Patent Description:
Marine pollution is a significant problem for the health of the ocean, and a hazard to marine life. Each year, over eight million tonnes of plastics enter the ocean, and over <NUM> species are known to have ingested or been entangled in plastic waste in the ocean (EIA, <NUM>).

The problem of marine pollution is significantly widespread and pervasive such that tackling it is difficult. A technological solution must be sufficiently scalable to make a noticeable difference to the problem, and a high cost is typically associated with producing and maintaining systems of the required scale.

Areas with high concentrations of waste are also home to large plankton populations. Conventional filtration and removal (e.g. removal with a sufficiently fine net) can lead to an increased mortality of the plankton, which would in turn affect other marine species in that area.

The present invention seeks to address or at least ameliorate the above mentioned problems.

<CIT> discloses a strainer in which water entraining solid matter flows into an element through an inflow pipe. The water is then sucked into a submersible pump through the water hole of the element and an outflow pipe. Solid matter in the river water is collected by the element, and striped off by a cleaning member rotating along with a rotary vane simultaneously with the inflow of river water. The solid matter existing in the vicinity of a discharge pipe is sucked along with water into a suction part kept at a pressure lower than the pressure in the strainer, and discharged to the outside from the diffuser part of the ejector.

<CIT> discloses a strainer comprising a pump and a motor. When the pump is started, solid matter having comparatively large particle diameter contained in raw water is trapped with a guard and is introduced into an element via an aperture in the guard and an inflow port and the water is passed through the water-passing holes of the elements and made into clean water. The clean water is sucked into a pump via an outflow port. Meanwhile, the solid from the raw water is trapped in the element, but is peeled off with brushes of a sweeping member. The filter face of the element is scoured with the brushes. The trapped and peeled solid matter and the other solid matter are transferred using screw blades and is discharged outside of the element through a discharge port.

According to a first aspect of the invention, there is provided a system for reducing marine pollution in accordance with claim <NUM>. Some optional or preferable features are set out in dependent claims. The housing may be elongate. The housing may define a longitudinal direction. The housing may be cylindrical and/or substantially hollow.

The or each pollutant filter unit may comprise a first element e.g. a static element configured to inhibit output of pollutants from the housing and/or to entrap pollutants in the fluid flowing therethrough.

The housing may comprise one or more walls or sidewalls The housing may comprise a filtration chamber (e.g. an interior chamber of the housing) configured to receive the incoming fluid flow containing pollutants and output the de-polluted fluid flow. A hollow interior of the housing may define the filtration chamber. The filtration chamber may comprise one or more chamber walls or sidewalls The chamber wall(s) may be or comprise an inner wall of the housing. The chamber may be substantially cylindrical.

The dynamic or second element may be moveable (e.g. rotatable) with respect to the static or first element. The second element may be rotatable with respect to the first element. Alternatively, the second element may reciprocate with respect to the first element.

The second element may be or comprise a substantially dynamic element. The second element may further be moveable (e.g. rotatable) with respect to the housing. The first element may be or comprise a substantially static element, e.g. a static filter element, and may be static with respect to the housing. Alternatively, the first element may be or comprise a substantially dynamic element, e.g. the first element may be moveable (e.g. rotatable) with respect to the housing.

The or each pollutant filter unit may be arranged or disposed within the housing, e.g. within the hollow space of the housing and/or with the filtration chamber.

The housing may comprise an inlet through which the incoming fluid flow may enter the housing. The housing may further comprise an outlet through which fluid may exit the housing. The pollutant filter unit(s) may be positioned downstream of the inlet and upstream of the outlet.

The housing may comprise a fluid flow path between the inlet and the outlet. The inlet, the filtration chamber and the outlet may define the fluid flow path. The pollutant filter unit(s) may be disposed in the flow path, such that fluid passes through the pollutant.

The pollutant filter unit(s), in use, act to collect pollutants from a water environment such as the sea, which can then be disposed of or otherwise dealt with. The pollutant filter unit(s) may be configured to collect the pollutants and transport and/or direct the collected pollutants towards an outer edge or radius of the pollutant filter unit(s), where they can be further collected, transported away and/or removed from the housing. The filter unit(s) are preferably disposed substantially perpendicular to the flow of fluid and/or the longitudinal direction of the housing. Alternatively, the filter units may be disposed at an angle with respect to the longitudinal direction. Optionally, this angle may be between substantially <NUM> and <NUM> degrees to the longitudinal direction. Optionally, the angle may be between substantially <NUM> and <NUM> degrees to the longitudinal direction. Optionally, the angle may be approximately <NUM> degrees to the longitudinal direction.

Advantageously, aspects or embodiments of the invention provide for extracting marine and fluvial plastic pollution through integrated, commensal technologies. Aspects or embodiments of the invention provide a scalable solution to marine plastic pollution. Aspects or embodiments of the invention provide a self-sustaining and selfcleaning system adaptable to both dynamic and static mountings. For example, if the system has a processing area of about <NUM><NUM>, it can remove up to <NUM> tonnes per year.

Advantageously, the system can run on or be powered by the flow of fluid through the housing, e.g. by tidal/wave power. The system can be attached or attachable to a ship or marine vessel. The system may be removably attachable to a ship or marine vessel. The system therefore can make use of existing infrastructure and tidal power and/or ship-powered movement through the ocean. Alternatively, the system can be powered by a power source, such as a power source (e.g. a generator, engine and/or motor) on a marine vessel or structure.

The housing may comprise a front end, a rear end, and/or one or more sides between the front and rear ends. The inlet may be or comprise an opening at or near the front end of the housing. The front end may be or comprise the inlet. The outlet may be or comprise an opening at or near the rear end of the housing. The rear end may be or comprise the outlet. The front end/inlet and the rear end/outlet may be in fluid communication.

The hollow space of the housing may further define a fluid passage extending between the front end and the rear end in the longitudinal direction (e.g. substantially parallel to the fluid flow).

In one arrangement, the fluid path through the housing and/or filtration chamber may be substantially straight. For example, the outlet may be aligned substantially co-axially with the inlet.

The system further comprises at least one turbine configured to drive the second or dynamic element.

The turbine may be configured to be actuated by fluid flowing into the housing and/or filtration chamber. Additionally/alternatively, an additional power supply may be provided to the system to power and drive the turbine, such as for use in non-tidal areas and/or at times of low wave activity (e.g. in low fluid flow conditions). In this way, the turbines may be driven by the fluid flow, or driven by a power source to create a fluid flow through the system (e.g. by sucking or drawing fluid through the housing).

The system may further comprise a driveshaft configured to move the dynamic filter element and/or the cleaning member(s). The driveshaft may define a driveshaft axis. Rotation of the driveshaft about the driveshaft axis may drive movement of the dynamic filter element and/or the cleaning member(s). The dynamic filter element and/or the cleaning member(s) may be coupled directly or indirectly (e.g. via one or more intermediate connections, linkages or couplings) to the driveshaft. The dynamic filter element and/or the cleaning member(s) may be configured to rotate with or about the driveshaft. The driveshaft may be substantially aligned with the longitudinal axis of the filtration chamber/housing and extend at least partially into the filtration chamber.

The driveshaft may be driven by a drive system, such as a motor, connectable to a power supply. The power source may be external to the system. The system may comprise the drive system or the drive system may be located remotely from the system.

The driveshaft may couple the at least one turbine and/or the one or more dynamic elements.

The dynamic element(s) may be fixedly coupled or attached to the driveshaft (but moveable with respect to the housing and/or driveshaft). The static element(s), by contrast, may be fixed with respect to the housing. Variations in configuration are envisaged; the important point is that there is relative movement between the first and second elements.

The filter units, in use, may act to collect pollutants from a water environment such as the sea, which can then be disposed of or otherwise dealt with. The filter unit(s) may be configured to collect the pollutants and transport and/or direct the collected pollutants towards an outer (radial) edge or radius of the filter unit(s), where they can be further collected, transported away and/or removed from the housing.

Each of the one or more static elements may be or comprise a filter element or membrane. The filter element or membrane may be configured to collect or trap particles in the fluid at or above a predetermined threshold size, whilst permitting flow of fluid and particle below the threshold size through the membrane. The filter membrane may comprise a plurality of pores or apertures and the threshold size may be determined by the pore size. The pore size of the filter membrane may be in the range substantially <NUM> to <NUM>.

The filter membrane may be or comprise a net, e.g. a fabric net, or a mesh e.g. a metal mesh or other configuration that enables materials of a certain size to pass through but not others. A metal mesh would be suitable for "trapping" larger particles, whereas a fabric net is more suitable for smaller particle sizes (e.g. less than <NUM> in diameter). As such, the system may be modified according to the desired particle sizes to be "trapped". A system may include both types of membrane, with a filter membrane comprising a fabric net being placed downstream of a filter membrane comprising a metal mesh. The dynamic and static elements are preferably positioned adjacent to or in the vicinity of one another. This ensures that pollutants "caught" or "trapped" by the filter membrane (i.e. prevented from following the fluid flow through the housing) can then be directed for removal by the one or more cleaning arm(s).

The static filter element may extend at least partially across the outlet of the housing and/or filtration chamber.

The filter membrane may be disposed substantially perpendicular to the flow of fluid (e.g. through the filter membrane) and/or the longitudinal direction of the housing. For example, a surface of the filter member may be arranged substantially perpendicular to the direction of fluid flow through the filter membrane. However, this perpendicular arrangement is not essential. Alternatively, the filter membrane or surface of the filter membrane may be disposed/arranged at a non-perpendicular angle with respect to the direction of fluid flow through the filter membrane. The key point is that the filter membrane presents a substantial cross-sectional area through which the fluid may flow.

Where the filter membrane is disposed or arranged at a non-perpendicular angle with respect to the direction of fluid flow therethrough, the angle may be less than <NUM> degrees from the direction of fluid flow therethrough. The angle may be in the range between substantially <NUM> degrees to <NUM> degrees. The optimum angle of the filter membrane to the flow direction therethrough may be a balance between using the angle to aid pollutant material transport to an outer edge or radius of the static filter element without impeding fluid flow through the static filter element.

The filter membrane may be or comprise a substantially planar element and/or planar filter surface. For example, filter membrane may be or comprise a planar sheet extending across the filtration chamber (i.e. between opposing housing/chamber sidewalls) and/or the outlet.

Alternatively, the filter membrane may be or comprise a substantially non-planar or curved element and/or filter surface. For example, the filter membrane may be or comprise a substantially conical element or a portion of a cone, e.g. where the axis of the cone is aligned substantially parallel to the direction of fluid flow through the filter membrane and/or the longitudinal axis of the housing. The tip of the cone may point towards the front end of the housing.

The angle of the filter membrane to the fluid flow therethrough or the cone angle (with respect to the cone axis) may be in the range between substantially <NUM> degrees to <NUM> degrees. Optionally, the angle may be between substantially <NUM> and <NUM> degrees. Optionally, the angle may be approximately <NUM> degrees.

Each of the one or more dynamic elements may be or comprise one or more cleaning arms or cleaning elements/members.

The cleaning element(s)/member(s) or arm(s) may be configured to rotate with or about the driveshaft to sweep or otherwise direct or transport the pollutants collected/trapped by the filter membrane for removal from the housing. For example, the cleaning arm(s) may be configured to sweep or otherwise direct or transport the pollutants collected/trapped by the filter membrane towards an outer (radial) edge or radius of the filter unit(s), where they can be further collected, transported away and/or removed from the housing. Each cleaning arm/member/element may comprise at least one of more of a brush; scraping blade; and/or a vortex generator. Additionally or alternatively, each cleaning arm may comprise any mechanism sufficient to direct the "trapped" pollutant for removal. Each cleaning arm may be straight, angled or curved. The or each cleaning member may be or comprise a helical or spiral member.

The cleaning arm(s)/member(s) may be disposed adjacent to the static filter element. The cleaning member(s) may be configured to move across a surface of the static filter element to direct the pollutants entrapped thereon towards the one or more pollutant outlets (e.g. by sweeping or otherwise transporting the pollutants). Where there is more than one cleaning member, each cleaning member may be coupling directly or indirectly to each other, such that the cleaning members move together.

The dynamic filter element and/or cleaning arm(s)/member(s) may be configured to direct or move the pollutants entrapped by the static filter element or filter membrane in one or more directions across or along the surface of the static filter element or filter membrane. The one or more directions may depend on the form of the static filter element and the cleaning member(s).

Where the filter membrane is disposed substantially perpendicular to the direction of fluid flow therethrough, the dynamic filter element and/or cleaning member(s) may direct the pollutants across the surface of the static filter element in one or more directions substantially perpendicular to the direction of the flow path through the static filter element or filter membrane.

Alternatively, where the filter membrane is disposed substantially non-perpendicular to the direction of fluid flow therethrough, the one or more directions may be at an angle between substantially <NUM> degrees to <NUM> degrees from the direction of fluid flow through the static filter element or filter membrane.

The housing may be configured such that the direction of fluid flow through the static filter element is substantially parallel to the longitudinal axis and/or to the driveshaft axis. For example, the static filter element may extend at least partially between opposing sidewalls of the housing/filtration chamber and the outlet may be positioned behind the pollutant filter unit (i.e. towards the rear end of the housing). In this arrangement, the static filter element or filter membrane surface may be arranged axially with respect to the dynamic filter element and/or cleaning member(s) (e.g. along the longitudinal axis or rotation axis of the dynamic filter element). In this arrangement, the dynamic filter element and/or cleaning arm(s)/member(s) may be configured to direct the pollutants entrapped by the static filter element in a direction substantially perpendicular to the driveshaft or longitudinal axis, or at an angle between substantially <NUM> degrees to <NUM> degrees from the driveshaft axis.

The system may further comprise a deflector element coupled to an end or the 'front' end of the housing for preventing large objects entering the system. Prevention of large objects entering the system can avoid or ensure that the system is not jammed by large pollutants, and can reduce the amount of marine life that can enter (and so potentially be affected by) the system.

The housing and/or the filtration chamber may further comprise one or more apertures or pollutant outlets configured to receive collected pollutants directed by the dynamic element. The or each aperture or pollutant outlet may be disposed at, in or near a wall of the housing and/or filtration chamber and adjacent to the dynamic filter element.

The deflector element may be configured to inhibit objects larger than a width of the apertures/pollutant outlets from entering the housing and/or filtration chamber.

A series of apertures or pollutant outlets may be arranged around the housing and/or filtration chamber, such as on/in the housing/chamber wall. In an embodiment, the apertures are aligned linearly or radially with the dynamic element (i.e. along a direction substantially perpendicular to the direction of fluid flow). The apertures may be configured to receive the pollutants directed by the dynamic elements for removal from the housing.

In use, the dynamic filter element may move with respect to the static filter element to direct pollutants entrapped by the static filter elements towards the one or more apertures or pollutant outlets.

The or each pollutant outlet may be or comprise a valve. The aperture(s) may be no-return valves, which will prevent the pollutants re-entering the system. Any valve of suitable robustness and simplicity could be used. For example, the or each no-return valve may be a ball check valve. Alternatively, the or each no-return valve may be a back water valve. Further alternatively, the series of apertures may comprise a combination of ball check and backwater valves. In the case where the dynamic element comprises cleaning arms/members, rotation of the cleaning arms/members may direct pollutants to the extreme radius of the (inner wall of the) housing or to an edge or outer radius of the filter unit, where the pollutants will exit through the series of apertures/no-return valves. The pollutants may be transported to the cavity or an external storage via one or more pipes.

The or each valve may be configured to actuate in response to rotation of the driveshaft and/or the dynamic filter element. The or each valve may be configured to actuate in synchronization with the movement of the dynamic filter element, and optionally or preferably, when the or a cleaning arm of the dynamic filter element is aligned with a respective valve. In this way, the driveshaft is used to actuate the valve(s) proceeding the passage of the/a cleaning arm/member past the respective valve, such that the valve actuation is synchronized with the driveshaft rotation.

Advantageously, this reduces the duty cycle of the valves (i.e. they not always open) and the number of valves that are open at any one time, which may reduce the amount of "escape flow" through the valve(s). This in turn may increase the amount of water directed through the static filter element and thus increase the efficiency of pollutant extraction from the water flow. For example, for a system with n valves and x cleaning arms (where n > x), with a synchronized valve actuation arrangement (as described above) only x valves are open at any one time. If all n valves were permanently open, the escape flow through the valves would be a factor n/x times greater than when using the synchronized valve actuation arrangement, and therefore a factor of x/n less efficient than when using the synchronized valve actuation arrangement.

The system may further comprise a valve actuator assembly disposed within the housing configured to actuate the valves in response to rotation of the driveshaft and/or the dynamic filter element. The valve actuator assembly may be part of the housing, pollution filter unit or the dynamic filter element.

The actuator assembly may comprise an actuator arm coupled at one to a respective valve, and a cam coupled to the driveshaft, wherein the actuator arm is actuated by a cam or profiled surface of a cam. The cam surface may be an axial surface or a radial surface of the cam. The actuator arm may be arranged to receive an actuating force from the cam surface to actuate the respective valve. The actuator arm may be or comprises a cam follower configured to run along the cam surface to actuate the respective valve.

The actuator assembly may further comprise a plate member disposed within the filtration chamber adjacent to the dynamic filter element. The plate member may form at least a part of a chamber wall comprising the or each valve. The or each actuating member may be coupled to the plate member. The or each actuating member may be pivotably coupled to the plate member. The actuating member may be configured to pivot or otherwise move when an actuating force is received by the cam surface thereby actuating the valve. For example, the cam or profiled surface may comprise one or more raised portions or projections that rotate with the cam and interact with the actuating arm periodically with each revolution of the cam. The profile of the cam surface may be configured such that each time the cam surface interacts with an actuator arm a cleaning member is aligned with the respective valve.

The housing may comprise an outer wall and an inner wall. The inner wall may be adjacent the fluid passage. The fluid passage, inlet, outlet, front end opening and/or the rear end opening may be defined by the inner wall. The filtration chamber may be defined by the inner wall of the housing. The filtration chamber and/or fluid passage may have a width W. Where the filtration chamber/housing and/or fluid passage is substantially circular in cross-section, the width W may correspond to a diameter of the filtration chamber and/or fluid passage. The width W may not be uniform in the longitudinal direction.

The inner surface/wall of the housing may comprise a front tapered section at or near the front end, and/or a rear tapered section at or near the rear end. The width W of the tapered section at or near the front end may increase in a frontward direction. The width W of the tapered section at or near the rear end may increase in a rearward direction. The front end opening or inlet may comprise the front tapered section. The rear end opening or outlet may comprise the rear tapered section. Where turbines are present, the turbine(s) and the filter unit(s) may be arranged downstream of the front tapered section.

Advantageously, the tapered front end may reduce the cross-sectional area of the fluid passage and thereby increase the velocity of fluid flowing through the housing. This may be particularly advantageous where one or more turbine(s) are used to drive the dynamic filter element. This may enable greater energy extraction from the fluid flow, thereby increasing the efficiency of the turbine(s). This may also improve the throughput through the filter unit(s).

The aperture(s) or pollutant outlet(s) may be provided in the inner wall of the housing (i.e. a wall of the filtration chamber). The apertures may lead into a cavity bounded by an outer wall of the housing. Pollutants may be swept into the cavity through the aperture(s), where they may be retained until a time when they are to be removed. One or more outlets e.g. doors or hatches may be provided in the outer housing wall to allow collected pollutants to be removed for recycling or disposal and to empty the system for further use.

Additionally or alternatively, the system may further comprise a pumping system. The pumping system may be connected to the or each aperture or pollutant outlet and/or to the cavity for transporting the pollutants out of the housing or cavity, e.g. to an external storage and/or a sorting system The pumping system may further comprise one or more pumps and one or a plurality of pipes connected to the one or more apertures or to the cavity (e.g. to the outer wall of the housing). The pipe(s) may be configured for transporting the pollutants out of the housing/cavity, e.g. to a processing stage and/or to external storage.

The pipes may further be connectable to the pumping system for pumping the pollutants through the pipes. The pumping system may be configured to pump pollutants out of the cavity or pump the pollutants through the apertures and/or no-return valves. The pumping system may comprise the pipes. The pumping system may further comprise one or more pumps. Any suitable/known pumping system may be used. The pipe(s) may be located alongside any electrical cables needed to connect electrical components of the system, to facilitate and save on infrastructure installation costs.

Once the pollutants have passed through the apertures/no-return valves into the cavity, collection chamber and/or pipe(s) they may be transferred to a processing stage such as a separation system. The apertures/no-return valves, the cavity and/or the collection chamber may be connectable to the processing stage via the one or more pipes. The separation system may be configured to separate pollutant materials (i.e. non-biological materials) from any biological materials also collected by the system. Biological material may then be re-introduced to the fluid source e.g. the water or sea. For example, the pipe(s) may pass from the aperture(s)/no-return valve(s) through the cavity and out to the separation system, or the pipe(s) may pass from the cavity and out to the separation system.

Alternatively or additionally, pollutants may be transferred from the apertures/no-return valves, the cavity and/or the collection chamber to an external storage stage via the pipe(s). The pollutants may be stored in the external storage stage for later removal and/or transportation to the processing stage. Pollutants may be transferred to the separation system immediately after being collected, or collected pollutants may be stored for a period of time (e.g. stored in the external storage stage or the cavity) before being transferred to the separation system.

The pumping system, external storage stage and/or the processing stage may be located remotely from the housing, e.g. on-shore or on a marine vessel or structure. In the case where the dynamic element comprises cleaning arms, rotation of the cleaning arms may direct pollutants to the extreme radius of the (inner wall of the) housing, where the pollutants will exit through the series of no-return valves. The pollutants may be transported to the cavity or an external storage via one or more pipes.

The system may further comprise a generator coupled to the turbine(s) and/or driveshaft, such that rotation of the turbine generates electricity. This generates electricity which may be used to power the pumping system. This may be the sole use of the electricity - an advantage of this is that the system is self-contained and so easy to maintain and replace when necessary. Alternatively, excess generated electricity may be sold to the grid, improving the cost-effectiveness of the system. This may be achieved in accordance with known generators/standard techniques. The generator may be mounted to the end of a power shaft extending from the turbine and/or driveshaft. The drive shaft may pass through an inner wall of the housing. The power shaft may further comprise any electrical cabling for extracting the electrical power output and optionally for powering the turbines (e.g. in low fluid flow conditions).

Alternatively, the electricity required by the pumping system may be sourced externally, such as from solar cells on a nearby marine vessel, or from an on-shore power supply This ensures that the system is as lightweight and space-efficient as possible.

Each turbine may be coupled to the same driveshaft, or to separate driveshafts coupled at a gearbox. In this way, each turbine rotates in a different direction and may rotate at a different speed.

One turbine, e.g. the first turbine of the pair, is configured to rotate one way, and the other turbine is configured to rotate the other way. These contra-rotating turbines may be coupled to either end of the driveshaft. Advantageously, a pair of contra-rotating turbines provides a more efficient system. Other advantages include reduced torque acting on the housing and reduced swirl and wake turbulence. Advantageously, with contra-rotating turbines, the system is gyroscopically stabilized, such that any rotational forces that act upon other components of the system as a result of one turbine is substantially cancelled by the rotational forces from the other turbine.

Both turbines can be driven by the fluid flow, providing a higher energy output over a given period of time. Alternatively, the system can be driven by an exterior power source such as a motor. The system may be driven, at least in part, via the powershaft. This may enable the speed of each turbine to be set or controlled separately. This may be advantageous in low fluid flow conditions, e.g. where the turbines are driven by fluid flow alone, the forward turbine may rotate at a faster rate than the rear turbine.

The system may further comprise a gearing system coupled to the driveshaft, configured to control the rate of movement of the dynamic element. The rate of movement (e.g. rate of rotation) of the dynamic element may be controlled to be at a proportional speed to the speed of at least one turbine, which in turn rotates proportionally to the fluid flow. Collection of pollution by the static element will also rely on the fluid flow rate. The gearing system ensures that the dynamic element moves at a rate necessary to prevent excess deposition of pollutants on the static element before being removed. The gearing system may be or comprise a set of bevel gears. The gearing system may be configured to gear down the speed of the turbine for the dynamic element. The gearing system may comprise a gearbox with a fixed ratio. Alternatively, the gearbox may have adjustable ratios. In either case, the gearing ratio can be set dependent on the expected concentration of pollutants at the site in the area where the system is situated/travels through.

Pollutants will collect on the static filter element and/or filter membrane at a rate proportional to the pollutant concentration C in the fluid flowing therethrough and the fluid flow rate, e.g. proportional to the tidal flow rate, river flow rate, or speed of movement of the housing relative to a body of fluid. The cleaning rate of the pollutant filter unit may be proportional to the rate or movement or rotation rate of the dynamic filter. The cleaning rate may be controlled or otherwise varied to ensure that pollutants collected on the filter membrane(s) are directed for removal at an appropriate rate (i.e. a rate that avoids/eliminates excess deposition of pollutants on the filter membranes). The cleaning rate may be controlled by the gearbox and/or the drive system based on the pollutant concentration C, tidal flow rate, river flow rate, and/or speed of movement of the housing relative to a body of fluid (e.g. speed of the marine vessel to which it is attached). The cleaning rate may be controlled manually by an operator or automatically based on the output of one or more sensors (e.g. fluid flow and/or pollutant concentration sensors).

In another arrangement of the system, the fluid path through the housing may not be straight. For example, the inlet may be or comprise an opening at or near the front end of the housing and the outlet is located in a side of the housing. Alternatively, the outlet and/or the inlet may located in a side (sidewall) of the housing and/or a chamber sidewall. For example, the inlet and/or the outlet may be or comprise an opening in the side of the housing and/or chamber sidewall. The housing and/or filtration chamber may comprise a sidewall opening leading to the outlet. Additionally or alternatively, the housing and/or filtration chamber may comprise a sidewall opening leading to the inlet. The opening in the housing sidewall and/or chamber sidewall opening may extend around the housing and/or chamber sidewall e.g. about the longitudinal axis.

In this arrangement, the housing may be configured such that the direction of fluid flow through the static filter element is substantially not parallel to the longitudinal axis and/or to the driveshaft axis. The direction of the fluid flow path through the static filter element may be substantially perpendicular to the driveshaft axis, or at an angle between substantially <NUM> degrees to <NUM> degrees from the driveshaft axis. For example, the static filter element or filter membrane may be arranged in a housing/chamber sidewall. The static filter element may extend at least partially across an opening in the chamber sidewall that leads to the outlet. The outlet may be positioned to the side of the pollutant filter unit. The static filter element or filter membrane surface may be arranged substantially radially with respect to the dynamic filter element and/or cleaning member(s).

In this arrangement, the static filter element or filter membrane surface may extend at least partially around the dynamic filter element (e.g. about the longitudinal axis or rotation axis of the dynamic filter element). The filter membrane may be or comprise a substantially cylindrical element or a portion of a cylinder (e.g. where the cylinder axis is substantially parallel to the longitudinal axis of the housing and/or filtration chamber and/or substantially parallel to the driveshaft axis).

In this arrangement, the dynamic filter element may be configured to direct the pollutants entrapped by the static filter element in a direction substantially parallel to the driveshaft or longitudinal axis.

The pollutant filter unit may further comprise a flow directing element configured to direct at least a portion of the incoming fluid flow towards the static filter element. For example, the flow directing element may be configured to produce a radial component to the direction of the flow path through the static filter element with respect to the longitudinal or driveshaft axis. The flow directing element may comprise a flow directing surface, said surface being inclined with respect to the longitudinal or driveshaft axis. The flow directing element may be coupled to the dynamic filter element and/or the driveshaft. The flow directing element or surface may be substantially conical.

The aperture(s) or pollutant outlet(s) may lead into a collection chamber within the housing. The collection chamber may be defined by an inner wall of the housing. Where the driveshaft is driven by a drive system (e.g. a motor), the drive system may be disposed within the collection chamber.

The system may comprise a plurality of filtration chambers. In this case, the aperture(s) or pollutant outlet(s) of the first filtration chamber may lead into a second filtration chamber, and so on. In this case, the pollutant outlet(s) of the first filtration chamber may or comprise the inlet(s) of the second filtration chamber, and so on. The pollutants in solution may pass through several filtration chambers before reaching the collection chamber. The housing may comprise each filtration chamber and the collection chamber. Alternatively, the system may comprise a modular housing including separate housing modules for each filtration chamber and/or the collection chamber. Each module may be connectable to each other and interchangeable. In this way, the system may be configurable.

The system may be configured to couple to a marine vessel, such as a (merchant) ship. Alternatively, the system may be configured to couple to a fixed marine structure, such as a pier or a floating platform. Alternatively, the system may be free-standing. In this case, the system can be selectively lowered into areas of high pollution, reducing unnecessary wear on the dynamic elements.

If the system is attachable or attached to a vessel, rather than a fixed structure, there may be occasions where the dynamic element does not need to move (e.g. in areas with minimal pollution). A gearing system ensures that the dynamic element can be isolated and so does not move or does not necessarily move with the turbines. This may increase the lifespan of the system, by reducing the wear on the dynamic element.

An advantage of coupling the system to a moving vessel is that a larger area of the ocean is covered, which in theory ensures a greater reduction of pollutants. However, installing the system on a fixed structure in areas where the pollution is significant may have an equally noticeable effect, with reduced cost and less international coordination required.

The system may be removably attachable to a vessel or other structure to enable it to be used at predetermined periods of time, and/or when the ship/structure is in a particular location.

The system may be primarily configured to reduce marine contaminants such as plastic pollution.

The system may further comprise a separation or sorting system configured to separate biological (e.g. plankton) and non-biological material (e.g. plastics), wherein the biological material is rejected prior to the removal of the pollutants from the housing. Alternatively, sorting may take place at a later stage e.g. on land. In either instance, the sorting system may comprise a froth flotation system, wherein the materials are separated into distinct layers with the use of a non-toxic biological detergent such as a fatty acid. Each distinct layer can then be skimmed from the group, and either stored or returned to the ocean (depending on whether the layer contains biological or pollutant material). For example, biological material such as plankton can be returned to the water whilst collected plastics materials can be stored for recycling at a later date. Note - references to "biological" materials are to be interpreted as references to life/organic matter, including plant and zoological cells, materials, etc..

According to a second aspect of the invention, there is provided a method of reducing marine pollution. The method may comprise providing or using a system according to any prior description. The method may comprise providing a storage unit to store the collected pollutants. The method may further comprise coupling the system to a fixed marine structure, such as a pipeline, floating platform or pier, or a marine vessel, such as a ship. The method may comprise periodically emptying collected pollutants.

Alternatively or additionally, the method may comprise providing an incoming fluid flow containing pollutants. The method may further comprise filtering pollutants from the fluid flow. The method may further comprise directing the filtered pollutants for removal from the system. The method may further comprise outputting a de-polluted fluid flow. The method may further comprise collecting the filtered and directed pollutants.

Alternatively or additionally, the method may comprise any of the following steps: filtering pollutants from an incoming fluid flow using a static filter to de-pollute the fluid flow; directing the pollutants entrapped on the static filter away from the static filter to clean the filter; collecting the directed pollutants; and/or outputting the de-polluted fluid flow.

"Periodically" could be at regular or irregular time intervals, and/or when emptying is required e.g. the cavity is too full. In the case where the system is coupled to a marine vessel, "periodically" may refer to each completed journey, or round-trip, or at every stop, dependent on the expected level of pollution for each journey. In the case where the system is coupled to a fixed marine structure, the frequency of "periodically" may depend on the measured level of pollution in the area where the structure resides.

The method may further comprise sorting the collected pollutants from the storage system into biological and non-biological material. The method may further comprise returning the biological material to the ocean.

The additional step of returning the biological material to the ocean may assist in reducing any potential negative effect that the pollution treatment may have on the local marine life. This is optimal for a fixed structure, as emptying a storage unit from a travelling ship into a single location may lead to introducing non-native species into coastal regions, which may cause disruption to the local species.

Features which are described in the context of separate embodiments may instead or also be provided in combination in a single embodiment and/or be interchangeable. Conversely, various features which are, for brevity, described in the context of a single embodiment may also be provided separately or in any suitable sub-combination. Features described in connection with a device or system may have corresponding feature definable with respect to a method, and vice versa.

Embodiments will be described, by way of example only, with reference to the drawings, in which:.

It should be noted that the Figures are diagrammatic and not drawn to scale. Relative dimensions and proportions of parts of these Figures may have been shown exaggerated or reduced in size, for the sake of clarity and convenience in the drawings. The same reference signs are generally used to refer to corresponding or similar feature in modified and different embodiments.

<FIG> illustrate schematic views of an example system <NUM>. The system <NUM> comprises a housing <NUM> configured to receive an incoming fluid flow <NUM>, and output a de-polluted fluid flow <NUM>. The incoming fluid flow <NUM> enters the housing <NUM> at a front end <NUM> of the housing <NUM>. In an embodiment, the flow exits the housing <NUM> at a rear end <NUM> () of the housing <NUM>. The front end <NUM> and the rear end <NUM> may be or comprise an opening in the housing <NUM> through which incoming fluid <NUM> may enter the system <NUM> and outgoing fluid <NUM> may exit the system <NUM>, respectively. The housing <NUM> may further define a fluid passage <NUM> extending between the front end <NUM> and the rear end <NUM> in a longitudinal axis of the housing <NUM> (and substantially parallel to the fluid flow). As such the front end <NUM> and the rear end <NUM> are in fluid communication. The front end may be or comprise an inlet <NUM> and the rear end may be or comprise an outlet <NUM>.

The system <NUM> further comprises a turbine <NUM>. The turbine <NUM> is located toward the front end <NUM> of the housing <NUM>. A second turbine <NUM> is provided, located toward the rear end <NUM> of the housing <NUM>. The pair of turbines <NUM>, <NUM> is a contra-rotating pair. One turbine, e.g. the first turbine <NUM>, may be configured to rotate one way, and the other turbine <NUM> is configured to rotate the other way. In this way, the system is gyroscopically stabilized, such that any rotational forces that act upon other components of the system <NUM> as a result of one turbine <NUM> is substantially cancelled by the rotational forces from the other turbine <NUM>.

The turbines <NUM>, <NUM> may be configured to be driven/rotated by the flow of fluid through the system <NUM>. For example, in use, the system <NUM> may be substantially submerged in a body of fluid and the flow of fluid may be driven by movement of the body of fluid relative to the system <NUM>, e.g. tidal flow or river flow or the like, and/or by movement of the system <NUM> relative to the body of fluid, e.g. the system <NUM> may be attachable to a marine vessel, such as a ship to be physically pulled through the body of fluid. The turbines <NUM>, <NUM> each sit in a plane that is substantially perpendicular to the longitudinal axis of the housing <NUM>, extending from the front end <NUM> to the rear end <NUM> of the housing <NUM>) (and substantially perpendicular to the fluid flow). The turbines <NUM>, <NUM> are coupled to and, when the turbine(s) <NUM>, <NUM> are driven by tidal or fluid flow, provide power to rotate a driveshaft <NUM>. Each turbine <NUM>, <NUM> may be coupled to the same drive shaft <NUM>, or to separate drive shafts <NUM> coupled at a gearbox <NUM>. In this way, each turbine <NUM>, <NUM> may rotate at a different speed and/or in a different direction.

The turbines <NUM>, <NUM> may also be configured to provide an electrical power output <NUM>. The electrical power output <NUM> may be stored in an electrical storage unit <NUM>, e.g. in a battery for later use (see <FIG>).

The system <NUM> may also comprise a generator (not shown), connected to the driveshaft <NUM>. The generator may also/instead be coupled to the turbine(s) <NUM>, <NUM>, and/or the gearbox <NUM>. This enables transformation of rotation into electrical power (e.g. as with hydro-electric turbines). Rotation of the driveshaft <NUM> will generate electricity (as with hydro-electric turbines), which can then be used to power the pumping system. The generator may be an alternator or dynamo-type generator or any other suitable generator known in the art. In the example shown in <FIG>, a power shaft <NUM> is coupled to the gearbox <NUM> for providing power to the drive shaft and/or for providing a power output from the turbines <NUM>, <NUM>. The power shaft <NUM> may be coupled to the gearbox <NUM> for receiving an electrical power output <NUM> produced by the generator (in this example, a generator may be provided in the gearbox <NUM>). Alternatively, the generator may be mounted to the power shaft and not housed in the gearbox.

Alternatively, such as in areas with low tidal power, the driveshaft <NUM> can be driven by a power source (such as by the excess electricity stored from a generator), which can the drive the turbines <NUM>, <NUM> and dynamic elements <NUM>.

Alternatively or additionally, the turbine(s) <NUM>, <NUM> and/or the cleaning arm(s) <NUM> may be configured to be electrically driven, e.g. by an electrical power input <NUM>, <NUM>. The electrical power input <NUM>, <NUM> may be provided to the drive shaft <NUM> from an external power supply via the power shaft <NUM>. The external power supply may be an external power source <NUM> such as an on-shore power source (e.g. from a generator, battery or the power grid) or an off-shore power source such as from/on a marine vessel or structure. Alternatively, the external power supply may be the electrical power storage unit <NUM> storing the electrical power generated by the system <NUM> (see <FIG>). In this driven mode, the system <NUM> may itself create a fluid flow <NUM>, <NUM> by sucking or drawing fluid through the front end <NUM> of the housing <NUM>. This driven mode may be particularly suitable in low fluid flow conditions, where the flow of fluid (e.g. tidal flow or river flow) is insufficient to drive the turbine(s) <NUM>, <NUM> to operate the system <NUM>.

Disposed between the turbines <NUM>, <NUM>, and coupled to the or each driveshaft <NUM>, is a series of pollutant filter units <NUM>. Each pollutant filter unit <NUM> comprises a static element <NUM> (being or comprising a filter membrane 120a) and a dynamic element <NUM> (being or comprising a cleaning arm). The filter units <NUM> are located in the vicinity of the first turbine <NUM>, i.e. nearer the front end <NUM> than the rear end <NUM> of the housing <NUM> and between the first turbine <NUM> and the gearbox <NUM>. Three filter units <NUM> are shown in <FIG>, but it will be appreciated that fewer (e.g. <NUM> or <NUM>) or more (e.g. <NUM>, <NUM>, <NUM> or more) could be used.

The filter units <NUM> are shown to be substantially perpendicular to the longitudinal direction and/or fluid flow, but they could instead be at an angle e.g. to the longitudinal direction. An advantage of a multi-stage system as shown may be that the risk of the system <NUM> clogging up or the pollution collecting too rapidly to be cleared may be reduced. Additional turbines could also be provided e.g. to better deal with stronger flow rates / higher pollution (not shown).

The power shaft <NUM> and optionally any electric cables required for connections to/from the gearbox <NUM> are proved within a sealed enclosure.

The housing <NUM> comprises an outer surface <NUM> and an inner surface 110b.

The fluid passage <NUM>, the front end opening <NUM> and the rear end opening <NUM> may be defined by the inner surface or wall 110b. The inner surface 110b or interior of the housing <NUM> may define a filtration chamber <NUM> in which the filter units <NUM> are arranged. The fluid passage <NUM> may be or comprise the chamber <NUM>. The inlet <NUM> may lead to the chamber <NUM> and an outlet <NUM> may lead from the chamber <NUM>.

In an embodiment, the fluid passage <NUM> has a width W, e.g. where the fluid passage <NUM> is substantially circular in cross-section, the width W may correspond to a diameter of the fluid passage <NUM>. Preferably the or each filter membrane 120a extends across the width of the fluid passage <NUM>. The width W may not be uniform in the longitudinal direction. The inner surface 110b may comprise a front tapered section 110f at or near the front end or inlet <NUM>, and/or a rear tapered section 110r at or near the rear end or outlet <NUM> in which the width W increases in a respective frontward or rearward direction (see <FIG>). The front end opening or inlet <NUM> may comprise the front tapered section 110f, and where present, the rear end opening or outlet <NUM> may comprise the rear tapered section 110r. The turbine(s) <NUM>, <NUM> and the filter unit(s) <NUM> are arranged downstream of the front tapered section 110f or front end opening <NUM>.

The tapered front end opening or inlet <NUM> (in which the width or cross-sectional area A of the opening decreases in size in the direction of fluid flow) may serve to accelerate fluid flow (velocity) through the turbine(s) <NUM>, <NUM> and the filter unit(s) <NUM>, since flow rate = velocity * A, where flow rate must be conserved (i.e. if A decreases, the velocity must increase). This may advantageously enable greater energy extraction from the fluid flow, thereby increasing the efficiency of the turbine(s) <NUM>, <NUM>. This may also improve the throughput through the filter unit(s) <NUM>.

The width of the front end opening <NUM> and/or the rear end opening <NUM> may be in the range of substantially <NUM> to <NUM>.

The width W of the fluid passage <NUM> between the two tapered sections 110f and 110r (the chamber <NUM>) may be substantially uniform. Alternatively, the portion of the inner surface 110b between the two tapered sections 110f, 110r may be non-uniform, e.g. comprising a further tapered section (not shown). The further tapered section may have a width W which decreases in the rearward direction. This may further serve to accelerate fluid flow through the second turbine <NUM>.

The gearbox <NUM> may be physically supported by one or more supports <NUM>. For example, the supports <NUM> may hold the gearbox <NUM> in the center of the fluid passage <NUM>. The support(s) <NUM> may extend between the gearbox <NUM> and the inner surface 110b of the housing <NUM>, e.g. radially or otherwise. The support(s) <NUM> may further served to support the drive shaft(s) <NUM> and turbines <NUM>, <NUM> through their coupling to the gearbox <NUM>. Alternatively, the drive shaft(s) <NUM> and turbines <NUM>, <NUM> may further be supported by the filter unit(s) <NUM> through their couplings thereto.

A cavity <NUM> is defined between the inner and outer surfaces 110b 110a. Pollutants passing through the system <NUM> may be collected in the cavity <NUM>, as described below. The pollutants may be in a solution, as water from the outside water environment will also pass into the cavity <NUM> e.g. along with the pollutants. The depth of the cavity may decrease towards the longitudinal extremes so as to provide a gradual and smooth passage for water and pollutants entering the system <NUM> and/or to direct the fluid flow.

The or each filter membrane 120a inhibits movement of pollutants through the system <NUM> and 'traps' pollutants in the system <NUM>, provided the pollutants are of a size greater than that which the filter membrane 120a permits passage of (e.g. the filter pore size). Preferably the or each filter membrane 120a extends to the inner surface 110b of housing <NUM>. The cleaning arm(s) <NUM> is(are) configured to rotate and direct pollutants trapped/collected at/on the filter member <NUM> for collection and removal from the housing <NUM>. Each filter membrane 120a is positioned adjacent to or in the vicinity of a or each cleaning arm <NUM>. Preferably the filter membrane 120a is positioned on the output or rearward side of the cleaning arm <NUM> with the cleaning arm <NUM> on the inflow or frontward side (e.g. the filter membrane 120a is positioned behind the cleaning arm <NUM>). This enables rotation of the cleaning arm <NUM> (e.g. in the plane of the cleaning arm <NUM>) to sweep and direct pollutants trapped by the filter membrane 120a.

The cleaning arm(s) <NUM> may be configured to rotate with or about the drive shaft <NUM>, such that the cleaning arm(s) <NUM> may rotate at the same speed or at a different speed to the turbine(s) <NUM>, <NUM>. In an embodiment, the cleaning arm(s) <NUM> is(are) driven indirectly by the turbine(s) <NUM>, <NUM> via the gearbox <NUM>. The or each cleaning arm <NUM> comprises a hub portion <NUM> that receives the driveshaft <NUM> and an arm portion <NUM> that extends away from the hub portion <NUM> (see <FIG>). In an embodiment, the or each hub portion <NUM> is connected to the gearbox <NUM> to control the rotational speed thereof (discussed further below). Alternatively, the or each cleaning arm <NUM> may be integral with or secured to the driveshaft <NUM> to rotate therewith.

Rotation of the cleaning arm <NUM> directs any collected pollutants (e.g. radially outwards) towards the exterior of the housing <NUM>, e.g. as indicated generally by the arrows labelled MF in <FIG>. The housing <NUM> may comprise one or more no-return valves <NUM>, e.g. on/in the inner housing surface 110b, that are aligned radially with the cleaning arms <NUM>, where the pollutants are removed. This enables collection of pollutants directed by the cleaning arm(s) <NUM>. In an embodiment, the or each no-return valve <NUM> comprises an aperture for receiving the pollutants directed by the cleaning arm <NUM>. The aperture of the or each n-return valve <NUM> may be larger than of the corresponding pore size of the filter membrane(s) 120a, such that pollutants trapped by the membrane 120a are able to pass through the no-return valves <NUM>. Alternatively, a single no-return valve <NUM> may be located in the wall of the housing <NUM>.

Where a plurality of pollutant filter units <NUM> are used, these may comprise filter membranes 120a of different or varying granularity or fine-ness, or pore size. The variation e.g. in pore size may be progressive. For example, the forward-most membrane 120a may be the coarsest, and each following membrane may be finer than the preceding membrane 120a. The coarsest, with the largest pore size, may be substantially <NUM>. Each finer membrane 120a may have a smaller pore size than the preceding membrane 120a. Alternatively, the filter membranes 120a may have the same granularity or pore size. The pore size of the filter membrane(s) 120a may be in the range substantially <NUM> to <NUM>.

The or each no-return valve <NUM> may provide a selective fluid communication between the fluid passage <NUM> and the cavity <NUM> of the housing, such that, once the pollutants have passed through the or each no-return valve <NUM> they may be collected in the cavity <NUM>. The or each no-return valve <NUM> may be actuated by a radially outward fluid flow generated by the cleaning arm(s) <NUM>. Alternatively or additionally, the system <NUM> may be connectable to a pumping system. The pumping system <NUM> is configured to transport collected pollutants from or through the no-return valves <NUM> to the cavity <NUM> or to a separate storage unit <NUM> where they can be held until sorting/separating and/or disposal is required (e.g. see <FIG>).

For example, the pollutants directed by the cleaning arm(s) <NUM> may gather or collect at the inner surface 110b at or near the no-return valve(s) <NUM>, and the pumping system <NUM> may be configured to provide a suction on the cavity <NUM> side of the no-return valve(s) <NUM> to actuate the no-return valves <NUM> and transport or suck the collected pollutants through the no-return valve(s) <NUM>.

The cleaning arm(s) <NUM> may comprise any one or more of a brush, a scraping blade or a vortex generator or any other suitable means for directing pollutants out of the housing <NUM>. The cleaning arm <NUM> may be configured to contact and e.g. sweep over the membrane 120a as it rotates.

In use, e.g. where the turbines <NUM>, <NUM> are driven by a fluid flow, incoming fluid flow <NUM> drives/rotates the turbines <NUM>, <NUM>, which in turn causes the cleaning arms <NUM> to rotate due to the coupling with the gearbox <NUM> or drive shaft <NUM>. The rate of rotation of the cleaning arms <NUM> can be controlled by the gearbox <NUM>. This ensures that the cleaning arms <NUM> rotate at a proportional speed to the rotation of the turbines <NUM>, <NUM>. The rotation rate of the cleaning arms <NUM> may be selected/adjusted to a rate necessary to prevent excess deposition of material on the filter membranes <NUM>.

In an embodiment, the rotational speed of the cleaning arm(s) <NUM> is dependent on the gearing ratio of the gearbox <NUM>. The gearing ratio steps down the rotational speed of the cleaning arm(s) <NUM> from the rotational speed of the turbine <NUM>, <NUM>. In other words, if the turbine <NUM>, <NUM> rotates at a speed X, and the clearing rate of the system <NUM> (e.g. related to the amount of pollutants being or expected to be filtered) requires the cleaning arm(s) <NUM> to rotate at a speed X/<NUM>, the gearing ratio from the turbine <NUM>, <NUM> to the cleaning arm(s) <NUM> is <NUM>:<NUM>, or for every <NUM> rotations of the turbine <NUM>, <NUM> the cleaning arm(s) rotate once. The gearing ratio is determined by number of gear teeth on the gears of the gearbox <NUM> and may be variable, as is known in the art. As the cleaning arm(s) <NUM> rotates on the same axis (i.e. defined by the driveshaft <NUM>) as the turbine(s) <NUM>, <NUM>, contra gears are needed to move the rotation perpendicular, then back again to the same axis, varying the speed between these steps.

The gearing ratio of the gearbox may be fixed or variable, e.g. variable between ratios, e.g. <NUM>:<NUM>, <NUM>:<NUM>, <NUM>:<NUM>, or <NUM>:<NUM>. Where the gear ratio is variable, the gear ratio may be selectable manually by an operator or automatically via a gear selection system (not shown). For example, an automatic gear selection system may comprise one or more pollutant sensors to determine the amount/level of pollution in the incoming fluid flow. If the detected amount/level exceeds a threshold value, the gear ratio may be adjusted to increase the rotation rate of the cleaning arms <NUM>. If the detected amount/level falls below a threshold value, the gear ratio may be adjusted to decrease the rotation rate of the cleaning arms <NUM>.

Pollutants will collect at a rate proportional to the fluid flow rate, e.g. the tidal flow rate. Pollutants will collect on the filter membrane(s) 120a at a rate proportional to the pollutant concentration C in the fluid and the fluid flow rate, e.g. proportional to the tidal flow rate, river flow rate, or speed of movement of the system <NUM> relative to a body of fluid. The cleaning arm <NUM> rotation rate can therefore be controlled e.g. by the gearbox <NUM> to ensure that pollutants e.g. collected on the filter membrane(s) 120a are directed for removal at an appropriate rate (i.e. a rate that avoids/eliminates excess deposition of pollutants on the filter membranes 120a). In an embodiment, the cleaning arm <NUM> rotation rate is a function of the tidal flow rate and is defined geographically, meaning the cleaning arm <NUM> rotatation occurs at a rate necessary to prevent excess deposition of material on the filter membranes 120a. For example, Country A may have an expected pollution concentration of Ca and Country B may have an expected pollution concentration of Cb, where Ca = k*Cb (and Ca and Cb are average values over a period of time). Therefore, the cleaning arm <NUM> rotation rate required for Country A will be k times that for Country B, as the required rotation rate is proportional to the concentration level (for a given flow rate through the system). The concentrations (e.g. Ca and Cb) will require local sampling and then the system <NUM> can be configured to match the cleaning rate associated with the particular pollutant concentration. The system <NUM> may also comprise a deflector (not shown) aimed at preventing large physical pollution (such as large pieces of plastic) entering the system <NUM> (e.g. through the front end <NUM>). This avoids or prevents e.g. large pollutant particles entering the system <NUM> that could cause blockage or malfunction (e.g. waste that is larger than the aperture of the no-return valves <NUM>).

<FIG> illustrates a front end photographic view of an example embodiment of the system <NUM>. In addition to the features illustrated in the schematic embodiments of <FIG>, each filter membrane 120a is or comprises an array of smaller membranes or membrane cells <NUM>, <NUM>. In the embodiment shown these membranes or membrane cells <NUM>, <NUM> are held and/or supported by a support structure <NUM> at or along the edges of each of the smaller membranes <NUM>, <NUM> but, in other embodiments no support structure may be necessary.

<FIG> illustrate schematic views of a pollutant filter unit <NUM>. The pollutant filter unit <NUM> comprises a static element <NUM> (being or comprising a filter membrane 120a). The filter unit <NUM> further comprises a dynamic element <NUM> (being or comprising a cleaning arm). The cleaning arm <NUM> rotates with or about the driveshaft <NUM>, which acts to direct pollutants to the exterior of the unit <NUM>, as is generally indicated by the arrows labelled MF in <FIG>. The or each cleaning arm <NUM> may comprise a hub portion <NUM> that receives the driveshaft <NUM> and an arm portion <NUM> that extends away from the hub portion <NUM>. A cleaning portion <NUM> may be coupled to the arm potion <NUM>. The cleaning portion <NUM> may be disposed adjacent the filter membrane 120a and be configured to direct the pollutants by moving across the surface of the filter membrane 120a, e.g. by contacting and sweeping over the filter membrane 120a as it rotates. The cleaning arm portion <NUM> may be or comprise any one or more of a brush, a scraping blade or a vortex generator or any other suitable means for directing pollutants out of the housing <NUM>. In an embodiment, the or each hub portion <NUM> is connected to the gearbox <NUM> to control the rotational speed thereof (discussed above). Alternatively, the or each cleaning arm <NUM> may be integral with or secured to the driveshaft <NUM> to rotate therewith.

Once the pollutants have passed through the no-return valves <NUM>, they may be collected in the cavity <NUM>. Pollutants can then be transferred to a separation system <NUM> (described further below with reference to <FIG>) to separate pollutant materials <NUM> from any biological material <NUM> also collected (that can be re-introduced to the fluid e.g. the water or sea). Alternatively, pollutants may be transferred directly from the or each no-return valve <NUM> to the separation system <NUM>. The no-return valve(s) <NUM> or the cavity <NUM> may be connectable to the separation system <NUM> via one or more transfer pipes or fluid conduits <NUM>. For example, the transfer pipe(s) <NUM> may pass from the no-return valve(s) <NUM> through the cavity <NUM> and out to the separation system <NUM>, or the transfer pipe(s) <NUM> may pass from the cavity <NUM> and out to the separation system <NUM>. Alternatively or additionally, pollutants may be transferred (from the no-return valves <NUM> or the cavity <NUM>) to an intermediate storage unit <NUM> before being transferred to the separation system <NUM>. Pollutants may be transferred to the separation system <NUM> immediately after being collected by the system <NUM>, or collected pollutants may be stored for a period of time (e.g. stored in the intermediate storage unit <NUM> or the cavity <NUM>) before being transferred to the separation system <NUM>.

The transfer pipe(s) <NUM> may further connect the system <NUM> to the pumping system <NUM> for pumping the pollutants through the no-return valves <NUM> and out to the cavity <NUM>, the intermediate storage unit <NUM> and/or the separation system <NUM>. Where the cavity <NUM> is not used for storing/collecting pollutants, the cavity <NUM> may simply be a space to house at least a portion of the transfer pipes <NUM> and/or any electrical cabling. In this case, the outer surface <NUM> of the housing may serve as a cowling and may be shaped or configured to reduce any drag from the fluid flow.

The pumping system <NUM>, intermediate storage unit <NUM> and/or the separation system <NUM> may be located remotely from the system <NUM>, e.g. on shore or on a marine vessel or structure. The pumping system <NUM> may be powered by the system <NUM> directly e.g. via the electrical power output <NUM> generated from one or generators, or indirectly e.g. via the electrical power storage unit <NUM> used to store the electrical power output <NUM>. Alternatively, the pumping system <NUM> may be powered by the external power source <NUM>.

<FIG> illustrates a schematic of an example froth flotation separation system <NUM>. Froth flotation is most commonly used in separation of minerals in water (as illustrated), but can be implemented to separate biological and non-biological materials. In a froth flotation process, materials are separated into distinct layers with the use of a non-toxic biological detergent such as a fatty acid. Each distinct layer can then be skimmed from the group, and either stored or returned to the ocean (depending on whether the layer contains biological or pollutant material).

The separation system <NUM> may be arranged downstream of the no-return valves <NUM> and/or cavity <NUM> (and, where present, the intermediate storage unit <NUM>), such that after the pollutants are directed to and pass through the no-return valves <NUM> they may be transported to a separation system <NUM>. In an embodiment, the pollutants may be transported directly from the no-return values <NUM> to the separation system <NUM>, e.g. by the pumping system <NUM> and via the pipes or fluid conduits <NUM>.

In the illustrated example separation system <NUM>, the mixture <NUM> (e.g. pollutant materials <NUM> and biological material <NUM> in solution) enters into a housing <NUM> of the system <NUM> via an inlet <NUM>. For example, the no-return valves <NUM> or the cavity <NUM> may be connectable to the inlet <NUM> by the transfer pipes <NUM>. The reagent <NUM> (such as fatty acid) is combined in with the mixture <NUM> in the inlet <NUM> before entering the housing <NUM>. The mixture <NUM> is then separated into distinct layers by the use of dissolved or dispersed air <NUM>. Biological materials float efficiently and so commonly form the top layer(s) to be skimmed (e.g. layer <NUM>). The suspended pollutant material <NUM> can be drained through outlet <NUM> and disposed of or stored for further sorting/recycling. This separation can be performed on the pollutant solution collected from the no-return valves <NUM> and/or in the cavity <NUM>, either as part of the system <NUM> or separately and later,.

<FIG> illustrates a workflow map of an example embodiment. This particular example is configured to reduce plastic pollution, and the collected waste is separated on land before returning the biological material (e.g. plankton) to the ocean.

The system <NUM> is positioned to receive a fluid flow or tidal flow such that flow <NUM> enters the housing <NUM> and rotates the front turbine <NUM>. The flow <NUM> will pass through the housing <NUM> and the one or more filtration units <NUM> (where pollutant particles will be trapped), and cause rear turbine <NUM> to rotate before exiting the system <NUM> as de-polluted (or reduced pollution) flow <NUM>.

The rotation of the turbines <NUM>, <NUM> rotates (or initiates) the driveshaft <NUM>. The driveshaft <NUM> is coupled to a generator, such that rotation of the driveshaft <NUM> generates electricity or electrical power output <NUM>. This electricity or electrical power output is used power a pumping system <NUM>. Any surplus electricity or electrical power can be sold to the grid. Alternatively, the excess can be stored e.g. in an electrical power storage unit <NUM> to drive the system <NUM> at a later time.

Rotation of the driveshaft <NUM> also initiates rotation of the dynamic element or cleaning arm <NUM> of the filtration unit <NUM>. Polluted fluid flow will have passed through the static element (filter membrane 120a) <NUM> and pollutants "trapped". Rotation of the dynamic element <NUM> across the face of the static element <NUM> directs the pollutants to the extreme edge of the housing <NUM>.

The pumping system <NUM> then extracts the pollutants to a separation system or storage <NUM>, where the pollutants can be separated from any collected biological material and dealt with accordingly. The biological material can then be returned to the ocean if appropriate.

<FIG> shows a system <NUM> according to alternative embodiment of the invention. System <NUM> has many features in common with the system <NUM> shown in <FIG> and described above and similar features are labelled with the same reference numerals. System <NUM> may be particularly suited to attachment to a marine vessel, such that the system <NUM> is moved through the water to be filtered by the marine vessel.

The system <NUM> comprises a housing <NUM>' configured to receive an incoming fluid flow <NUM>, and output a substantially de-polluted fluid flow <NUM>. The housing <NUM>' comprises a filter unit <NUM>' with a static filter element <NUM>' (including one or more filter membranes 120a') to trap pollutants contained in the fluid flowing therethrough, and a dynamic filter element <NUM>' (being or comprising a cleaning arm) to direct the pollutants trapped by the static filter element <NUM>' for removal from the housing <NUM>'. The filter unit <NUM>' is disposed within the filtration chamber <NUM>' of the housing <NUM>' and coupled to the driveshaft <NUM>'. In this embodiment, the incoming fluid flow <NUM> enters the housing <NUM> through an inlet <NUM>' at a front end of the housing <NUM>' and exits the housing <NUM>' through an outlet <NUM>' in the side of the housing <NUM>'. As such, unlike system <NUM>, the fluid or flow path <NUM> through the housing <NUM>' is not straight.

The outlet <NUM>' may comprise an opening in a sidewall of the filtration chamber <NUM>. The housing <NUM>' may comprise a plurality of outlets <NUM>' arranged radially around the housing <NUM>'. Alternatively, the outlet <NUM>' may be an annular outlet that extends around the housing <NUM>', as shown in <FIG>.

<FIG> illustrates a schematic view of a pollutant filter unit <NUM>'. The filter unit <NUM>' is a substantially cylindrical unit to match the substantially cylindrical filtration chamber <NUM>' defined by the interior space of the housing <NUM>'. The static filter element <NUM>' is a substantially hollow cylindrical element <NUM>' comprising one or more filter membranes 120a' (such as membrane cells 121a', 121b', 121c'). In this way, the static filter element <NUM>' forms a filter membrane ring.

The filter unit <NUM> is positioned within the filtration chamber <NUM>' such that the filter membrane 120a' ring is aligned radially with the outlet <NUM>' or sidewall opening and extends at least partially across the outlet <NUM>' or sidewall opening. This ensures that the fluid flows though the filter membrane 120a' on its passage to the outlet <NUM>', as indicated by the arrows in <FIG>. To reduce the resistance of the flow path through the chamber <NUM>' and/or turbulence within the chamber <NUM>, the dynamic filter element <NUM>' further comprises a flow directing element <NUM>' to direct the flow through the filter membrane 120a' (see <FIG>). The flow directing element <NUM>' comprises a surface inclined with respect to the driveshaft axis to deflect the fluid flow outwards from the driveshaft axis or center of the chamber <NUM>'. Where there are a plurality of outlets <NUM>' around the housing <NUM>' or an annular outlet, the flow directing element may be substantially conical, as shown in <FIG>.

The or each filter membrane 120a' or membrane cell 121a', 121b', 121c' may be supported by a frame structure <NUM>'. The static filter element <NUM>' extends around the dynamic filter element <NUM>' such that the filter membrane(s) 120a' is/are arranged radially with respect to the cleaning arm(s) of the dynamic filter element <NUM>'.

The or each cleaning arm <NUM>' comprises one or more helical cleaning portions <NUM>, as shown in <FIG> and in more detail in <FIG>. The helical cleaning portion(s) <NUM> rotates with the cleaning arm(s) <NUM>' with/about the driveshaft <NUM>, such that pollutants trapped on the filter membrane 120a' are directed/moved across the surface of the filter membrane 120a' towards the edge or end of the filter unit <NUM>, as is generally indicated by the arrow labelled MF in <FIG>. The helical cleaning portion <NUM>' provides a velocity component of the material flow across the filter membrane that is parallel to the driveshaft <NUM>' or rotation axis of the cleaning arm <NUM>' (or longitudinal axis of the housing <NUM>').

<FIG> illustrates the pollutant material flow (arrows) through the filter unit <NUM>'. Pollutants that are initially suspended in the fluid are directed upwards towards the filter membrane 120a' by the flow directing element <NUM>'. Rotation of the cleaning arm <NUM>' directs any collected pollutants towards a rear wall <NUM>' of the chamber <NUM>'. The dynamic filter element <NUM>' may be disposed adjacent the rear wall <NUM>. The rear wall <NUM>' may comprise a track <NUM>' on which the dynamic filter element <NUM>' runs (see <FIG>).

The one or more apertures <NUM>' or valves <NUM>' (e.g. no-return valves) are disposed in/on the rear wall <NUM>' for receiving the pollutants directed by the cleaning arm <NUM>, as shown in <FIG>. A series of apertures <NUM>' or valves <NUM> may be arranged around the perimeter of the rear wall <NUM>' and aligned with the cleaning portion <NUM>' as shown in <FIG>. As the cleaning member <NUM>' rotates, each apertures <NUM>' or valves <NUM> of the series receives sequentially an amount of pollutants directed from the filter membrane 120a' by the cleaning member <NUM>'. Each apertures <NUM>' or valves <NUM> may receive an amount of pollutants periodically, e.g. when the or each cleaning member <NUM>' passes a respective apertures <NUM>' or valves <NUM> with each revolution. Alternatively, an amount of pollutant will be deposited (sequentially and/or periodically) over, on or near each aperture <NUM>' or valve <NUM> with each rotation of the cleaning member <NUM>'.

The apertures <NUM>' or valves <NUM> lead to a collection chamber or cavity <NUM>' behind the rear wall <NUM>'. Once the pollutants have passed through the apertures <NUM>' or valves <NUM>, they may be collected and/or stored in the collection chamber <NUM>' until a time when they are to be removed or transferred, e.g. to a storage unit and/or processing stage. The system <NUM> may be connectable to the pumping system <NUM>, intermediate storage unit <NUM> and/or the separation system <NUM> as previously described in relation to system <NUM>. The pumping system <NUM> may be configured to pump the pollutants from the collection chamber <NUM>' to the intermediate storage unit <NUM> and/or to the separation system <NUM>. The pumping system <NUM> may be connectable to the collection chamber <NUM>' or directly to the apertures <NUM>' or valves <NUM>' via the one or more pipes <NUM>, as previously described.

The or each valve <NUM>' may be actuated by the rearward fluid flow generated by the motion of the cleaning arm(s) <NUM>'. Alternatively or additionally, the pollutants directed by the cleaning arm(s) <NUM>' may gather or collect at the rear wall <NUM>' at or near the valve(s) <NUM>, and the valves <NUM> may be actuated by a suction on the cavity <NUM> side of the valve(s) <NUM>' provided by the pumping system <NUM> that pumps or sucks the pollutants through the valves <NUM>'.

Alternatively or additionally, actuation of the or each valve <NUM>' may be synchronized with the rotation of the cleaning arm <NUM>'. For example, the or each valve <NUM>' may be configured to open or actuate when the cleaning member <NUM>' passes a respective valve <NUM>'. <FIG> show an example valve actuator assembly <NUM> configured to actuate each the or each valve <NUM>' in response to the rotation of the cleaning arm <NUM>'. The assembly <NUM> comprises a cam <NUM>' configured to rotate about the driveshaft axis with the cleaning arm <NUM>'. The cam <NUM>' may be coupled to the drive shaft <NUM>' and/or any part of the dynamic filter element <NUM>' that rotates with the cleaning arm <NUM>. The assembly <NUM> further comprises one or more actuating members <NUM>' or arms <NUM>' (e.g. an actuator member for each valve <NUM>'). The actuating arms <NUM>' are arranged and configured to transfer an actuating force from the cam <NUM>' to a respective valve <NUM>' to actuate the valve <NUM>'.

The or each actuating arm <NUM>' is actuated by a cam surface (not shown) of the cam <NUM>'. The cam surface has a profile (e.g. one or more projections, or depressions) configured to actuate the actuating arm <NUM>' when the cleaning member <NUM>' is aligned with a respective valve <NUM>'. The cam surface may be axial surface or a radial surface of the cam <NUM>'. In the example shown, each actuating arm <NUM>' is coupled at one end to a respective valve <NUM>' and the other end is arranged at or near the cam surface to receive the actuating force from the cam surface upon rotation of the cam <NUM>'. For example, the actuator arm <NUM>' may be or comprise a cam follower configured to run along the cam surface to actuate the respective valve. The or each actuating arm <NUM>' is coupled to the rear wall <NUM>'. In the example shown, the or each actuating arm is pivotably coupled to rear wall at a coupling 162a'. Actuation of the actuating arm <NUM>' by the cam surface pivots the arm about the coupling 162a' to apply an actuating force to the valve <NUM>'. The cam surface and the coupling 162a' may be configured to pivot the actuating arm <NUM>' away from the rear wall <NUM>', as shown in <FIG>. Alternatively, the cam surface and the coupling 162a' may be configured to pivot the actuating arm in the plane of the rear wall <NUM>' (e.g. to one side, in the plane of the rear wall <NUM>').

The assembly <NUM> may further comprise a cover <NUM>' to seal or house the cam <NUM>' and at least a portion of the actuating arms <NUM>' (see <FIG>).

The rear wall <NUM>' may be integral with the housing <NUM>' or chamber <NUM>'. Alternatively, the rear wall may be part of the assembly <NUM> and/or the filter unit <NUM>', either of which may be removable from the housing <NUM>'. In this case, when installed into the housing <NUM>', the rear wall <NUM>' may be configured to seal against the chamber wall(s) <NUM>'b of the housing <NUM>' to prevent fluid leaking into the collection chamber <NUM>' from around the rear wall <NUM>'.

Although only one filtration chamber <NUM>' is shown in the example or <FIG>, in another embodiment, the system <NUM> may comprise a series of filtration chambers 106a', 106b', 106c', as shown in <FIG>. In this case, the valve(s) <NUM>' of the first filtration chamber may lead into a second filtration chamber, and so on. The valve(s) <NUM>' of the first filtration chamber may be or comprise the inlet(s) <NUM>' of the second filtration chamber, and so on. In this way, pollutants may pass through several filtration chambers before reaching the collection chamber <NUM>'. The housing <NUM>' may comprise each filtration chamber <NUM>' and the collection chamber <NUM>'. Alternatively, the system <NUM> may comprise a modular housing including separate modules 110a', 110b', 110c' for each separate filtration chamber 106a', 106b', 106c'. Each module 110a', 110b', 110c' may be connectable to each other and interchangeable. In this way, the system <NUM> may be configurable.

The driveshaft <NUM>' of the system <NUM> may be driven by a drive system (not shown), e.g. including a motor. The drive system may be powered by an external power source, e.g. where the system <NUM> is attached to a marine vessel, power may be provided by the marine vessel. It will be appreciated that the drive system may include any means capable of rotating the driveshaft known in the art. Alternatively or additionally, although not shown, the system <NUM> may also include one or more turbines to drive the driveshaft <NUM>' and the dynamic element <NUM>' in a similar way to the system <NUM> shown in <FIG>. For example, the or each turbine may be located in the first (front) chamber 106a' upstream of the filter unit <NUM>'.

<FIG> shows an example deflector element 112d that may be coupled to the housing <NUM>', <NUM> in front of the inlet <NUM>', <NUM> to inhibit objects larger than a width of the valves <NUM>', <NUM> from entering the chamber <NUM>', <NUM>. The deflector 112d may comprise a grill or a plurality of ribs extending across the inlet <NUM>', <NUM>. The grill or the ribs are configured to define a plurality of openings having a width equal to or less than the width the of the valves <NUM>', <NUM>.

From reading the present disclosure, other variations and modifications will be apparent to the skilled person. Such variations and modifications may involve equivalent and other features which are already known in the art and which may be used instead of, or in addition to, features already described herein.

Although the appended claims are directed to particular combinations of features, it should be understood that the scope of the disclosure of the present invention also includes any novel feature or any novel combination of features disclosed herein either explicitly or implicitly or any generalisation thereof, whether or not it relates to the same invention as presently claimed in any claim and whether or not it mitigates any or all of the same technical problems as does the present invention.

Features which are described in the context of separate embodiments may instead or also be provided in combination in a single embodiment and/or be interchangeable. Conversely, various features which are, for brevity, described in the context of a single embodiment may also be provided separately or in any suitable sub-combination. Features described in connection with a device or system may have corresponding feature definable with respect to a method, and vice versa. The applicant hereby gives notice that new claims may be formulated to such features and/or combinations of such features during the prosecution of the present application or of any further application derived therefrom.

Claim 1:
A system (<NUM>) for reducing water pollution, comprising:
a housing (<NUM>) configured to receive an incoming fluid flow (<NUM>) containing pollutants from a water environment, and output a de-polluted fluid flow (<NUM>) to the water environment;
one or more pollutant filter units (<NUM>) disposed within the housing, each comprising: one or more dynamic elements (<NUM>), optionally or preferably, one or more dynamic filter elements, configured to direct pollutants for removal from the housing; and
at least one turbine (<NUM>) configured to drive the dynamic element, wherein the turbine is actuated by the fluid flow into the housing and/or by a power supply,
characterized in that the at least one turbine is a pair of contra-rotating turbines (<NUM>, <NUM>).