Ship equipped for algae sterilization, and sterilization method implemented

Abstract

The present invention relates to a ship (1) equipped with: means for collecting floating algae; a crusher capable of crushing the collected algae; a press capable of pressing the crushed algae, in order to separate the solid algae residues from the pressing water; means for packaging the solid algae residues in a sealed biodegradable packaging; and means for sterilizing the pressing water. The invention also relates to a method for sterilizing algae on board a ship (1), comprising: a step of crushing the algae; a step of pressing the crushed algae, in order to separate the solid algae residues from the pressing water; a step of packaging the solid algae residues in an airtight biodegradable packaging; and a step of sterilizing the pressing water, these steps being implemented on board the ship (1).

Description

Vessel equipped for algae sterilization, and sterilization process implemented Scope of the invention

[0001] The present invention relates to means of combating the proliferation of floating algae, particularly at sea.

[0002] In particular, the invention relates to means for sterilizing floating algae that are collected at sea, that is to say means for preventing these algae from reproducing, in order to limit their proliferation.

[0003] The invention relates in particular to such means carried by a ship, capable of sterilizing floating algae collected by that ship. Previous art

[0004] Many marine algae float near the surface of the water, without being rooted. One such algae is Sargassum, which encompasses several species, including Sargassum fluitans and Sargassum natans. These algae thrive particularly in tropical areas of the Atlantic Ocean, in and around the Sargasso Sea, and off the coast of Brazil. They benefit from a nutrient-rich environment, largely due to the runoff from rivers in Africa and the Americas. They grow in large quantities and form patches that drift across the sea.

[0005] These algae reproduce primarily vegetatively, notably through fragmentation and continuous growth of the fragments. They can also, under certain conditions, reproduce sexually.

[0006] Sargassum seaweed poses a particular problem when it washes ashore. Such seaweed strandings can be massive, especially in the Caribbean islands and the Gulf of Mexico. It is estimated that between 20,000 and 40,000 tons of sargassum accumulate annually on the Guadeloupe coastline alone. There, the seaweed forms unsightly deposits whose decomposition releases hydrogen sulfide, causing an unpleasant stench. When such deposits attach to coral reefs, they can lead to coral damage. Finally, these deposits hinder swimming and water sports on the beaches. Removing this seaweed from the beaches generates a significant cost for local communities. These deposits therefore cause considerable harm to areas where a large part of the economy relies on tourism.

[0007] Several technical solutions exist for collecting these algae, both on the coast and at sea near the coast. These solutions are hampered by the problem of storing the collected algae, which can represent significant volumes. During a sea-based collection campaign, it is difficult to store enough algae on board vessels for the collection to have a substantial impact. Onshore storage itself requires large areas, where the decomposition of the stored algae generates pollution. This decomposition leads to the emission of hydrogen sulfide into the air and the runoff of polluted water. It should be noted that this runoff from algae storage sites can contain reproductive elements capable of generating new algae. Therefore, algae storage can become a contributing factor to the proliferation of these algae near the coast.

[0008] Document FR3042169A1 describes a vessel equipped with a seaweed harvesting system and a system for compacting the harvested seaweed to remove the water contained within it. This water is sterilized, for example, by a UV lamp, before being discharged at sea. The compacted seaweed is then bundled into bales, held together by a film, wire, or string, which may be biodegradable, allowing the bales to be sunk at sea.

[0009] This prior art solution, however, proved ineffective for sterilizing the collected sargassum seaweed, that is, for preventing the sargassum seaweed gathered by the ship from giving rise to new algae. Indeed, even if the press water is recovered and treated, the compressed bundles of seaweed still contain gametes capable of reproduction.

[0010] Since the boots are not sealed, after being put back in the water, they can release water and live gametes, which can then allow new algae to grow.

[0011] Furthermore, the boots sunk at sea, held in place by biodegradable packaging, can release algae capable of reproducing vegetatively, through fragmentation, as the packaging degrades. Some of these algae can remain alive, despite being compressed, and reproduce, giving rise to new algae. This reproduction occurs all the more easily when compression strongly fragments this type of algae.

[0012] This vessel, proposed by earlier art, while collecting algae floating on the surface of the water, therefore causes the birth of new algae, promoting their proliferation.

[0013] The present invention aims to overcome these drawbacks of the prior art.

[0014] In particular, one objective of the invention is to propose technical solutions enabling more effective control of the proliferation of floating algae at sea.

[0015] A particular objective of the invention is to limit the negative impact on the environment of such algae, and in particular Sargassum algae.

[0016] Another objective of the invention is to enable the collection of such floating algae by a vessel, without the storage of the collected algae excessively limiting the quantity of algae that can be collected.

[0017] Yet another objective of the invention is to enable the collection of such floating algae by a ship, without the storage of the collected algae generating pollution.

[0018] Yet another objective of the invention is to enable the collection of such floating algae by a ship, without the storage of the collected algae allowing the dissemination at sea of ​​reproductive elements capable of causing the appearance of new algae, and which could promote their proliferation.

[0019] Another objective of the invention is to provide a process enabling the sterilization of algae, that is to say, enabling these algae to prevent them from giving rise to new algae, whether by vegetative reproduction or by sexual reproduction.

[0020] These objectives, as well as others which will become clearer later, are achieved by the proposed process, using a vessel equipped with: means for collecting floating algae, a crusher capable of shredding algae collected by the means of collection, a press for compressing the crushed algae, packaging means capable of conditioning the solid residues of algae in an airtight biodegradable envelope, a means of recovering the pressing water, and means of sterilizing the pressing water.

[0021] The vessel equipped according to the invention can thus treat the algae in such a way that they cannot reproduce. This vessel can discharge the sealed, solid algae residues and the pressing water into the sea without risking the release of algae reproductive elements into the sea that could lead to their proliferation.

[0022] Indeed, the crushing of seaweed before pressing breaks it down to such an extent that it is impossible for it to reproduce by fragmentation if it is subsequently released into the sea. Furthermore, the airtight packaging of the solid seaweed residue prevents the release of the algae's reproductive elements. This airtight packaging also leads to the rapid death of the living cells it contains. If these airtight packages containing seaweed residue are discarded at sea, the algae cells that could allow for reproduction die before the packaging degrades. Only dead cells, unable to give rise to any new algae, are thus spread across the seabed when the packaging breaks down.

[0023] Such a vessel can therefore carry out campaigns to collect large quantities of seaweed, without it being necessary to store all the collected seaweed on board the vessel.

[0024] The packaged solid algae residues can thus be submerged in the sea without generating lasting pollution.

[0025] Preferably, the means for sterilizing the pressing water include: means for heating this water to a temperature suitable for destroying the reproductive elements of algae, and / or means for exposing this water to ultrasound, and / or means for exposing this water to ultraviolet radiation.

[0026] Advantageously, the means of sterilizing the pressing water include a pressing water storage tank in the vessel.

[0027] The invention also relates to a method for sterilizing algae on board a ship, comprising: a step of pressing algae on board the ship to separate the solid algae residues from the pressing water, a step of packaging the solid algae residues on board the ship, and a step of sterilizing the pressing water on board the ship. This method comprises, according to the invention, a step of grinding algae on board the ship before the pressing step, such that the pressing step is carried out on the ground algae, and the packaging step consisting, according to the invention, of packaging said solid algae residues in an airtight biodegradable package.

[0028] According to an advantageous embodiment, the packaging step is followed by a step of immersion, at sea, of the packaged solid seaweed residues.

[0029] Advantageously, the pressing water sterilization step is followed by a step of discharging the sterilized water into the sea.

[0030] Advantageously, the sterilization step of the pressing water includes: heating this pressing water to a temperature suitable for destroying the reproductive elements of said algae, and / or exposing this pressing water to ultrasound, and / or exposing this pressing water to ultraviolet radiation.

[0031] Preferably, the process includes a preliminary step of collecting floating algae on board the ship. Description of the figures

[0032] The invention will be better understood upon reading the following description of preferred embodiments, given by way of simple figurative and non-limiting example, and accompanied by the figures among which: is a side view of a vessel equipped, according to an embodiment of the invention, for the collection and sterilization of floating algae, is a front view of the vessel, in a configuration facilitating its movement, is a front view of the vessel, in a configuration allowing the collection of floating algae, is a cross-sectional view of the vessel, along a vertical longitudinal plane, is a cross-sectional view of the vessel, along a horizontal longitudinal plane, is a cross-sectional view of the vessel, along a vertical transverse plane.

[0033] Figures 1 to 6 are schematic representations of a vessel 1 equipped, according to an embodiment of the invention, for the collection and sterilization of floating algae, and in particular sargassum seaweed. The term "sargassum seaweed" refers, in this description, to floating algae which may include several species of algae, for example, the species *Sargassum fluitans* and *Sargassum natans*. The expression "algae sterilization" refers, in this description, to a treatment which prevents these algae from giving rise to new algae, whether by vegetative or sexual reproduction.

[0034] This vessel 1 is advantageously of the catamaran type, 46 m long and 13.50 m wide. It has a port hull 11 and a starboard hull 12 connected by connecting arms supporting the central cabin 13.

[0035] In the embodiment shown, the vessel 1 includes a conveyor belt 2 for collecting floating seaweed. In the embodiment shown, this conveyor belt consists of a fixed upper section 21 and a movable lower section 22. The lower section 22 is movable between an upper and a lower position. It is shown in its upper position in Figure 1, and in its lower position in Figures 3 and 6. Figure 1 represents this lower section 22 both in its upper position as a dashed line (referenced 221) and in its lower position as a solid line (referenced 222).

[0036] When the lower section 22 is in its upper position, it is maintained in a substantially horizontal position above the water level, so as not to impede the navigation of the ship 1.

[0037] When the lower section 22 is in its lowered position, the conveyor belt 2 forms an inclined plane whose forward edge 220 dips into the water, at a shallow depth, between the two hulls 11 and 12 of the vessel 1. As the vessel 1 moves forward, the floating algae passing between the two hulls come to rest on this conveyor belt 2. This is mainly made up of meshes close enough to collect the algae, but allowing water to pass through, so as not to unduly slow the vessel 1 down.

[0038] Conveyor belt 2 is in motion, in order to transport the algae resting on it from its front edge 220, immersed in the water, to its rear end 210.

[0039] Advantageously, this rear end 210 is located at the level of the central cabin 13 of the ship 1, under the pilot station, where the collected algae are brought.

[0040] Such a method of collecting floating algae by a ship is well known in itself to the person skilled in the art, for example from document FR3042169A1.

[0041] The collected seaweed is first conveyed, via conveyor belt 2, to a first zone 3 of the central compartment 13 of the vessel 1. This first zone 3 is equipped with a crusher or grinder suitable for grinding the seaweed. The crusher or grinder used is advantageously configured to grind the seaweed into pieces smaller than those required for the seaweed to reproduce vegetatively.

[0042] After being crushed in the first zone 3, the crushed seaweed is conveyed into a second zone 4 of the central cabin 13 of the ship 1. In the embodiment shown, the second zone 4 is located below the first zone 3, so that the conveyance of the crushed seaweed from the first zone 3 to the second zone 4 can be done by gravity.

[0043] This second zone 4 is equipped with a press capable of crushing, or pressing, the ground seaweed in order to extract the water and reduce its volume. Such pressing can, for example, be carried out by one or more hydraulic presses, with the ground seaweed placed between sieves that allow the water to drain during the pressing process.

[0044] Such pressing can advantageously reduce the crushed seaweed to a solid residue whose weight and volume are less than, respectively, the weight and volume of the seaweed collected before crushing and pressing. Thus, in a preferred embodiment, pressing reduces the crushed seaweed to a solid residue whose weight and volume are less than half the weight and volume of the seaweed collected before crushing and pressing.

[0045] After pressing, the resulting seaweed residue is compact and relatively solid. Depending on the pressing method, it can be in the form of blocks or compact bundles.

[0046] After pressing in the second zone 4, the seaweed residue is conveyed to a third zone 5 of the central compartment 13 of the vessel 1. This third zone 5 is equipped with packaging means suitable for packing bundles of seaweed residue in airtight packaging. This packaging is preferably biodegradable.

[0047] This packaging can, for example, be made using polyethylene film. It can be done manually or with an automatic packaging machine. The airtightness of the packaging can be ensured, for example, by welding the films used to make the packaging, by gluing these films, or by applying adhesive tape to seal the film sections airtight.

[0048] Such packaging of algae residues in airtight packaging destroys, in a relatively short time, the living cells of the algae, and in particular the reproductive elements of these algae.

[0049] The packaged bales can be stored on the vessel 1. In the embodiment shown, the vessel 1 is equipped with a telescopic crane 61, or an overhead crane, enabling the transfer of the bales of seaweed residue 9 from the third area 5 to a storage position on the rear deck 6 of the vessel 1.

[0050] The relatively small volume of the seaweed residue bales 9, compared to the amount of seaweed collected, allows for the storage of a significant quantity on the aft deck 6. Furthermore, since the seaweed residue in these bales is packaged in an airtight container, no liquid containing algae reproductive elements can leak out. Nor can any gases from the decomposition of the seaweed escape, thus preventing any atmospheric pollution.

[0051] These bundles of seaweed residue 9 can then be brought back to shore for further processing.

[0052] It is also possible, according to an alternative embodiment of the invention, for these bundles of seaweed residue 9 to be submerged at sea, preferably at a great depth, with ballast if necessary. Preferably, such a submersion of the bundles of seaweed residue 9 is carried out after these bundles have been stored on the vessel 1 for a few days, which ensures the destruction of the reproductive elements of the algae, such as spores and gametes, present in the bundles. The telescopic crane 61 or the overhead crane fitted to the aft deck 6 can advantageously be sized to allow the bales of seaweed residue 9 to be dropped from the stern of the vessel 1.

[0053] The bundles of seaweed residue, submerged in the water and deprived of oxygen, decompose naturally. Over time, the biodegradable polyethylene film breaks down, allowing the seaweed residue to return to its natural environment on the seabed, without producing more pollution than the natural decomposition of the algae, and without causing the proliferation of new algae.

[0054] The seaweed harvesting campaign conducted by vessel 1 can therefore continue for a relatively long period. The deep-sea immersion of the seaweed residue bundles 9 allows vessel 1 to continuously collect and sterilize seaweed at sea, without having to interrupt the harvesting campaign to bring the seaweed residue bundles 9 back to shore.

[0055] According to an important feature of the invention, the water from the crushing and pressing of the crushed seaweed is not discharged directly into the sea. On the contrary, this water is advantageously sterilized in order to eliminate the microorganisms it contains, and in particular the reproductive elements of the seaweed.

[0056] In the embodiment shown, this grinding and pressing water is thus recovered and treated on board the ship 1. This grinding and pressing water first undergoes filtration through one or more sieves, which reduces the number of particles suspended in the grinding and pressing water.

[0057] This water from grinding and pressing is then sterilized. Those skilled in the art know several ways to sterilize water, that is, to destroy the germs, microorganisms, and viruses it contains.

[0058] In the preferred embodiment, the grinding and pressing water collected on vessel 1 is heated to a temperature sufficient to destroy the reproductive elements of algae that may be contained in the water, in order to sterilize it.

[0059] In another possible embodiment, the grinding and pressing water collected on the vessel 1 can, in addition to or instead of heating, be exposed to ultrasound or ultraviolet rays, capable of destroying the reproductive elements of algae that may be contained in the water, in order to sterilize it.

[0060] In the embodiment shown, to ensure even more effective sterilization, the treated grinding and pressing water is temporarily stored in a tank 7 of the vessel 1. While stored in this tank, the water can undergo treatments, known per se, to remove pollutants such as arsenic or heavy metals. After a storage period, it undergoes further sterilization before being discharged into the sea. The sterilized grinding and pressing water discharged into the sea no longer contains algae reproductive elements capable of generating new algal blooms.

[0061] Vessel 1, as shown in the figures, is an ocean-going vessel capable of operating autonomously at sea for extended periods. It can advantageously collect and sterilize floating seaweed, such as sargassum, during long-duration campaigns, thus avoiding the interruptions that would be necessary for unloading the seaweed, bundles of seaweed residue, or pressing water. It can, in fact, submerge the bundles of seaweed residue, once they have ceased to reproduce, in deep water. Within a few months, the biodegradable outer layers of these bundles disappear, and the degraded seaweed is returned to its natural environment in the same state of decomposition as if it had died naturally. Vessel 1 can also discharge the sterilized seaweed water back into the sea.

[0062] Advantageously, such a vessel can operate at a speed of three knots over a width of 9 meters. It is thus capable of cleaning a sea surface of approximately 5 hectares in one hour. Since the position of the seaweed beds can be located using satellite imagery, it is possible to direct the vessels' actions towards them. Collecting the seaweed at sea, before it reaches the coast, prevents the negative impacts of these algae on the shoreline.

[0063] In other embodiments, the invention can also be implemented on a smaller vessel, such as a barge. Such a barge, for example, 21 m long and 8 m wide, could clean a sea surface of approximately 3 hectares per hour, for example in the immediate vicinity of an island to be preserved.

Claims

Vessel (1), equipped with means for collecting floating seaweed, at least one press suitable for pressing said seaweed, to separate the solid seaweed residues from the pressing water, means for packaging said solid seaweed residues, and means for sterilizing said pressing water, characterized in that the vessel is also equipped with a crusher suitable for crushing seaweed collected by said means of collection, before the crushed seaweed is pressed by said press, and in that said packaging means are suitable for packaging said solid seaweed residues in an airtight biodegradable package. Vessel (1) according to the preceding claim, characterized in that said means for sterilizing the pressing water comprise: means for heating said water to a temperature suitable for destroying the reproductive elements of algae, and / or means for exposing said water to ultrasound, and / or means for exposing said water to ultraviolet radiation. Vessel (1) according to any one of the preceding claims, characterized in that said means for sterilizing the press water comprise a press water storage tank (7) in said vessel (1). A process for sterilizing seaweed on board a ship (1), comprising: a step of pressing seaweed on board said ship to separate the solid seaweed residue from the pressing water, a step of packaging said solid seaweed residue on board the ship, and a step of sterilizing said pressing water on board said ship, characterized in that it comprises a step of grinding seaweed on board said ship, before said pressing step, such that said pressing step is carried out on said ground seaweed, and in that said packaging step consists of packaging said solid seaweed residue in an airtight biodegradable package. A process according to claim 4, characterized in that said packaging step is followed by a step of immersing said packaged solid seaweed residues in the sea. A process according to any one of claims 4 and 5, characterized in that said pressing water sterilization step is followed by a discharge of the sterilized water into the sea. A process according to any one of claims 4 to 6, characterized in that said pressing water sterilization step comprises: heating said pressing water to a temperature suitable for destroying the reproductive elements of said algae, and / or exposing said pressing water to ultrasound, and / or exposing said pressing water to ultraviolet radiation. A method according to any one of claims 4 to 7, characterized in that it comprises a preliminary step of collecting floating algae on board said vessel.

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