Clear water discharge device, especially for sewage treatment plants and storage basins

Abstract

Device for drawing off clear water from below a water surface, especially for a sewage treatment plant or for emptying storage basins, comprising the following components: - A pump is held in a container, which has a suction opening and a pressure outlet connected to an outlet line, - the outlet pipe leads out of the container, - the container has a particularly lower inlet opening, which can be temporarily closed by a valve, - the container is preferably a floating container.

Description

[0001] The invention relates to a device for drawing off clear water from below a water surface, in particular for a wastewater treatment plant, preferably a small-scale wastewater treatment plant, or for emptying storage basins, e.g., for rainwater. The invention also relates to a wastewater treatment plant and a storage basin.

[0002] In wastewater treatment plants operating in a reservoir system, wastewater is fed into a treatment chamber or aeration tank in portions and cyclically aerated. This process produces activated sludge, which is suspended freely in the aeration tank in the form of flocs. In a settling phase following the aeration phase, the sludge flocs settle very slowly. The clarified water in the upper section is then pumped out.

[0003] Commercially available submersible wastewater pumps are typically used for pumping, preferably installed at a fixed level within the aeration basin. During pumping, turbulence occurs on the suction side of the pumps, particularly because these types of pumps generate a relatively high flow rate. Consequently, the settled activated sludge can be stirred up and partially removed with the clear water in an undesirable manner. Furthermore, activated sludge can settle in the pump's intake area even during the settling phase.

[0004] Instead of electric pumps, airlift pumps can also be used to draw off the clear water; see, for example, EP 1 582 263 B1. With airlift pumps, the flow rate is lower, and consequently less turbulence is generated on the suction side.

[0005] Wastewater treatment plants are sized according to demand. Larger plants have multiple chambers for treating the wastewater. So-called small-scale treatment plants can also be built this way, but may also have only a single treatment chamber for sludge storage and treatment basins. In the latter case, there is no separate primary treatment stage to remove solids from the plant's influent. These solids can also settle in the pump's intake area for the treated water, along with the activated sludge.

[0006] A similar situation can occur in storage basins used for rainwater or other purposes. The incoming water contains solids that can impair the operation of the pump over time and / or that should not be discharged from the storage basin.

[0007] The object of the invention is to create a novel device for extracting clear water, in particular avoiding the aforementioned disadvantages.

[0008] According to the invention, the device comprises at least the following components: - A pump is held in a container, which has a suction opening and a pressure outlet connected to an outlet line, - the outlet pipe leads out of the container, - the container has a particularly lower inlet opening, which can be temporarily closed by a valve, - the container is preferably a floating container.

[0009] This device is primarily designed and suitable for small wastewater treatment plants, especially those with only one chamber, but can also be used for larger plants with multiple chambers or for storage tanks. The tank shields the pump from suspended solids. The valve opens the tank only intermittently, significantly reducing the amount of activated sludge / solids that can enter the pump's intake area. Because it can be configured as a floating tank, the intake and / or inlet openings are always at the same distance from the water surface.

[0010] According to a further aspect of the invention, the device can additionally have the following features: - the valve is equipped with a valve body which can be moved from a closed position to an open position, - the pressure outlet of the pump is connected to the outlet line and an actuating device for the valve body, - the valve body is in particular self-closing with a closing force which is less than a force acting from the pressure outlet on the actuating element when the pump starts up or is in operation.

[0011] The valve body is pushed out of the inlet opening by the actuating element to open it. This means that the valve body partially seals the inlet opening even when open.

[0012] According to a further aspect of the invention, the container with its components can be buoyant such that the intake and inlet openings are located below the water surface, while an upper opening for air exchange is located above the water surface. The buoyancy of the container is designed accordingly.

[0013] According to a further aspect of the invention, the container can have buoyancy elements, in particular circumferential ones on the sides. Besides ensuring the vertical position of the container relative to the water surface, the buoyancy elements preferably also maintain the container's orientation, preventing it from tipping over, for example. Separate buoyancy elements also allow the container to be adapted to different pumps.

[0014] According to a further aspect of the invention, the valve body can be a buoyancy element or be provided with a buoyancy element. The buoyancy acting on the valve body results in a force that preferably acts on the valve body in the direction of its closed position.

[0015] According to a further aspect of the invention, the pump can be fixed in the container. In particular, the pump is arranged or held in the container in a way that is both secure and detachable.

[0016] Alternatively, the pump can be located on the outside of the container. In this case, pipes run from the pump into the container and from the container back to the pump.

[0017] According to a further aspect of the invention, the container can have a valve seat which, in the closed position and in conjunction with the valve body, does not completely seal the lower inlet opening. The valve seat is preferably permanently leaky, which can be achieved simply by using a larger manufacturing tolerance. A continuous pressure equalization is possible via the leaky valve seat, so that the water level in the container does not differ from the water level outside the container for any extended period. The main function of the valve, namely the protection of the intake opening, is not impaired by this.

[0018] According to a further aspect of the invention, the container may preferably have permanently open openings below the water surface for pressure equalization, particularly adjacent to the lower inlet opening and / or below the suction opening. These permanently open openings essentially serve the same function as a leaking valve seat and may be provided additionally or alternatively. A permanently open, free cross-section formed in this way (also by a leaking valve seat) preferably comprises 1 to 5% of the effective cross-section of the inlet opening when the valve is open or with the valve body in the open position.

[0019] According to a further aspect of the invention, the valve body can be designed as a cone, partial cone, sphere, partial sphere or hemisphere, or at least partially have such a shape.

[0020] Due to its shape, the valve body self-centers upon closing. The valve seat can have a corresponding partial cone shape, sealing chamfer, or sealing radius, but this is not strictly necessary for its function.

[0021] According to a further aspect of the invention, the valve body can be held resiliently on the container, with a spring force acting towards the closed position. A corresponding holder can be resiliently designed and, in particular, attached to the inside of the container.

[0022] According to a further aspect of the invention, the actuating element can have a length that varies with pressure, and can in particular be designed as a bellows or an actuating cylinder with a piston. After the pump starts, fluid flows from the pressure outlet into the bellows, which then expands and opens the valve or moves the valve body from the closed position to its open position. An actuating cylinder with a protruding piston or piston rod also has a length that varies as a unit.

[0023] According to a further aspect of the invention, the pressure outlet can be connected to the outlet line and the actuating element via a T-piece or a branch. This enables a particularly simple and effective connection of the pressure outlet to both the outlet line and the actuating element.

[0024] According to a further aspect of the invention, the container can be funnel-shaped above the inlet opening. This prevents deposits and facilitates the removal of solids from the area of ​​the inlet opening.

[0025] According to another aspect of the invention, the pump can be a centrifugal pump. Electric centrifugal pumps, in particular, are proven effective for pumping wastewater.

[0026] According to a further aspect of the invention, an electric drive for the pump can be operated with a safety extra-low voltage, in particular with 12 V or 24 V.

[0027] The pump is advantageously driven by a brushless motor with an electronically generated rotating magnetic field and speed control capability. The motor can also be designed as a so-called wet-rotor motor, meaning the rotor can come into contact with water. This significantly increases the pump's service life and allows for considerably longer operating times than with conventional submersible pumps.

[0028] A wastewater treatment plant according to the invention has the features of claim 17. It is a wastewater treatment plant with one or more chambers, in particular a small wastewater treatment plant, and with a device according to one of claims 1 to 16 in a chamber, in particular in an aeration basin.

[0029] A storage basin according to the invention has the features of claim 18. The storage basin is provided with a device according to any one of claims 1 to 16.

[0030] Further features of the invention will become apparent from the description below and from the claims. Advantageous embodiments of the invention are explained in more detail below with reference to the drawings. These show: Fig. 1 a cross-section of a container with pump and valve body in closed position, Fig. 2 the cross-section according to Fig. 1, however with the valve body in the open position.

[0031] In a chamber of a wastewater treatment plant (not shown), wastewater is treated using a settling process. The wastewater is fed in portions, aerated over a period of time, and after a settling phase, the supernatant of clarified water is pumped out. The wastewater level in the chamber fluctuates. To pump out the clarified water, a pump 11 is suspended but submerged in the chamber – the principle of floating intake. For this purpose, the pump 11 is arranged in a floating container 12, which can be closed at the bottom, in the area of ​​an inlet opening 13, by a valve 14 and is preferably open at the top, having at least one opening 15 for pressure equalization.

[0032] Pump 11 is specifically an electric centrifugal pump, but it can also be a pump of another type. The centrifugal pump preferably has a flow rate of approximately 20 to 30 l / min.

[0033] In this case, the pump 11 is detachably fixed to a side wall 16 of the container 12. The container 12 is essentially cylindrical, so that the side wall 16 is circumferential. The side wall 16 has a funnel-shaped section 17 at the bottom, which terminates in the inlet opening 13.

[0034] The pump 11 has a suction opening 18 below the level 10, with a suction strainer (not shown), and a pressure outlet 19. The pressure outlet 19 leads into a T-piece 20 and is hydraulically positioned above the suction opening 18. The T-piece 20 branches downwards into an actuating element 21, which expands downwards under water pressure and is designed here in the form of a bellows. The T-piece 20 branches upwards into an outlet line 22, which is preferably a hose and leads out of the container 12 and the chamber in a manner not shown. The pump 11, with pressure outlet 19, T-piece 20, and actuating element 21, is attached to the side wall 16 by a quick-release coupling (not shown).

[0035] The container 12 has buoyancy bodies 23 in the area of ​​the side wall 16, particularly on the outside. The buoyancy of the buoyancy bodies 23 is matched to the mass of the container 12 and the parts arranged therein, so that the level 10 is below the opening 15 and above the intake opening 18, preferably also above the pressure outlet 19.

[0036] The valve 14 has a valve seat 24 in the area of ​​the inlet opening 13 and a valve body 25. The valve body 25 is designed as a partial cone or cone, with a cross-section increasing towards the bottom. The valve body 25 is held by a resilient holder 26, for example, a spring steel sheet. The holder 26 is fixed at one end 27 inside the container 12, particularly in the funnel-shaped area 17, and holds the valve body 25 or a projection 29 thereof at a free end 28. At the same time, the free end 28 rests against the actuating element 21. The design and arrangement of the holder 26, valve body 25, and actuating element 21 are such that the valve 14 is closed when the pump 11 is not running and, accordingly, there is no pressure at the pressure outlet 19 (see closed position in [reference]). Fig. 1. There, the valve body 25 closes the lower inlet opening 13.

[0037] As soon as the pump 11 starts, particularly triggered by an external control, water flows into the suction opening 18 via the pressure outlet 19 to the T-piece 20 and from there into the outlet line 22. At the same time, pressure builds up in the actuating element 21, causing the actuating element 21 to expand and move the valve body 25 downwards against the pressure of the holder 26, thus opening the valve 14 (see open position in [reference]). Fig. 2. The holding force of the holder 26 is designed to be sufficiently low for this purpose.

[0038] The valve body 25 can itself be designed as a buoyancy element, have neutral buoyancy, or be heavier than water. After the pump 11 is switched off, the pressure in the actuating element 21 is released, and the holder 26 pulls the valve body 25 back into the closed position as described in [reference]. Fig. 1. A buoyancy force of the valve body 25 may also contribute to this.

[0039] The control for switching pump 11 on and off is preferably dependent on signals from a timer or a sensor. The sensor is, for example, a float switch as a level sensor in the chamber containing the container 12. However, the sensor can also be mounted outside the container 12.

[0040] In closed position according to Fig. The intake opening 18 of pump 11 is protected. Suspended solids can only settle if they are already present in the container 12. This is rather unlikely, or in practice only a relatively small amount of suspended solids will be present, since pump 11 is only activated and valve 14 only opens once the settling phase in the clarification process is complete.

[0041] In the closed position according to Fig. 1. The valve 14 preferably does not close completely. A small free cross-section remains. This can be achieved by slightly different shapes of the valve seat 24 on the one hand and the valve body 25 on the other. The aim is to ensure continuous pressure equalization even when the valve 14 is closed. Alternatively or additionally, pressure equalization can be achieved by openings (not shown) in the funnel-shaped area 17 or another area of ​​the side wall 16 below the level 10. The openings can also be slots in the area of ​​the valve seat 24 or above it.

[0042] The free cross-section is preferably about 1 to 5% of the flow cross-section of the valve 14 in the open position. The flow cross-section when the valve 14 is open is in Fig. 2 indicated by arrows 30. The closed valve body 25 is in Fig. 1 is symbolized by the two “X”. Reference symbol list (as part of the description): 10 Water level 11 Pump 12 containers 13 Entrance opening 14 valve 15 Opening 16 surrounding side wall 17 funnel-shaped areas 18 Intake opening 19 Pressure outlet 20 T-pieces 21 Actuating element 22 Output line 23 Buoyancy aids 24 valve seat 25 valve bodies 26 holders 27 End 28 free ending 29 continuation 30 arrows X symbols for closed valve body QUOTES INCLUDED IN THE DESCRIPTION

[0000] This list of documents cited by the applicant was automatically generated and is included solely for the reader's convenience. The list is not part of the German patent or utility model application. The DPMA accepts no liability for any errors or omissions. Cited patent literature

[0000] EP 1 582 263 B1

[0004]

Claims

[1] Device for drawing off clear water from below a water surface, in particular for a sewage treatment plant or for emptying storage basins, comprising the following components: - A pump is held in a container, which has a suction opening and a pressure outlet connected to an outlet line, - the outlet pipe leads out of the container, - the container has a particularly lower inlet opening, which can be temporarily closed by a valve, - the container is preferably a floating container. [2] Device according to claim 1, characterized by the following characteristics: - the valve has a valve body which can be moved from a closed position to an open position, - the pressure outlet of the pump is connected to the outlet line and an actuating device for the valve body, - the valve body is in particular self-closing with a closing force which is less than a force acting from the pressure outlet on the actuating element when the pump starts up or is in operation. [3] Device according to claim 1 or 2, characterized by , that the container with components arranged therein has a buoyancy such that the suction opening and the inlet opening are located below the water surface and an upper opening of the container for air exchange is located above the water surface. [4] Device according to any one of claims 1 to 3, characterized by that the container has buoyancy aids, in particular circumferential ones on the sides. [5] Device according to any one of claims 1 to 4 characterized by that the valve body is a buoyancy body or is equipped with buoyancy bodies. [6] Device according to any one of claims 1 to 5, characterized by that the pump is fixed in the container. [7] Device according to any one of claims 1 to 5, characterized by that the pump is located on the outside of the container. [8] Device according to any one of claims 1 to 7, characterized by that the container has a valve seat which, in the closed position and in conjunction with the valve body, does not completely close the lower inlet opening. [9] Device according to any one of claims 1 to 8, characterized by that the container preferably has permanently open openings below the water surface for pressure equalization, in particular adjacent to the lower inlet opening and / or below the suction opening of the pump. [10] Device according to any one of claims 1 to 9, characterized by that the valve body is designed as a cone, partial cone, sphere, partial sphere or hemisphere, or at least partially has such a shape. [11] Device according to any one of claims 1 to 10, characterized by, that the valve body is held to the container by a spring force in the direction of the closed position. [12] Device according to any one of claims 1 to 11, characterized by that the actuating element has a length that varies by pressure, in particular being designed as a bellows or actuating cylinder with piston. [13] Device according to any one of claims 1 to 12, characterized by that the pressure outlet is connected to the outlet line and the actuating device via a T-piece or a branch. [14] Device according to any one of claims 1 to 13, characterized by that the container is funnel-shaped above the inlet opening. [15] Device according to any one of claims 1 to 14, characterized by that the pump is a centrifugal pump. [16] Device according to any one of claims 1 to 15, characterized bythat the electric drive of the pump is operated with a safety extra-low voltage, in particular with 12 V or 24 V. [17] Wastewater treatment plant, in particular small wastewater treatment plant, with one or more chambers, characterized by a device according to one of claims 1 to 16 in a chamber, in particular in an aeration basin. [18] Reservoir, characterized by a device according to any one of claims 1 to 16.

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