Cleaning system, especially for wastewater, for the separation of light liquids and / or greases, and method for operating this cleaning system

Description

[0001] The invention relates to a purification system, particularly for wastewater, for separating light liquids and / or fats. The purification system comprises one or more separation tanks forming at least one separation volume and one storage volume. The separation volume has at least one inlet for liquids to be purified, particularly wastewater. The separation volume and the storage volume are fluidically connected via a separator for separating light liquids and / or fats. Furthermore, a pumping system is provided for conveying liquid from the storage volume.

[0002] The invention further relates to a method for operating a purification plant, particularly for wastewater, for separating light liquids and / or fats. The invention specifically relates to a method for operating the aforementioned purification plant. The purification plant comprises one or more separation tanks forming at least one separation volume and one storage volume, which are fluidically connected via a separator for separating light liquids and / or fats. Liquids to be purified, particularly wastewater, are fed into the separation volume. Contaminants, particularly in the form of light liquids and / or fats, are separated via the separator, and the purified liquids are collected in the storage volume.

[0003] Treatment plants of the type mentioned above are well known from the prior art. For example, DE 199 54 437 A1 describes a wastewater treatment plant for separating light liquids, comprising an upstream sludge trap into which wastewater can be discharged and a downstream storage basin for collecting treated water. The sludge trap is fluidically connected to the storage basin via an overflow pipe. A light liquid separator, whose outlet is connected to the overflow pipe, is provided to separate light liquid components from the incoming wastewater. The treated wastewater can be pumped out of the storage basin using a pump or lifting line. The inlet to the sludge trap can have a self-closing inlet valve.

[0004] Furthermore, US 5,122,280 A discloses a separator for separating oil from water, comprising a storage container and a separation tank fluidically connected to the storage container. The separator includes a pump and a sensor probe that are signal-coupled to a control unit.

[0005] Furthermore, WO 2009 / 011660 A1 describes a device for separating fats, comprising a collection tank and a separation tank. The separation tank is equipped with sensors that detect the presence of water or fat. Depending on whether the sensors detect water or fat, either a valve is opened and water is drained, or a pump is activated and fat is pumped into a storage tank.

[0006] Automatic shut-off devices are required by regulations, particularly for light liquid separators. Currently, inlet barriers or floats at the inlet element are typically used for this purpose. These shut off the flow to the light liquid separator when the maximum operating water level is reached. Most commonly, so-called floats are used that close the outlet when the maximum permissible storage quantity of light liquid is reached by resting on the float valve. These floats are calibrated to the density of the light liquid and react to the density of the surrounding liquid (water or light liquid) and thus to the position of the separation layer between the separated light liquid and water.

[0007] For example, US Patent 2,670,848 A describes a separation device for separating oil from water, which includes a separation tank with an inlet and an outlet. A skimming tank with an integrated float is arranged within the separation tank, dividing the skimming tank into two sections.

[0008] The known inlet valves, by design, only react to the existing process water level and not to the amount of light liquid stored. Therefore, the shut-off device is only triggered when the process water level rises above a predetermined level. This can be caused, for example, by a heavy rainfall event exceeding the design value, or by the separator not providing the intended free flow due to backflow or a blocked coalescing element.

[0009] The floats commonly used are generally integrated into the design of the drain and close the separator when the maximum storage capacity for light liquid is reached. For this purpose, they are calibrated to the density of the predominant light liquid or have a density slightly higher. Floats only react to the density of the liquid immediately surrounding them. If different liquids with varying densities are present, separation layers can form that are not located in the immediate vicinity of the float. If the float is located within the separation layer, it reacts to the average density of the surrounding liquids, corresponding to the thickness of the separation layer. Furthermore, the float is always calibrated to only one light liquid, so it generally reacts inadequately when multiple liquids with different densities are present.Furthermore, there is the inherent problem that the density of the float can be altered by impurities. This can cause the float to close the separator prematurely or become so heavy that its density approaches that of water. In this case, the float may close the drain even during normal operation.

[0010] Floats remain sensitive to the strength of the inflow. If a treatment system becomes overloaded due to heavy rainfall, faulty design, or additional inflow from a wider area, water can flow over the coalescing element to the outlet. This exerts an additional downward force on the float. This force, combined with the potential for strong suction due to the high flow rate, can cause the float to be pulled downwards, closing the separator, even though the system could otherwise continue operating normally.

[0011] The object of the invention is to provide a cleaning system of the type mentioned above or a method for operating such a cleaning system in which the disadvantages described above can be avoided, at least in part.

[0012] This problem is solved by a cleaning system with the features of claim 1 or by a method for operating such a cleaning system with the features of claim 9.

[0013] Advantageous embodiments of the invention are the subject of the dependent claims.

[0014] A purification system, particularly for wastewater, for separating light liquids and / or fats, comprises one or more separation tanks, which form at least one separation volume and one storage volume. The separation volume has an inlet for liquids to be purified, particularly wastewater. The separation volume and the storage volume are fluidically connected via a separator for separating light liquids and / or fats. Furthermore, a pumping system is provided for conveying liquid from the storage volume. During operation, the separator separates light liquids and / or fats from the supplied liquid, and the separation volume collects the separated light liquids and / or fats. According to the invention, at least one layer thickness sensor is arranged in the separation volume for measuring the layer thickness of at least one separating layer.A control unit is designed to release or lock the lifting system for pumping liquids from the storage volume, depending on the detected layer thickness. It is possible to configure the separation volume and storage volume in two separate containers that are fluidically connected. The control unit is configured to electronically release the lifting system when the layer thickness of the separating layer in the separation volume is less than a predefined or predetermined critical threshold.

[0015] In contrast to previously known designs of automatic shut-off devices for cleaning systems of the aforementioned type, which use floats or inlet valves, a new cleaning system without floats is presented, and a pumping station is provided as the shut-off device. Floats and inlet valves are always "open" in their default state, meaning that incoming liquid, especially wastewater, can flow out again through such shut-off devices to the same extent after treatment. In contrast, pumping stations, in which a pump must be actively operated to create a drain, are always closed in their default state. This is exploited according to the invention by coupling the pumping station with a control unit that activates or deactivates the pumping station depending on the sensor-detected layer thickness and, if applicable, on any detected or identified errors.If the operating parameters detected or recorded in this way are within a normal range, electronic authorization is granted and the treated water can be pumped from the storage volume into the connected sewer system using the pumping station. Otherwise, the pumping station is electronically shut down or blocked.

[0016] For the purposes of this specification, a separating layer is defined as a layer whose components have a lower density than water. Specifically, a separating layer is understood to be the line where a lighter and a heavier liquid meet. For example, the line that forms between oil and water – it can also be described as a phase boundary. Such a separating layer therefore always accumulates above the water. The separating layer does not necessarily have to be homogeneous and can, in particular, contain various components whose densities are lower than that of water. The separating layer can, for example, be formed by various light liquids, mineral oil components, oils, and / or greases. The layer thickness sensor measures the thickness of the entire layer, which is a measure of the total volume of the separated light liquids or greases.Since the density of the components forming the separation layer is not decisive for determining the layer thickness, a reliable determination of the total volume deposited can be achieved, particularly in applications where, for example, a heterogeneous mixture of light liquids is to be separated.

[0017] The pumping station includes, in particular, at least one pump and a lifting pipe to pump the treated wastewater from the storage volume. The use of a pumping station for this purpose is especially advantageous in the event of power outages, as the pumping station cannot be put into operation, thus preventing operational disruptions.

[0018] In certain configurations, a pressure sensor for measuring the fill level (also: level, liquid level) is arranged in the separation volume and / or the storage volume. In such configurations, the control unit is designed to enable or disable the pumping system for conveying liquids from the storage volume, depending on the detected fill level. The pressure sensor is, for example, designed as a level sensor and preferably detects the hydrostatic pressure of the surrounding liquid or wastewater, which is a measure of the fill level in the separation volume or storage volume. In this way, it can be ensured that the pumping system is only enabled for conveying treated wastewater from the storage volume when a sufficient volume of treated wastewater has accumulated in the storage volume. Alternatively or additionally, the level in the separation volume is monitored using a pressure sensor.This is particularly useful in configurations where wastewater can flow directly from the separation volume into the storage volume when the water level is too high, for example, when the separation volume and the storage volume are formed by two sections of a monolithic separation basin separated by a partition wall. In such cases, the control unit is designed to automatically lock the pumping station.

[0019] In certain configurations, an electronically lockable barrier is provided at the outlet to the separation volume. In such configurations, the control unit is preferably designed to release or lock the barrier depending on the detected layer thickness and / or the detected fill level, particularly within the separation volume. The control unit may include a readable electronic operating log. The layer thickness sensor can be used, in particular, to detect whether the total separated volume has already reached its maximum capacity and the separator needs to be emptied. In this case, an automatic interruption of the outflow is advantageous. For example, if the liquid level in the separation volume becomes too high, further water outflow can be automatically prevented.

[0020] In some designs, the separation volume and the storage volume are realized by two separate separation tanks, in particular made of concrete, polymer concrete, reinforced concrete, plastic, metal, or GRP.

[0021] In alternative embodiments, the separation volume and the storage volume are formed by two separate compartments of a separation vessel, divided by a partition wall. In this case as well, the separation vessel and / or the partition wall preferably consist of concrete, polymer concrete, reinforced concrete, plastic, metal, or GRP (glass fiber reinforced plastic). The separation vessel and the partition wall can preferably be monolithic.

[0022] In certain embodiments, the layer thickness sensor is configured to measure the conductivity or polarity, in particular the dipole moment, of the surrounding liquid. Such measurements allow for a sufficient characterization of the liquid surrounding the layer thickness sensor. In particular, it is possible to distinguish polar liquids, such as water, from nonpolar liquids, such as fats, oils, or other light liquids. Preferably, the layer thickness sensor for detecting the thickness of the separating layer comprises several spatially distributed individual sensors, each configured to measure the conductivity or polarity, in particular the dipole moment, of the respective surrounding liquid.

[0023] In certain embodiments, the separator has at least one coalescing element, which in particular comprises at least one wire mesh or perforated sheet. The coalescing element serves in particular to promote the adhesion of light liquid components, fats, and / or oils and has a suitable surface finish for this purpose. In certain embodiments, the coalescing element is formed at least partially from an oelophilic material and / or has at least partially an oelophilic coating.

[0024] In some configurations, a warning device is provided for emitting an acoustic and / or visual warning signal. The warning device is designed to emit the warning signal depending on the detected layer thickness and / or the detected fill level.

[0025] In a method for operating a purification plant, particularly for wastewater, for separating light liquids and / or fats, at least one separation volume and one storage volume are provided, which are formed by one or more separation tanks. The separation volume and the storage volume are fluidically connected to each other via a separator for separating light liquids and / or fats. Liquids to be purified, particularly wastewater, are fed into the separation volume. Contaminants, particularly in the form of light liquids and / or fats, are separated by the separator, and purified liquid is collected in the storage volume.According to the invention, a lifting system for conveying the purified liquid from the storage area is electronically released when the layer thickness of a separating layer located in the separation volume is less than a predefinable or predetermined critical threshold value.

[0026] In normal operation (also known as standard operation), the water to be treated passes through the separator and is collected in the storage volume of the pumping station before being pumped into the connected sewer system. A key criterion for the treatment system to operate in normal operation is that the thickness of the separating layer, which characterizes the total volume already separated, remains below the critical threshold. This critical threshold corresponds specifically to the maximum storage capacity for separated light liquids or fats. During normal operation, the measured layer thickness should always remain below the critical threshold, as the separator must be emptied regularly as standard practice. If the measured layer thickness nevertheless reaches the specified or predefined critical threshold, the pumping station is electronically shut down. Operation is only reactivated after user authorization.It is planned to record such events in a log of the control unit. Manual release only occurs after a visual inspection has confirmed that normal operation is occurring.

[0027] Electronic locking of the lifting system has the advantage, among others, that the normal operating state (regular operation) can be restored by the user simply by resetting the control unit. This is not the case with conventional locking devices, as these generally require manual intervention followed by emptying.

[0028] In certain configurations, the pumping station is activated to transfer the treated liquid from the storage area when the detected fill level in the separation volume and / or the storage volume is within a standard range. For example, treated wastewater is collected in the storage volume of the pumping station until the pressure sensor (e.g., a level probe) installed there registers a sufficient volume for the treated water to be pumped into the connected pipeline. In other cases, the liquid level in the separation volume may rise too high due to an excessive inflow. This is particularly critical in configurations implemented in a single separation basin, i.e., when the separator and pumping station are integrated into a monolithic separation tank divided into two functional areas by a partition.There is a risk that an excessive inflow could cause the liquid level in the separation volume to rise so high that already separated light liquid overflows the partition. In this case, the sensor in the separation volume sends a corresponding signal to the control unit, which then electronically locks the lifting system and only releases it for normal operation again after user confirmation. Preferably, such error messages are logged in the control unit's log.

[0029] In some configurations, a warning signal is issued when the detected layer thickness reaches or exceeds a predefined or configurable limit value that is below the critical threshold. The issuance of such warning signals is intended, in particular, to prevent already separated light liquid from entering the storage volume uncontrollably once the maximum separation capacity of the separator has been reached.

[0030] In certain configurations, the critical threshold corresponds to a critical layer thickness with a corresponding critical volume. The critical volume corresponds, in particular, to the maximum amount of material the separation volume can hold. The threshold value that triggers the audible and / or visual warning signal preferably corresponds to a volume that is 80% of the critical volume. This ensures that an alarm is triggered when the total volume of material removed reaches approximately 80% of the maximum separation volume. This typically gives the operator sufficient time to empty the separation volume before the system shuts down due to reaching the maximum separation volume.

[0031] The invention is further explained below with regard to its features and advantages by means of a description of exemplary embodiments and with reference to the accompanying schematic drawings. These show FIG. 1 a cleaning system in the open state, shown from above; FIG. 2 the cleaning system of the FIG. 1 in a cross-sectional view; FIG. 3 the cleaning system of the FIG. 1 in another sectional view; FIG. 4 the cleaning system of the FIG. 1 in another sectional view.

[0032] Corresponding parts and components are marked with the same reference symbols in all figures.

[0033] FIG. 1 Figure 1 shows a treatment plant 10 for separating light liquids and / or fats from wastewater in a top view. The treatment plant comprises a monolithic separation tank 12 made of concrete, which, when installed, is closed by a lid (not shown), also made of concrete. A partition 14 divides the interior of the separation tank 12 into a separation volume 16 and a storage volume 18.

[0034] The separation volume 16 and the storage volume 18 are fluidically connected via a separator 20 for separating light liquids and / or fats. A lifting line 22 of a pumping station 24 is arranged in the storage volume 18 for pumping treated wastewater from the storage volume 18. A pump (not shown) is connected to the lifting line 22 for pumping the treated wastewater.

[0035] Wastewater enters the separation volume 16 via an inlet 26. The inlet 28 is equipped with a baffle plate 30 to allow the incoming wastewater to settle and, in particular, solid components to settle out by sedimentation.

[0036] In the separation volume 16, at least one layer thickness sensor 52 is arranged for measuring the layer thickness of at least one separating layer consisting of already separated light liquid or fat components. The layer thickness sensor 52 is designed to measure the conductivity or polarity, in particular the dipole moment, of the surrounding liquid. The layer thickness sensor 52 has a certain spatial resolution so that the thickness of the separating layer can be detected.

[0037] A control unit (not shown in detail) is configured to enable or disable the lifting system 24 for pumping liquid from the storage volume 16, depending on the detected layer thickness. The lifting system 24 is thus coupled to the control unit in such a way that electronic enabling or disabling of the lifting system 24 occurs depending on the sensor-detected layer thickness and, if applicable, depending on detected errors.

[0038] In the illustrated embodiment, the separator 20 is designed as a coalescing separator and comprises a substantially cylindrical coalescing element 32, which is formed by perforated plates and arranged concentrically to one another. The separator 20 further comprises an overflow pipe 34, which provides the fluidic connection between the separation volume 16 and the storage volume 18.

[0039] Pressure sensors for measuring the fill level in the respective areas are arranged in the separation volume 16 and the storage volume 18. The control unit communicates with these pressure sensors either wired or wirelessly and is designed to enable or disable the lifting system 24 for pumping liquids from the storage volume 18, depending on the respective measured fill levels. The pressure sensors are designed to detect the hydrostatic ambient pressure in the respective areas.

[0040] At the outlet 22 leading to the separation volume 16, an electronically lockable barrier (not shown in detail) is also provided. The control unit is designed to release or lock the barrier depending on the detected layer thickness and the detected fill levels in the separation volume 16 and the storage volume 18.

[0041] Furthermore, a warning device (not shown in detail) is provided for emitting an acoustic and / or visual warning signal. The warning device is designed to emit the warning signal depending on the detected layer thickness and / or fill level.

[0042] A sampling area 50 is provided between separation volume 16 and storage volume 18. The sampling area is integrated into the partition wall 14. If separation volume 16 and storage volume 18 are arranged in separate containers, the sampling area is also designed as a separate container that is fluidically connected to separation volume 16 and storage volume 18.

[0043] FIG. 2 shows a cross-sectional view of cleaning plant 10. The course of the cross-section shown is in FIG. 1 shown and labelled II.

[0044] FIG. 3 This shows another cross-sectional view of cleaning plant 10. The course of the section shown is in FIG. 1 shown and labelled III.

[0045] FIG. 4 Figure 1 shows another sectional view of the cleaning system 10, in which in particular the position of the layer thickness sensors 52 and the position of a backwater probe 54 in the separation volume 16 are shown.

[0046] During operation of the treatment plant 10, light liquids and / or fats are separated from the incoming wastewater by means of the separator 20 and collected in the separation volume 16. The treated wastewater then flows via the overflow pipe 34 into the storage volume 18 and collects there. Depending on the sensor data acquired by the pressure sensors and the layer thickness sensor 52, the control unit electronically enables or disables the pumping station 24 to convey the treated wastewater from the storage area 18. Enabling occurs, in particular, when the layer thickness of a separating layer located in the separation volume 18 is less than a predefined or predetermined critical threshold value and the other acquired data do not indicate any other operational malfunction. Sampling can be carried out in the area of ​​the overflow pipe 34, or a sampling area 50 can be located there.

[0047] In normal operation, the water to be treated passes through the separator 20 and is collected in the storage volume 18 of the pumping station 24, from where it is pumped into the connected sewer system. A necessary, but not necessarily sufficient, criterion for the normal operation of the treatment plant 10 is that the total volume of light liquids, oils, and / or greases already separated is below the maximum separation volume that the separation volume 16 can accommodate. The maximum separation volume corresponds to the critical threshold for the thickness of the separating layer.

[0048] Under normal operating conditions, the layer thickness of the separating layer in the separation volume 16 should always remain below the critical threshold, as an alarm will be triggered beforehand, instructing the operator to empty the separation volume. If the detected layer thickness nevertheless reaches the critical threshold, the lifting unit 24 will be electronically locked. Operation will only be reactivated after user authorization. This is intended to be recorded in a log by the control unit.

[0049] For normal operation, it is generally also necessary that the fill level in the separation volume 16 and the storage volume 18 remains within a normal range. In particular, the level in the storage volume 18 must be high enough to activate the pumping station 24. The liquid level in the separation volume 16 may be too high, for example, due to an excessive inflow, creating the risk that already separated light liquid or grease could pass over the partition 14 into the storage area 18. In such cases, the control unit is designed to automatically lock the pumping station 24 electronically and only release it for normal operation again after user confirmation. Such malfunctions are logged in the control unit's log.

[0050] The aforementioned warning signal is triggered when the measured layer thickness of the separating layer reaches or exceeds a predefined or configurable limit value, which is below the critical threshold. As mentioned previously, the critical threshold corresponds to a maximum separation volume for light liquids and / or fats. The threshold value relevant for issuing the acoustic and / or visual warning signal preferably corresponds to a volume that is 80% of the maximum separation volume. Thus, when the warning signal is issued, the operator typically has sufficient time to empty the separation volume 16 before the system shuts down due to reaching the maximum separation volume.

Claims

1. A cleaning system (10), in particular for waste water, for separating light liquid and / or fats, with one or more separating containers (12) forming at least one separating volume (16) and one storage volume (18), wherein the separating volume (16) has at least one inlet (28) for to-be-cleaned liquids, in particular waste water, and the separating volume (16) and the storage volume (18) are fluidically connected via a separator (20) for separating light liquids and / or fats, wherein a lifting system (24) is provided for transporting liquid from the storage volume (18), characterised in that, during operation, the separator (20) separates light liquids and / or fats from the supplied liquid and the separating volume (16) collects the separated light liquids and / or fats, wherein at least one layer thickness sensor for measuring a layer thickness of at least one separating layer is arranged in the separating volume (16) and a control unit is designed to release or lock the lifting system (24) for transporting liquids from the storage volume (18) as a function of the sensed layer thickness, wherein the control unit is configured to release the lifting system (24) electronically if the layer thickness of the separating layer located in the separating volume (16) is smaller than a predeterminable or predetermined critical threshold.

2. The cleaning system (10) according to claim 1, characterised in that a sensor, in particular a pressure sensor, filling level sensor, vibration sensor, capacitive sensor or thermal sensor, for measuring the filling level is arranged in the separating volume (16) and / or in the storage volume (18), and the control unit is designed to release or lock the lifting system (24) for transporting liquids from the storage volume (18) as a function of the sensed filling level.

3. The cleaning system (10) according to claim 1 or 2, characterised in that an electronically lockable barrier is provided at an outlet and / or inlet (22, 24, 28), and the control unit is designed to release or lock the barrier as a function of the sensed layer thickness and / or as a function of the sensed filling level, in particular in the separating volume (16) and / or in the storage volume (18).

4. The cleaning system (10) according to one of the preceding claims, characterised in that the separating volume (16) and the storage volume (20) are realised by two separate separating containers, in particular made of concrete, polymer concrete, metal, GRP or plastic.

5. The cleaning system (10) according to any of claims 1 to 3, characterised in that the separating volume (16) and the storage volume (18) are formed by two areas of a separating container (12) separated from one another by a partition wall (14), which are in particular made of concrete, polymer concrete, metal, GRP or plastic.

6. The cleaning system (10) according to one of the preceding claims, characterised in that the layer thickness sensor is designed for measuring the conductivity or the polarity of the liquid surrounding it.

7. The cleaning system (10) according to one of the preceding claims, characterised in that the separator (20) has at least one coalescence element (32), which in particular comprises at least one wire mesh or a perforated plate.

8. The cleaning system (10) according to one of the preceding claims, characterised in that a warning device is provided for outputting an acoustic and / or visual warning signal, wherein the warning device is designed to output the warning signal as a function of the sensed layer thickness and / or the sensed filling level.

9. A method for operating a cleaning system (10), in particular for waste water, for separating light liquid and / or fats according to one of the preceding claims, with one or more separating containers (12) forming at least one separating volume (16) and one storage volume (18), which are fluidically connected via a separator (20) for separating light liquids and / or fats, wherein to-be-cleaned liquids, in particular waste water, are fed into the separating volume (16), impurities in the form of light liquids and / or fats are separated via the separator (20), the separated light liquids and / or fats are collected in the separating volume (16) and cleaned liquid is collected in the storage volume (18), wherein a lifting system (24) for transporting the cleaned liquid out of the storage area (18) is released electronically if the layer thickness of a separating layer located in the separating volume (16) is smaller than a predeterminable or predetermined critical threshold.

10. The method according to claim 9, characterised in that the lifting system (24) is released for transporting the cleaned liquid from the storage area (18) if a sensed filling level in the separating volume (16) and / or in the storage volume (18) is within a nominal range.

11. The method according to claim 9, characterised in that a warning signal is output if the sensed layer thickness reaches or exceeds a predetermined or predeterminable limit which is below the critical threshold.

12. The method according to claim 11, characterised in that the critical threshold corresponds to a critical layer thickness with a respective critical volume, and the limit corresponds to a volume corresponding to 80 % of the critical volume.