Microflotation plant for removing contaminants from a body of water

Abstract

Microflotation plant for removing contaminants from a body of water, in particular from a stormwater basin, the microflotation plant comprising: • a device (16) for producing dispersion water by enriching water under increased pressure with a gas, • a dispersion water line (20) leading from the device (16) for producing dispersion water to an outlet opening (24), and • a clearing device (36), characterized by • a first positioning device to which the dispersion water line (20) is attached so that the outlet opening (24) is located at a fixed position of the body of water and at a predetermined water depth, • a second positioning device to which the clearing device (36) is fastened, so that the clearing device (36) is arranged at a fixed position of the body of water and detects a defined surface area (38) on the surface of the body of water, wherein the defined surface area (38) is arranged at a distance (40) in a flow direction of the body of water from the outlet opening (24).

Description

[0001] The invention relates to a microflotation plant for removing contaminants from a body of water, in particular from a stormwater basin.

[0002] Microflotation systems can be used in a wide variety of applications for the efficient separation of contaminants such as solid particles or oil droplets, for example in the treatment of wastewater in industry or in sewage treatment plants. For this purpose, the wastewater is fed into a flotation tank specially designed for microflotation. So-called dispersion water is also fed to the flotation tank; this is water that has been enriched with air or another gas under increased pressure. The gas is dissolved in the dispersion water. As a result of pressure relief when the dispersion water is introduced into the flotation tank, countless microbubbles are created, which slowly rise to the surface of the flotation tank. The contaminants are deposited on the microbubbles and are also transported to the surface, where a flotate is formed. This flotate is removed using suitable cleaning equipment.

[0003] Also known are floating microflotation systems, which are arranged floating on the surface of a body of water to clean it. In this case, the dispersion water can be discharged directly into the body of water instead of into a special flotation tank. For example, EP 3 647 272 A1 describes a flotation system for cleaning a body of water with a barrier enclosing a surface area of the body of water and a relief valve arranged below this surface area. The known microflotation system can, in particular, be used floating freely on the body of water.

[0004] Based on this, the object of the invention is to provide a microflotation system for removing contaminants from a body of water, which can be used more easily and with greater efficiency in a body of water having a current.

[0005] This object is achieved by the microflotation system having the features of claim 1. Advantageous embodiments are specified in the subsequent subclaims. A method that can be carried out using the microflotation system is also described below.

[0006] The process is used to remove contaminants from a body of water, in particular from a stormwater basin, and comprises the following steps: • Production of dispersion water by enriching water under increased pressure with a gas, • Introducing the dispersion water into the water through a dispersion water pipe which has an outlet opening at a given water depth, whereby a pressure release occurs and a large number of microbubbles are formed which attach themselves to contaminants and rise to the surface of the water, so that a flotate is formed on the surface, • Removal of the flotate from a defined surface area using a cleaning device, whereby • the outlet opening is located at a fixed position in the water body, • the water in the vicinity of the outlet opening has a flow with a flow velocity and a flow direction, and • the defined surface area is arranged at a distance in the direction of flow from the outlet opening.

[0007] The dispersion water can be produced in a pressure saturator, i.e. in a pressure vessel to which the water and the gas to be dissolved in it are fed.

[0008] Preferably, enough gas is dissolved in the water until a saturation concentration is reached.

[0009] The dispersion water produced in this way is introduced into the body of water via a dispersion water pipe. A separate flotation tank is not used. The dispersion water pipe has an outlet opening located at a predetermined water depth. The water depth at which the outlet opening is located refers to the distance of the outlet opening from the water surface. When the dispersion water is introduced into the body of water, pressure is released, particularly at a relief valve located in the dispersion water pipe, creating a multitude of microbubbles that attach to contaminants and rise to the surface of the body of water.By maintaining the specified water depth, even when the water level in the body of water fluctuates greatly, the microbubbles travel a minimum distance on their way to the surface and thus remain underwater long enough for the contaminants to adhere well to the microbubbles. The outlet opening can be formed by the expansion valve or be located at a distance from it. It is understood that several dispersion water lines and / or several outlet openings can be used simultaneously. In this case, the several outlet openings can, for example, all be arranged at the same water depth, in particular next to one another in a row transverse to the direction of flow and / or distributed evenly or almost evenly across the entire width of the body of water.

[0010] A flotate containing the separated contaminants forms on the surface of the water body. The flotate is removed using a cleaning device, which, due to its functionality and design, captures a defined surface area of the treated water body. The flotate removed by the cleaning device can be conveyed into a collection tank, which can be located in the water body but is preferably located on the shore.

[0011] In the invention, the outlet opening is arranged at a fixed horizontal position in the body of water. A fixed position means that the outlet opening does not move with the current in the body of water, but is arranged at a fixed location relative to the bottom or a bank of the body of water, independent of the current. A current is formed in the body of water, in particular in the vicinity of the outlet opening. There, the current has a flow velocity and a flow direction. The flow velocity and direction depend on the type of body of water, but also on the current environmental conditions. If the body of water is a river or a canal, the flow velocity can be relatively high. It also depends on how much water the river or canal is carrying at a given time.In the particularly relevant application of a stormwater retention basin, stormwater treatment basin or surface water collection basin, the flow in the basin in question results from the incoming and outgoing water volumes. Like the water level in the basin, it is subject to extreme fluctuations, especially during a sudden onset of heavy rainfall. The basin can be a natural depression in the landscape, or it can be artificially created. In the first case, the bank and the bed of the body of water are usually irregularly shaped. In an artificially created basin, for example made of concrete, there can be a uniform depth. The edge of such an artificially created basin can be formed by straight walls, which are referred to below as banks, just like the irregularly shaped edge of a natural body of water.

[0012] A special feature of the invention is that the defined surface area captured by the clearing device is arranged at a distance from the outlet opening, specifically at a distance in the direction of flow. This ensures that the flotate formed by the microbubbles slowly rising to the surface, which may, due to the flow, form at a considerable lateral distance from the outlet opening on the surface, is reliably captured by the clearing device. In particular, this prevents the flotate or parts of it from sinking again before they can be removed by the clearing device. This allows optimal removal of the flotate to be achieved with a relatively simple clearing device.In particular, it is not necessary to cover the entire surface of the body of water or a large part of it with the cleaning device, as is the aim in conventional flotation tanks, for example, using a chain cleaning device. A distance in the direction of flow means that the defined surface area is located downstream of the outlet opening relative to the current in the body of water.

[0013] Tests have shown that, with careful coordination of the arrangement of the defined surface area relative to the outlet opening, very high separation rates can be achieved in bodies of water with a current. A microflotation system floating freely on the water body has proven to be disadvantageous, in particular because, firstly, a free-floating microflotation system quickly reaches a downstream bank of the water body due to the current. At this point at the latest, the current means that the flotate cannot be removed or can only be removed incompletely. Secondly, with a microflotation system floating freely in the current, it cannot be guaranteed that all relevant areas of the water body will be affected by the cleaning effect.

[0014] With the procedure according to the invention, the outlet opening can be fixed at a particularly suitable location in the water body, allowing the resulting flotate to be removed almost completely. Furthermore, the fixed arrangement of the microflotation system simplifies the transport of the removed flotate to the shore.

[0015] In one embodiment, the distance is adjusted to the flow velocity so that a large proportion of the microbubbles rising to the surface reach the defined surface area. The distance adjustment can be performed experimentally or calculated from the average ascent velocity of the microbubbles and the flow velocity.

[0016] In one embodiment, the body of water is a stormwater retention basin, a stormwater treatment basin, or a surface water collection basin. As mentioned, it can be natural or artificial. Characteristic of all of these basins are the highly fluctuating pollution levels, water levels, and flow conditions. The method according to the invention can be easily adapted to these, thus achieving high efficiency even in dynamic situations.

[0017] In one embodiment, the flow velocity is measured, and the spacing is adjusted according to the measured flow velocity. This allows for optimal spacing adjustment, thus achieving high efficiency, even with changing flow velocities.

[0018] In one embodiment, the predetermined water depth at which the outlet opening is arranged is adjustable, wherein the predetermined water depth is set in particular according to an average ascent velocity of the microbubbles. The ascent velocity of the microbubbles depends on many factors, on the one hand on the size distribution of the microbubbles, and on the other hand on the nature and quantity of adhering contaminants and thus also on the contamination of the water with contaminants. The flow velocity in the body of water can also have an influence because the number of microbubbles per volume of water is lower due to the faster distribution of the microbubbles at higher flow velocities, and the microbubbles ascend much faster in a cluster than individually. Therefore, the predetermined water depth can alternatively or additionally be set according to the flow velocity.The average ascent velocity of the microbubbles can be determined experimentally or during operation of the microflotation system, or it can be approximately calculated based on one or more of the above-mentioned influencing factors. The specified water depth can be set manually or automatically using a suitable actuator.

[0019] In one embodiment, a baffle plate is arranged in the body of water between the outlet opening and the defined surface area. The baffle plate represents a barrier for the dispersion water escaping from the outlet opening and the microbubbles forming. The width of the baffle plate, measured transversely to the flow direction, can be selected such that at least a large proportion of the microbubbles coming from all existing outlet openings enter the sphere of influence of the baffle plate. In particular, the baffle plate can extend across the entire width of the body of water. Tests have shown that the baffle plate can significantly influence the spatial distribution of the resulting microbubbles. In particular, with a suitable arrangement of the baffle plate, a higher microbubble concentration and a higher probability of contact between the microbubbles and individual particles can be achieved.Both parameters have a significant influence on the deposition rates and thus on the efficiency of the process.

[0020] In one embodiment, the flow velocity is measured, and the arrangement of the impact plate is adjusted according to the measured flow velocity. The arrangement of the impact plate refers, in particular, to the distance of the impact plate from the outlet opening, the water depth at which the impact plate is arranged, the horizontal extent of the impact plate, the vertical extent of the impact plate, and / or the inclination of the impact plate relative to the vertical. In order to adjust the horizontal or vertical extent of the impact plate, the impact plate can have several impact plate elements that can be moved relative to one another. Tests have shown that further efficiency increases are possible by adapting the arrangement of the impact plate to the measured flow velocity.It is assumed that the improvements are due to the fact that, particularly at high flow velocities, the appropriate positioning of the baffle plate prevents the dispersion water emerging from the outlet from being distributed too quickly and over too much of the water body. This distribution is accompanied by a dilution of the dispersion water and can result in a significant reduction in the number of microbubbles formed.

[0021] The microflotation plant with the features of claim 1 serves to remove contaminants from a body of water, in particular from a stormwater basin, and comprises the following: • a device for producing dispersion water by enriching water under increased pressure with a gas, • a dispersion water line leading from the dispersion water production facility to an outlet opening, • a room facility, • a first positioning device to which the dispersion water pipe is attached so that the outlet opening is located at a fixed position in the body of water and at a predetermined water depth, and • a second positioning device to which the clearing device is attached, so that the clearing device is arranged at a fixed position of the body of water and detects a defined surface area on the surface of the body of water, wherein the defined surface area is arranged at a distance in a flow direction of the body of water from the outlet opening.

[0022] The microflotation system is particularly suitable for carrying out the described process. Regarding the features and advantages of the microflotation system, reference is made to the above statements, which apply accordingly. The special arrangement of the outlet opening and the clearing device is achieved in the microflotation system by the fact that the microflotation system has two positioning devices with which the arrangement of the outlet opening or the clearing device in the body of water can be specified such that the distance between the defined surface area and the outlet opening is in the direction of flow. The positioning devices coordinate the arrangement of the outlet opening and the clearing device in the vertical direction with the water level in the body of water, thus ensuring that the outlet opening is at the specified water depth and the clearing device is at the surface of the body of water.This can be achieved, for example, using the floating bodies described below. Alternatively, the water level in the body of water can be measured and the vertical positions adjusted using a hydraulic or electric actuator, for example. The actuator can be anchored, for example, to the bank or the bottom of the body of water.

[0023] In one embodiment, • the first positioning device comprises a first buoyant unit to which the dispersion water line is attached, and a first attachment device connected to the first buoyant unit, and / or • the second positioning device comprises a second buoyant unit to which the clearing device is attached, and a second attachment device connected to the second buoyant unit.

[0024] The dispersion water pipe is attached to the first floating unit, ensuring that it is always at a predetermined water depth, even when the water level in the body of water changes. The clearing device is attached to the second floating unit and is therefore also positioned appropriately relative to the surface of the body of water. The first floating unit is held in a fixed position in the body of water by a first fastening device. It therefore does not move with the current in the body of water. A second fastening device is provided to hold the second floating unit and the clearing device in a fixed position. The fastening of the two floating units means that the defined surface area covered by the clearing device is arranged at a distance from the outlet opening in the direction of flow of the body of water.

[0025] In one embodiment, the first fastening device and / or the second fastening device is anchored to a bank of the body of water or to the bottom of the body of water. At least one of the two fastening devices is anchored to the bank or bottom of the body of water to ensure the fixed arrangement of the first or second buoyant unit directly connected to it. The other fastening device, which is assigned to the other buoyant unit, can also be anchored to a bank or to the bottom of the body of water; alternatively, attachment to the first (or second) fastening device or to the first (or second) buoyant unit is possible. In any case, the two fastening devices ensure that both buoyant units are firmly arranged on the surface of the body of water, regardless of the flow, and that the distance between the outlet opening and the defined surface area is maintained.

[0026] In one embodiment, the device for producing dispersion water is set up on the bank of the body of water or attached to the first positioning device, e.g. to the first floating unit. For example, the first floating unit can have a floating dock on which the device for producing dispersion water is arranged. Due to the fixed arrangement of the first floating unit, the device for producing dispersion water can also be easily set up on the bank and the dispersion water line can run from there to the outlet opening. A particular advantage of this solution is that the elements of the microflotation system arranged on the body of water are particularly compact and have less impact on the flow in the body of water.

[0027] In one embodiment, the microflotation system has a measuring device for the flow velocity of the water body. The distance can be specified, in particular, based on the flow velocity detected by the measuring device.

[0028] In one embodiment, the first positioning device and / or the second positioning device comprises an actuator with which the position of the outlet opening in the body of water, the predetermined water depth at which the outlet opening is located, and / or the position of the clearing device in the body of water can be changed. This allows, in particular, the distance between the outlet opening and a defined surface area to be adjusted.

[0029] In one embodiment, the microflotation system comprises a controller connected to the measuring device and the actuator and configured to adjust the distance between the outlet opening and the defined surface area according to a measured flow velocity and / or connected to the actuator and configured to adjust the predetermined water depth at which the outlet opening is located according to an average ascent velocity of the microbubbles. In this way, maintenance of the optimal distance can be automatically ensured.

[0030] In one embodiment, the microflotation system has a baffle plate arranged in the body of water between the outlet opening and the defined surface area. In a further embodiment, the microflotation system has an actuator for the baffle plate, with which the arrangement of the baffle plate, in particular a distance of the baffle plate from the outlet opening, a water depth at which the baffle plate is arranged, an extension of the baffle plate in the horizontal direction, an extension of the baffle plate in the vertical direction and / or an inclination of the baffle plate relative to the vertical can be adjusted, wherein the controller is connected to the actuator for the baffle plate and is designed to adjust the arrangement of the baffle plate in accordance with a measured flow velocity. Reference is made to the above explanations of the correspondingly designed method.

[0031] In one embodiment, the clearing device comprises a suction device with at least one suction opening or at least one screw conveyor, wherein the surface area covered by the clearing device is defined by the arrangement of the at least one suction opening or the at least one screw conveyor. In both cases, the defined surface area is predetermined by the arrangement and structural design of the clearing device.

[0032] The invention is explained in more detail below with reference to the figures. They show: Fig. 1 a microflotation plant in a stormwater retention basin in a schematic side view, Fig. 2 the microflotation plant Fig. 1 in a schematic view from above, Fig. 3 another microflotation plant in a stormwater retention basin in a schematic side view, and Fig. 4 the microflotation plant Fig. 3 in a schematic view from above.

[0033] Fig. 1 shows a rainwater retention basin 10 with an inlet 12 and an outlet 14. The water flowing in and out via the inlet and outlet creates a flow within the rainwater retention basin, which in the Fig. 1 flows from right to left. In the inlet 12, the surface water coming from several sources is combined and discharged into the stormwater retention basin 10.

[0034] On the shore of the stormwater retention basin 10 there is a device 16 for producing dispersion water, which in the example has three pressure vessels 18. Water taken from the outlet 14 of the stormwater retention basin 10 is introduced into the pressure vessels 18 via a line 56. In addition, air is supplied (not shown) and dissolved in the water in the pressure vessels 18 under increased pressure. The dispersion water produced in this way passes via three dispersion water lines 20, each having a relief valve arrangement 22, to three outlet openings 24, each arranged at an outlet of the respective relief valve arrangement 22. Downstream of the outlet openings 24, countless microbubbles 26 form under pressure relief, which in Fig. 1 is represented by a cone.

[0035] Each of the relief valve assemblies 22 with the associated outlet opening 24 is attached to a first buoyant unit 28, which has a walkable walkway 30. Also attached to the first buoyant unit 28 is a baffle plate 32, the arrangement of which is adjustable. By attaching the relief valve assemblies 22 with the outlet openings 24 to the first buoyant unit 28, the outlet openings 24 are always located at a predetermined water depth, regardless of the fill level of the stormwater retention basin 10.

[0036] Also shown is a second buoyant unit 34 having a clearing device 36. The clearing device 36 covers a defined surface area 38 and is designed to remove a flotate formed on the surface from this defined surface area 38.

[0037] A distance 40 is formed between the outlet opening 24 and the defined surface area 38 in the flow direction; the defined surface area 38 is located downstream of the outlet opening 24 with respect to the flow formed in the rainwater retention basin 10.

[0038] In Fig. 2, the elements already explained are provided with the same reference numerals as in Fig. 1. Also visible is a first fastening device with four cables 42, with which the first buoyant unit 28 is braced on both sides to the bank of the stormwater retention basin. The second buoyant unit 34 is also braced on both sides to the bank of the stormwater retention basin 10 with two cables 42, thereby securing its position in the water. The clearing device 36 has a flotate line 44 leading to the bank of the stormwater retention basin 10. Several suction openings 46 of the clearing device 36 are arranged distributed across approximately the entire width of the stormwater retention basin 10. The resulting defined surface area 38, covered by the clearing device 36, is strip-shaped and is located at a distance 40 from the outlet openings 24 of the three relief valve assemblies 22.

[0039] In the Fig. 3 and Fig. 4 is an alternative to the arrangement of the Fig. 1 and Fig. 2, which differs with respect to the first and second fastening devices. A base 50 is anchored to the bottom 48 of the stormwater retention basin 10. A first fastening device for the first buoyant unit 28 comprises two vertically upwardly pointing rods 52 attached to the base 50, which extend through openings in the first buoyant unit 28. They fix the position of the first buoyant unit 28 without impairing its up-and-down movement when the water level in the stormwater retention basin 10 changes.

[0040] The second buoyant unit 34 is also attached to the base 50 via two rods 52, the position of these rods 52 in the flow direction being adjustable by an actuator (not shown), as indicated by the double arrow 54.

[0041] In Fig.4 it can be seen that with the described anchoring of the two floating units 28, 34 at the bottom 48 of the rainwater retention basin 10, it is not necessary to tie them with ropes to the banks of the rainwater retention basin 10. List of reference symbols 10 standard retention basins 12 Inlet 14 Procedure 16 Equipment for producing dispersion water 18 pressure vessels 20 Dispersion water line 22 Relief valve arrangement 24 Exit opening 26 microbubbles 28 first buoyant unit 30 jetty 32 impact plate 34 second buoyant unit 36 Room furnishings 38 defined surface area 40 distance 42 rope 44 Flotation line 46 Intake opening 48 Reason 50 sockets 52 rods 54 Double arrow 56 Line QUOTES CONTAINED IN THE DESCRIPTION

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

[0000] EP 3 647 272 A1

[0003]

Claims

[1] Microflotation plant for removing contaminants from a body of water, in particular from a stormwater basin, the microflotation plant comprising: • a device (16) for producing dispersion water by enriching water under increased pressure with a gas, • a dispersion water line (20) leading from the device (16) for producing dispersion water to an outlet opening (24), and • a clearing device (36), characterized by • a first positioning device to which the dispersion water line (20) is attached so that the outlet opening (24) is located at a fixed position of the body of water and at a predetermined water depth, • a second positioning device to which the clearing device (36) is fastened, so that the clearing device (36) is arranged at a fixed position of the body of water and detects a defined surface area (38) on the surface of the body of water, wherein the defined surface area (38) is arranged at a distance (40) in a flow direction of the body of water from the outlet opening (24). [2] Microflotation plant according to claim 1, characterized by , that • the first positioning device comprises a first buoyant unit (28) to which the dispersion water line (20) is attached, and a first attachment device connected to the first buoyant unit (28), and / or • the second positioning device comprises a second buoyant unit (34) to which the clearing device (36) is attached, and a second attachment device connected to the second buoyant unit (34). [3] Microflotation plant according to claim 2, characterized by that the first fastening device and / or the second fastening device is anchored to a bank of the body of water or to a bottom (48) of the body of water. [4] Microflotation plant according to one of claims 1 to 3, characterized by that the device (16) for producing dispersion water is set up on the bank of the body of water or is attached to the first positioning device. [5] Microflotation plant according to one of claims 1 to 4, characterized by that the microflotation plant has a measuring device for the flow velocity of the water. [6] Microflotation plant according to one of claims 1 to 5, characterized bythat the first positioning device and / or the second positioning device has an actuator with which the position of the outlet opening (24) in the body of water, the predetermined water depth at which the outlet opening (24) is arranged, and / or the position of the clearing device (36) in the body of water can be changed. [7] Microflotation plant according to claim 6, characterized by that the microflotation system has a control which is connected to the measuring device and the actuator and is designed to adjust the distance (40) between the outlet opening (24) and the defined surface area (38) in accordance with a measured flow velocity and / or which is connected to the actuator and is designed to adjust the predetermined water depth at which the outlet opening (24) is arranged in accordance with an average ascent velocity of the microbubbles. [8] Microflotation plant according to one of claims 1 to 7, characterized by in that the microflotation system has a baffle plate (32) which is arranged in the body of water between the outlet opening (24) and the defined surface area (38), wherein the microflotation system in particular has an actuator for the baffle plate (32), with which the arrangement of the baffle plate (32), in particular a distance of the baffle plate (32) from the outlet opening (24), a water depth in which the baffle plate (32) is arranged, an extension of the baffle plate (32) in the horizontal direction, an extension of the baffle plate (32) in the vertical direction and / or an inclination of the baffle plate (32) relative to the vertical can be adjusted, wherein the control is connected to the actuator for the baffle plate (32) and is designed to adjust the arrangement of the baffle plate (32) in accordance with a measured flow velocity. [9] Microflotation plant according to one of claims 1 to 8, characterized by that the clearing device (36) has a suction device with at least one suction opening (46) or at least one screw conveyor, wherein the surface area (38) covered by the clearing device (36) is defined by the arrangement of the at least one suction opening (46) or the at least one screw conveyor.

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