The present invention relates to an apparatus for mechanically removing water plants, in particular water hyacinths, from waters, such as rivers, lakes, canals etc.

Said water hyacinth is a great and still increasing problem in tropical and subtropical areas, since they cause water areas to become choked and irrigation canals to become clogged, for instance. The growth of these water plants is boisterous in areas outside the area of origin, because there are no natural enemies there. As a matter of fact this spread of the water hyacinth is initiated by human beings.

Furthermore, the water hyacinth can reproduce itself in several ways, that is by sexual reproduction (seeds) and by vegetative reproduction (any part of the plant is capable of growing into a new plant) . Particularly this latter manner of reproduction causes problems in mechanically removing water plants, because the water plants should be removed entirely and no parts may remain within the water, otherwise new water plants may spring therefrom.

In the past several methods and apparatuses are developed in order to remove the water hyacinths. Besides the biologic and chemical removal, the mechanical removal has proved to involve the smallest risk for the environment. The most simple mechanical removal is of course pulling the water hyacinths out of the water by rakes and hay forks, but this method is not only difficult, it also exposes the workers to dangers due to the risk of diseases (for instance larvas causing Bilharzia live in the water hyacinths) and due to the presence of dangerous animals, such as snakes and crocodiles. The machines developed include buckets pulling the water hyacinths out of the water, and dredges which are suited only for working in very shallow water. In the most recently developed apparatus, which is used as starting point for the invention, the water hyacinth is mown and the mown water plants are received within a container-like receptacle where the water plants are shred and then pressed into bales. These bales have to be transported over the water in a laborious way

enabling only a low production. Mowing and cutting the water hyacinths also create very many loose water hyacinth parts from which new water hyacinths arise so that the removal of water hyacinths is only a temporary solution for the problem and sometimes the water hyacinths return in an aggravated exten .

The object of the present invention is to provide an apparatus for mechanically removing water plants, in particular water hyacinths, from waters wherein this removal is accurate and more complete.

For this purpose the invention provides an apparatus for mechanically removing water plants, in particular water hyacinths, from waters, such as rivers, lakes, canals etc., comprising a driven container-like receptacle which is open at the front side for receiving the waterplants in a reception space thereof and which has front lateral sides extending in upward direction and to one of which there are mounted cutting means to laterally cut-off the water plants to be received, means for shredding the water plants received in the container-like receptacle, and means for discharging the shredded water plants, which apparatus is characterized in that the apparatus is provided, on the side where the cutting means are arranged, with suction openings positioned backwardly of said cutting means and communicating with suction means.

Due to these features, the cutting waste is sucked in through suction openings arranged directly behind the cutting means, so that there is no risk of water plant parts coming into or remaining within the water and it is prevented that immediately after removal of the water plants new water plants may develop. In this manner a permanent and not a temporary solution of the problem for the water plants is provided.

In larger and deeper waters the water hyacinths form a floating layer having a thickness of about 1,5 meter so that the apparatus according to the invention should only cut away water hyacinths on one or on both sides for removing a strip of water hyacinths before this strip may be received within the container-like receptacle. In shallow waters and the neighbourhood of the banks of deep waters, the water hyacinths will be rooted into the bottom thereby making it more

difficult to completely remove the water hyacinths. For this case the invention provides an apparatus in which the container-like receptacle is provided at its lower front edge with rooting means which may be mechanical, pneumatic or hydraulic. With this rooting means the bottom may be rooted to a certain depth thereby loosening the roots of the water hyacinths from the bottom and being able to receive the water hyacinths together with their roots within the container-like receptacle so that also in this case a complete removal of the water plants can be effected.

For safely discharging a large quantity of received and shredded water plants, the invention proposes to provide the discharge means for discharging the shredded water plants from the container-like receptacle with drawing means connected to the container-like receptacle and to a discharge line adapted to extend to the main land.

Hydraulically discharging the shredded water plants is a very good manner of discharging the water plants in a large volume and without spillage. On land the water plant pieces may be dumped where they will become harmless within a couple of days. Then the water plants may be converted into compost so that the removal of the water plants not only makes water available again for irrigation purposes, but also enables the production of a compost with which the soil can be made fertile.

It is favourable to transport the shredded water plants through the discharge line to the shore with a minimum quantity of water to maximize the pump efficiency. This is possible by sucking-in water from the reception space of the container-like receptacle in a controlled manner and through water suction means including a sieve. This sieve will generally not be able to sieve all water plant parts out of the water and in this case it is favourable to provide the apparatus with a circulation circuit for water containing water plant parts. It is also an advantage to incorporate the suction openings behind the cutting means within the circulation circuit. This circulation circuit preferably comprises on the pressure side one or more spray nozzles opening at the front side of the container-like receptacle in a downwardly and backwardly inclined direction to spray water

containing water plants under high pressure into the reception space of the container-like receptacle such that the water plants to be received within the container-like receptacles are blown inside by these spray nozzles. This also causes a capacity increase.

The invention will hereafter be elucidated with reference to the drawing schematically showing an embodiment of the invention by way of example.

Fig. 1 is a very schematic plan view of a lake covered with water hyacinths and in which an apparatus according to the invention is removing these water hyacinths. Fig. 2 is an enlarged plan view of an embodiment of the apparatus for mechanically removing water hyacinths according to the invention by way of example. Fig. 3 is a vertical longitudinal sectional view of the front portion of the apparatus according to Fig. 1.

Fig. 1 shows in plan view a water area in this case consisting of a lake, but which may also include rivers, canals and the like, and which is fully covered with water hyacinths. These water hyacinths form a tightly joined floating layer, in which the water hyacinths near the banks being rooted into the bottom, but floating loose of the bottom in the middle of the lake.

The apparatus for removing the water hyacinths is adapted to either make a channel through the water hyacinths or remove the water hyacinths strip after strip from one side. Such a method is shown in Fig. 1 in which a strip of. water hyacinths is cut off, whereafter the water hyacinths are shredded in a manner to be described hereinafter and are discharged through a hydraulic line 2 to a place on the shore. Figs. 2 and 3 show an embodiment of the apparatus for mechanically removing water hyacinths. This apparatus 1 has two parts, that is a front container-like receptacle 3 and a machine part 4. During operation of the apparatus 1 the container-like receptacle 3 moves on the front side thereof. The container-like receptacle 3 is a floating body deriving its floating power from air chambers 5 , for example. The container-like receptacle 3 has a reception space 6 opened at the front side of the apparatus to allow the water hyacinths to enter, said water hyacinths being indicated with

W in Fig. 3. In order to laterally cut-off the water hyacinths W to be received from those which will remain, there are provided cutting means 7 on both vertical front edges of the receptacle 3 , said cutting means 7 consisting in this case of four rotary cutters arranged one above the other, but which may also consist of all kinds of other rotating or translating cutting or clipping means. The water hyacinths W entered into the reception space 6 of the receptacle 3 first meet a rotary tiller 8 rotating about a horizontal axis and chopping the water hyacinths into coarse pieces and then meets a shredder 9 finally shredding the water hyacinths into small pieces. After that the water hyacinth pieces arrive in a suction funnel 6' to which a suction line 10 connects in which a high powered pump is incorporated which is capable of discharging the water hyacinths with water a large distance through the discharge line 2 to the shore. The pump 11 is driven by means of a motor 12.

In order to obtain a maximum transport efficiency, that is to discharge a maximum quantity of water hyacinths and a minimum quantity of water through the discharge line 2, a double water suction line 13 connects to the reception space 6, both branches of which commencing in chambers 14 sideways of the reception space 6. The chambers 14 communicate with the reception space 6 through perforation holes 15 in the partition between the chambers 14 and the reception space 6. By producing a large underpressure within the chambers 14 water is forcedly sucked from the reception space 6 through the perforation holes 15. The partitions including the perforation holes 15 act as a sieve so that mainly water and only a small portion of water hyacinth pieces are allowed to enter the chambers 14 and the water suction line 13. To prevent the perforation holes 15 from becoming clogged there is provided a rotating chopper 29 within the chambers 14 behind the perforation holes 15 in the partition. As mentioned before, the water which is sucked in by the water suction line 13 will still contain a quantity of water hyacinth pieces so that this water cannot be discharged into the lake because these water hyacinth pieces may act as slips to reproduce new water hyacinths. According to the invention this water containing water hyacinth pieces is

circulated within the apparatus by connecting the pump 16 at the end of the water suction line 13 to a pressure line 17 extending to the front side of the apparatus and terminating there via a curved portion 18 into a spray nozzle 19. This spray nozzle 19 is inclined downwardly and backwardly into the opening of the reception space 6 of the container-like receptacle 3 and blows water with great force against the water hyacinths W to be received, so that they are forced into the reception space 6 by the water jet which substantially increases the capacity of the apparatus. If desired, the spray nozzle 19 may be made adjustable such as shown by dashed lines and may be provided with a control means for controlling the flow rate. It should be guaranteed at all times that all the water coming out of the spray nozzle 19 and containing water hyacinth parts end up in the reception space 6. The water overpressure caused by the spray nozzles at the entrance of the reception space 6 and the large underpressures produced by the suction line 10 and the water suction line 13 at the sides and the rear side of the reception space 6 cause a large flow capacity for the water hyacinths.

As described before, it is of great importance that no water hyacinth parts arrive in or remain in the surrounding water. It is inevitable, however, that cutting waste in the form of water hyacinth pieces are produced when the water hyacinths W are cut of by the cutting means 7. In order to prevent them from ending up in the water, the invention proposes to arrange suction openings 20 at the side of the container-like receptacle 3 within the area behind the cutting means 7, said suction openings 20 in this case being arranged in the front wall of a chamber 21 formed adjacent to the side wall of the container-like receptacle 3. Furthermore, there are formed further suction openings 20 in the outer wall of these chambers 21, which are adapted to suck-in any loose water hyacinth parts present in the remaining water hyacinths. For this purpose, there is connected to the chambers 21 a suction line 22 adapted to effect a very large underpressure within the chambers 21. This suction line 22 may be equipped with its own pump or, as is shown, may be connected to the water suction line 13. Another possibility is to connect the suction line 22 both to the water suction line 13 and to the

suction line 10 and to provide it with valve means in order to permit control of suction through the suction line 22. It is further possible to arrange a translating cutting knife 23 within the chambers 21 behind the suction openings 20 to prevent the suction openings 20 from becoming clogged. These suction openings 20 and the strong suction force therethrough will cause all the cutting waste of the cutting means 7 to be sucked in strongly so that no or only a minimal amount of water hyacinth parts will end up in or remains within the surrounding water. Any water hyacinths which are still intact but which are sucked in through the lateral suction openings 20 will be cut off by the cutting knifes 23.

At the lower front side of the reception space 6 of the container like receptacle 3 there is positioned a bottom body 25 which is rotatable about a horizontal shaft 24 in the embodiment shown and which determines the operative depth of the container-like receptacle 3. In the embodiment shown the bottom body 25 also serves as buoyant body for the container¬ like receptacle 3. The bottom body 25 is further provided at its front end with rooting means in this case consisting of a plurality of spray nozzles 26 spaced along the width of the bottom body 25 and serving to loosen water hyacinths W rooted into the bottom from said bottom by blowing the bottom away to a certain depth thereby permitting the water hyacinths W to be removed together with their roots so that no new water hyacinths may develop from the roots which are left behind. The spray nozzles 26 may spray air or water, but on the other hand it is also possible to arrange a mechanical rooting means loosening the bottom by a vibrating or scooping movement. The propelling means of the apparatus according to the invention may be selected independent of the area of operation. For deeper waters one may choose for a screw drive which may be arranged in the machine part 4, for example. In more shallow waters other suited drives may be selected. In many cases, however, a substantial part of the driving power of the apparatus will be produced by its own operation. That is, by sucking in water and water plants with great force at the front side of the vehicle produces a substantial forward propelling force so that the apparatus almost automatically progresses forwardly. In the embodiment shown in which the

apparatus 1 consists of two parts 3 and 4, a steering action may be provided by cylinder piston assemblies 27 mounted between both parts 3 and 4 and being adapted to change the angle between the machine part 4 and the container-like receptacle 3. In that case the lines 10 and 13 should be equipped with accordion portions 28. It should be noted that it is of course also possible to construct the apparatus 1 with only one part.

From the foregoing it will be clear that the invention provides an apparatus for mechanically removing water hyacinths or other kinds of water plants, with which the water hyacinths may be removed entirely with a large capacity without leaving water hyacinth parts within the water thereby preventing new water hyacinths developing therefrom. As a result the apparatus provides a lasting solution for the problem of the water hyacinths and the water hyacinths will not return after their removal, or only in a very limited extent. By using large apparatuses having very powerful cutting and chopping means, pumps and engines a substantial capacity can be obtained so that also very large water areas (such as for example the Victoria lake) may effectively be freed of the water hyacinths. For smaller irrigation channels and ditches it is possible to design adjusted smaller apparatuses. The invention is not restricted to the embodiment shown in the drawing and described herein before, which may be varied in different manners within the scope of the invention. It is for instance possible to provide the container-like receptacle 3 at its front side with adjustable arms in order to increase and vary the operative width thereof. The cutting means 7 and the suction openings 20 will then be arranged on the front end of these adjustable arms or adjustable walls. The tiller 8 and the shredder 9 may be replaced by other efficient chopping or cutting means.