NL2019016B1 - System and method for cleaning and/or purifying a waste fluid, and conversion kit there for - Google Patents

Abstract

System for cleaning a fluid comprising a reservoir that is at least partially fillable with carriers. The reservoir comprises - a reservoir that is at least partially fillable with carriers, the reservoir comprising: - a fluid inlet and a fluid outlet; - a carrier inlet and a carrier outlet; and - a separation unit that is positioned in the reservoir between the fluid inlet and the fluid outlet and that is configured for supporting carriers, wherein the separation unit comprises a carrier guiding opening that is operatively connected to the carrier outlet of the reservoir and wherein the separation unit comprises a plurality of fluid openings configured for passage of fluid, wherein the fluid openings are operatively connected with the fluid outlet; - a carrier recirculation conduit connecting the carrier outlet and the carrier inlet of the reservoir, wherein the carrier recirculation conduit is operatively connected to a fluid supply unit; and - a carrier discharge unit that is positioned in the carrier recirculation conduit, wherein the carrier discharge unit comprises a carrier discharge unit inlet that is connected to the carrier outlet of the reservoir and a carrier discharge unit outlet that is connected to the carrier recirculation conduit; wherein the carrier discharge outlet unit is configured to selectively provide carriers in a fluid stream from the fluid supply unit.

Description

Netherlands Patent Office © 2019016 © Application number: 2019016 © Application filed: June 2, 2017 © BI PATENT © Int. CL:

C02F 3/08 (2017.01) B01J 19/30 (2017.01) C02F

3/10 (2017.01) B01D 15/02 (2017.01)

(4 ^ Request registered: © Patent holder (s): December 7, 2018 Dennis van der Herberg in HEERENVEEN. © Request published: - © Inventor (s): Dennis van der Herberg in HEERENVEEN. © Patent granted: December 7, 2018 © Authorized representative: © Patent issued: ir. P.J. Hylarides et al. In The Hague. April 15, 2019

© SYSTEM AND METHOD FOR CLEANING AND / OR PURIFYING A WASTE FLUID, AND CONVERSION KIT THERE FOR

57) System for cleaning a fluid including a reservoir that is at least partially tillable with carriers. The reservoir comprises

- a reservoir that is at least partially tillable with carriers, the reservoir including:

- a fluid inlet and a fluid outlet;

- a carrier inlet and a carrier outlet; and

- a separation unit that is positioned in the reservoir between the fluid inlet and the fluid outlet and that is configured for supporting carriers, the separation unit comprises a carrier guiding opening that is operatively connected to the carrier outlet or the reservoir and the separation unit comprises a variety of fluid opening configured for passage of fluid, containing the fluid opening are operatively connected with the fluid outlet;

- a carrier recirculation conduit connecting the carrier outlet and the carrier inlet or the reservoir, the carrier recirculation conduit is operatively connected to a fluid supply unit; and

- a carrier discharge unit that is positioned in the carrier recirculation conduit, the carrier discharge unit comprising a carrier discharge unit that is connected to the carrier outlet and a carrier discharge unit outlet that is connected to the carrier recirculation conduit;

in the fluid discharge outlet unit is configured to selectively provide carriers in a fluid stream from the fluid supply unit.

NL Bl 2019016

This patent has been granted regardless of the attached result of the research into the state of the art and written opinion. The patent differs from the documents originally submitted. All submitted documents can be viewed at the Netherlands Patent Office.

SYSTEM AND METHOD FOR CLEANING AND / OR PURIFYING A WASTE FLUID, AND CONVERSION KIT THERE FOR

The invention relates to a system for cleaning and / or purifying a fluid, such as waste air and / or waste water. Trickling bed filters for cleaning and / or purifying waste fluid are known from practice and often include a stationary filtering bed that is positioned in a filtering tank. The use of a stationary filtering bed requires a relatively large filtering surface, which may extend up to 20 meters in diameter with circular tanks.

An alternative trickling bed filter may be provided in a closed tank or reservoir. Such a filter is known for example from WO 96/1168.

A disadvantage of this apparatus is that it is relatively complex and sensitive to malfunctioning, which increases cost and downtime.

The invention is aimed at providing an improved system for cleaning and / or purifying waste fluid, which obviates or at least reduces the disadvantages of the prior art.

The invention therefore provides a system for cleaning and / or purifying a fluid, such as waste water and / or waste air, including:

a reservoir that is at least partially fillable with carriers, the reservoir including:

a fluid inlet and a fluid outlet;

a carrier inlet and a carrier outlet; and a separation unit that is positioned in the reservoir between the fluid inlet and the fluid outlet and that is configured for supporting carriers, the separation unit comprises a carrier guiding opening that is operatively connected to the carrier outlet of the reservoir and the separation unit comprises a variety of fluid opening configured for passage of fluid, including the fluid passages are operatively connected with the fluid outlet;

a carrier recirculation conduit connecting the carrier outlet and the carrier inlet or the reservoir, the carrier recirculation conduit is operatively connected to a fluid supply unit; and a carrier discharge unit that is positioned in the carrier recirculation conduit, in which the carrier discharge unit comprises a discharge unit that is connected to the carrier outlet or the reservoir and a discharge unit outlet that is connected to the carrier recirculation conduit;

the fluid supply unit is placed upstream of the carrier discharge unit, the carrier discharge outlet unit is configured to selectively provide carriers in a fluid stream from the fluid supply unit such that the fluid stream and the carrier circulation can be regulated independently of each other.

It should be noted that the terms cleaning and purifying / purification are used interchangeably in the document, the terms both refer to the removal of pollution from a waste fluid. Cleaning should therefore also be read as purifying / purification, whereas purifying / purification should also be read as cleaning. The skilled person would understand that these terms both refer to the same process. The term fluid supply unit should be a unit configured for supplying and / or displacing a fluid. The fluid supply unit may be for example preferably a pump, such as a hydraulic pump, yet may also be a different fluid supply unit that is useable for transporting a fluid under pressure.

The system according to the invention functionally decouples the circulation of the (waste) fluid and the circulation of carriers, therewith allowing independent regulation of both. The functional decoupling is achieved through the use of the carrier discharge unit according to the invention. The carrier discharge unit according to the invention is configured to selectively discharge carriers in the fluid stream from the fluid supply unit, while simultaneously allowing a fluid stream to flow through the carrier discharge unit. As a result, the circulation speed of the carriers can be regulated independently of the fluid flow supplied by the fluid supply unit. The fluid supply unit may be configured for supplying a waste water stream and / or for supplying a flow or a different fluid.

The use of the carrier discharge unit according to the invention provides several advantages about the prior art. First of all, the circulation of the carriers can be optimized to provide a more efficient cleaning and / or purification process. The optimization can be performed using different predetermined parameters and / or combinations of different and / or predetermined parameters, such as the amount of pollution of the waste fluid, the growth rate of biological material on the carriers and / or the assimilation / removal rate of the waste from the waste fluid from the biological material on the carriers.

Another advantage of the functional decoupling provided with the system according to the invention is a reduction of energy needed for cleaning and / or purifying the waste fluid. Rather than continuously circulation the carriers and / or having to start and stop the purification process, the carriers in the system according to the invention are only circulated when this is required for the process while simultaneously allowing the (waste) fluid to be circulated continuously. This provides an energy efficient and continuous purification process.

Yet another advantage of the system according to the invention is that the fluid supply unit is preferably placed upstream of the carrier discharge unit, while still allowing a continuous flow or fluid to the recirculation conduit. As a result, the carriers that are transported through the recirculation conduit are not transported through the fluid supply unit. This lowers the wear on the fluid supply unit and consequently reduces system cost.

The system according to the invention may be used to provide a continuous cleaning process or used to provide a batch-wise cleaning process. The carrier discharge unit may be configured to periodically release carriers into the fluid stream to the carrier recirculation conduit, therewith effectively introducing a settling stale in which the carriers are in a steady, non-moving state in the reservoir and a recirculation state, in which carriers are discharged into the fluid stream to the carrier recirculation conduit. Alternatively, the carrier discharge unit may also be configured to provide a constant intermittent stream or carrier batches to the carrier recirculation conduit.

In an embodiment, the fluid supply unit may be configured to provide a substantial continuous flow or fluid to the carrier recirculation conduit, the fluid supply unit and the carrier discharge unit may also be configured to, preferably when programmed or regulated, periodically and / or based on a regulation signal, switched off such that the continuous flow of fluid is at least temporarily ceased and no circulation of fluid is provided. This feature may be used during maintenance or malfunctioning of the carrier discharge unit and / or fluid supply unit, which allows the reservoir to remain filled (and operational), whereas the carrier discharge unit, fluid supply unit and / or recirculation unit become accessible to personnel.

In an embodiment, the system according to the invention may be provided with one or more sensors for measuring physical parameters or system conditions, which may include pollution grade, waste water transparency and / or viscosity, the amount of bacteria in the waste water, the temperature in the reservoir and / or other parameters.

In an additional or alternative embodiment, the system may include a control system that is part of the system or integrated therein, which control system, for example based on measurement values from sensor inputs, may be configured for selectively switching the system between the recirculation state and the settling state and / or adjusting the carrier recirculation settings allowing for a faster or slower recirculation of the carrier, hi an elaboration of the embodiment, the control system is provided with adaptive learning and / or multiple program inputs that are configured for selecting a specific type of waste water and / or waste air that is treated to allow a more efficient purification and / or cleaning process. Also, the system may be configured to regulate the fluid supply speed and the recirculation state / settling state intervals based on external information on pollution and / or in combination with system information, such as information from measurements from sensors in the system.

Furthermore, in an embodiment, the control system may be provided with a remote access unit for allowing remote control over the process and / or the process parameters by means of the control system.

In an embodiment of the invention, the system may include a sludge removal unit that is configured for removal and discharging at least part of the sludge from the carriers, the sludge removal unit having a removal unit inlet that is connected to the carrier recirculation conduit, a removal unit outlet that is connected to the carrier inlet or the reservoir and a sludge discharge conduit.

In the known systems, the sludge removal is an integrated, passive part of the recirculation process in which the sludge is (partially) removed from the carriers, for example by making the carriers fall down a conduit. The downward motion and the impact near a low end of the conduit dislodges sludge, after which the carriers are reintroduced in the reservoir. The disadvantage of this process is that the dislodging or sludge is virtually not controllable. Furthermore, the dislodged sludge is removed from the system as part of a water stream, therewith providing "wet" sludge having a low dry matter content. This increases the processing cost of the sludge after removal. The use of a sludge removal unit according to the invention allows a more sophisticated control to be exercised over the sludge removal process. The control comprises the amount of sludge that is to be removed and may even include shutting down the removal unit during recirculation to preserve the biological material that is on the carriers. This is not possible using the sludge removal known in practice. Furthermore, the sludge removal unit according to the invention also provides the advantage that allows a separation of water and carriers before dislodging and removing the sludge from the carriers. This results in a more compact sludge with relatively low water content. This reduces the cost of subsequent processing steps after removal of the sludge from the system.

In an embodiment of the invention, the sludge removal unit may comprise a fluid discharge conduit.

Preferably, the sludge removal unit is provided with both a sludge discharge conduit as well as a fluid discharge conduit to separately discharge the fluid, which may be recirculated into the reservoir, for example through the fluid supply unit, and the sludge, which may be removed from the system, for example for additional processing. By providing to different discharge conduits, the sludge that is removed from the system has a relatively low water content and can be processed more easily and at lower costs.

In an embodiment of the invention, the sludge removal unit may include a first filter that may be configured for separating fluid from carriers, a first filter outlet may be connected to the fluid discharge conduit, and a second filter that may be configured for at least partially removing sludge from the carriers, carrying the carriers may be brought in contact with the second filter with a predetermined force for dislodging sludge from the carriers, carrying a second filter outlet may be connected to the sludge discharge conduit.

The advantage of a sludge removal unit including two subsequent filters is that any water may have been filtered from the carrier / water mixture before removing excess sludge from the carriers. As a result, the water content of the sludge that is dislodged from the carriers by the second filter is relatively low. Furthermore, the speed and / or force that is used to connect the carriers and the second filter may be regulated more accurately, therewith providing a more sophisticated control over the amount of sludge that is removed from the carrier and system.

In an embodiment, the sludge removal unit may include a housing having an inlet that is connected to the carrier recirculation conduit and an outlet that is connected to the carrier inlet, the first filter may be positioned adjacent the inlet and may comprise a plate- like structure having fluid opening for separating fluid, such as water, from the earners. The first filter may preferably be placed under a downward angle for transporting the carriers towards an adjacent accelerator that may be configured to accelerate the carriers towards the second filter. The second filter may include a structure having sludge opening, the carriers are connecting to the second filter with a predetermined speed and / or force for dislodging sludge from the carriers. The second filter may be positioned under a downward tingle towards the carrier inlet, such that the carriers may be automatically transported to the carrier inlet after connecting to and dislodging sludge in the second filter.

Several different may be envisioned in which the functionally decoupled (waste) fluid flow may be circulated in the system, each of which falls within the scope of the system according to the invention.

In an embodiment according to the invention, the fluid outlet or the reservoir is connected to an inlet or the fluid supply unit.

By providing a connection between the fluid outlet of the reservoir and an inlet of the fluid supply unit, the fluid from the reservoir may be in a simple way (at least partially) recirculated through the system. At least a part of the fluid from the reservoir is provided to the fluid supply unit, which recirculates the water to the carrier discharge unit and further the carrier recirculation conduit. Due to the carrier discharge unit being configured to allow a fluid flow without the necessity or simultaneously having to discharge carriers to the fluid stream, the fluid recirculation flow from the reservoir is functionally decoupled from the carrier recirculation flow. In this embodiment, the reservoir or the conduit between the fluid outlet and the fluid supply unit is preferably also provided with a clean fluid outlet for at least partially discharging clean fluid.

In an embodiment according to the invention, the system may include a fluid recirculation conduit that extends between the fluid outlet and the fluid inlet of the reservoir, the reservoir may additionally include a clean fluid outlet for discharged cleaned fluid from the system.

The fluid outlet may also be directly connected to the fluid inlet for the recirculation or at least part of the fluid from the reservoir. The fluid supply unit is provided in this embodiment with a different fluid stream for displacing the carriers that are discharged from the carrier discharge unit. By providing different recirculation conduits for both the fluid stream from the reservoir and the fluid stream from the carrier discharge unit, a more specific regulation of the fluid flows can be obtained. Each flow can be separately controlled and regulated since the carriers are not discharged into the recirculation fluid stream supplied from the reservoir fluid outlet.

In an embodiment according to the invention, the fluid outlet and the clean fluid outlet or the reservoir may include closing means for selectively opening and / or closing the fluid outlet and / or the clean fluid outlet.

The discharge of fluid from the reservoir may be regulated by providing closing means, such as valves, shutters or similar known reclosable closing means, in one or both of the fluid outlets from the reservoir. The fluid flow through or both of the fluid outlets may be controlled based on process parameters.

In an embodiment according to the invention, the system may include a controller and a measuring unit, the controller may selectively open and / or close one or both of the closing means based on a measured parameter that is received from the measuring unit.

By providing a controller and a measuring unit, controlling the fluid flows from the reservoir may be performed on the basis or detailed information obtained using the measuring unit. This allows for a detailed control of the cleaning process based on actual parameters of the process.

In an embodiment according to the invention, the fluid discharge conduit may be connected to an inlet or the fluid supply unit.

In an embodiment, the fluid flow that is obtained from the sludge removal unit may advantageously be discharged to the fluid supply unit. This allows process fluid, preferably water, to be recirculated for transportation or carriers through the carrier recirculation conduit.

In an embodiment according to the invention, the system may include a rotating sludge separator having an inlet that may be connected to the sludge discharge conduit and an outlet that may be connected to the fluid supply unit.

The system may advantageously be provided with a rotating sludge separator for separating any sludge in the fluid discharge conduit from the sludge removal unit before supplying the fluid to the fluid supply unit. In this way, the fluid supply unit is not damaged by any sludge that may have been enclosed in the fluid stream that is discharged from the fluid discharge conduit or the sludge removal unit.

In an embodiment of the invention, the separation unit may include an upper plate including a diverse or fluid opening and a carrier guiding opening that is operatively connected to the carrier outlet. The separation may further include a lower plate that extends substantially parallel and at a distance to the upper plate, the lower plate including a fluid opening that is operatively connected to the fluid outlet for discharging fluid.

This embodiment allows the filtered water that has passed the upper plate to more easily be guided to a different part of the reservoir, such as the fluid outlet or a settling area within the lower compartment. Preferably, the lower compartment comprises a settling area in which the filtered fluid is collected and in which remaining sludge and / or particles in the fluid may settle near the bottom of the lower compartment of the reservoir. The settling area of the lower compartment could Lie provided with a sludge removal conduit for removing the settled sludge and / or particles, whereas a side wall of the reservoir, preferably a side wall of the reservoir in the lower compartment, may be provided with the fluid outlet, such that the cleaned and / or purified fluid may be removed from the upper part of the settling area.

In an embodiment of the invention, the upper and lower plate may delineate an inner space, the inner space may be provided with an air inflow opening for supplying air through the fluid opening in the upper plate.

The inner space may advantageously be used to distribute the waste air over substantially the entire surface of the upper plate so that the waste air is also supplied to the upper compartment for cleaning. Simultaneously, the lower plate prevents the waste air from contacting the fluid outlet, therewith allowing waste air to be discharged from the fluid outlet. The lower plate also directs the waste air towards the upper compartment and substantially avoid a prolonged contact between the (settling) fluid in the settling area and the waste air that is supplied to the reservoir.

Additionally or alternatively, the fluid outlet may also be provided with a control element, such as a valve, to prevent the waste air from entering the fluid outlet.

In an embodiment of the invention, the separation unit may be a modular unit in that the separation unit may include a number of pie-shaped separation elements that may be connectable to each other for forming a substantial funnel-shaped separation unit having a central opening for discharging carriers from the upper compartment.

By providing a modular separation unit, the system may be applied to existing tanks or reservoirs. Additionally, a modular unit is more easily transportable and can be installed more easily in a reservoir.

In an embodiment according to the invention, the system may include a fluid supply device that is positioned in the reservoir and that is operatively connected to the waste fluid inlet for supplying fluid, the fluid preferably including waste water, to the carriers.

The use of a fluid supply device that is operatively connected to the fluid inlet allows for a more even distribution of the fluid over the carriers in the reservoir. This results in a more effective cleaning of the waste fluid and an increased removal of pollution during cleaning.

In an embodiment according to the invention, the fluid supply device may include a sprinkler system having at least one shower head, each shower head may include an outflow surface having more or outflow opening for supplying fluid to the reservoir, preferably for supplying fluid over the carriers, and a shower head axis that is substantially perpendicular to the shower head outflow surface, the shower head may preferably be rotatably mounted for rotating around the shower head axis.

By providing a fluid supply device having at least one shower head that is rotatable around a shower head axis, the supply of fluid such as waste water, to the carriers in the reservoir can be regulated by increasing or decreasing the rotation speed of the shower head . As a result, the amount of fluid supplied to the carriers and the time of supply can be regulated.

In an embodiment according to the invention, the fluid supply device may include a sprinkler system having at least two shower heads, the shower heads may be mounted on a sprinkler frame having a rotation axis that extends in a substantial vertical direction, the frame may be rotatable around the rotation axis.

By providing a fluid supply device having at least two shower heads that are rotatable around a shower head axis and also around a frame rotation axis, the flexibility with regard to the supply of water is further increased compared to the prior art. Furthermore, the direction of the fluid flow from the shower heads can be influenced by the multiple degrees of freedom in this embodiment. As a result, the amount of fluid supplied to the carriers and the time of supply can be regulated.

In an embodiment according to the invention, the fluid supply device may include fluid supply groups, each fluid supply group may include a number of radially outwardly extending branches, each branch may include a multiple of fluid outflow opening for supplying fluid to the reservoir , each fluid supply group may be provided with a regulation element, such as a valve, for regulating the flow of water from the fluid inlet to said fluid supply group.

This embodiment provides an alternative fluid supply device that is relatively simple, robust and reliable. Preferably, the length of the branches is adaptable to provide a single fluid supply device for different sizes or reservoirs. Furthermore, the fluid supply device according to this embodiment of the invention may be effectively used to divide the cross-sectional area of the reservoir in different sectors. This is especially advantageous in the purification of waste air having hydrophobic waste components. The fluid supply device may be regulated to cease supply or fluid to a specific sector of the different sectors that are formed in the reservoir, which allows hydrophobic air to flow through the carriers and contact the biological material on the carriers to purify the waste air. The biological material is able to assimilate the hydrophobic components from the waste air. In order to also provide the biological material with moisture to prevent degradation of the material, the fluid supply device may be regulated and / or configured to periodically provide different sectors for the purification of waste air having hydrophobic components. Furthermore, spraying the water over the carriers rather than (completely) submerging the carriers in water also provides the advantage that a reduced pressure is required to supply a stream of air, preferably opposite to the direction of the water stream, to the reservoir. This obviates the use of a compressor and makes it possible to use a fan only. As a result, the cost and energy use or the system are reduced.

In an embodiment of the invention, the system comprises air supply means for supplying air to the reservoir.

The air supply means may be used to supply clean air or may be used to supply waste air to be purified to the system. The air supply means may include a compressor and / or fan, an air inlet and an air outlet. Preferably the air inlet is provided with a fan to force the air into the reservoir. Additionally or alternatively, the air inlet and the air outlet may be connected with an air recirculation conduit for recirculation the air to the reservoir. This may for example advantageously used when waste air supplied to the system contains a large amount of pollutant. The air recirculation conduit may also be used to reverse the air flow in the reservoir, by switching the air inlet and the air outlet with each other.

In an embodiment, the air inlet is provided near a lower end of the reservoir and the air outlet is provided near an upper side of the reservoir for providing a stream of (waste) air to the reservoir that is in counterflow with the flow of water supplied to the reservoir. In an alternative embodiment, the air inlet is positioned near an upper end of the reservoir and the air outlet is provided near a lower end of the reservoir. In this embodiment, the direction of the flow of (waste) air is equal to the direction of the flow of water in the reservoir.

In an embodiment of the invention, the carrier discharge unit may be a housing in which the carrier discharge unit inlet and the carrier discharge unit outlet are positioned. The carrier discharge unit may additionally include an elongated cylindrical drum that is rotatably mounted in the housing and that is rotatable around a longitudinal drum axis. The drum may include at least one recess that extends substantially parallel to the longitudinal drum axis in a drum outer surface over substantially an entire length of the drum, the recess being configured to receive a batch of carriers from the carrier outlet and at least one central fluid channel that extends substantially parallel to the longitudinal drum axis from a first channel opening to a second channel over the entire length of the drum, the central channel being configured for transporting fluid.

The advantage of the carrier discharge unit according to this embodiment is that it provides a relatively simple and efficient unit for decoupling the carrier flow from a fluid flow provided by the fluid supply unit. The drum allows a batch-wise release of carriers from the reservoir, while simultaneously allowing a flow or fluid to flow uninterrupted through the central channel or channels. The carrier discharge unit according to this design is easy to maintain and has a low amount of wear.

In an elaboration of the embodiment, the drum may be provided as a single drum or may be provided as an extendible drum that has a variable length and may be used advantageously in different system. Such a one-size-fits-all drum reducing manufacturing cost or the carrier discharge unit (and the system).

The invention also relates to a carrier for a cleaning waste fluid system, preferably for a system for cleaning waste fluid according to the invention, the carrier comprises an elongated cylindrical structure delineating an inner space, the inner space is provided with an elongated star-like insert that is integrally formed in the cylindrical structure, and having a height of the cylinder and a diameter of the cylinder having substantially equal dimensions.

The carrier according to the invention provides the same advantages and effects as the system according to the invention as described above. Carriers for waste fluid cleaning system are known from practice. Such carriers are often made or at least partially permeable material that is spherically shaped to provide a large outer surface on which biological material can be adhere and form. In some other, such spherically shaped carriers are provided with opening. Applicant found that an elongated cylindrical structure, such as a pipe-like structure, can advantageously provide a large surface area, while simultaneously providing high deformation resistance. Preferably, the elongated cylindrical structure is provided with a star-like insert that extends along the entire length of the inner space of the, preferably pipe-like, structure. Such a starlike insert not only provides additional resistance to deformation, but also increases the surface area on which biological material may form. In an especially preferred embodiment, the carrier according to the invention is an integrally formed carrier in which the star-like insert forms are an integral part of the carrier.

The carrier may be manufactured form a great variety of materials, which may include plastics, metal or alloys or combinations. Preferably, plastics and more preferably environmentally friendly and / or sustainable plastics, are used for forming the carriers since plastics provide durable, reusable carriers. In an embodiment, the surface area of the carriers may be roughened or provided with a coating to increase the roughness of the surface to improve the adherence properties for biological material or the carrier surface.

The invention also relates to a conversion kit for converting a reservoir, such as a water tank, into a system for cleaning waste fluid according to the invention, the conversion kit including:

a separation unit, preferably a modular separation unit, that is placeable in an existing reservoir and that is dimensioned to be contiguous with a reservoir wall for forming an upper and a lower compartment;

a predetermined amount of carriers that are added to the reservoir;

a carrier discharge unit that is connectable to an outlet of the reservoir for discharging carriers from the reservoir;

a carrier recirculation conduit that is connectable to an inlet or the reservoir and the outlet or the carrier discharge unit; and a sludge removal unit that is connectable to or placeable in the recirculation unit; and a fluid supply unit that is operatively connectable to the carrier discharge unit and the recirculation unit and that is preferably connected to a fluid outlet or the reservoir or a fluid discharge outlet or the sludge removal unit.

The conversion kit according to the invention provides the same advantages and effects as the system and the carrier according to the invention as described above.

A conversion kit according to the invention provides a relatively simple tool for converting existing reservoirs and / or waste fluid purification systems into a waste fluid cleaning system according to the invention.

The conversion kit may advantageously be used in refurbishing existing reservoirs and / or cleaning systems to provide a system according to the invention. This may be especially useful in areas in which strict environmental regulations are in force with regard to environmentally friendly waste fluid purification systems. The conversion kit allows an existing system to have a relatively high energy use to be converted to a system to the invention that has a relatively low energy use.

In an embodiment according to the invention, the conversion kit further may include a fluid circulation conduit that is connectable to a fluid outlet and a fluid inlet of the reservoir.

The conversion kit according to the invention may be provided with a fluid circulation conduit to provide physically separated recirculation circuits for the fluid flow from the fluid outlet or the reservoir and a fluid flow in the recirculation conduit in which the carriers are recirculated.

The invention also relates to a method for cleaning waste fluid, such as waste water and / or waste air, the method including the steps of:

providing a system for cleaning waste fluid according to the invention;

at least partially filling the reservoir with carriers;

supplying waste fluid to the reservoir, preferably by spraying waste water over the carriers from an upper side of the carriers;

circulating at least part of the carriers;

circulating at least part of the waste fluid independently or carrier circulation; and extracting and discharging cleaned waste fluid from the reservoir.

The method according to the invention provides the same advantages and effects as the system, the carrier and the conversion kit according to the invention as described above. The method according to the invention provides a cleaning process having a relatively low energy use, while still providing an effective and efficient cleaning of waste fluid. This is mainly due to the fact that the circulation of fluid, preferably including waste fluid, is decoupled form the circulation of carrier material. As a result, a more improved control can be exercised over the carriers and the growth of biological material thereon, which allows a more efficient and effective cleaning process. At the same time, the energy use of the system is reduced due to the fact that the carriers are not continuously circulated, thus reducing the energy load of the system. Furthermore, by spraying the water on the carriers rather than submerging the carriers in water, the use of a compressor for feeding (waste) air to the reservoir can be obviated. Instead the use of a fan suffices, which reduces complexity and costs of the system. The advantage of providing a method in which a continuous circulation of fluid, which preferably at least partially comprises waste fluid, is performed is that the circulation increases the contact between the waste (fluid) and the biological material, therewith achieving an improved cleaning.

In an embodiment of the invention, the method further may include dislodging and discharging at least part of the sludge that is formed on the carriers during recirculation of the carriers.

In an embodiment of the method according to the invention, the method may further comprise adapting a carrier recirculation speed and / or a waste fluid circulation speed.

In an embodiment of the method according to the invention, the method may include adapting one of the speeds based on measured parameters in the system, such as pollution grade or sludge growth.

In an embodiment of the method according to the invention, the method may further comprise circulating waste air in the system.

Further advantages, features and details of the invention are elucidated on the basis or preferred otherwise, where reference is made to the accompanying drawings, in which:

figure 1 shows an example of a system according to the invention;

figures 2A - 2F show an example of a carrier discharge unit according to the invention in various stages of operation;

figure 3 shows an example of a sludge removal unit according to the invention; figure 4 shows an example of a modular separation element or a modular separation unit according to the invention;

figures 5A - 5C show an example of a fluid supply device according to the invention in various modes of operation; and figure 6 shows an example of the method according to the invention including several.

System 2 for cleaning waste water and / or waste air (see Figure 1) comprises reservoir 4 that is partially filled with carriers 6. Reservoir 4 comprises fluid inlet 8, which is positioned near upper end 4a or reservoir 4, and fluid outlet 10, which is positioned near lower end 4b or reservoir

4. In this example the fluid outlet 10 is provided in a side wall or reservoir 4 near lower end 4b. In this example, fluid inlet 8 is connected to waste fluid conduit 23 that is configured for providing waste fluid to system 2. Reservoir 4 is also provided with carrier inlet 12 and carrier outlet 14, which are positioned opposite each other on upper end 4a and lower end 4b respectively. Reservoir 4 furthermore includes separation unit 16 that in this example is funnel-shaped and is provided with carrier opening 18 for transporting carriers 6 to carrier outlet 14 or reservoir 4. Separation unit 16 extends substantially horizontally in reservoir 4, forming upper compartment 4c in effect and lower compartment 4d in reservoir 4.

Upper compartment 4c contains carriers 6 through which waste water and / or waste air is LED for cleaning and / or purification. Upper compartment 4c therefore functions as cleaning or purification compartment.

Lower compartment 4d functions as a collector for cleaned or purified water that has been transferred from upper compartment 4c through fluid opening 20 in separation unit 16 to lower compartment 4d. In this example, lower compartment 4d is at least partially funnel-shaped. Fluid outlet 10, which is used to discharge cleaned or purified water, is positioned in a side wall of the funnel. A bottom wall of lower compartment 4d is provided with sludge discharge outlet 22. During operation, water flows through fluid opening 20 in separation unit 16. The water flow may carry along sludge that is sloughed off the carriers 6. The sludge will settle on the bottom or lower compartment 4d, from which it is removed through sludge discharge outlet 22. In this example, lower compartment 4d also includes a fluid recirculation conduit 24 from which water is extracted and resupplied to water supply device 26 or reservoir 4, therewith forming a fluid recirculation circuit that is separate from the carrier recirculation circuit. Furthermore, waste fluid conduit 23 emanates in fluid recirculation conduit 24 and the combined fluid flows are supplied to fluid inlet 8. Fluid recirculation conduit 24 may additionally or alternatively also be connected to an inlet or fluid supply unit 32 for providing a continuous fluid flow to carrier recirculation conduit 30. In that case, waste fluid conduit 23 is preferably connected directly to fluid inlet 8.

Carrier outlet 14 is connected to carrier discharge unit 28, which is configured for providing batches or carriers 6 to carrier recirculation conduit 30 for recirculation or carriers 6 to carrier inlet 12. Fluid supply unit 32 is connected upstream or carrier discharge unit 28 and is configured to provide a flow or waler to carrier discharge unit 28 and carrier recirculation conduit 30. This flow may be continuous or intermittent, for example depending on process parameters.

System 2 in this example further comprises a sludge removal unit 34 (see also figure 3), which is positioned in carrier recirculation conduit 30 upstream or carrier discharge unit 28 and which connects carrier recirculation conduit 30 with carrier inlet 12. During operation, batches of carriers 6 are discharged from reservoir 4 through carrier outlet 14 into carrier recirculation conduit

30. Each batch of carriers 6 is transported by fluid supply unit 32 through carrier recirculation conduit 30 to sludge removal unit 34 in which excess sludge is removed from carriers 6. Carriers 6 are reintroduced in reservoir 4 through carrier inlet 12, while excess sludge dislodged by sludge removal unit 34 has been removed from system 2 through sludge conduit 36 and / or a second sludge conduit 38. Sludge conduit 38 is connected to a rotating sludge remover 40. In this example, the water that is removed from rotating sludge remover 40 forms the fluid supply for fluid supply unit 14. Therewith a carrier recirculation circuit 14, 28, 30, 34, 38, 40 is formed in which fluid for transportation or batches or carriers 6 is circulated. As a result, the number of waste streams from system 2 is kept relatively low. Furthermore, the separation of carrier recycling circuit 14, 28, 30, 34, 38, 40 and waste fluid circulation circuit 24, 8, 16, 4 allows separate control of the flows in those circuits.

Reservoir 4 also comprises a waste air inlet 42, which introduces waste air into reservoir 4 below separation unit 16. The waste air flows upwardly through fluid opening 20 or separation unit 16 and subsequently through the carriers 6 towards upper end 4a or reservoir 4. During the upward movement, the waste air is cleaned and / or purified by biological material on carriers 6. The purified air is discharged through air outlet 44 that is positioned near upper end 4a or reservoir 4. In this example, system 2 also comprises air recirculation conduit 46, which can be used to at least partially recirculate waste air from air outlet 44 to air inlet 42. Furthermore, air recirculation conduit 46 can alternatively also be used to reverse the flow of waste air in reservoir 4 by switching the functions of air inlet 42 and air outlet 44, therewith effectively reversing the flow of waste air in reservoir 4.

In this example fluid inlet 8 is connected to fluid supply device 26, which is used to equally distribute the waste water over the surface of carriers 6 present in reservoir 4.

In an example of the carrier discharge unit 28 according to the invention (as shown in figures 2A - 2F), carrier discharge unit 28 comprises housing 202, which is provided with opening 204 that is connected to carrier outlet 14. Cylindrical drum 206 is mounted in housing 202 and rotatable around axis 208. Cylindrical drum 206 is provided with four groove-formed channels 210 that extend along the length of cylindrical drum 206. The groove-formed channels 210 are equally spaced along a circumference or front end 206a or cylindrical drum 206 such that front end 206a or cylindrical drum 206 is symmetrical with respect to both axis Al and axis A2. Cylindrical drum 206 further comprises inner channels 212 that extends over the length of the cylindrical drum 206. Inner channels 212 are configured for continuous transportation of a flow of water for maintaining pressure in carrier recirculation conduit 30 and, optionally, for the continuous circulation of water in reservoir 4 or a carrier recirculation circuit.

In the example of figure 1, system 2 can be continuously operated, carrier discharge unit 28 discharges a batch or carriers 6 to the carrier recirculation conduit 30 with each rotation or drum 206. Carrier discharge unit 28 may also be provided with a periodic rotation , in which it has a recirculation state and a settling state, which are periodically alternated. In the recirculation state of system 2, carrier discharge unit 28 forms an open connection between carrier outlet 14 and carrier recirculation conduit 30. A batch of carriers 6 is discharged from reservoir 4 through carrier outlet 14 into one of the groove-formed channels 210. Due to the pressure of a water flow from fluid supply unit 32, the batch of carriers 6 is transported from groove-formed channel 210 into carrier recirculation conduit 30 for recirculation.

During operation, cylindrical drum 206 is rotated around its axis for fluid flow from fluid supply unit 14 to flow through groove-formed channels 210, inner channels 212 or a combination of both. As such, a continuous flow or fluid is achieved, while intermittently supplying carriers 6 to the fluid stream. The alternating flow through cylindrical drum 206, as well as the flow during various stages of rotation or drum 206 is shown in figures 2A - 2F.

In an example of a sludge removal unit 334 according to the invention (as shown in figure 3), the unit 334 includes housing 302 having removal unit inlet 304 that is connected to carrier recirculation conduit 330 and removal unit outlet 308 that is connected to carrier inlet 312, first filter 310 is positioned adjacent removal unit inlet 304 and comprises a plate-like structure having fluid opening for separating fluid and carriers 306. First filter 310 preferably is placed under a downward angle for transporting carriers 306 towards adjacent accelerator 314 that is configured to accelerate carriers 306 towards second filter 316. Water as well as sludge that is dislodged from carriers 306 on first filter 310 are removed from the system through fluid discharge conduit 338. Fluid discharge conduit 338 can optionally be connected with a rotating sludge separator to separate any sludge in the water / sludge mixture that is discharged from fluid discharge conduit 338.

Second filter 316 comprises a structure having sludge discharge opening 318, carriers 306 are connecting to second filter 316 with a predetermined speed and / or force for dislodging sludge from carriers 306. Second filter 316 is preferably positioned under a downward angle towards carrier inlet 312 , such carriers 306 are automatically transported to carrier inlet 312 after connecting to dislodging sludge in second filter 316. The sludge that is dislodged from carriers 306 has been removed from the system through sludge discharge conduit 336.

An example of a part of modular separation unit 416 (see figure 4) comprises a pie-shaped separation element 400 that is connectable to similar separation elements for forming separation unit 416. Separation unit 416 that is formed out of a number of separation elements 400 is essentially funnel shaped and is provided with a central opening 404 (not shown) for discharging carriers 6 from a reservoir 4 to which separation unit 416 is connected.

Separation element 400 comprises upper plate 402 that is provided with a various or fluid opening 420 and carrier opening 404 (not shown). Carrier opening 404 is, in use of the system, connected to carrier outlet 14 such that carriers 6 can be discharged, in batches, through carrier opening 404 towards carrier outlet 14 or reservoir 4 (not shown). Waste fluid supplied to the reservoir from an upper end to trickles down between carriers 6 and subsequently passing through fluid opening 420 onto lower plate 410. Lower plate 410 extends substantially parallel and at a distance to upper plate 402 and comprises a fluid opening 412 (not shown). Fluid opening 412 opens up to lower compartment 4d or reservoir 4, in which the fluid is discharged (see figure 1). Lower plate 410 further includes air inlet opening 414, which in this example is provided near the middle of lower plate 410. Waste air can be introduced through air inlet opening 414 in the inner space 408 that is delineated by upper plate 402 and lower plate 410 In this example, the air inlet opening 414 is partially protected by deviation wall 416, which is configured to prevent cleaned fluid on the lower plate from flowing into air inlet opening 414.

An example of a fluid supply device according to the invention is shown in figures 5A 5C. In this example, fluid supply device 526 comprises three fluid supply groups 502a, 502b, 502c. Each fluid supply group 502a, 502b, 502c includes a number of radially outwardly extending branches 504 that vote from a single connection point 506. Connection point 506 in this example is a fixed connection point. However, fluid supply device 526 may be configured to be rotatable around single connection point 506. Each branch 504 includes a fluid or fluid outflow opening (not shown) for supplying fluid to reservoir 4. Additional, each fluid supply group 502a, 502b, 502c is provided with a regulation element 508a, 508b, 508c for regulation the flow of waler from fluid inlet 8 (figure 1) to a corresponding fluid supply group 502a, 502b, 502c. In this example, each regulation element 508a, 508b, 508c is a valve that is directly connected to fluid inlet 8, preferably a valve allowing remote control, that is used to control the flow of waste water to the respective fluid supply group 502a, 502b , 502c. Each of the figures 5A - 5C show a single one of the fluid supply groups 502a, 502b, 502c providing waste water to carriers 6 or reservoir 4.

Referring to figure 1, it is noted that during operation, waste waster is supplied through conduit 24 to fluid inlet 8 at a speed SI and is provided to fluid supply device 26 for supplying it over at least part of the upper surface of carriers 6 Waste water that is supplied over carriers 6 in reservoir 4 slowly trickles down with a speed S2 between carriers 6 towards separation unit 16. During the downward movement, pollution is filtered from the waste water by biological material on carriers 6. The cleaned water flows through opening 18 in separation unit 16 and is received in lower part 4d or reservoir 4, which is funnel-shaped. During storage in lower part 4d any remaining sludge settles on the bottom and is subsequently removed through conduit 22. Clean water is extracted through conduit 10 at a speed S3, whereas part of the water is recirculated through conduit 24. The supply speed SI can be adapted in relation to the speed S2 with which the waste water trickles down in reservoir 4. Furthermore, during operation batches or carriers 6 are guided through carrier outlet 14 or reservoir 4 towards carrier discharge unit 28.

Fluid supply unit 32 provides a flow of fluid, preferably water, at a speed S3 and a pressure Pl, which transports discharged carriers 6 through carrier recirculation conduit 30 to sludge removal unit 34. The speed S3 and the speed of discharging carriers 6 by carrier discharge unit 28 determine the recirculation speed of carriers in system 2. In sludge removal unit 34, first filter 310 is used to separate fluid and carriers 6 from each other. The separated fluid stream is discharged through fluid removal conduit 38 to rotating sludge remover 40, in which any (heavy) sludge is removed from the fluid stream. The fluid stream is delivered to fluid supply unit 32 for recirculation. Carriers 6, which are separated in sludge removal unit 34 are launched and / or accelerated towards second filter 316 by accelerator 314 and collide with a certain speed to second filter 316. As a result, sludge is dislodged from carriers 6, after which the relatively dry sludge is discharged from system 2 through sludge removal conduit 36. Carriers 6 are recirculated by supplying them to reservoir 4 through carrier inlet 12, which in this example is executed by means of gravity. Waste air is provided to system 2 through air inlet 42 into separation unit 16. The air flow flows upward through opening 18 into separation unit 16 into upper part 4c or reservoir 4. In upper part 4c it flows upward between carriers 6 towards air outlet 44 which is positioned near upper end 4a or reservoir 4. During the upward movement, pollution is removed from the waste air stream by biological material on carriers 6, such that air outlet 44 is provided with clean air. Alternatively, part of the cleaned air from air outlet 44 may be recirculated in an air recirculation conduit 46 to air inlet 42, which allows more intensive cleaning of the waste air stream.

The invention also relates to a method for cleaning a fluid, such as waste water and / or waste air. An example of the method steps according to the invention are shown in figure 6. The method comprises providing 1002 a system for cleaning a fluid according to the invention. Reservoir 4 or system 2 requires partially filling 1004 reservoir 4 with carriers 6 to provide a bed for filtering waste water and / or waste air. Subsequently, the method includes supplying 1006 waste fluid to reservoir 4. Optionally, method step 1006 comprises selecting one or more groups of fluid supply device 46 for selectively spraying 1006a waste water over carriers 6. Furthermore, alternatively or additionally, the method includes supplying 1008 waste air to reservoir 4 from waste air inlet 42.

Substantially, the method includes the step of periodically circulating 1010 at least part of the carriers, and the step of extracting and discharging 1012 cleaned waste fluid from reservoir 4 for removal of system 2. This step may include the additional step of reintroducing 1012A at least part of the waste fluid in reservoir 4 for additional cleaning. The method may in this respect also include additional step of measuring 1012B the cleaned fluid and, based on the measurement results, reintroducing and / or discharging 1012C cleaned from system 2.

In this example, the method also includes the step of circulating 1014 the fluid and carriers through carrier recirculation conduit 30 and reservoir 4. Furthermore, this example also includes dislodging and discharging 1016 at least part of the sludge that is formed on the carriers during the recirculation of carriers.

The method according to this example therewith provides a number of optional steps that are specifically designed to enhance the control options with regard to system 2 for achieving an 5 energy efficient and effective purification system.

The present invention is by no means limited to the above described preferred expend. The rights sought are defined by the following clauses within the scope of which many modifications can be envisaged.

Claims (22)

CLAUSES 1. System for cleaning a fluid, such as waste water and / or waste air, including: - a reservoir that is at least partially fillable with carriers, the reservoir including: - a fluid inlet and a fluid outlet; - a carrier inlet and a carrier outlet; and - a separation unit that is positioned in the reservoir between the fluid inlet and the fluid outlet and that is configured for supporting carriers, the separation unit comprises a carrier guiding opening that is operatively connected to the carrier outlet or the reservoir and the separation unit comprises a variety of fluid opening configured for passage of fluid, containing the fluid opening are operatively connected with the fluid outlet; - a carrier recirculation conduit connecting the carrier outlet and the carrier inlet or the reservoir, the carrier recirculation conduit is operatively connected to a fluid supply unit; and - a carrier discharge unit that is positioned in the carrier recirculation conduit, the carrier discharge unit comprising a carrier discharge unit that is connected to the carrier outlet and a carrier discharge unit outlet that is connected to the carrier recirculation conduit; in the fluid discharge outlet unit is configured to selectively provide carriers in a fluid stream from the fluid supply unit, 2. System according to clause 1, including a sludge removal unit that is configured for removing and discharging at least part of the sludge from the carriers, the sludge removal unit having a removal unit inlet that is connected to the carrier recirculation conduit, a removal unit outlet that is connected to the carrier inlet or the reservoir and a sludge discharge conduit. 3. System according to clause 2, where the sludge removal unit comprises a fluid discharge conduit. 4. System according to clause 3, including the sludge removal unit comprising: - a first filter that is configured for separating fluid from carriers, where a first filter outlet is connected to the fluid discharge conduit; and - a second filter that is configured for at least partially removing sludge from the carriers, the carriers are brought in contact with the second filter with a predetermined force for dislodging sludge from the carriers, and a second filter outlet is connected to the sludge discharge conduit. 5. System according to clause any one of the preceding clauses, the fluid outlet or the reservoir is connected to an inlet or the fluid supply unit. 6. System according to any of the clauses 1-4, comprising the system comprises a fluid recirculation conduit that extends between the fluid outlet and the fluid inlet of the reservoir, additionally comprises a clean fluid outlet for discharging cleaned fluid from the system. 7. System according to any one of the clauses 1-4, when dependent on clause 3, where the fluid discharge conduit is connected to an inlet or the fluid supply unit. 8. System according to clause 7, where the system comprises a rotating sludge separator having an inlet that is connected to the fluid discharge conduit and an outlet that is connected to the fluid supply unit. 9. System according to any of the previous clauses, including the separation unit comprising: - an upper plate including the multiple of fluid opening and a carrier guiding opening that is operatively connected to the carrier outlet of the reservoir; and - a lower plate that extends substantially parallel and at a distance to the upper plate, the lower plate including a fluid opening that is operatively connected to the fluid outlet for discharging fluid. 10. System according to clause 9, the upper and lower plate delineate an inner space, the inner space is provided with an air inflow opening for supplying air through the fluid opening in the upper plate. 11. System according to any one of the preceding clauses, the separation unit is a modular unit in that the separation unit comprises a number of, preferably pie-shaped, separation elements that are connectable to each other for forming a substantially funnel-shaped separation unit having a central opening for discharging carriers from the upper compartment. 12. System according to any one of the preceding clauses, comprising the system comprises a fluid supply device that is positioned in the reservoir and that is operatively connected to the waste fluid inlet for supplying waste water to the carriers. 13. System according to clause 12, the fluid supply device comprises fluid supply groups, each fluid supply group includes a number of radially outwardly extending branches, each branch includes a multiple of fluid outflow opening for supplying fluid to the reservoir, each fluid supply group is provided with a regulation element, such as a valve, for regulating the flow of water from the fluid inlet to said fluid supply group. 14. System according to any one of the preceding clauses, comprising the system comprises air supply means for supplying air to the reservoir. 15. System according to any one of the preceding clauses, comprising the carrier discharge unit comprising: - a housing in which the carrier discharge unit inlet and the carrier discharge unit outlet are positioned; - an elongated cylindrical drum that is rotatably mounted in the housing and that is rotatable around a longitudinal drum axis, the drum including: - at least one recess that extends substantially parallel to the longitudinal drum axis in a drum outer surface over substantially an entire length of the drum, the recess being configured for receiving a batch of carriers from the carrier outlet; - at least one central fluid channel that extends substantially parallel to the longitudinal drum axis from a first channel opening to a second channel over the entire length of the drum, the central channel being configured for transporting fluid. 16. Carrier for a system for cleaning waste fluid, preferably for a system for cleaning waste fluid according to any of the previous clauses, where the carrier comprises an elongated cylindrical structure delineating an inner space, the inner space is provided with an elongated star-like insert that is integrally formed in the cylindrical structure, and having a height of the cylinder and a diameter of the cylinder having substantially equal dimensions. 17. Conversion kit for converting a reservoir, such as a water tank, into a system for cleaning waste fluid according to any one of the clauses 1-15, including the conversion kit: - a separation unit, preferably a modular separation unit, that is placeable in an existing reservoir and that is dimensioned to be contiguous with a reservoir wall for forming an upper and a lower compartment; - a predetermined amount of carriers that has been added to the reservoir; and - a carrier discharge unit that is connectable to an outlet of the reservoir for discharging carriers from the reservoir; - a recirculation conduit that is connectable to an inlet or the reservoir and the outlet or the carrier discharge unit; - a sludge removal unit that is connectable to or placeable in the recirculation unit; and - a fluid supply unit that is operatively connectable to the carrier discharge unit and the recirculation conduit and that is preferably connected to a fluid outlet or the reservoir or a fluid discharge outlet or the sludge removal unit. 18. Conversion kit according to clause 17, further including a fluid circulation conduit that is connectable to a fluid outlet and a fluid inlet of the reservoir. 19. Method for cleaning a fluid, such as waste water and / or waste air, the method including the steps of: - providing a system for cleaning a fluid according to any one of the clauses 1-15; - at least partially filling the reservoir with carriers; - supplying waste fluid to the reservoir, preferably by spraying waste water over the carriers from an upper side of the carriers; - circulating at least part of the carriers; - circulating at least part of the waste fluid independently or carrier recirculation; and - extracting and discharging cleaned waste fluid from the reservoir. 20. Method according to clause 19, the method further including dislodging and discharging at least part of the sludge that is formed on the carriers during recirculation of carriers. 21. Method according to clause 19 or 20, further including adapting a carrier recirculation speed and / or a waste fluid circulation speed. 22. Method according to clause 21, where adapting one of the speeds is based on measured parameters in the system, such as pollution grade or sludge growth. CONCLUSIONS Device for cleaning a fluid, such as waste water and / or waste air, comprising: - a reservoir that is at least partially fillable with carriers, the reservoir comprising: - a fluid inlet and a fluid outlet; - a carrier inlet and a carrier outlet; - a separation device which is positioned in the reservoir between the liquid inlet and the liquid outlet and which is adapted to support the carriers, wherein the separation device comprises a carrier guide opening which is operatively connected to the carrier outlet of the reservoir and wherein the separation device comprises a plurality of fluid openings comprises those arranged for passage of a fluid, the fluid openings being operatively connected to the fluid outlet; - a carrier recirculation conduit connecting the carrier outlet and the carrier inlet of the reservoir, the carrier recirculation conduit being operatively connected to a liquid supply device; and - a carrier discharge device positioned in the carrier recirculation conduit, the carrier discharge device comprising a carrier discharge device inlet connected to the carrier outlet of the reservoir and a carrier discharge device outlet connected to the carrier recirculation conduit ; wherein the liquid supply device is positioned upstream of the carrier discharge device, wherein the carrier discharge device outlet is adapted to selectively provide carriers to a liquid flow from the liquid supply device, such that the liquid flow and carrier flow can be controlled independently of each other. Device as claimed in claim 1, comprising a sludge removal device which is arranged for removing and discharging at least a part of the sludge from the carriers, wherein the sludge removal device is provided with a removal device inlet connected to the carrier recirculation line, a removal device- outlet connected to the carrier inlet of the reservoir and a sludge discharge conduit. Device according to claim 2, wherein the sludge removal device comprises a liquid discharge line. Device according to claim 3, the sludge removal device comprising: - a first filter adapted to separate liquid from carriers, wherein a first filter outlet is connected to the liquid discharge conduit; and - a second filter adapted to at least partially remove sludge from the carriers, wherein the carriers are brought into contact with the second filter with a predetermined force for loosening sludge from the carriers, and wherein a second filter outlet is connected to the sludge discharge line. Device as claimed in any of the foregoing claims, wherein the liquid outlet of the reservoir is connected to an inlet of the liquid supply device. The device of any one of claims 1 to 4, wherein the device comprises a liquid recirculation line extending between the liquid outlet and the liquid inlet of the reservoir, the reservoir further comprising a cleaned liquid outlet for discharging cleaned liquid from the device . Device as claimed in any of the claims 1-4, when dependent on claim 3, wherein the liquid discharge line is connected to an inlet of the liquid supply device. Device as claimed in claim 7, wherein the device comprises a rotary sludge remover which is provided with an inlet which is connected to the liquid discharge line and an outlet which is connected to the liquid supply device. Device as claimed in any of the foregoing claims, the separating device comprising: - a top plate comprising the fluid openings and a carrier guide opening which is operatively connected to the carrier outlet of the reservoir; and - a bottom plate extending substantially parallel and at a distance from the top plate, the bottom plate comprising a fluid opening operatively connected to the fluid outlet for draining fluid. Device as claimed in claim 9, wherein the top plate and the bottom plate define an inner space, wherein the inner space is provided with an air inlet opening for supplying air through the fluid openings in the top plate. Device as claimed in any of the foregoing claims, wherein the separating device is a modular separating device, which comprises a number of, preferably pie-shaped, separating elements which can be connected to each other for forming a substantially funnel-shaped separating device provided with a central opening for draining off carriers of the upper compartment. 12. Device as claimed in any of the foregoing claims, wherein the device comprises a liquid supply device which is positioned in the reservoir and which is operatively connected to the waste water inlet for supplying waste water to the carriers. The apparatus of claim 12, wherein the fluid supply device comprises fluid supply groups, each fluid supply group including a plurality of radially outwardly extending branches, each branch containing a plurality of fluid outflow openings for supplying fluid to the reservoir, each fluid supply group having a control element , such as a control valve, for controlling the flow of water from the liquid inlet to the relevant liquid supply group. Device as claimed in any of the foregoing claims, wherein the device comprises air supply means for supplying air to the reservoir. Device as claimed in any of the foregoing claims, the carrier discharge device comprising: - a housing in which the carrier discharge device inlet and the carrier discharge device outlet are included; - an elongated cylindrical drum which is rotatably mounted in the housing and which is rotatable about a drum longitudinal axis, the drum comprising: - at least one notch extending substantially parallel to the drum longitudinal axis in a drum outer surface over substantially the entire length of the drum, the notch being arranged to receive a batch of carriers from the carrier outlet; - at least one central fluid channel that extends substantially parallel to the drum longitudinal axis from a first channel opening to a second channel opening over the entire length of the drum, the central channel being adapted to transport liquid. A carrier for a waste fluid cleaning device, preferably a waste fluid cleaning device according to any one of the preceding claims, wherein the carrier comprises an elongated cylindrical structure defining an inner space, the inner space being provided with an elongate star-shaped insert integrally formed in the cylindrical structure, and wherein the height of the cylinder and a diameter of the cylinder have substantially the same dimensions. 17. Conversion kit for converting a reservoir, such as a water tank, to a device for cleaning waste fluid according to one of claims 1-15, the conversion kit comprising: - a separation device, preferably a modular separation device, which can be placed in an existing reservoir and which is dimensioned to be in contact with a reservoir wall for forming an upper and a lower compartment; - a predetermined amount of carriers that is added to the reservoir; and - a carrier discharge device which is connectable to an outlet of the reservoir for discharging carriers from the reservoir; - a carrier recirculation conduit connectable to an inlet of the reservoir and an outlet of the carrier discharge device; - a sludge removal device which can be connected to or placed in the carrier recirculation line; and - a liquid supply device which is operably connectable to the carrier discharge device and the carrier recirculation line and which is preferably connectable to a liquid outlet of the reservoir or a liquid discharge line of the sludge removal device. The conversion kit of claim 17, further comprising a fluid recirculation conduit connectable to a fluid outlet and a fluid inlet of the reservoir. A method for cleaning a fluid, such as waste water and / or waste air, the method comprising: - providing a device for cleaning a fluid according to any one of claims 1-15; - at least partially filling the reservoir with carriers; - supplying waste fluid to the reservoir, preferably spraying waste water from the top over the carriers; - circulating at least a part of the carriers; - circulating at least a part of the waste fluid independently of the carrier recirculation; - the removal and removal of cleaned waste fluid from the reservoir. The method of claim 19, the method further comprising loosening and removing at least a portion of the sludge formed on the carriers during the recycling of the carriers. 21. A method according to claim 19 or 20, further comprising adjusting a carrier recirculation speed and / or a waste fluid recirculation speed. A method according to claim 21, wherein adjusting one of the speeds is based on measured parameters in the device, such as the degree of contamination or sludge growth. 3/7 5/7 o> o> ΊΠ L J