaminated by FOGs into the device; a separator chamber that is configured to receive waste water from the inlet and to separate FOGs from the waste water under the action of gravity; a waste water outlet that is configured to emit waste water that has passed through the separator chamber from the device; and a contaminated water inlet that is configured to receive waste water contaminated by chemicals into the device, the contaminated water inlet being in fluid communication with the waste water outlet in parallel to the separator chamber such that waste water entering the device via the contaminated water inlet is able to exit the device via the waste water outlet without passing through the separator chamber. By providing an alternate flow path via which waste water contaminated by chemicals can bypass the separator chamber, the device of the present invention is able to handle waste water containing chemicals that can disrupt the separation of FOGs from water, for example floor cleaning chemicals and de-greasing agents, without interfering with the separation of FOGs from waste water in the separator chamber. The contaminated water inlet may comprise a chemical waste sink, for example a janitor's sink, for receiving waste water that is contaminated by chemicals, for example effluent from floor cleaning operations. The chemical waste sink may be mounted to a body of the device, for example to a separator tank or a water tank of the device, via a pillar that is designed to support the weight of the sink. The chemical waste sink may be provided with a removable perforated basket that is configured to be received in the chemical waste sink and to filter silt and / or debris out from waste water entering the device via the chemical waste sink before the waste water leaves the chemical waste sink. The removable perforated basket in the chemical waste sink may be formed of a stainless steel mesh, and may have perforations with a size in the range 0.75-2.5mm. The device may further comprise a filter chamber located downstream of the separator chamber that is configured to receive a FOG filter for removing FOGs that remain in waste water that has passed through the separator chamber before the waste water exits the device via the waste water outlet. The contaminated water inlet may be configured to deliver waste water that has entered the device via the contaminated water inlet to the filter chamber such that waste water that has entered the device via the contaminated water inlet also passes through the filter chamber before exiting the device via the waste water outlet. The filter chamber may include a FOG filter, for example a FOG filter as disclosed in WO2021001352A1. The device may comprise a removable perforated basket through which water entering the filter chamber from the contaminated water inlet passes before reaching the FOG filter, the removable perforated basket being configured to filter silt and / or debris out from waste water entering the filter chamber from the contaminated water inlet. The removable perforated basket may be formed of a stainless steel mesh, and may have perforations with a size in the range 0.5-2.5mm. The waste water inlet may comprise an inlet pipe or port that is configured to receive waste water from one or more sinks or appliances external to the device. Alternatively, the waste water inlet may comprise an additional sink forming part of the device. The additional sink may be an organic waste sink for receiving organic waste such as food waste and / or water that is contaminated by organic waste. The additional sink may also be mounted to a body of the device, for example to a separator tank or a water tank of the device, via a pillar that is designed to support its weight. The device may include a plurality of waste water inlets in addition to the contaminated water inlet, for example an inlet pipe or port that is configured to receive waste water from one or more sinks or appliances external to the device, and an additional sink forming part of the device. Kitchen sink with UV disinfection system According to another aspect of the present invention there is provided a kitchen sink that is provided with at least one UV light emitter or lamp that is configured to emit UV light into the sink. It will be appreciated that a kitchen sink is a sink that is designed and intended for use in kitchens, that is rooms and other areas in which food is prepared. The sink may be formed of stainless steel, and may have a capacity in the range 7.5 to 75 litres. The UV light emitter advantageously acts to disinfect the sink, breaking down FOGs, silt and debris in the sink and preventing the spread of pathogens in the sink and at other locations downstream of the sink. The sink may be provided with a single UV light emitter, or alternatively with a plurality of UV light emitters that are provided at different locations in order to ensure that all parts of the sink can be disinfected effectively. The UV light emitter may be elongate, and may take the form of a mercury vapor lamp. The UV light emitter may be configured to emit UV light with a wavelength of around 254nm in order to maximise effectiveness against pathogens such as salmonella and E. coli. The UV light emitter may have a minimum waterproof rating of IP68 in order to ensure reliable operation in the wet environment of the sink. The sink may comprise a lid that is movable between an open position in which it allows access to an interior of the sink and a closed position in which it covers the sink and prevents access to the interior of the sink. The lid may be formed of stainless steel, and maybe configured to prevent UV light emitted by the UV light emitter from escaping from the sink into the surrounding environment when the lid is in the closed position. The UV light emitter may be mounted on an underside of the lid. The lid may be connected to the sink by a hinge, and may be pivotable relative to the sink between the open and closed positions. The sink may comprise a rim or flange that extends around an upper opening of the sink, and the lid may be configured to engage the rim or flange of the sink when in the closed position, optionally with continuous engagement around the entire rim or flange of the sink, in order to form a seal between the sink and the lid when the lid is in the closed position. The lid may include a main body that is configured to cover an opening of the sink when the lid is in the closed position, and a skirt that extends downwardly from the main body. The skirt may be provided around at least a portion of a perimeter of the main body of the lid, optionally around the entire perimeter of the main body of the lid. The skirt may be configured to overlap with at least one side of the sink when the lid is in the closed position, optionally extending around all sides of the sink when the lid is in the closed position. The skirt may enhance the ability of the lid to prevent UV light from escaping from the sink into the surrounding environment when the lid is in the closed position. The skirt may overlap with the side(s) of the sink by at least 15mm when the lid is in the closed position. The UV light emitter may be configured to switch on automatically in response to the lid being moved into the closed position and / or to switch off automatically in response to the lid being moved out of the closed position. The sink may, for example, be provided with a switch that is configured to be closed when the lid is moved into the closed position and opened when the lid is moved out of the closed position, and the UV light emitter may be configured to be switched on when the switch is closed and switched off when the switch is opened. By switching the UV light emitter on automatically when the lid is moved into the closed position it is possible to ensure that the sink is disinfected when not in use. By switching the UV light emitter off automatically when the lid is moved out of the closed position it is possible to ensure that people working in the environment in which the sink is located are not exposed to UV light from the UV light emitter. The UV light emitter may be switched on continuously whenever the lid is in the closed position. Alternatively the UV light emitter may only remain switched on for a predetermined time period after the lid is moved into the closed position. The skirt may be configured to overlap with the side(s) of the sink before the UV light emitter is switched on as the lid is being moved into the closed position and / or to maintain an overlap with the side(s) of the sink until after the UV light emitter has been switched off as the lid is being moved out of the closed position. For example, the switch that controls operation of the UV light emitter may be configured to be closed and opened at a displacement from the closed position that is smaller than the distance by which the skirt overlaps with the side(s) of the sink when the lid is in the closed position. In this way it is possible to ensure that UV light is not able to escape from the sink into the surrounding environment as the lid is being closed and opened. The sink may be provided with a removable perforated basket that is configured to be received in the sink and to filter silt and / or debris out from waste water entering the sink. The removable perforated basket may be formed of a stainless steel mesh, and may have perforations with a size in the range 0.75-2.5mm. The basket may include a main body that is formed by a base and sidewalls that extend upwardly from the base, and a flange that extends outwardly from the upper ends of the sidewalls. The main body may be configured to sit inside and to at least substantially fill the opening of the sink when viewed from above when located therein. The flange may be configured to engage the rim or flange of the sink in order to mount the basket to the sink. The basket may also include at least one handle to facilitate manual removal of the basket from the sink. The sink may form part of a device for removing FOGs from waste water, the device further comprising: a separator chamber that is configured to separate FOGs from waste water under the action of gravity; and a waste water outlet that is configured to emit waste water that has entered the device via the sink. The sink may be in fluid communication with the waste water outlet in series with the separator chamber such that waste water entering the device via the sink passes through the separator chamber before exiting the device via the waste water outlet. Alternatively, the sink may be in fluid communication with the waste water outlet in parallel to the separator chamber such that waste water entering the device via the sink exits the device via the waste water outlet without passing through the separator chamber. The device may include a plurality of sinks, for example an organic waste sink and a chemical waste sink such as a janitor's sink. In this case each of the sinks may be provided with a UV light emitter that is configured to emit UV light into its respective sink. Where the device comprises a plurality of sinks, at least a first one of the sinks, for example an organic waste sink, may be in fluid communication with the waste water outlet in series with the separator chamber such that waste water entering the device via the first sink passes through the separator chamber before exiting the device via the waste water outlet, and at least a second one of the sinks, for example a chemical waste sink, may be in fluid communication with the waste water outlet in parallel to the separator chamber such that waste water entering the device via the second sink exits the device via the waste water outlet without passing through the separator chamber. The sink(s) may be mounted to a body of the device, for example to a separator tank or a water tank of the device, via pillars that support the weight of the sink(s). According to another aspect of the present invention there is provided a kitchen comprising a sink or a device for removing FOGs from waste water as described above. The kitchen may be a commercial or industrial kitchen or a kitchen of a food service establishment. The various different aspects of the invention that are described above work together in a synergistic manner to provide a FOG removal system that is particularly effective at removing FOGs and other contaminants from waste water, that has improved reliability and reduced maintenance requirements compared to known GRUs, and that enables all of the waste water emitted therefrom to be discharged into drainage and sewerage systems without contravening laws and regulations governing the content of waste water. It will be appreciated that features of the different aspects of the invention that are described above may be combined with each other in any suitable combination. Brief description of the drawings Embodiments of the invention will now be described as non-limiting examples with reference to the accompanying drawings in which: Figures 1 and 2 schematically illustrate front views of a device for removing FOGs from waste water according to one possible embodiment of the present invention; Figures 3 and 4 schematically illustrate front perspective views of the device; Figure 5 schematically illustrates a plan view of the device; Figure 6 schematically illustrates a cross-section view of the device; Figures 7 and 8 schematically illustrate front perspective views of the device with parts of the device cut away to reveal internal portions of the device; Figures 9 and 10 schematically illustrate perspective views of a sink forming part of the device; Figures 11 and 12 schematically illustrate a first removable perforated basket of the device; Figures 13 to 16 schematically illustrate a FOG outlet of the device; Figure 17 schematically illustrates a second removable perforated basket of the device; Figure 18 schematically illustrates the second removable perforated basket with part of the basket cut away to show the interior of the basket; Figure 19 schematically illustrate a third removable perforated basket of the device; Figure 20 schematically illustrates a cross-section view of a FOG filter that is received in the device. Detailed description of embodiments Figures 1 to 8 schematically illustrate a device 1 for removing fats, oils and / or grease ("FOGs") from waste water according to one possible embodiment of the present invention. The device 1, which may also be referred to as a grease removal unit or "GRU", is designed and intended for use in commercial and industrial kitchens and in catering or food service establishments. As shown in Figures 1 to 8, the device 1 comprises a stainless steel main tank 2 having a base 3, a first end wall 4 that defines a first end or upstream end 2a of the tank 2, a second end wall 5 that defines an opposed second end or downstream end 2b of the tank 2, and a pair of sidewalls 6, 7 that extend between the first and second end walls 4, 5 and define opposed sides of the tank 2. The tank 2 has a length direction extending between the first and second end walls 4,5, and a width direction extending between the first and second side walls 6, 7. As shown in Figure 6, the tank 2 defines an inlet chamber 8, a separator chamber 9 and a filter chamber 10 through which waste water flows when passing through the device 1. The inlet chamber 8, the separator chamber 9 and the filter chamber 10 are arranged in series with each other such that waste water passing through the device 1 enters the tank 2 via the inlet chamber 8, passes from the inlet chamber 8 into the separator chamber 9, and then flows from the separator chamber 9 into the filter chamber 10 before exiting the device 1. The separator chamber 9 is configured to allow FOGs to separate from waste water under the action of gravity before the waste water flows into the filter chamber 10, and the filter chamber 10 houses a filter 70 that is configured to perform final filtering of the waste water that has passed through the separator chamber 9 before it exits the device 1. The separator chamber 9 of the illustrated device 1 has a capacity of approximately 50 litres in order to retain waste water for a dwell time of approximately 30 seconds when the device 1 is operating at a flow rate of 1.7 litres per second. However, other capacities may be used in other embodiments depending on the maximum intended flow rate and the target dwell time for waste water in the separator chamber 9. The tank 2 includes first, second and third sections 2', 2", 2"' having different heights, as shown in Figures 1 and 2. The first section 2' extends from the first end 2a of the tank 2, the third section 2"' extends up to the second end 2b of the tank 2, and the second section 2" extends between the first and third sections 2', 2"'. As shown in Figure 6, the inlet chamber 8 is located above the separator chamber 9 in an upper portion of the first section 2' of the tank 2. The inlet chamber 8 is separated from the separator chamber 9 by a weir plate 11 which extends between the opposed side walls 6, 7 of the tank 2. The weir plate 11 extends in a direction towards the first end 2a of the tank 2 and is angled downwardly in a direction towards the first end 2a of the tank 2 at an angle of approximately 20 degrees from a horizontal plane of the device 1. The weir plate 11 has a distal end that is spaced apart from the first end wall 4 of the tank 2 to define a gap through which waste water may pass in orderto progress from the inlet chamber 8 into the separator chamber 9. The separator chamber 9 is located below the inlet chamber 8 and extends along a majority of the length of the tank 2 through the first and second sections 2', 2" of the tank 2. The separator chamber is separated from the filter chamber 10 by a pair of vertical weir walls 12,13, each of which extends between the opposed side walls 6, 7 of the tank 2. The first vertical weir wall 12 has a lower edge that is spaced apart from the base 3 of the tank 2 to define a first weir wall gap, and the second vertical weir wall 13 has an upper edge that is spaced apart from the top of the tank 2 to define a second weir wall gap through which waste water may pass in order to progress from the separator chamber 9 into the filter chamber 10. The filter chamber 10 is located downstream of the separator chamber 9 in the third section 2"' of the tank 2. The first section 2' of the tank 2 has an upper wall 8a that extends a first height above the base 3 of the tank 2. The second section 2" of the tank 2 has an upper wall 9a that is lower than the upper wall 8a of the first section 2' and includes an angled first portion and a flat second portion. The angled first portion extends from the first section 2' of the tank 2 along a majority of the length of the second section 2" at an angle of approximately 5 degrees from a horizontal plane such that the height of separator chamber 9 increases in a direction towards the second end 2b of the tank 2. The flat second portion extends in a horizontal direction from the end of the angled first portion up to the third section 2"' of the tank 2. The third section 2"' of the tank 2 has an upper wall 10a that is higher than the upper wall 9a of the second section 2”. As the second section 2" of the tank 2 is lower than the first and third sections 2', 2"' a gap is formed above the second section 2" between the first and third sections 2', 2'". A cuboidal water tank 15 is located in and substantially fills this gap. The water tank 15 is connected to a mains water supply and to the main tank 2 of the device 1, as described in more detail below. A layer of polyurethane insulation 15a is also provided between the upper wall 9a of the second section 2" of the tank 2 and the water tank 15 in order to reduce heat loss from the separator chamber 9 into the water tank 15. As shown in Figures 1, 2 and 6, the device 1 comprises three waste water inlets that are configured to receive waste water into the device 1. The first waste water inlet 16 comprises an inlet pipe 17 that is configured to be connected to and receive waste water from one or more sinks and / or other appliances external to the device 1. The inlet pipe 17 extends through the first end wall 4 of the tank 2 in a horizontal direction and has an open inner end that is configured to discharge waste water that has entered the device 1 via the inlet pipe 17 into the inlet chamber 8 of the tank 2. The second waste water inlet 18 comprises a first sink or basin 19 that is mounted to the top of the tank 2 above the inlet chamber 8 via a first pillar 20. The first sink 19 is formed of stainless steel, includes a base, sidewalls that extend upwardly from the base, and a planar rim or flange that extends outwardly from the sidewalls around an upper opening of the sink 19, and has a capacity of approximately 13 litres. The first sink 19 is provided with a first down tube 21 that is connected to a port or plughole provided in the base of the sink 19. The first down tube 21 extends downwardly from the first sink 19 through the first pillar 20, and has an open lower end that is configured to discharge waste water that has entered the device 1 via the first sink 19 into the inlet chamber 8 of the tank 2. The first sink 19 is an organic waste sink for receiving organic waste such as food waste and water that is contaminated by organic waste. The third waste water inlet 22 comprises a second sink or basin 23 that is mounted to the top of the water tank 15 above the separator chamber 9 via a second pillar 24. The second sink 23 is formed of stainless steel, includes a base, sidewalls that extend upwardly from the base, and a planar rim or flange that extends outwardly from the sidewalls around an upper opening of the sink 23, and has a capacity of approximately 13 litres. The second sink 23 is provided with a second down tube 25 that is connected to a port or plughole provided in the base of the sink 23. The second down tube 25 extends downwardly from the second sink 23 through the second pillar 24, and has an open lower end that is configured to discharge waste water that has entered the device 1 via the second sink 23 directly into the filter chamber 10 without passing through the separator chamber 9, as described in more detail below. The second sink 23 is a janitor's sink for receiving waste water that is contaminated by chemicals such as effluent from floor cleaning operations. The second sink 23 is set further back than the first sink 19 relative to a front side of the device 1 from which the device 1 is designed to be accessed. One or both of the pillars 20, 24 on which the first and second sinks 19, 23 are mounted may be adjustable in order to enable the positions of the sinks 19, 23 to be adjusted in a vertical direction, in a fore / aft direction (aligned with the width of the main tank 2) and / or in a lateral direction (aligned with the length of the main tank 2). As shown in Figure 9, each of the sinks 19, 23 is provided with a removable perforated basket 50 that is configured to be received in the sink 19, 23 and to filter silt, debris and other waste material out from waste water entering the device via the sink 19, 23. The sink baskets 50 are formed of a stainless steel mesh, and have perforations with a size of approximately 2mm. The sink baskets 50 each include a main body that is formed by a base and sidewalls that extend upwardly from the base, and a flange that extends outwardly from the upper ends of the sidewalls. The main bodies of the sink baskets 50 are configured to sit inside and to at least substantially fill the openings of the sinks 19, 23 when viewed from above, and the flanges are configured to engage the rims or flanges of the sinks 19, 23 in order to mount the baskets 50 to the sinks 19, 23. The sink baskets 50 are also provided with handles to facilitate movement of the baskets 50, for example to facilitate periodic removal and emptying of the sink baskets 50 into a separate waste container. Figure 10 illustrates the same sink as Figure 9 with the basket 50 removed and the base and plughole of the sink visible. As shown in Figures 1 to 4, 9 and 10, each of the sinks 19, 23 is also provided with a stainless steel lid 51 that is pivotally connected to a rear edge of the sink 19, 23 by a hinge 52 and pivotable relative to the sink 19, 23 between an open position (as shown in Figures 1, 3 and 9) in which it allows access to an interior of the sink 19, 23 and a closed position (as shown in Figures 2, 4 and 10) in which it covers the sink 19, 23 and prevents access to the interior of the sink 19, 23. Each of the lids 51 includes a planar main body 53 that is configured to cover the upper opening of its respective sink 19, 23 when the lid 51 is in its closed position. Each of the lids 51 also includes a contact portion that extends downwardly from the main body 53 and includes a planar contact surface that is configured to engage the rim or flange of the sink 19, 23 continuously around the perimeter of the sink 19, 23 (optionally via the flange of the sink basket 50, if present) in order to form a seal between the sink 19, 23 and the lid 51 when the lid 51 is in its closed position. Each of the lids 51 also includes a skirt 54 that extends downwardly from the perimeter of the main body 53 of the lid 51 outboard of the contact portion and is configured to overlap with the sides of the sink 19, 23 by approximately 20mm when the lid 51 is in its closed position. Each of the lids 51 also includes a handle on a front side thereof to facilitate opening and closing of the lid 51. Each of the lids 51 is also provided with a pair of gas struts that are configured to maintain the lid 51 in its fully open position until the lid 51 is pulled away from its fully open position with a predetermined force, and to control the speed of the lid 51 as it moves towards its closed position. Each of the lids 51 is provided with a pair of UV lamps 55 that are mounted on the underside of the lid 51 and configured to emit UV light into the sink 19, 23 to which it is attached when the lid 51 is in its closed position. The UV lamps 55 are configured to disinfect the sinks 19, 23 and their baskets 50, for example by breaking down FOGs, silt and debris and killing pathogens. The UV lamps 55 take the form of elongate, tubular mercury vapor lamps, and extend across the majority of the lengths of the lids 51 and their respective sinks 19, 23 in order to ensure that all parts of the sinks 19, 23 can be disinfected effectively. The UV lamps 55 have a minimum waterproof rating of IP68, and are configured to emit UV light with a wavelength of around 254nm in order to maximise effectiveness against pathogens such as salmonella and E. coli. The lids 51 are configured to prevent UV light emitted by the UV lamps 55 from escaping from the sinks 19, 23 into the environment around the device 1 when in their closed positions. Each of the sinks 19, 23 is also provided with a magnetic switch that is configured to turn its respective UV lamps 55 on when the lid 51 is closed but to turn them off again when the lid 51 is opened. In this way it is possible to ensure that the sinks 19, 23 are disinfected whenever the lids 51 are closed, and to prevent UV light from being emitted into the environment around the device 1 whenever the lids 51 are opened. The switches are provided in the contact surfaces of the lids 51, and are configured to be aligned with magnets provided in the rims or flanges of the sinks 19, 23 when the lids 51 are closed. The magnets are provided at locations at or close to the front sides of the sinks 19, 23. The switches are configured to open and close at a displacement of approximately 10mm from the magnets, and are spaced apart from the magnets by a distance of approximately 5mm when the lids 51 are in their fully closed positions. The switches are therefore configured to only turn the UV lamps 55 on when the lids 51 are within approximately 5mm of their fully closed positions, and to switch the UV lamps 55 off once the lids 51 have been moved out of their fully closed positions by approximately 5mm. The switches therefore ensure that the skirts 54 of the lids 51 overlap with the sides of the sinks 19, 23 before the UV lamps 55 are turned on when the lids 51 are closed, and that the skirts 54 of the lids 51 continue to overlap with the sides of the sinks 19, 23 until after the UV lamps 55 have been turned off when the lids 51 are opened, thereby preventing UV light from escaping from the sinks 19, 23 into the environment around the device 1 as the lids 51 are being closed and opened. As shown in Figure 6, the inlet chamber 8 of the tank 2 is provided with a removable perforated basket 60 that is configured to filter silt and debris out from waste water that has entered the device 1 via the inlet pipe 17 and the first sink 19 in order to prevent large quantities of silt and debris from reaching the separator chamber 9 of the device 1. The inlet chamber basket 60 is elongate, extends in a length direction across a majority of the width of the inlet chamber 8, and is located above the working water level of the separator chamber 9 (which is governed by the height of the second vertical weir wall 13). The inlet chamber basket 60, which is shown in isolation in Figure 11, includes two compartments 61, 62 that each extend between end walls of the basket 60 and are separated from each other by a vertical dividing wall 63. Each of the first and second compartments 61, 62 has a substantially constant cross section along the length of the basket 60, and is U-shaped with a curved base when viewed from the end of the basket 60 to facilitate cleaning and emptying of the basket 60 and reduce the tendency for silt and debris to collect in corners of the basket 60. The first compartment 61 has a greater width than the second compartment 62 when viewed from the end of the basket 60, and the second compartment 62 has a higher outer side wall than the first compartment 61. The inlet chamber basket 60 is formed of a stainless steel mesh. The mesh forming the first compartment 61 has perforations with a size of approximately 2mm, and the mesh forming the second compartment 62 has perforations with a size of approximately 1.5mm. The basket 60 is also provided with handles 64 at both of its ends to facilitate handling of the basket 60, for example to facilitate periodic removal and emptying of the basket 60 into a separate waste container. The first compartment 61 of the inlet chamber basket 60 is located below the open inner end of the inlet pipe 17 and is configured to receive waste water that has entered the device 1 via the inlet pipe 17. The second compartment 62 of the inlet chamber basket 60 is located below the open lower end of the down tube 21 that is connected to the first sink 19, and is configured to receive waste water that has entered the device 1 via the first sink 19. The dividing wall 63 is configured to reduce the velocity of waste water entering the inlet chamber 8 before it progresses towards the separator chamber 9. The dividing wall 63 has a section of increased height towards its mid-point that is aligned with the inlet pipe 17 in order to prevent waste water entering the basket 60 via the inlet pipe 17 from flowing over the dividing wall 63 and into the second compartment 62 of the basket 60. As shown in Figures 6 and 12, the inlet chamber basket 60 is housed within a drawer 65 that is mounted to the inner walls of the inlet chamber 8 via drawer runners 66, and is configured to be pulled out from the inlet chamber 8 in order to facilitate removal and replacement of the basket 60. The drawer 65 includes a handle 67 to facilitate movement of the drawer 65 with respect to the tank 2. The drawer 65 also comprises a plurality of rollers 68 that are arranged along the length of the drawer 65, each having an axis of rotation that is perpendicular to the length of the drawer 65. The rollers 68 together form a base of the drawer 65 that is configured to support the inlet chamber basket 60 thereon, and facilitate removal of the inlet chamber basket 60 from the drawer 65 without requiring the drawer 65 to be fully opened. The rollers 68 are spaced apart from each other along the length direction of the drawer 65 to allow waste water to fall downwardly from the basket 60 towards the separator chamber 9. As shown in Figure 6, the inlet chamber basket 60 is located above the weir plate 11 that separates the inlet chamber 8 from the separator chamber 9. The weir plate 11 is configured to be impacted by waste water falling downwardly from the basket 60 in order to further reduce the velocity of the waste water before it enters the separator chamber 9. As shown from the outside in Figures 1 to 4 and in more detail in Figures 13 to 16, the device 1 further comprises a FOG outlet 27 that is configured to discharge FOGs that have been separated from waste water in the separator chamber 9 under the action of gravity from the separator chamber 9 to a FOG collection receptacle 34 located to one side of the tank 2 adjacent to the separator chamber 9. The FOG outlet 27 comprises a FOG outlet port 28 that is provided in the upper wall 9a of the separator chamber 9. The FOG outlet port 28 is located in a downstream portion of the separator chamber 9 in proximity to the first vertical weir wall 12 in the flat second portion of the separator chamber upper wall 9a downstream of the angled first portion. The angled first portion of the separator chamber upper wall 9a is therefore angled upwardly in a direction towards the FOG outlet port 28, which promotes the movement of FOGs that have separated from waste water in the separator chamber 9 towards the FOG outlet port 28. The FOG outlet 27 further comprises a pipe 29 that extends upwardly from the FOG outlet port 28, and a chute 30 that is connected to upper end of the pipe 29 and extends outwardly and downwardly therefrom to a distal end that is located outboard of the side of the tank 2 above the FOG collection receptacle 34. The chute 30 includes a cover that is pivotable upwardly in order to facilitate cleaning of the chute 30. The FOG outlet 27 further comprises a high-density polyethylene (HDPE) ball 31 that is retained in proximity to the FOG outlet port 28 by a steel cage 32. The FOG outlet port 28 and the HDPE ball 31 form a FOG outlet valve 33 having a closed configuration in which the ball 31 is in engagement with an angled rim of the FOG outlet port 28 and prevents fluid flow out of the separator chamber 9 via the FOG outlet 27, and an open configuration in which the ball 31 is moved out of engagement with the angled rim of the FOG outlet port 28 and fluid is able to flow out of the separator chamber 9 via the FOG outlet 27. The HDPE ball 31 has a density that is lower than the density of water but greater than the density of most low-density FOGs, and will therefore float on water but sink in low-density FOGs that collect at the top of the water in the separator chamber 9. The FOG outlet valve 33 is therefore configured to move into its open configuration automatically in response to a FOG / water interface level in the separator chamber 9 falling below a predetermined level, thereby enabling FOGs that have separated from waste water in the separator chamber 9 to be discharged from the separator chamber 9 via the FOG outlet 27 under hydrostatic pressure, and to move into its closed configuration automatically in response to the FOG / water interface level in the separator chamber 9 exceeding the predetermined level, thereby preventing waste water from being discharged from the separator chamber 9 via the FOG outlet 27. As shown in Figures 1 and 3, the FOG collection receptacle 34 comprises a container into which FOGs which have been separated from waste water in the separator chamber 9 may be discharged via the FOG outlet 27. The FOG collection receptacle 34 is removably mounted to the side of the tank 2 by a FOG receptacle station 35. The FOG receptacle station 35 comprises rails that are configured to receive and engage a lip or flange of the FOG collection receptacle 34. The rails allow the FOG collection receptacle 34 to be slid into the FOG receptacle station 35 into a FOG collection position in which it is able to receive FOGs from the FOG outlet 27 of the device 1, and to be slid out of the FOG receptacle station 35 in order to facilitate periodic emptying of the FOG collection receptacle 34 into larger containers such as barrels for storage prior to recycling. Figures 2 and 4 illustrate the device from the same angles as Figures 1 and 3 with the FOG collection receptacle 34 removed. As shown in Figures 6 and 16, the separator chamber 9 is provided with a heater 36 for heating waste water as it passes through the separator chamber 9. The heater 36 comprises an elongate electric immersion heater that is mounted to one of the sidewalls 6, 7 of the tank 2 and extends in a width direction of the tank 2 (perpendicular to a flow direction in which waste water travels through the separator chamber 9) across a majority of the width of the tank 2. The underside of the heater 36 is located within 20mm of the base 3 of the separator chamber 9. The heater 36 is located directly below the FOG outlet valve 33 formed by the FOG outlet port 28 and the HDPE ball 31, and is spaced apart from the FOG outlet port 28 by approximately 120mm. The heater 36 is configured to heat waste water as it passes through the separator chamber, thereby speeding up the separation of FOGs from waste water in the separator chamber 9 and reducing the probability of FOGs congealing around the FOG outlet valve 33, which could prevent FOGs from being able to exit the separator chamber 9 via the FOG outlet 27. The heater 36 is located inside and surrounded by a housing or "hydroramp" 37. The housing 37 comprises a wall 38 with an inverted U shape that extends around the heater 36 and is connected to the base 3 of the separator chamber 9 along its lower edges on either side of the heater 36. The wall 38 extends in a length direction between the sidewalls 6, 7 of the tank 2, and has a substantially constant cross-section along its length. The housing 37 includes a pair of end walls that are located slightly inboard of the ends of the housing 37 and the sidewalls 6, 7 of the tank 2. The end walls are connected to the base 3 of the separator chamber 9 and to the interior surface of the housing wall 38 in order to define sealed pockets at the ends of the housing 37. These sealed pockets, which are filled with air and sealed off from the waste water in the separator chamber 9, prevent heated water inside the housing 37 from coming into direct contact with the sidewalls 6,7 of the tank 2 and provide a layer of insulation between the heated water inside the housing 37 and the sidewalls 6, 7 of the tank 2, thereby limiting temperature rises on the outer surface of the sidewalls of the tank 2 around the location of the heater 36 and and reducing heat loss through the sidewalls 6, 7. The housing 37 is configured to prevent FOGs that have separated from waste water in the separator chamber 9 from coming into direct contact with the heater 36, thereby reducing the risk of smoke or fire and enabling the heater 36 to be located closer to the FOG outlet valve 33 in a position in which it is able to provide more targeted heating of the FOG outlet valve 33. The housing 37 is also configured to act as a barrier in order to prevent silt and debris that has collected on the base 3 of the separator chamber 9 from moving from the separator chamber 9 onward through the device 1 and into the filter chamber 10. The heater housing 37 is located in proximity to the first vertical weir 12 that separates the separator chamber 9 from the filter chamber 10, with a spacing of approximately 60mm between the heater housing 37 and the first vertical weir wall 12 at the narrowest point. Waste water that has passed over the heater housing 37 is therefore corralled through a narrow space formed between the heater housing 37 and the first vertical weir wall 12 before exiting the separator chamber 9, which facilitates the targeting of FOGs that remain in waste water that has already passed over the heater housing 37, as described in more detail below. The heater housing 37 is provided with a plurality of inlet apertures 39 that are configured to allow water to enter the housing 37 to be heated by the heater 36. The inlet apertures 39 comprise elongate slots that extend through the housing wall 38. The inlet apertures 39 are located on a downstream side of the housing 37 adjacent to a lower edge of the housing wall 38 in proximity to the base 3 of the separator chamber 9 in order to reduce the probability of silt and debris that have collected on an upstream side of the housing 37 from entering the housing 37. The heater housing 37 is also provided with a heated water outlet 40 that is located directly below the FOG outlet valve 33. The heated water outlet 40 comprises a tube that is in fluid communication with the interior of the heater housing 37. The tube 41 extends outwardly from the wall 38 of the heater housing 37 in a vertical direction directly towards the FOG outlet valve 33, and has a distal end that is spaced apart from the FOG outlet port 28 by approximately 60mm. The heated water outlet 40 is configured to direct a jet of water that has been heated by the heater 36 in a direction towards the FOG outlet valve 33 in order to providing more targeted heating of the FOG outlet valve 33, thereby further reducing the probability of FOGs congealing around the FOG outlet valve 33. The heater housing 37 is also provided with a plurality of outlet apertures 42 in addition to the heated water outlet 40. The outlet apertures 42 comprise elongate slots that extend through the housing wall 38, and are provided across the top and on the downstream side of the heater housing 37. The outlet apertures are configured to direct plumes or "hydroblades" of water that has been heated by the heater 36 outwardly from the heater housing 37 in various different directions, including in a direction towards the first vertical weir wall 12 that separates the separator chamber 9 from the filter chamber 10. The plumes of heated water increase the effectiveness of the separation of FOGs from waste water in the separator chamber 9. The plumes that are directed into waste water as it is corralled through the narrow space formed between the heater housing 37 and the first vertical weir wall 12 are particularly effective for helping to separate FOGs that still remain in waste water that has already passed over the heater housing 37 and is about to exit the separator chamber 9 and move into the filter chamber 10. Water is expelled from the heater housing 37 via the heated water outlet 40 and the additional outlet apertures 42 due to heating from the heater 36 without the need for any additional propulsion mechanism, and may be expelled as boiling and / or superheated water. The separator chamber 9 is also provided with a temperature sensor or thermostat 43 that is configured to measure the temperature of waste water entering the separator chamber 9. The temperature sensor or thermostat 43 is located approximately 250mm upstream of the heater 36 around a mid-point along the length of the separator chamber 9. The temperature sensor or thermostat 43 is located in an upper portion of the separator chamber 9 approximately 100mm above the base 3 of the separator chamber 9. The heater 36 is configured to be switched on and off automatically in dependence on the temperature of waste water entering the separator chamber 9 as measured by the temperature sensor or thermostat 43 falling below or exceeding a predetermined level. The fact that the temperature sensor or thermostat 43 is separated from and provided at a different location to the heater 36 enables the heater 36 to be located closer to the base 3 of the separator chamber 9 and the FOG outlet valve 33, while also allowing the position of the temperature sensor or thermostat 43 to be optimised to more accurately measure the temperature of waste water entering the separator chamber 9. As shown in Figure 6, the filter chamber 10 houses a filter 70 that is configured to perform final filtering of waste water that has passed through the separator chamber 9 before it exits the device 1. The filter 70 is a FOG filter as disclosed in WO2021001352A1, which is incorporated by reference in its entirety. As shown in Figure 20 and described in more detail in WO2021001352A1, the filter 70 comprises first to fifth perforated layers 70a to 70e located inside a casing 70f. The first and fifth perforated layers 70a, 70e are formed from strands of pre-galvanised steel which are arranged to form multiple pores. The second perforated layer 70b comprises polyester. The third perforated layer 70c comprises polyester impregnated with carbon. The fourth perforated layer 70d comprises granular activated carbon bonded together using adhesive and surrounded by a protective layer of polyester. The second to fourth perforated layers 70b to 70d have progressively smaller average pore diameters. The perforated casing 70f surrounds and encases the first to fifth perforated layers 70a to70e, and includes front and back surfaces each including multiple pores. The filter 70 is arranged with the first perforated layer 70a at its upstream side and the fifth perforated layer 70e at its downstream side such that waste water flowing through the filter chamber 10 flows through the front surface of the casing 70f to enter the filter 70, through the first to fifth perforated layers 70a to 70e, and through the back surface of the casing 70f to exit the filter 70. The filter 70 is able to remove FOGs that still remain in waste water that has already passed through the separator chamber 9, in particular high-density FOGs and FOGs with a droplet size of less than 150 pm, before the waste water exits the device 1. As shown in Figure 6, the filter 70 is held in position within the filter chamber 10 by a filter holder 71. The filter holder 71 is formed by two pairs of guide rails that are provided on opposed side walls of the filter chamber 10, which are configured to receive and retain side edges of the FOG filter 70 therebetween. The FOG filter 70, when located in the filter chamber 10 between the guide rails of the filter holder 71, extends between the opposed side walls of the filter chamber 10 and down to the base of the filter chamber such that all waste water that passes through the filter chamber 10 will flow through and be purified by the filter 70 during normal use of the device 1. However, a gap is provided between the top of the filter 70 and the upper wall 10a of the filter chamber 10 through which waste water may flow if the flow rate of waste water entering the filter chamber 10 exceeds a maximum flow rate capacity of the filter 70. The upper wall 10a of the filter chamber 10 is removable or pivotable relative to the tank 2 in order to provide access to the interior of the filter chamber 10 and enable the filter 70 to be inspected and replaced as required. As shown in Figures 6 to 8, the filter chamber 10 further comprises two waste water outlets 26a, 26b that are configured to emit cleaned waste water from the device 1. The waste water outlets 26a, 26b comprise outlet pipes that are connected to and extend outwardly from the second end wall 5 of the tank 2, through which cleaned waste water may exit the device 1 after having passed through and been cleaned by the separator chamber 9 and the filter chamber 10. The first and second waste water outlets 26a, 26b are arranged one above the other. The lower waste water outlet 26a is configured to emit cleaned waste water from the device 1 whenever waste water is flowing through the device 1. The upper waste water outlet 26b, which has a larger diameter than the lower waste water outlet 26a, allows additional waste water to be emitted from the device 1 therethrough when the flow rate of waste water entering the device 1 exceeds the flow rate capacity of the lower waste water outlet 26a. The first and second waste water outlets 26a, 26b may be connected to the main drains and configured to discharge waste water that has been cleaned by the device 1 directly into the main drains. As mentioned above, the down tube 25 that is connected to the second sink 23 is configured to discharge waste water that has entered the device 1 via the second sink 23 into the filter chamber 10 without passing through the separator chamber 9. In particular, as shown in Figures 6 to 8, the down tube 25 that is connected to the second sink 23 has an open lower end that is located above the second vertical weir wall 13 such that waste water that enters the device 1 via the second sink 23 will pass over the second vertical weir wall 13 and be discharged into the filter chamber 10 upstream of the filter 70. As waste water that enters the device 1 via the second sink 23 bypasses the separator chamber 9, the second sink 23 is able to receive waste water containing chemicals that can disrupt the separation of FOGs from water, for example floor cleaning chemicals and de-greasing agents, without interfering with the separation of FOGs from waste water in the separator chamber 9. However, as waste water that enters the device 1 via the second sink 23 is discharged into the filter chamber 10 upstream of the filter 70, the filter 70 is still able to remove FOGs from the waste water before it exits the device 1. As shown in Figures 6 to 8, the filter chamber 10 also includes a removable perforated basket 72 that is located between the second vertical weir wall 13 and the filter 70 and configured to filter silt and debris out of waste water entering the filter chamber 10 via the down tube 25 before the waste water reaches the filter 70. The filter chamber basket 72 is mounted to the second vertical weir wall 13 on a downstream side thereof by a basket holder 73 that extends upwardly and outwardly from the upper edge of the second vertical weir wall 13. The basket holder 73 includes a pair of supporting struts that extend upwardly from the upper edge of the second vertical weir wall 13 at either side thereof, and a horizontal basket supporting portion that extends outwardly from the upper ends of the supporting struts in a direction towards the second end 2b of the tank 2. The basket supporting portion of the basket holder 73 includes an aperture that is configured to receive the filter chamber basket 72 therein, and a supporting surface that extends around the aperture. The filter chamber basket 72, which is shown in isolation in Figures 17 and 18, is elongate, extends in a length direction across a majority of the width of the filter chamber 10, is U-shaped with a curved base when viewed from the end of the basket 72, and is formed of a stainless steel mesh having perforations with a size of approximately 1.5mm. The filter chamber basket 72 includes a flange 74 that extends outwardly from the upper edges of its sidewalls, which is configured to engage the supporting surface of the basket holder 73 in order to mount the basket 72 to the basket holder 73. The filter chamber basket 72 also includes an aperture 75 in its upstream sidewall that is aligned with the open lower end of the down tube 25 in order to allow waste water exiting the down tube 25 to enter the basket 72, and an angled plate 76 that is configured to direct waste water exiting the down tube 25 downwardly towards the base of the basket 72 in order to prevent the waste water from the down tube 25 from flowing over the top of the basket 72 instead of passing therethrough. The filter chamber basket 72 is also provided with a handle 77 to facilitate handling of the basket 72, for example to facilitate periodic removal and emptying of the basket 72 into a separate waste container. As shown in Figure 6, a flow redirecting plate 14 extends downwardly from the downstream end of the basket holder 73. The flow redirecting plate 14 is located between the filter chamber basket 72 and the filter 70, and extends downwardly to a lower edge that is around the same height as the top of the filter 70. The flow redirecting plate 14 prevents waste water that has entered the filter chamber basket 72 via the down tube 25 from flowing out of the downstream side of the basket 72 and passing over the top of the filter 70, thereby ensuring that all of the waste water that enters the device 1 via the second sink 23 will pass through the filter 70 before exiting the device 1. As also shown in Figure 6, the filter chamber basket 72 is spaced apart from the downstream side of the second vertical weir wall 13 such that waste water entering the filter chamber 10 from the separator chamber 9 is able to flow over the second vertical weir wall 13 and downwardly through a gap formed between the second vertical weir wall 13 and the filter chamber basket 72 without passing through the filter chamber basket 72. The filter chamber basket 72 therefore only receives and filters waste water that has entered the device 1 via the second sink 23. As also shown in Figure 6, the device 1 further comprises a silt outlet 80 that is configured to allow silt and debris that collects at the base 3 of the separator chamber 9 to be drained out of the separator chamber 9. The silt outlet 80 comprises a silt outlet pipe 81 that is connected to the first end wall 2a of the tank and in fluid communication with the separator chamber 9 at the upstream end thereof. The silt outlet pipe 81 is connected to the separator chamber 9 adjacent to the base 3 of the separator chamber 9 in order to maximise the efficiency with which silt and debris can be evacuated from the separator chamber 9 via the silt outlet pipe 81. The base 3 of the separator chamber 9 is also angled downwardly in a direction towards the silt outlet pipe 81 to promote the movement of silt and debris towards the silt outlet pipe 81. The silt outlet pipe 81 is provided with a silt outlet valve 82 that is movable between an open configuration in which the silt outlet valve 82 allows fluid to flow out of the separator chamber 9 via the silt outlet pipe 81 and a closed configuration in which the silt outlet valve 82 prevents fluid from flowing out of the separator chamber 9 via the silt outlet pipe 81. The position of the silt outlet valve 82 is controlled by a motor 83, which is configured to open the silt outlet valve 82 automatically, for example according to a predetermined schedule, at a predetermined time interval or in response to the detection of a build-up of silt or debris in the separator chamber 9. The distal end of the silt outlet pipe 81 is connected to a small, cuboidal tank 84 located outside the main tank 2, which defines a silt outlet chamber 85 that is configured to receive silt and debris-laden water from the separator chamber 9 via the silt outlet pipe 81 when the silt outlet valve 83 is opened. The silt outlet chamber 85 is provided with a removable perforated basket 86 that is configured to filter silt and debris out of water entering the silt outlet chamber 85 via the silt outlet pipe 81. The silt outlet chamber basket 86, which is shown in isolation in Figure 19, is elongate, extends in a length direction across a majority of the width of the silt outlet chamber 85, and is formed of a stainless steel mesh having perforations with a size of approximately 1.5mm. The silt outlet chamber basket 86 includes a flange 86a that extends outwardly from the upper edges of its sidewalls for mounting the basket 86 to a basket holder provided in the silt outlet chamber 85. The silt outlet chamber basket 86 also includes an aperture 86b in its upstream sidewall that is aligned with the silt outlet pipe 81 in order to allow silt and debris-laden water entering the silt outlet chamber 85 via the silt outlet pipe 81 to enter the basket 86. The silt outlet chamber basket 86 is also provided with a pair of handles 86c to facilitate handling of the basket 86, for example to facilitate periodic removal and emptying of the basket 86 into a separate waste container. The silt outlet chamber 85 is also provided with a filter 87 that is located downstream of the silt outlet chamber basket 86. The filter 87 is configured to filter water as it passes through the silt outlet chamber 85 after having passed through the silt outlet chamber basket 85. As with the filter 70 that is located in the filter chamber 10, the silt outlet chamber filter 87 is a FOG filter as disclosed in WO2021001352A1, and is held within the silt outlet chamber 85 by a filter holder including two pairs of guide rails that are provided on opposed side walls of the silt outlet chamber 85. The silt outlet chamber 85 also comprises a waste water outlet 88 in the form of a discharge pipe. The discharge pipe is located downstream of the silt outlet chamber basket 86 and the FOG filter 87, and is configured to emit waste water from the silt outlet chamber 85 after the waste water has passed through the silt outlet chamber basket 86 and the FOG filter 87. The silt outlet chamber basket 86 and the FOG filter 87 together ensure that the water that is emitted via the waste water outlet 88 is substantially free of silt and FOGs, thereby enabling water from the waste water outlet 88 to be discharged to a main drain. The upper wall of the silt outlet chamber 85 is removable or pivotable relative to the tank 84 in order to provide access to the interior of the silt outlet chamber 85 and enable the silt outlet chamber basket 86 to be emptied into a separate waste container and the FOG filter 87 to be replaced as required. As mentioned above, the device 1 includes a water tank 15 that is located above the middle section of the main tank 2 and connected to a mains water supply and to the main tank 2. As shown in Figure 8, the water tank 15 is connected to the main tank 2 by a water pipe 89 that extends outwardly from the water tank 15 and is connected to the main tank 2 at a flushing water inlet 90 located in the third section 2"' of the tank 2 between the first and second vertical weir walls 12, 13. The flushing water inlet 90 is provided with a flushing water inlet valve 91 that is configured to open and close automatically in response to changes in the water level within the main tank 2. In particular, the flushing water inlet valve 91 comprises a float 92 that is configured to open the flushing water inlet valve 91 automatically in response to the water level in the main tank 2 falling below a predetermined threshold level and to close the flushing water inlet valve 91 automatically when the water level in the main tank 2 reaches the predetermined threshold level again. When the silt outlet valve 82 is opened, the flow of silt and debris-laden water out of the separator chamber 9 via the silt outlet 80 causes the water level in the main tank 2 to drop. However, the resulting drop in the water level in the main tank 2 causes the flushing water inlet valve 91 to open, thereby enabling flushing water from the water tank 15 to flow into the main tank 2 via the flushing water inlet 90. The flushing water that enters the main tank 2 via the flushing water inlet 90 is able to flow under the first vertical weir wall 12 and into the separator chamber 9, thereby reducing the extent to which the water level in the separator chamber 9 drops during de-silting operations. The flushing water is also able to flow through the separator chamber 9 in a direction towards the silt outlet 80, thereby helping to wash silt and debris that has collected on the base 3 of the separator chamber 9 towards the silt outlet 80. As shown in Figure 6, the water tank 15 is connected to the mains water supply via a mains water inlet 93 that is provided with a mains water inlet valve 94 for regulating the supply of water into the water tank 15. The mains water inlet valve 94 comprises a float 95 that is configured to open the mains water inlet valve 94 automatically in response to the water level in the water tank 15 falling below a predetermined threshold level, thereby enabling the water tank 15 to be refilled automatically when flushing water is allowed to flow from the water tank 15 into the main tank 2. The water tank 15 has a capacity of approximately 16 litres in order to ensure that a sufficient quantity of flushing water can be delivered to the separator chamber 9 when the silt outlet valve 82 is opened. The above-described GRU includes many features that work together to provide a GRU that is particularly effective at removing FOGs and other contaminants from waste water, that has improved reliability and reduced maintenance requirements compared to known GRUs, and that enables all of the waste water emitted therefrom to be discharged into drainage and sewerage systems without contravening laws and regulations governing the content of waste water. The description provided above relates to one possible embodiment of the present invention, and is provided for illustrative purposes only. It will be appreciated that many modifications and variations may be made to the above-described embodiment without departing from the scope of the invention as defined in the appended claims.

Claims

1. A device for removing FOGs from waste water, the device comprising:a waste water inlet that is configured to receive waste water contaminated by FOGs into the device;a separator chamber that is configured to receive waste water from the inlet and to separate FOGs from the waste water under the action of gravity;a waste water outlet that is configured to emit waste water that has passed through the separator chamber from the device;a FOG outlet that is configured to emit FOGs that have been separated from the waste water in the separator chamber from the separator chamber;a FOG outlet valve that is movable between an open configuration and a closed configuration, the FOG outlet valve being configured to allow fluid flow out of the separator chamber via the FOG outlet when in the open configuration and to prevent fluid flow out of the separator chamber via the FOG outlet when in the closed configuration; anda heating system located in the separator chamber, the heating system comprising a heater that is configured to heat waste water in the separator chamber, and a housing that at least partially surrounds the heater.

2. A device according to Claim 1, wherein the FOG outlet valve comprises a ball valve or float valve that is configured to open and close automatically in dependence on the level of a FOG / water interface within the separator chamber.

3. A device according to Claim 1 or Claim 2, wherein the heater is located in a downstream portion of the separator chamber, at least substantially directly below the FOG outlet valve and / or in proximity to the FOG outlet valve, for example within 200mm of the FOG outlet valve.

4. A device according to any preceding claim, wherein device further comprises a temperature sensor or thermostat located in the separator chamber, wherein heater is configured to be switched on automatically in response to the temperature in the separator chamber as measured by the temperature sensor or thermostat falling below a predetermined level.

5. A device according to Claim 4, wherein the temperature sensor or thermostat is provided at a different location to the heater outside the housing in which the heater is located.

6. A device according to Claim 4 or Claim 5, wherein the temperature sensor or thermostat is provided at a location upstream of the heater, at a higher position than the heater, in an upper portion of the separator chamber and / or at a location that is at least 50mm above a base of the separator chamber.

7. A device according to any preceding claim, wherein the device further comprises a filter chamber located downstream of the separator chamber that is configured to receive a FOG filter for removing FOGs that remain in waste water that has passed through the separator chamber before the waste water exits the device via the waste water outlet.

8. A device according to Claim 4, wherein the device comprises a weir located between the separator chamber and the filter chamber, wherein the housing in which the heater is located is located in proximity to the weir, for example within 100mm of the weir.

9. A device according to Claim 8, wherein the housing in which the heater is located comprises a wall with an inverted U-shape that at least partially surrounds the heater.

10. A device according to any preceding claim, wherein the housing extends in a direction perpendicular to the flow direction of the separator chamber between opposed sidewalls of the separator chamber.

11. A device according to any preceding claim, wherein the housing is connected to a base of the separator chamber and configured to act as a barrier in order to prevent silt and / or debris that has collected on the base of the separator chamber from moving from the separator chamber in a direction towards the waste water outlet.

12. A device according to any preceding claim, wherein the housing includes at least one heated water outlet that is configured to direct a jet of water that has been heated by the heater in a direction towards the FOG outlet valve.

13. A device according to Claim 12, wherein the heated water outlet comprises a tube that is connected to a body of the housing and extends outwardly therefrom in a direction towards the FOG outlet valve.

14. A device according to any preceding claim, wherein the housing is provided with a plurality of apertures that are configured to direct plumes of water that has been heated by the heater outwardly from the housing.

15. A device according to Claim 14, wherein the apertures are provided in an upper portion of the housing and / or on a downstream side of the housing.

16. A device according to Claim 14 or Claim 15 when dependent on Claim 8, wherein at least some of the apertures are configured to direct plumes of water towards the weir separating the separator chamber from the filter chamber.

17. A device according to any of Claims 12 to 16, wherein water is expelled from the housing via the heated water outlet and / or the apertures due to heating from the heater without any additional propulsion mechanism.

18. A device according to any preceding claim, wherein the housing comprises at least one inlet aperture for allowing water to enter the housing in order to be heated by the heater.

19. A device according to Claim 18, wherein the inlet aperture(s) are provided at or adjacent to a lower edge of the housing on a downstream side of the housing.

20. A device according to any preceding claim, wherein the waste water inlet comprises an inlet pipe or port that is configured to receive waste water from one or more sinks or appliances external to the device, or a sink forming part of the device.

21. A device for removing FOGs from waste water, the device comprising:a waste water inlet that is configured to receive waste water contaminated by FOGs into thedevice;a separator chamber that is configured to receive waste water from the inlet and to separate FOGs from the waste water under the action of gravity;a waste water outlet that is configured to emit waste water that has passed through the separator chamber from the device;a silt outlet that is configured to emit silt and / or debris from the separator chamber;a silt outlet valve that is movable between an open configuration and a closed configuration, the silt outlet valve being configured to allow fluid flow out of the separator chamber via the silt outlet when in the open configuration and to prevent fluid flow out of the separator chamber via the silt outlet when in the closed configuration; anda flushing water inlet separate to the waste water inlet that is configured to allow flushing water to enter the separator chamber when the silt outlet valve is opened.

22. A device for removing FOGs from waste water, the device comprising:a waste water inlet that is configured to receive waste water contaminated by FOGs into the device;a separator chamber that is configured to receive waste water from the inlet and to separate FOGs from the waste water under the action of gravity;a waste water outlet that is configured to emit waste water that has passed through the separator chamber from the device; anda removable perforated basket that is located between the waste water inlet and the separator chamber such that waste water entering the device through the waste water inlet passes through the removable perforated basket before entering the separator chamber, the removable perforated basket being configured to filter silt and / or debris out of the waste water before it reaches the separator chamber.

23. A device for removing FOGs from waste water, the device comprising:a waste water inlet that is configured to receive waste water contaminated by FOGs into the device;a separator chamber that is configured to receive waste water from the inlet and to separate FOGs from the waste water under the action of gravity;a waste water outlet that is configured to emit waste water that has passed through the separator chamber from the device; anda contaminated water inlet that is configured to receive waste water contaminated by chemicals into the device, the contaminated water inlet being in fluid communication with the waste water outlet in parallel to the separator chamber such that waste water entering the device via the contaminated water inlet is able to exit the device via the waste water outlet without passing through the separator chamber.

24. A kitchen sink that is provided with at least one UV light emitter or lamp that is configured to emit UV light into the sink.

25. A kitchen comprising a device according to any of Claims 1 to 23 and / or a sink according to Claim 24.

Images