Wastewater treatment device

Abstract

1. A wastewater treatment device comprising: a housing having a settling tank mounted therein adapted to receive wastewater; a skimmer mounted to the settling tank to remove any FOG (fats, oils, grease) that remains on the surface of the wastewater; a drain pipe provided at a downstream end of the settling tank for removing water from the settling tank; an inlet end of the drain pipe defined by a weir that controls the water level within the settling tank; and a sediment removal system adapted to remove sediment that collects at the bottom of the settling tank.

Description

Technical Field

[0001] The present invention relates to a wastewater treatment device, and more specifically, to a wastewater treatment device for removing fats, oils and greases, as well as solid waste, from wastewater from, for example, a sink in a commercial kitchen.

Background Art

[0002] Normal wastewater discharged from a sink in a commercial kitchen or a catering facility usually contains food waste, in addition to emulsified grease in the form of other solid waste, and in addition, grease-containing solids in suspension. Such contaminants can cause blockage of the drainage system and / or fouling of the filtration system or pump in the water treatment facility downstream of the drainage system.

[0003] Waste liquid from FOG (fats, oils, greases) contaminated parts of a commercial kitchen usually results from steam combination ovens, convection rotisserie ovens, pot sinks, pre-rinse sinks, dishwashers, canopies, etc. These commonly apply warm water in the temperature range of 40°C to 85°C to handle FOG contaminants, and the FOG is washed away by the wastewater flow from such devices.

[0004] For these reasons, depending on the country, in many cases, commercial kitchen businesses are obliged to equip some kind of blocking device, usually called a grease trap, to collect FOG before it enters the sewer. In addition, if FOG is a concern in the local wastewater collection system, an inspection program is set up so that these grease traps and / or blocking means are routinely maintained.

[0005] Known grease traps range in complexity from simple sedimentation tanks known as "passive" grease traps that require periodic manual removal of grease, to complex arrangements that automatically scoop up fats, oils, and grease (FOG) and collect the scooped FOG in an external container placed adjacent to a trap assembly, commonly called an "automated" grease trap or GRU.

[0006] Passive grease traps are essentially simple sedimentation tanks that have a wastewater inlet at one end and an outlet for connection to a drain pipe at the opposite end. Often, baffle plates are placed in the tank to block the direct flow of wastewater between the inlet and the outlet. Periodically, employees must manually scoop the FOG that accumulates on the surface of the wastewater.

[0007] Automated grease traps are equipped with an automatic scooping arrangement that utilizes a scooping device, usually in the form of a disk, drum, endless belt, or tube, mounted on top of the tank and connected to a drive arrangement that moves through the layer of FOG floating on the wastewater in the tank of the grease trap. The scooping device collects the FOG from the surface of the water in the tank and is then cleaned by means that provide a scraping or squeezing action on top of the scooping arrangement, such as a wiper blade, positioned to direct the collected FOG towards a collection device before the scooping arrangement returns into the water. The collection device is usually a separate container or reservoir located on one side of the tank.

[0008] Known grease traps require a regular maintenance program to pump out such traps and replenish with clean water. European Standard EN1825 requires that grease traps be pumped out monthly and preferably every two weeks. If the grease trap contains some, if not all, of the mixed FOG and food waste, these are separated, with FOG having a specific gravity of less than 1 rising to the surface and food waste having a specific gravity of more than 1 sinking to the bottom.

[0009] The skimming device can continuously remove FOG from the surface of the water in the tank, but food waste and other solid substances carried in the wastewater collect at the bottom of the tank as organic sediment. If this is not addressed, indigenous mesophilic bacteria will deplete the dissolved oxygen in the wastewater, causing odors in the commercial kitchen and unpleasant working conditions for the staff, and potentially leading to the need to frequently discard the tank to remove the sediment.

Summary of the Invention

[0010] According to the present invention, a wastewater treatment apparatus is provided, the wastewater treatment apparatus including a housing having a sedimentation tank therein adapted to receive wastewater, a skimming device mounted in the sedimentation tank for removing any FOG remaining on the surface of the wastewater, a drain pipe provided at a downstream end of the sedimentation tank for removing water from the sedimentation tank, an inlet end of the drain pipe defined by a weir for controlling the amount of water in the sedimentation tank, and a sediment removal system adapted to remove sediment collected at the bottom of the sedimentation tank.

[0011] Preferably, the sediment removal system includes a sediment removal pump having an inlet, connected to a sediment extraction passage extending into a sediment collection area at the bottom of the sedimentation tank and adapted to draw out sediment accumulating in the sediment collection area of the sedimentation tank.

[0012] Preferably, the bottom wall of the sedimentation tank slopes downwardly towards the sediment collection area and towards the inlet end of the extraction passage within the sedimentation tank, facilitating the movement of sediment towards the inlet end of the extraction passage.

[0013] The sediment removal pump may be adapted to pump sediment from the sedimentation tank as a slurry into the drain pipe of the sedimentation tank or alternatively into a separate collection container or the drain pipe outlet.

[0014] In one embodiment, the settling tank may include first and second end walls disposed opposite to each other and separated by first and second side walls disposed opposite to each other. A longitudinal baffle or dividing wall may extend inwardly from the first end wall to the second end wall in parallel with the first and second side walls, and the dividing wall may terminate adjacent to the second end wall so as to divide the interior of the settling tank into an inlet region and a settling region, and the skimming arrangement and the sediment removal system may cooperate with the settling region. The dividing wall may be disposed adjacent to the first side wall of the tank such that the inlet region of the tank is narrower than the settling region.

[0015] In one embodiment, a pair of parallel, vertically disposed baffle plates may extend between the dividing wall and the second side wall of the settling tank across the width of the settling region of the settling tank. The baffle plates may have a lower edge terminating on the bottom wall of the settling tank and an upper edge extending above the normal water level in the settling tank. The baffle plates may be spaced apart from each other to define a cavity therebetween, and the inlet end of the sediment extraction passage may extend into the cavity through one of the baffle plates, whereby the cavity defines the inlet region of the sediment extraction passage. The cavity may function as a vent for the sediment removal pump.

[0016] The sediment extraction passage may be defined by a pipe extending from the sediment removal pump into the settling tank and terminating at the cavity. The inlet end of the sediment extraction pipe may extend into the cavity through one of the baffle plates.

[0017] Preferably, the drain pipe of the settling tank extends from the rear wall of the housing.

[0018] In one embodiment, the wastewater collection tank can be mounted within the housing adjacent to a settling tank that functions as a solid waste blocking means, and a food waste collection tray is located within the wastewater collection tank to collect solid waste therein. A removable strainer basket can be mounted within the food waste collection tray to collect food waste and other solid waste therein, the strainer basket incorporating openings or slots through which wastewater can pass while solid waste entrained in the wastewater is collected within the strainer basket. Wastewater containing, for example, FOG from a sink drainpipe, as well as entrained food waste and other solids, can be supplied to the strainer basket within the wastewater collection tank through an inlet pipe passing through supply holes in the rear wall of the tray and the rear wall of the basket. The bottom wall of the food waste collection tray can be perforated to drain water through the holes to the wastewater collection tank. The bottom wall of the wastewater collection tank can incorporate a drain gutter at its lowest point and connect to a downwardly sloping supply passage that communicates with the settling tank. An additional strainer can be provided between the wastewater collection tank and the supply passage, the additional strainer preferably comprising the perforated portion of the bottom wall of the food waste collection tray through which wastewater must pass to reach the supply passage.

[0019] The skimming device can comprise an elongate drum having a surface coated with or formed from hydrophobic and lipophilic substances, the drum being mounted within the settling tank so as to be partially submerged in the wastewater maintained within the tank during use, the drum being rotatably mounted within the tank by the action of a motor. The FOG collection tank can be mounted on one side of the housing adjacent to the skimming arrangement and is arranged to engage the drum surface of the skimming arrangement and comprises a scraper or wiper blade that scrapes FOG from the surface and delivers the FOG to the collection tank.

[0020] One or more sensors adapted to measure one or more of the dissolved oxygen content of the water in the sedimentation tank, the amount of FOG remaining on the surface of the water in the sedimentation tank, the water temperature in the sedimentation tank, and the turbidity of the water can be attached to the sedimentation tank. The one or more sensors may comprise non-contact sensors that are not in direct contact with the wastewater. Data from the one or more sensors can be transmitted to a central monitoring and / or control center by wired or wireless communication means to facilitate the monitoring and management of the device or multiple installations.

[0021] With reference to the accompanying drawings, by way of example only, a wastewater treatment device according to an embodiment of the present invention will now be described.

Brief Description of the Drawings

[0022]

Figure 1

Figure 2

Figure 3

Figure 4

Figure 5

Mode for Carrying Out the Invention

[0023] As shown in the drawings, a wastewater treatment device according to an embodiment of the present invention comprises a substantially rectangular housing 2 in which a sedimentation tank 4 is mounted and which defines a grease trap, and FOG separated from the wastewater and floating on the surface of the wastewater is removed before the water passes through the drain pipe, thereby significantly reducing the passage of FOG through the drain pipe.

[0024] The wastewater collection tank 6 is located within the housing adjacent to the sedimentation tank 4 that functions as solid waste blocking means. The food waste collection tray 8 is located within the wastewater collection tank 6, and a strainer basket 10 is mounted within the tray 8 for collecting food waste and other solid waste. Wastewater containing, for example, FOG from a sink drainpipe, as well as commingled food waste and other solids, can be supplied to the strainer basket within the wastewater collection tank 8 through an inlet pipe 12 passing through supply holes in the rear wall of the tray 8 and the rear wall of the basket 10.

[0025] The food waste collection tray 8 is slidably mounted within the wastewater collection tank 6 in a drawer-like manner, and the tray 8 is adapted to slide horizontally on and from the front side of the wastewater collection tank 6 between a closed position where the strainer basket 10 receives wastewater from the wastewater inlet pipe 12 and an open position where the tray 8 extends horizontally from the front of the tank 2 and approaches the strainer basket 10 to enable removal of the strainer basket 10 to empty the collected food waste. Runners 14 (Figure 4) can be provided on the inner surface of the sidewall of the tank 2 on which the tray 8 can be supported and guided. A separate strainer basket 10B is housed in the lower space of the wastewater collection tank 8.

[0026] The bottom wall of the food waste collection tray 8 is perforated to allow water to drain through the holes to the wastewater collection tank 6, thereby further separating solid waste within the collection tray 8.

[0027] The bottom wall of the wastewater collection tank 6 incorporates a central groove 15 at the lowest part of the tank, extending parallel to the sidewalls of the tank 6, and the floor of the tank 6 preferably slopes downward on either side of the groove 15 to facilitate drainage of wastewater into the groove 15. The groove 15 connects to a downwardly inclined supply passage 21 that communicates with the sedimentation tank 4. The supply passage 21 increases the retention and removal efficiency by reducing the velocity of the wastewater and decreasing turbulence before the wastewater reaches the sedimentation tank 4.

[0028] An additional strainer, for example, the perforated portion 9 of the bottom wall of the tray 8 through which the wastewater must pass to reach the supply passage 21, is provided between the wastewater collection tank 6 and the supply passage 21. For example, when the food waste collection tray 8 is open and the wastewater has passed to the wastewater collection tank 6, solid waste can be captured without passing it to the sedimentation tank 4.

[0029] The sedimentation tank 4 includes first and second end walls 16, 17 arranged opposite to each other and separated by first and second side walls 18, 19 arranged opposite to each other. As best shown in FIG. 2, a longitudinal baffle or dividing wall 20 extends inwardly from the first end wall 16 to the second end wall 17 in parallel with the first and second side walls 18, 19, and the dividing wall 20 terminates adjacent to the second end wall 17. The dividing wall 20 divides the interior of the sedimentation tank 4 into an inlet region 22 and a sedimentation region 24. The dividing wall 20 is arranged adjacent to the first side wall 18 of the tank such that the inlet region 22 of the tank 8 is narrower than the sedimentation region 24.

[0030] The dividing wall 20 defines a flow path for the wastewater through the sedimentation tank 4 and substantially doubles the transverse length of the wastewater passing through the tank 4. When the wastewater passes through the tank 4, the change in direction imparted to the wastewater also slows down the flow of the wastewater and promotes the separation of FOG and water in the sedimentation region 24 of the sedimentation tank 4.

[0031] A water drain pipe 26 is provided at the downstream end of the sedimentation region 24 of the sedimentation tank 4. The inlet end of the drain pipe 26 is defined by a weir 28 that controls the water level in the sedimentation tank 4. The clarified water overflows the weir 28, passes through the drain pipe 26 and through the tank 4, and the inlet end of the drain pipe 26 extends from the rear wall of the housing 2.

[0032] The skimming device is attached to the settling area 24 of the sedimentation tank 6. In the embodiment shown in the drawings, the skimming device comprises an elongated drum 40 having a surface coated with or formed from hydrophobic and lipophilic substances, and the drum 40 is installed in the settling area 24 of the sedimentation tank 4 so as to be partially submerged in the wastewater maintained in the tank 4 during use. The drum 54 is rotatably attached to the tank 4 by the action of a motor 56 and rotates about an axis extending substantially parallel to the first and second sides 16, 17 of the sedimentation tank 4.

[0033] The FOG collection tank 50 is attached to one side of the two housings adjacent to the second side 17 of the sedimentation tank 4 adjacent to the skimming device, and is arranged to mesh with the surface of the drum 40, and is provided with a scraper or wiper blade 52 arranged to scrape the FOG from the surface and deliver the FOG to the collection tank 50.

[0034] As shown in FIG. 3, the wiper blade 52 extends and is attached to one side of the FOG collection tank 50, and when the FOG collection tank 50 is attached to the side surface of the housing 2, the wiper blade 52 comes into contact with the drum 40. When the FOG collection tank 50 is removed so that it can be emptied, the wiper blade 52 can also be cleaned at the same time.

[0035] As best shown in FIG. 4, the sedimentation tank 4 is provided with a sediment removal system, whereby the sediment collected at the bottom of the tank is automatically removed as described in more detail below, and the efficiency of the device can be improved. In the prior art, a grease trap for capturing such sediment mainly containing food waste having a specific gravity greater than 1 had to be manually removed during the regular maintenance of the grease trap.

[0036] The sediment removal pump 60 is arranged in the housing 2 adjacent to the first end 16 of the sedimentation tank 4. The inlet of the pump 60 extends horizontally into the sediment collection area in the sedimentation tank 4 and is connected to a sediment extraction pipe 62 adapted to draw out the sediment accumulated in the sediment collection area at the bottom / lowest point of the sedimentation area 24 of the sedimentation tank 4. The bottom wall 61 of the sedimentation area 24 of the sedimentation tank 4 preferably slopes downward from the second end wall 17 to the first end wall 16 towards the inlet end of the extraction pipe 62, facilitating the movement of the sediment towards the extraction pipe 62. The sediment removal pump 60 can pump the sediment collected in the sediment collection area in the form of a thick slurry out of the sedimentation tank into the drain pipe 26, or alternatively, into a separate collection container or drain outlet.

[0037] A pair of parallel, vertically arranged baffle plates 64, 66 can extend across the width of the sedimentation area 24 of the sedimentation tank 4 between the partition wall 20 and the second side wall 19 of the tank 4. The baffle plates 64, 66 have a lower edge terminating on the bottom wall of the sedimentation tank and an upper edge extending above the normal water level in the sedimentation tank 4. The baffle plates 64, 66 are spaced apart to define a relatively narrow (preferably about 10 mm) cavity therebetween. The cavity functions as a vent for the sediment removal pump and as an inlet area for the sediment extraction pipe 62. The inlet end of the sediment extraction pipe 62 extends through one of the baffle plates into the cavity. The sediment moves through between the lower ends of the baffle plates 64, 66 to the extraction pipe 62. The baffle plates 64, 66 also maximize the removal of sediment by causing the sediment removal pump 60 to draw out only the slurry from the lowermost sediment collection area of the sedimentation tank 4. The relatively narrow cavity defined between the baffle plates 64, 66 can create a Venturi effect, increasing the flow rate at the inlet end of the extraction pipe 62, thereby improving the extraction of sediment.

[0038] A programmable controller is preferably provided to control the operation of the skimmer and the sediment removal pump. By including a timer, the controller enables the skimmer and the sediment removal pump to be operated periodically at a predetermined programmed time and for a predetermined period.

[0039] The controller can receive inputs from a plurality of sensors in communication with the sedimentation tank to measure, for example, one or more of the dissolved oxygen content of the water in the sedimentation tank, the amount of FOG remaining on the surface of the water in the sedimentation tank, the water temperature in the sedimentation tank, and the turbidity of the water. Preferably, non-contact sensors are used. The data from the sensors can be transmitted to a central monitoring and / or control center by wired or wireless communication means, for example, via the Internet, to facilitate the monitoring and management of the device or multiple installations. The collected data can be used to ensure the accurate operation and use of the device.

[0040] By removing the pollution source, the wastewater treatment device according to the present invention can protect the drainage and waterway systems. By using the device according to the present invention, the load on the wastewater treatment plant can be significantly reduced while blocking the FOG source in the drain pipe, protecting the pumping station. When wastewater sampling is performed, a large amount of BOD, SS, and FOG may be detected, resulting in a significant load on the wastewater treatment. The wastewater treatment device according to the present invention can achieve a significant reduction in the load of wastewater with BOD; COD: FOG, and SS load levels that are conventionally discarded in food service facilities.

[0041] It is no longer necessary to perform frequent maintenance inspections on known grease traps and fill them with clean water. Similarly, the use of costly biological agents, enzymes, and chemicals can be eliminated.

[0042] The wastewater treatment device according to the present invention can remove emulsified FOG, particularly saturated animal fat, before solidifying, by utilizing waste heat energy present in the waste liquid discarded from a commercial kitchen. By not using a heating element, energy and operating costs, as well as CO2-related emissions, are reduced. This is estimated to save up to 5 tons of CO2-related emissions per year compared to passive traps and mechanical grease traps that utilize a heating element and require regular pumping with the use of a tank truck.

[0043] The present invention is not limited to the embodiments described herein and can be amended or modified without departing from the scope of the invention as defined by the appended claims.

Claims

1. A wastewater treatment apparatus, comprising a housing with a sedimentation tank mounted therein adapted to receive wastewater, said sedimentation tank comprising a bottom wall, a first end wall and a second end wall, a longitudinal baffle or dividing wall, a skimming device, a drain pipe, an inlet end of said drain pipe, and a sediment removal system, wherein said first end wall and said second end wall are arranged opposite to each other and are spaced apart by a first side wall and a second side wall arranged opposite to each other, wherein said longitudinal baffle or said dividing wall extends inwardly from said first end wall to said second end wall in parallel with said first side wall and said second side wall, wherein said dividing wall defines a flow path through said sedimentation tank and terminates adjacent to said second end wall such that the transverse length of said wastewater through said sedimentation tank is doubled, wherein said dividing wall divides the interior of said sedimentation tank into an inlet region and a sedimentation region, said sedimentation region having a width, wherein said skimming device is mounted on said sedimentation tank and removes any FOG (fat, oil, grease) remaining on the surface of said wastewater, wherein said drain pipe is provided at the downstream end of said sedimentation region of said sedimentation tank for removing water from said sedimentation tank, wherein said inlet end is defined by a weir for controlling the water level in said sedimentation tank, wherein said sediment removal system is adapted to cooperate with said sedimentation region to remove sediments collected at the bottom of said sedimentation tank, and wherein said sediment removal system comprises a sediment removal pump and a pair of parallel vertically arranged baffle plates, wherein said sediment removal pump is arranged in said housing adjacent to the downstream end of said sedimentation region of said sedimentation tank, and wherein said sediment removal pump is connected to a sediment extraction passage extending to a sediment collection region at the bottom of said sedimentation region of said sedimentation tank and has an inlet adapted to draw out sediments accumulated in said sediment collection region from said sedimentation tank, wherein said baffle plates extend between said dividing wall and said second side wall of said sedimentation tank across the width of said sedimentation region of said sedimentation tank, wherein said baffle plates have a lower edge and an upper edge, said lower edge terminating on said bottom wall of said sedimentation tank and said upper edge extending above the normal water level of said sedimentation tank, wherein said baffle plates are spaced apart from each other to define a cavity therebetween, The inlet end of the sediment extraction passage extends into the cavity through one of the baffle plates, whereby the cavity defines an inlet region of the sediment extraction passage. The cavity functions as a vent for the sediment removal pump, and the sediment extraction passage extends from the sediment removal pump into the sedimentation tank and is defined by a pipe that terminates within the cavity. Wastewater treatment device.

2. The device according to claim 1, wherein the sediment extraction passage extends horizontally within the sedimentation tank.

3. The bottom wall of the sedimentation tank is inclined downwardly toward the sediment collection region and toward the inlet end of the extraction passage, facilitating the movement of sediment toward the sediment collection region. The device according to claim 1 or claim 2.

4. The sediment removal pump is adapted to deliver sediment as a slurry from the sediment collection region of the sedimentation tank into the sediment drain pipe of the sedimentation tank or alternatively into a separate collection container. The device according to any one of claims 1 to 3.

5. The dividing wall is arranged adjacent to the first side wall of the tank such that the inlet region of the tank is narrower than the sedimentation region. The device according to any one of claims 1 to 4.

6. The drain pipe of the sedimentation tank extends from the first end wall of the housing. The device according to any one of claims 1 to 5.

7. A wastewater collection tank is mounted within the housing adjacent to the sedimentation tank that functions as a solid waste blocking means, and a food waste collection tray is located within the wastewater collection tank for collecting solid waste therein. The device according to any one of claims 1 to 6.

8. A removable strainer basket is mounted within the food waste collection tray for collecting food waste and other solid waste. The strainer basket incorporates openings or slots through which wastewater can pass while solid waste mixed in the wastewater is collected within the strainer basket. The device according to claim 7.

9. The apparatus according to claim 8, wherein FOG, and wastewater containing entrained food waste and other solids, pass through an inlet pipe through supply holes in the walls of the food waste collection tray and the basket on the second side wall side, and are supplied to the strainer basket in the wastewater collection tank.

10. The apparatus according to any one of claims 7 to 9, wherein the bottom wall of the food waste collection tray is perforated, and water is drained through the holes into the wastewater collection tank.

11. The apparatus according to any one of claims 7 to 10, wherein the bottom wall of the wastewater collection tank incorporates a drain gutter that communicates with the sedimentation tank at the lowest part of the bottom wall and leads to a downwardly inclined supply passage.

12. The apparatus according to claim 11, wherein an additional strainer is provided between the wastewater collection tank and the downwardly inclined supply passage.

13. The apparatus according to claim 12, wherein the additional strainer comprises a perforated portion through which the wastewater must pass in order to reach the downwardly inclined supply passage.

14. The skimming device comprises an elongated drum having a surface coated with or formed from hydrophobic and lipophilic substances, the drum being mounted within the sedimentation tank so as to be partially submerged in the wastewater maintained within the tank during use, the drum being rotatably mounted within the tank by the action of a motor, the apparatus according to any one of claims 1 to 13.

15. The apparatus according to claim 14, wherein a FOG collection tank is attached to one side of the housing adjacent to the skimming device and is arranged to engage with the surface of the drum of the skimming device, and comprises a scraper or wiper blade for scraping FOG from the surface of the drum and delivering the FOG to the FOG collection tank.

16. The apparatus according to any one of claims 1 to 15, wherein one or more sensors adapted to measure one or more of the dissolved oxygen content of the water in the sedimentation tank, the amount of FOG remaining on the surface of the water in the sedimentation tank, the water temperature in the sedimentation tank, and the turbidity of the water are attached to the sedimentation tank.

17. The apparatus according to claim 16, wherein the one or more sensors comprise non-contact sensors that are not in direct contact with the wastewater.

18. The apparatus according to claim 16 or 17, which transmits data from the one or more sensors to a central monitoring and / or control center by means of wired or wireless communication means to facilitate monitoring and management of the apparatus.

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