EP2179110A1

EP2179110A1 - Installation and method for reducing eutrophication in a basin

Info

Publication number: EP2179110A1
Application number: EP08786907A
Authority: EP
Inventors: Johann Prod'homme; Eric Boucheron
Original assignee: Hemisphere Sub
Current assignee: 2venir Conseil Sarl
Priority date: 2007-08-09
Filing date: 2008-08-05
Publication date: 2010-04-28
Also published as: FR2919884A1; FR2919884B1; WO2009019275A1

Abstract

The present invention relates to an installation (100) intended to be incorporated into a natural (B) or artificial (B') basin in order to reduce eutrophication, the installation comprising a means (200) external to the basin (B, B') for collecting and transferring water from the bottom of the basin (B, B') and which is liable to contain sediment(s) which has settled under gravity. The collection and transfer means (200) comprises a drain or a network of drains (300) connected to an outfall (400) that passes through a rocky belt (R) or the casing (V) of the basin (B, B') and which emerges, on a slope, outside the basin (B, B') through a valve (410) that allows said basin to be drained or filled. A method for reducing eutrophication in a natural or artificial basin is also claimed.

Description

Installation and method for reducing the eutrophication phenomenon in a pond

The present invention relates to the field of the extraction of sediments likely to be deposited on the bottom of a natural or artificial basin, whether or not placed in a marine environment, in order to maintain the biological functioning within the basin. The invention thus covers an installation intended to be incorporated in a natural or artificial basin to reduce the phenomenon of eutrophication and a method for reducing the phenomenon of eutrophication in a natural or artificial basin.

To reduce the phenomenon of eutrophication of water contained in a pond, a phenomenon caused by an enrichment of water in organic matter and which leads to a proliferation of the flora and certain organisms and a decrease in the oxygen content of the water. water, a known solution is to remove, by dredging, the sediment deposited on the bottom. The regular use of this technique, often using machines injecting large quantities of water under pressure on the bottom of the pond, and aspiration of the dispersed sediments can certainly remove a large amount of these sediments but also temporarily disturbs the equilibrium of the environment by increasing the turbidity of the water and erodes the bottom. This dredging technique that implements powerful machines is also very expensive.

The document WO-A1-2004 / 012502 still shows a fish farm in a reservoir situated at the seaside. It consists of a tank placed on the ground, pumps and pipes for supplying the water tank. from the sea, from an evacuation pipe to the sea, from the water contained in the reservoir. A perforated waste collection pipe is placed longitudinally in the bottom of the tank to siphon the water laden with waste produced by the fish in order to discharge it into a settling tank. Filtered water flows into the sea. A looped filter tank sucks in and releases water into the tank. This is arranged so as to have its main or longitudinal axis substantially parallel to the shore.

The object of the invention is therefore to provide an installation capable of extracting sediments likely to be deposited on the bottom of a basin without disturbing the environment and whose operating cost can be much lower than that of dredging machines. .

For this purpose, an installation intended to be incorporated in a natural or artificial basin to reduce the eutrophication phenomenon is proposed, the installation comprising means of captation and transfer outside the water basin at the level of the bottom of the basin and which is likely to contain sediments deposited by gravity. According to the invention, the capture and transfer means comprises a drain or a network of drains connected to an outfall passing through a rock belt or the basin envelope and which opens on a slope outside. basin through a valve for draining or filling said basin.

The sediments contained in the water of the basin, and which are deposited on the bottom, can in this way be extracted with the water that the means of capture and transfer withdraws. Sediment extraction does not erode the bottom of the pond and does not increase the turbidity of the water. The operation of the facility reduces the eutrophication of the water contained in the pond, increases the natural lighting by reducing the turbidity of the water, which contributes to improving the biological functioning of the basin and therefore contributes to maintaining local species (marine or freshwater). The cost of operating the facility is much less expensive than that of dredging techniques.

When the basin is built in a marine environment, the outfall is placed so as to emerge in it below the level of the lowest low tides. It is therefore possible, by opening the valve for a short time at low tide, to siphon the water from the bottom of the basin containing sediment, that is to say without consuming energy. It is also possible by opening the valve at high tide for some time to complete the filling of the basin with water from the marine environment.

According to an additional feature of the invention, the drains are connected to a collection pipe and a turbine driven by an electric motor is interposed between the collection pipe and the outfall to pump water from the basin containing sediments to transfer to the outside of the pond or add water to the basin from a marine environment if there is no tidal flow or when the tides are small. Extraction of the sedimented water or the filling of the basin is thus carried out by pumping.

According to an additional feature of the invention, the electric motor is of the type that can operate as an alternator to produce electrical energy when the turbine is driven by a stream of water. The installation can thus produce electrical energy from the potential energy of the water circulating by gravity between the pond and the natural environment and vice versa. This energy is preferably stored in batteries for later use.

According to an additional feature of the invention, the installation is provided with a wave generator capable of lifting and transporting sediments towards the bottom of the basin to be picked up more quickly.

This wave generator is also used to create in the water basin a hydraulic flow reproducing natural turbulence, for example, beaten mode or sheltered mode, so as to improve the biological functioning of the basin. According to an additional feature of the invention, the wave generator comprises a reservoir and a siphon designed to periodically drain into the basin a quantity of water stored in the tank, the wave generator using the turbine to fill the tank. According to an additional feature of the invention, the turbine is placed on a separating wall separating the reservoir into an upper cavity and a lower cavity, a suction pipe being connected to the reservoir on the outside thereof while opening in the lower cavity through a second valve while its free end opens into the basin, the siphon being placed in the upper cavity, the collection pipe opening into the upper cavity, through a third valve while the emissary opens into the lower cavity.

The turbine is thus exposed to the flow of water circulating between the two cavities for pumping or producing electrical energy. According to an additional feature of the invention, a tube passes horizontally through a wall of the upper cavity of the tank, a fourth valve being connected to this tube to open or close its internal passage.

By opening this valve and that of the emissary and closing the other two, it can achieve a water intake in the basin from the marine environment. It can be done by pumping since the turbine is placed in the flow or by siphoning between the marine environment and the basin. In this case, the turbine drives the electric motor that should be switched to alternator to produce energy.

According to an additional feature of the invention, the installation comprises a wave generator device. The formation of waves on the surface of the pond water by the generating device increases the exchange surface between the water and the air, which makes it possible to increase the oxygen content of the water. The generating device still produces a surface hydrodynamism to simulate natural conditions.

According to an additional feature of the invention, the wave generating device comprises a floating sphere internally provided with means able to move the position of its center of gravity.

The floating sphere is locally held in place, for example by a rope, and its operation generates waves.

According to an additional characteristic of the invention, the installation comprises several capture and transfer means and / or several wave generators and / or several wave generating devices.

According to an additional characteristic of the invention, the installation comprises a control unit able to control, as a function of parameters, the operation of the electric motor of the turbine, the various valves and that of the wave generating device.

According to an additional feature of the invention, the drain or drains are arranged against the bottom of the basin. According to an additional feature of the invention, the drain or drains are placed under the basin and open through a collection mouth located in the bottom of the basin.

According to an additional characteristic of the invention, at least one side wall of the basin forms a slope for directing the sediments towards the collecting mouth.

According to an additional characteristic of the invention, the drain or drains open through a side wall of the basin.

According to an additional feature of the invention, a drain is placed in a side wall of the basin. According to an additional feature of the invention, a drain is disposed against the side wall, inside the basin.

A method for reducing the phenomenon of eutrophication in a natural or artificial pond is also proposed, the method consisting in drawing water from the bottom of the pond that may contain sediments deposited by gravity and rejecting it at the same time. outside the basin. According to the invention, the method consists in draining or filling said basin through a drain or a network of drains connected to an emissary passing through a rock belt or envelope of the basin and which opens sloping outside the basin through a valve.

When the basin is built in a marine environment, the sedimented water of the basin can be withdrawn and filled to its optimum level by simple siphoning. We can still proceed by pumping in the absence of tide.

According to an additional feature of the invention, the method consists in generating in the basin of the swell, by periodic siphoning, the water stored by pumping in a reservoir adjacent to said basin. According to an additional characteristic of the invention, the method consists in generating below the surface of the water of the basin a surface current which participates in recreating marine currents.

According to an additional characteristic of the invention, the method consists in generating waves on the surface of the water of the basin. The characteristics of the invention mentioned above, as well as others, will appear more clearly on reading the following description of an exemplary embodiment, said description being made in connection with the attached drawings, among which: FIG. . 1 is a sectional view of a basin isolated from a marine environment incorporating an installation for reducing the eutrophication phenomenon operating in a sediment extraction phase according to the invention, FIG. 2 is an enlarged sectional view of an installation shown in FIG. 1 according to the invention, FIG. 3 is a sectional view of a pond incorporating an installation for reducing the eutrophication phenomenon shown in FIG. 1 and in which operates a wave generator according to the invention, FIG. 4 is a sectional view of a pond incorporating an installation for reducing the eutrophication phenomenon shown in FIG. 1 operating in a filling phase of the basin according to the invention, FIG. 5 is a sectional view of an alternative embodiment of a floating type basin incorporating an installation for reducing the eutrophication phenomenon according to the invention,

Fig. 6 is a schematic view of a basin provided with a sediment collection drain which is placed under the basin according to the invention, FIG. 7 is a schematic view of a basin inclined wall according to the invention, FIG. 8 is a schematic view of a basin provided with a sediment uptake drain opening through a side wall according to the invention and FIG. 9 shows a schematic view of a basin provided with a sediment capture drain placed in a side wall and a drain placed against a side wall according to the invention.

It is shown in FIG. 1 a basin B which is isolated from a marine environment M by a rock belt R. In this embodiment, it is an artificial basin intended to recreate the environmental conditions of a natural marine environment subjected to tidal to constitute a refugium ®. A refugium ® is defined by the applicant as a semi-open system, which preferentially uses the forces of nature for the conservation of the local natural heritage. It should be noted that the invention could be applied to other types of aquatic enclosures such as, for example, a natural quarry, an artificial structure, a structure installed in the open sea or in the heart of the natural aquatic environment in the case of freshwaters, a port in deep water and mainly of the type that has a threshold or even the management of large aquariums.

Regarding the application of the invention in the ports, its interest lies in the capture and extraction of pollutants such as hydrocarbons likely to be sequestered in the sludge. In the case of ports with locks, it is possible to achieve autonomy of their operation by using the tidal cycle. For ports with thresholds, it is possible to consider active pumping, but not significantly lowering the level. The use of the invention in ports could develop the civic sense of its users.

The basin B presented in FIG. 1, incorporates an installation 100 intended to reduce the eutrophication phenomenon of the water contained in the basin, eutrophication can be defined as a phenomenon caused by an enrichment of water in organic matter and which leads to a proliferation of flora and some organisms and a decrease in the oxygen content of the water. By reducing this eutrophication, we can improve the biological functioning of the basin which is favorable to the maintenance of local marine species. The installation 100 thus comprises a means 200 for capturing and transferring sediment S outside the basin, which may deposit by gravity on the bottom of the basin.

The capture and transfer means 200 consists essentially of a drain or a network of drains 300 arranged against the bottom of the basin B, these drains are connected to a collection pipe 310, itself connected to an outfall 400 passing through through the rocky belt R and which opens into the marine environment M below the level of the lowest low tides which is materialized, in this FIG. 1, by a dashed line MB. In Figs. 1 to 5, the outfall 400 emerges into the marine environment on a downward slope to reach the level of the lowest low tides and to better control the flow therein.

The sediments S which settle on the bottom of the basin B can thus be sucked, mixed with water through the drains 300 to be discharged into the marine environment, either by pumping or by simple siphoning. A riprap E covers the network of drains 300 to protect the animal species near the locations of the perforations of the suction drains.

A valve 410 is connected to the outfall 400, at its outlet in the marine environment M to close or open the passage between the basin B and the marine environment thus draining the sedimented water contained in the basin or the fill to its optimum level. In the open position of the valve 410, the basin is placed in communication with the marine environment M and thus, a natural drainage of the sediments captured on its bottom towards the marine environment is obtained when the water level of the medium Marine M is lower than that of Basin B. Arrows Fl show sediment circulation towards the marine environment M.

On the other hand, when the water level of the marine environment is higher than that of the basin as shown in FIG. 4, the opening of the valve 410 causes an influx of water from the marine environment in the basin. This can be used to renew the amount of water in the basin that has evaporated or used to drain sediment. Arrows F2 show the circulation of water from the marine environment M.

A turbine 420, driven by an electric motor 422, is interposed between the collection pipe 310 and the outfall 400 to pump water from the basin B containing sediments S in order to transfer it to the outside thereof, for example. example in the marine environment M or make a contribution of water in the basin B from the marine environment M and this in the absence of tidal range or when the tides are of small amplitudes.

The electric motor 422 of the turbine 420 is capable of being supplied with current by batteries, a wind turbine or by an apparatus producing energy from the movement of waves, tides or ocean currents, solar energy or any other source of energy, when the pool is remote from a power source. This motor can, in the opposite case, be connected to the electrical network.

The turbine 420 may be driven by the gravity flow circulating between the marine environment M and the basin B or vice versa. This faculty is interesting because it makes it possible to recover the potential energy of the water resulting from the difference in the level of water existing between the level of the basin B and that of the marine environment M. For this one can use, as motor unit connected to the turbine 420, an electric motor 422 of the reversible type, that is to say that can also operate as an alternator to produce electrical energy when it is driven by the turbine while it is exposed to a stream of water. This energy is stored in batteries so that it can be used by the installation 100 when necessary.

In order to simulate the movement of the waves inside the basin, the installation 100 is provided with a wave generator 500 capable of lifting and transporting the sediments contained in the water of the basin towards its bottom to be there. picked up faster.

In FIG. 2, the wave generator 500 thus comprises a tank 510, arranged for example against a wall of the rock belt R, and a siphon

520 designed to periodically drain in the basin B a quantity of water stored in the tank 510. The wave generator 500 also uses the turbine 420 to pump water contained in the basin B to fill the tank 510.

To allow this, the turbine 420 is mounted in a particular manner. Indeed, this turbine is placed on a separation wall 512 separating into two cavities, an upper 514 and a lower 516, the tank 510. The turbine is thus exposed to the flow of water flowing between the two cavities 514 and 516 to pump or produce electrical energy.

A suction line 530 is connected to the tank 510 outside thereof. It opens into the lower cavity 516 through a second valve 540 while its free end opens into the basin B. The siphon 520 is placed in the upper cavity 514 of the tank 510. Moreover, the collection pipe 310 opens into the upper cavity, through a third valve 320 while the emitter 400 opens into the lower cavity 516.

Thus, when the two valves 410 and 320 are closed and the valve 540 is open, driving the turbine 420 in a direction of rotation by its motor 422 pumps water contained in the basin B to transfer it into the tank 510 which fills up then.

The siphon 520 comprises an angled portion 522 facing the top of the tank and which extends on one side and downwards by a first portion 524 opening into the tank 510 and on the other side by a second portion 526 which extends also downwards, then by a bent portion which opens into the basin B passing through a wall of the tank.

During operation of the electric motor 422, and as shown by the arrows F3 in FIG. 3, the turbine fills the tank 510. In FIG. 2, the water level then rises to fill the first portion 524 and when this water through the bent portion 522, the siphon 520 begins and discharges violently in the basin B a quantity of water contained in the tank 510 as shown by the arrows F4 in FIG. 3. Draining continues until the water level drops below the outlet of the first portion 524, visible only in FIG. 2, then causing the siphon to be defused. A new filling and emptying cycle starts next.

The sudden rejection of a quantity of water in the basin causes the suspension of sediments deposited and which will move by gravity towards the bottom of the basin where they can be sucked, mixed with water, by means of Capture and transfer 200. This water spill also generates, through the strong turbulence it produces, a hydrodynamic circuit in the B basin that helps to recreate the maritime environmental conditions. The power of these turbulences logically decreases with the distance of the outlet of the siphon 520. Depending in particular on the pumping capacity of the turbine 420, it is possible to obtain turbulence generation cycles more or less close together.

As mentioned above, with reference to FIG. 4, the opening of the valve 410 makes it possible to add water from the marine environment M to the pond B. This works as long as the valves 540 and 320 remain closed and the water level of the marine environment M greater than that of basin B. In FIG. 2, this water supply in the basin B is advantageously carried out via the tank 510 and more precisely through a tube 550 horizontally traversing a wall of the tank 510, in its upper cavity 514, being located at below the siphon 520. A fourth valve 560 is connected to this tube 550 to open or close its internal passage. Thus, and as shown in FIG. 4 by the arrows F2, the admission, through the tube 550, in the basin B, water from the marine environment M produced in the basin, a surface current that participates in recreating marine currents. In addition, the turbine 420 which is exposed to the water flow is used to produce electrical energy. This turbine 420 drives the electric motor 422 switched alternator and supply power storage batteries. In the absence of a difference in level between the marine environment and the pond, the electric motor 422 is supplied with electric current by means of batteries, a wind turbine or an apparatus producing energy from the wave movement or by being connected to an electricity grid or any other renewable source of energy.

The particular arrangement of the turbine 420 on a partition wall 512, shown in particular in FIG. 2, has the further advantage of allowing maintenance operations of the installation 100 and in particular interventions on the turbine 420 and its motor 422, on the siphon 520, as well as on the two valves 320 and 560.

In Figs. 1, 3, 4 and 5, the installation 100 also comprises a wave generating device 600 intended to allow the oxygenation of the water in the pond B to be increased by increasing the exchange surface on the surface of the water and maintain a hydrodynamic movement of water in the basin.

The wave generating device 600 comprises a floating sphere 610 held locally in place, for example by ropes, and which is provided with a means capable of being able to move the position of the center of gravity of the floating sphere 610. This means is advantageously housed inside the floating sphere 610. It comprises an electric motor capable of moving a mass so as to modify the position of its center of gravity. In this way, the movement of the mass produces a vertical movement of the floating sphere 610 which generates a wave of waves favoring the oxygenation of the water and a movement of the water near the surface of the water . The power supply, advantageously made by battery, is also housed inside the floating sphere 610 to make autonomous the operation of the wave generator 600. The floating sphere also incorporates a means of remote control of the operation of the electric motor.

The operation of the installation 100 is implemented by a control unit, not shown, which controls, as a function of parameters, the operation of the electric motor 422 of the turbine 420, the various valves 410, 320, 540 and 560 and than that of the wave generator device 600.

Although this is not shown in Figs., The installation 100 may comprise in relatively large basins several capture and transfer means 200, several wave generators 500 and several wave generating devices 600.

We will now discuss the operation of the installation 100, the main phases of the operation of the installation 100 being as follows. In order to withdraw the sediments S deposited at the bottom of the basin B in order to transfer them into the marine environment M, the valves 320 and 410 are open and the other two, that is to say the valves 540 and 560 are closed. When the level of the water in the marine environment M is lower than that of the pond, the sediment-laden water is siphoned into the marine environment M via the drains 300. The drive of the electric motor 422 switched to an alternator turbine 420, produces electric current and charges batteries.

In the absence of tidal movement, the electric motor 422 is connected to a source of electric power so that the turbine 420 pumps the water and the sediments that it contains to the marine environment M.

To fill the basin, the valves 560 and 410 are open and the other two, that is to say the valves 540 and 320 are closed. Basin B is preferably filled when the level of the water of the marine environment M is greater than that of the pond so that this operation does not consume energy or even produce it. Water is admitted into the pond through the tube 550 producing a surface current.

To generate swell in the basin, the valves 320, 410 and 560 are closed while the valve 540 remains open. Energizing the electric motor 422 of the turbine 420, as well as the operation of the siphon 520, regularly generate a massive influx of water into the pool simulating a swell.

During wave periods, but preferably outside thereof, the wave generating device 600 can be used to oxygenate the water in the pond and produce a hydrodynamic movement of water in the basin.

In the variant embodiment shown in FIG. 5, the basin B 'is an artificial pond floating on a marine environment M, such as a sea, being anchored to the seabed via an anchor A or similar means. Basin B 'can be placed in a place where one wishes to preserve a local biodiversity.

It can still be used as an experimental device to study the effects of environmental parameters on an ecosystem, serve as an aquaculture farm, acclimation basin or temporary storage tank for living species (case of buffer tanks for example). Note that in this variant shown in Fig.5, the renewal of the water can be provided by a capture, not shown, the overflow of waves on the outer walls of the basin B '. This water supply manages to create a difference in hydrostatic pressure inside the basin B 'by relative to the natural environment M, thus promoting an evacuation of the sediment-laden bottom water through the pipe 400. To evacuate this water outside the basin, the valve 410 remains permanently open. The operation of this valve is however, in an alternative embodiment not shown, controlled by the control unit taking into account, by means of a suitable sensor, the hydrostatic pressure inside the basin B '. The closure of this valve can be controlled, for example, in case of pollution of the natural environment.

Basin B 'incorporates an installation 100 intended to reduce the phenomenon of eutrophication of the water it contains. It consists of an envelope V containing a relatively large amount of water from the surrounding marine environment to reproduce the local living conditions in which plant and animal species can develop.

In the embodiments of tanks B or B 'shown in Figs. 6-9, attempts have been made to minimize the network of drains based on associated ancillary devices designed to concentrate the sediments or better capture them. These devices are:

* Brewing pump, injection of water or air into the pond water, to suspend the sediment.

* Slope at the bottom of the basin to facilitate drainage in the drains. * Various sediment removal techniques such as vibrations.

In FIG. 6, the drain or drains 300 are placed under the basin B or B 'and open through a catchment mouth BC located in the bottom of the basin. They are no longer visible in the pool and are not troublesome. A pump P1 can pump water from the basin containing sediment.

In FIG. 7, at least one side wall L of the basin B or B 'forms a slope P to direct the sediments towards the catchment mouth BC.

In FIG. 8, the drains 300 open through a side wall of the basin B or B '. Their pose is easier than those presented in FIG. 6. In FIG. 9, and on the left of the figure, a drain 300 is placed in a side wall L of the basin B or B 'so that it is not apparent. On the right of the figure, a drain 300 is disposed against the side wall L, inside the basin, simplifying its installation. The pump P1 shown in Figs. 1, 2 and 3 can be split so that one of the pumps can take over in case of failure of the other pump.

Conversely, the pump may not exist to fill, drain the pond by gravity with the tide. The applications targeted by these variants relate to the port domains for which we seek to clarify the water by preventing the ports from being silted up. The clarity of the water is sought because it is an important security element. For example, we can appreciate the depth of the basin to compare it with the draft of a boat. The installation intended to reduce the eutrophication phenomenon of the water contained in a basin of the invention makes it possible to model the natural environment by proceeding with the extraction of the sediments of the basin by a partial emptying of the latter, by proceeding to filling, producing waves or surface currents or producing waves. It reduces management costs by using the potential energy of moving water bodies or by using renewable energies.

It helps to maintain species and biological communities in large volumes of water while getting as close as possible to the parameters of the natural environment. The management of the operation of the valves, the turbine engine and the wave generator by the control unit provides a modularity of the operation of the installation to adapt the quality and quantity of the water of the basin to the desired goal.

In addition, the installation can operate in a closed circuit for several days by completely isolating the basin from the surrounding environment. For example, in the event of a harmful environmental impact on the marine environment, the facility protects the biological communities living in the basin.

Claims

1) Installation (100) intended to be incorporated in a natural basin (B) or artificial (B ') to reduce the phenomenon of eutrophication, the installation comprising a means of capture and transfer (200) outside the basin (B, B ') of the water at the bottom of the basin (B, B') and which is capable of containing sediments (S) deposited by gravity, characterized in that the means of capture and transfer (200) comprises a drain or a network of drains (300) connected to an outfall (400) passing through a rock belt (R) or a shell (V) of the basin (B, B ') and which debouches on a slope outside the basin (B, B ') through a valve (410) for draining or filling said basin. 2) Installation (100) according to claim 1, characterized in that the drains

(300) are connected to a collection line (310) and a turbine (420) driven by an electric motor (422) is interposed between the collection line (310) and the outfall (400) for pumping basin water (B, B ') containing sediments (S) for transfer to the outside of the pond (B, B') or adding water to the basin (B, B ') from a marine environment (M) in the absence of tidal range or when the tides are small.

3) Installation (100) according to claim 2, characterized in that the electric motor (422) is of the type that can operate as an alternator to produce electrical energy when the turbine (420) is driven by a stream of water . 4) Installation (100) according to any one of claims 1 to 3, characterized in that it is provided with a wave generator (500) capable of lifting and transporting sediment (S) towards the bottom of the basin (B, B ') to be picked up more quickly.

5) Installation (100) according to claim 4, characterized in that the wave generator (500) comprises a reservoir (510) and a siphon (520) adapted to periodically drain into the basin (B, B ') a amount of water stored in the tank (510), the wave generator (500) using the turbine (420) to fill the tank (510).

6) Installation (100) according to claim 5, characterized in that the turbine (420) is placed on a partition wall (512) separating the tank (510) into an upper cavity (514) and a lower cavity (516) , a suction line (530) being connected to the tank (510) on the outside thereof, opening into the lower cavity (516) through a second valve (540) while its free end opens into the basin (B, B '), the siphon (520) being placed in the upper cavity (514), the collecting duct (310) opening into the upper cavity (514), through a third valve (320) while the outfall (400) opens into the lower cavity (516).

7) Installation (100) according to claim 6, characterized in that a tube (550) passes horizontally through a wall of the upper cavity (514) of the tank (510), a fourth valve (560) being connected to this tube ( 550) to open or close its internal passage. 8) Installation (100) according to any one of the preceding claims, characterized in that it comprises a wave generating device (600).

9) Installation (100) according to claim 8, characterized in that the wave generating device (600) comprises a floating sphere (610) internally provided with a means adapted to move the position of its center of gravity.

10) Installation (100) according to any one of the preceding claims, characterized in that it comprises a plurality of capture and transfer means (200) and / or several wave generators (500) and / or several wave generating devices (600). 11) Installation (100) according to any one of claims 8, 9 or 10, characterized in that it comprises a control unit adapted to control, depending on parameters, the operation of the electric motor (422) of the turbine (420), different valves (410, 320, 540 and 560) as well as that of the wave generating device (600). 12) Installation (100) according to any one of claims 1 to 11, characterized in that the drain (s) (300) are arranged against the bottom of the basin (B, B ').

13) Installation (100) according to any one of claims 1 to 11, characterized in that the drain (s) (300) are placed under the basin (B, B ') and open through a collecting mouth ( BC) located in the bottom of the basin.

14) Installation (100) according to claim 13, characterized in that at least one side wall (L) of the basin (B, B ') forms a slope (P) for directing the sediments towards the collecting mouth ( BC). 15) Installation (100) according to any one of claims 1 to 11, characterized in that the drain (s) (300) open through a side wall of the basin (B, B ').

16) Installation (100) according to any one of claims 1 to 11, characterized in that a drain (300) is placed in a side wall (L) of the basin (B,

B ').

17) Installation (100) according to any one of claims 1 to 11, characterized in that a drain (300) is disposed against the side wall (L), inside the basin (B, B '). 18) Method for reducing the eutrophication phenomenon in a natural basin

(B) or artificial (B '), consisting of withdrawing from the bottom of the pond (B, B') water likely to contain sediment (S) deposited by gravity and to discharge it outside the basin ( B, B '), characterized in that it consists in draining or filling said basin through a drain or a network of drains (300) connected to an emissary (400) passing through a belt rock (R) or a shell (V) of the basin (B, B ') and which opens on a slope outside the basin (B, B') through a valve (410).

19) A method according to claim 18, characterized in that it consists in generating in the basin (B, B ') of the swell by periodic siphoning water stored by pumping into a tank (510) adjacent said basin.

20) A method according to claim 18 or 19, characterized in that it consists in generating below the surface of the water basin (B, B ') a surface current that participates in recreating marine currents.

21) Method according to claim 18, 19 or 20, characterized in that it consists in generating waves on the surface of the water basin (B, B ').