WO2010036123A1

WO2010036123A1 - Apparatus and method for removing of aquatic plants

Info

Publication number: WO2010036123A1
Application number: PCT/NO2009/000328
Authority: WO
Inventors: Odd Pettersen
Original assignee: Odd Pettersen
Priority date: 2008-09-23
Filing date: 2009-09-21
Publication date: 2010-04-01
Also published as: NO329344B1; NO20084033L

Abstract

Cleaning device (2) for removing of aquatic plants (9) from their habitat (92) wherein the cleaning device (2) is allocated a movable structure (1) where the cleaning device (2) includes at least one rotatable drum (21) provided with at least one carrier (3) arranged to engage the aquatic plants (9) and wherein the carrier (3) is designed to hold on to the aquatic plants (9) while they are being removed from the habitat (92).

Description

APPARATUS AND METHOD FOR REMOVING OF AQUATIC PLANTS

The present invention relates to a cleaning device for removing aquatic plants from their habitat, where the cleaning device is allocated to a movable structure.

The expression aquatic plants is here used for plants growing in freshwater, brackish water and in seawater. They may be attached to the bottom with a true root or other attachment organ. Aquatic plants may be loose, floating mats of plants. For simplicity micro algae and microorganisms are also in- eluded in the following in the term aquatic plants.

The term habitat is here used for the natural place of growth for the aquatic plant, including the bottom around the root of the aquatic plant or attachment organ and the water column and the water surface where the aquatic plant is floating.

In the last 20 to 40 years an increasing overgrowing of rivers, ponds and lakes has been observed. The overgrowing is caused by for example imported plants such as waterweed (EIo- dea canadensis) imported to Europe from North America. The overgrowing is also caused by plants previously considered not to be a problem such as common bulbous rush (Juncus bul- bosus = supinus) .

Several explanations have been put forward as to why this overgrowing has increased. Regulating of watercourses may _o

lead to vigorous increase in the amount of common bulbous rush, but there are also many watercourses, which are not regulated where the common bulbous rush is a problem. The winters have become warmer so that less ice is formed than before. From this follows that the common bulbous rush is less prone to be carried away by ice drift in the spring. It is known that the growth is kept down when there is enough ice drift. Nitrogen in the form of ammonium (NH₄ ⁺) gives increased growth. There has been an increasing amount of aitirao- nium in the precipitation where the source is emissions from industry and motor traffic.

The common bulbous rush can form coherent floating mats and may dominate the water column down to a depth of 3 metres, but may also grow down to 8 metres. In addition to being a problem in the water column, the vigorous growth leads to mud settling on the bottom. Gravel in rivers has been covered by mud up to a thickness of 1 metre. This is caused by particles in the water being caught by stems and leaves and subsequently sedimenting.

The overgrowing with common bulbous rush is a hindrance for outdoor life and is also a problem for business interests tied to outdoor life execution. Bathing places are fouled up and it is impossible to set out fishing nets and to fish with a rod. It is difficult to travel by boat through the rush mats. It is also observed that traditional spawning grounds for fish are overgrown and this will over time reduce the fish population.

Aquatic plants may also form floating mats not being anchored by root or other attachment organs. Examples of these float- ing mats of macro algae are such as drifting seaweed and kelp. Micro algae and microorganisms like green algae and blue green algae may also form coherent floating mats. There are few known methods for fighting common bulbous rush, waterweed and other species causing overgrowth. The extent means that it is not possible to remove sufficient common bulbous rush manually.

Mechanical methods have been tried. In some regulated watercourses it is possible to lower the water surface so that the common bulbous rush is made dry. The weeds and the mud may then be removed mechanically using excavators. This method may not be used in watercourses that are not regulated and it presupposes also that it is justifiable to lower the water level for economical and other reasons. Using excavators wading into the water has also been tried. This method is limited as to how deep the excavator may wade . In addition it has appeared that digging in the mud stirs up large amounts of particles in the water, which may damage aquatic life downstream. Some local environmental authorities have prohibited the use of excavators for this purpose.

There is known a particular cutting machine having the purpose to remove common bulbous rush. The cutting machine is provided with a boom whereon is mounted a cutting device where a set of knives moves along a cam. The machine is on the same boom further provided with a silo-loading device. The common bulbous rush is cut just under the water surface. The cut grass is collected with the silo-loader and driven onshore for landfilling. Such a machine has turned out to have several weaknesses. The cutting has to be discontinued when there is enough rush to fill the silo-loader. It takes time to drive onshore with the cut rush and it is not accepted to deposit the cut rush along riverbanks and waters edges. The rush is cut, but the roots are left. It has turned out that cutting of rush stimulates growth and the problem of overgrowing is therefore only temporary solved. Large boul- ders and other obstacles limit in addition the practicability of such a machine .

There is thus a need for an apparatus and a method that is able to remove common bulbous rush and other aquatic plants 5 causing overgrowing of rivers, ponds and lakes in a rational and at the same time economic way. There is further a need to be able to handle the leaves and stems being removed in an environmentally and economical way.

The object of the invention is to remedy or reduce at leasto one of prior art drawbacks .

The object is achieved by the features stated in the below description and in the following claims.

In a first aspect the invention comprises a cleaning device for removing aquatic plants from their habitat where thes cleaning device is allocated to a movable structure and where the cleaning device includes at least one rotatable, motor driven drum provided at least with one protruding finger arranged to engage the aquatic plants and the protruding finger is designed to hold on to the aquatic plants while they areo removed from the habitat .

The invention is not limited by a particular part of the drum being under water. The cleaning device may be attached to the movable structure, hereafter called the craft, in such a way as to be adjusted height wise from being completely submerged5 in water to be completely raised above water. The amount of aquatic plants attaching themselves to the drum will depend on how deep into the water the drum is submerged. The vertical and horizontal force component being transmitted from the aquatic plant and floating leave mass held via the stem too the root or attachment organ, will depend among other things on the vertical position of the drum in addition to the rota- tional force of the drum. In one embodiment the drum has a circular cross-section appearing as a cylinder. Other geometric shapes are also possible, for example but not limited to hexagonal and octagonal cross-section.

The invention is not limited to be allocated to a floating craft. In another embodiment the cleaning device may be allocated to a vehicle wading or moving on firm ground along such as a riverbank. Such a vehicle may be an excavator. In a further embodiment an excavator allocated to the cleaning device may be positioned on a floating device such as a raft. In a further embodiment the cleaning device may be allocated to a movable boom or outrigger from a floating device.

The cleaning device described above may be arranged so that the drum in its working position is placed apart from a bot- torn. This has the advantage that the drum will not stir up sediments and sand when the aquatic plants are being removed.

The cleaning device described above may be arranged so that the drum in its working position is rotatable about the horizontal axis. In the working position the rotational direction may be such that the lower portion of the drum rotates away from the craft. In an alternative embodiment the rotational direction may be such that the lower portion of the drum rotates toward the craft .

The cleaning device described above may in one embodiment be arranged so that the angle between the finger and the drum is approximately 90 degrees. In another embodiment the finger is slanted having an angle of less than 90 degrees in the direction of rotation as shown in Figs. 2 and 3. The end portion of the finger may have different designs; it may for example be pointed, round, square or skewed. The cleaning device is in one embodiment arranged such that the one or the several protruding fingers are fixedly arranged relative to the drum. In an alternative embodiment the cleaning device is arranged such that the protruding fingers are displaceable along their longitudinal directions relative to said drum.

The cleaning device described above may be arranged such that the cleaning device is further provided with a cleaning apparatus arranged to remove aquatic plants from the drum and the carrier. In one embodiment the cleaning apparatus is a stripper. The stripper may be fixed or movable relative to the drum. A vibrator may be allocated to the stripper to facilitate the movement of the aquatic plants away from the drum and the stripper.

The cleaning device described above is in one embodiment arranged such that :

- a finger is movably arranged in a guide tube attached to the drum;

- the finger is via a connecting element through a slot in the guide tube attached to a sleeve, the central axis of which is horizontal and perpendicular to the finger;

- a horizontal shaft is supported in the sleeve and in each end allocated to a guide element positioned in a guide channel; - the guide channels are attached to stationary end portions allocated to the cleaning device;

- the guide channels are in one portion designed to bring the carrier end portion approximately level with the drum shell surface, alternatively to bring the carrier end portion within the drum shell surface.

In one embodiment the finger, the connecting element and the sleeve are formed as one component in the same material. In another embodiment the finger, the connecting element and the sleeve are constituted by two components of the same or different materials, and in a further embodiment the finger, the connecting element and the sleeve are produced separately in the same or different materials and connected to each other by means of per se prior art .

In one embodiment the diameter of the shaft is approximately the same as the inside diameter of the sleeve. In another embodiment a bushing is arranged in the sleeve to reduce fric- tion and noise. In a further embodiment there is arranged a bearing such as a ball bearing in the sleeve so that the shaft is supported in the ball bearing.

In one embodiment the guide element is a wheel where the shaft is supported in the centre of the wheel . In an alterna- tive embodiment the guide element is a sliding element stationary attached to the shaft. In a further alternative embodiment the sliding element and the shaft are rotatably connected.

In one embodiment at least one of the fixed end pieces is formed as a plate. In another embodiment at least one of the end pieces is a frame.

In a second aspect the invention comprises a method to use a cleaning device for picking up and removing aquatic plants from their habitat, characterised in that a movable structure allocated to a cleaning device as described above is arranged to engage aquatic plants, hold on to aquatic plants and apply a force to these which at least has a vertical force component.

The invention further relates to a method for use of a clean- ing device applying a force to the aquatic plants by means of a rotating drum. In the following is described an example of a preferred embodiment which is illustrated in the accompanying drawings, wherein:

Fig. 1 shows a movable structure with allocated cleaning device;

Fig. 2 shows a section through a rotating cleaning device having movable carriers;

Fig. 3 shows in a larger scale a detail of Figure 2;

Fig. 4 shows a longitudinal section through a rotating cleaning device.

In Figure 1 the reference numeral 1 indicates a movable, floating structure allocated to a cleaning device 2 where the cleaning device 2 is attached to the movable structure 1 with a fastening element 11. The structure 1 floats on water 12.

Figure 2 shows the cleaning device 2 engaging with at least one carrier 3 an aquatic plant 9 fastened to a habitat 92 with a fastening organ 91. When the cleaning device 2 drum 21 is brought to rotate, the aquatic plant 9 is led over the drum 21 and further over a cleaning apparatus 22 to a re- ceiver 23 or after the receiver 23 the aquatic plant may possibly undergo further treatment (not shown) . A foot screw 24 may adjust the position of the cleaning apparatus 22 relative to the shell surface 26 of the drum.

Figure 3 shows a carrier in the form of a finger 3 positioned inside a guide tube 32, which is attached to the drum 21. The finger 3 is attached via a connecting element 33, arranged in a slot 34 (see Figure 4) in the guide tube 32, to a sleeve 35. The finger 3 ends in an end portion 36 prepared for engagement with the aquatic plant 9. Figure 4 shows a shaft 4 supported in the sleeve 35 and in each end allocated a guide element 41. Each of the guide elements 41 is positioned in a guide channel 42. The guide channels 42 are attached to the respective end pieces 25 of the cleaning device 2.

The drum 21 of the cleaning device 2 is arranged to be turned by a motor 5 connected by a central shaft 51 to the drum 21.

Figure 1 shows a floating craft allocated to a cleaning device 2 shown in Figure 2 and 4 which engages the aquatic plant 9 and jerks it up with the root, brings the aquatic plant up into the craft and cuts it into suitable pieces (not shown) . Cut plant material may for example be mixed with water to a pumpable slurry. This may be stored in the craft 1 until the craft docks, and then the slurry is pumped to a disposal site or to another vessel, truck or other transport means, which may bring the slurry to a disposal site. By disposal site is in this connection also meant spreading of the slurry in a field as fertiliser, for composting or other finishing treatment. The slurry may alternatively be pumped ashore from the craft 1 through a hose .

To remove aquatic plants from a watercourse it has turned out to be expedient to utilise a per se known craft 1 being sold under the commercial name of "OP Skimmer" and which is adapted to the purpose. OP Skimmer is particularly suited in that it is flat-bottomed and has a draught of approximately 1.1 m. It is thus suited to operate in shallow water close to the banks. The craft 1 may in addition be provided with side- mounted pontoons (not shown) . These pontoons may be connected to the craft 1 by hydraulic connectors (not shown) . By so do- ing the craft 1 hull may be raised so that the total draught for hull and pontoons is less than 0.5 m. The cleaning device 2 for picking up aquatic plants 9 is positioned in the bow portion of the craft 1. The cleaning device 2 is in each end allocated a fixed end piece 25, exemplified here by an end plate, serving to attach the cleaning device 2 to the craft. In one embodiment the rotating drum 21 is approx. 1 metre in diameter and approx. 2.25 m long, but the drum may be made in any desired dimension. Along the shell surface 26 of the drum 21 is provided carriers 3, which at rotation of the drum 21 engages the aquatic plant 9 where it floats in the water surface and somewhat below the water surface. The carrier 3 consists of a protruding, mainly cylindrically shaped finger 3. In one embodiment, to be described closer, the fingers 3 are movable so that during part of the rotational run the fingers are protruding, while they in other parts of the rotational run of the drum 21 are withdrawn having the end portions 36 approximately flush with the shell surface 26 of the drum 21.

The direction of rotation is in the embodiment shown such that the lower portion of the drum 21 in the working position moves away from the craft 1. This makes it more difficult for the craft 1 to run aground.

In one embodiment there are provided carriers 3 along nine rows in the longitudinal direction of the drum. The fingers 3 in each row are somewhat displaced relative to the fingers in the adjacent rows. Each row contains 20 or 21 fingers 3.

There are allocated totally 186 fingers 3 to the cleaning device 2. A person familiar with the art will know that another arrangement and another number of fingers 3 may also be suited to the purpose.

The finger 3 is positioned in a guide tube 32. The guide tube 32 is attached to the shell surface 26 of the drum 21. To the finger 3 is attached a connecting element 33. The connecting element 33 connects the finger 3 to a sleeve 35. The connecting element 33 runs through a slot 34 in the guide tube 32.

The sleeve 35 is arranged such that the central axis is perpendicular to the longitudinal direction of the finger 3. In the working position the central axis of the sleeve 35 is nearly horizontal .

A shaft 4 running along the whole length of the drum 21 is placed through the sleeve 35.

In each end of the shaft 4 is provided a guide element 41, shown here as a wheel, where the shaft 4 is supported in the centre of the wheel .

The guide channels 42 are attached to the fixed end plates 25 of the cleaning device 2. The guide channels 42 have a cross- section adapted to the diameter of the wheel 41. The cross- section of the guide channels 42 has a shape such that the wheel 41 cannot accidentally jump out of the guide channel 42 when the drum 21 rotates and via guide tube 32, finger 3, connecting element 33, sleeve 35 and shaft 4 makes the wheels 41 move in the guide channels 42.

The guide channels 42 track decides how much the fingers 3 shall protrude beyond the shell surface 26 of the drum 21 in the course of one drum 21 revolution. Figure 2 shows a verti- cal cross-section of the cleaning device 2. Positions and directions are given in the following as on a clock dial where the dial centre and the drum 21 centre correspond. From 6 o'clock to 12 o'clock the guide channel 42 tracks are circular. The outside circumference of the guide channels 42 fol- lows the inner circumference of the drum 21 but may be somewhat smaller. Guide elements 41 positioned in the guide channels 42 between 6 o'clock and 12 o'clock will through the shafts 4, the sleeves 35 and the connecting elements 33 keep the fingers 3 in a position where they protrude maximum beyond the shell surface 26 of the drum 21. From 12 o'clock to 3 o'clock the track of the guide channels 42 deviates from a circle and such that the radial distance from the inside of the drum 21 to the outside circumference of the guide channels is constantly increasing. This track causes the fingers 3 in this portion of the rotation to move inward in the guide tubes 32 and reaches a maximum inner position when the centres of the sleeves 35 are in a position corresponding to 3 o'clock. The length of the fingers 3, the connecting elements 33 and the guide tubes 32 are adjusted so that the end portions 36 of the fingers 3 in this position are approximately flush with the shell surface 26, alternatively are positioned inside the shell surface 26. From 3 o'clock to 6 o'clock the tracks of the guide channels 42 are still deviating from a circle but such that the radial distances from the inside of the drum 21 and to the outer circumference of the guide chan- nels 42 are constantly decreasing. This track leads to the fingers 3 in this portion of rotation moving outward in the guide tubes 32 and achieving a maximum protruding position when the sleeve centres 35 are in a position corresponding to 6 o'clock.

The person versed in the art will know that also other tracks or designs of the guide channels 42 will cause a movement of the carriers 3 end portions 36 relative to the shell surface 26 of the drums 21. Thus the tracks of the guide channels 42 in another embodiment may be circular but with a smaller di- ameter than the inside diameter of the drum 21. The guide channels 42 may be mounted eccentrically relative to the drum 21 so that for example the smallest distance between the outer circumference of the guide channels 42 and the inner surface of the shell 26 are in a position diametrically positioned relative to the cleaning device 2 allocated cleaning apparatus 22 and that the corresponding largest distance between the outer circumference of the guide channels 42 and the inner surface of the shell 26 are in the vicinity of the cleaning apparatus 22. Such an arrangement will cause the carrier 3 end portions 36 to continuously change the distance to the shell surface 26 of the drum 21 during a revolution.

The cleaning apparatus 22 is in the form of a stripper. The stripper 22 is placed in a position about 3 o'clock and runs approximately horizontally along the drum when the drum is in the working position. The position of the stripper 22 relative to the shell surface 26 is adjusted with a foot screw 24. Aquatic plants 9, which after engagement with the carri- ers 3, are pulled out of the water and over the drum 21 as this rotates. The rotational speed may be in the order of 10 - 50 rpm and tests have shown that 28 rpm fits well to one type of aquatic plants. The fingers 3 are pulled back and loose contact with the aquatic plants 9. At the stripper 22 the aquatic plants are led away from the drum 21 to a receiver 23 and is brought on to further treatment.

Aquatic plants removed from the drum 21 via the stripper 22 are brought to a suitable mill (not shown) milling these into pieces having a maximum size of for example 90 mm. Such a mill may for example be of the type Muffin Monster^" . The person versed in the art will know what equipment is suitable for the purpose .

After milling the cut material is mixed with water to a pump- able slurry. The slurry is stored temporarily in a collection tank (not shown) in the craft 1. At suitable intervals the slurry is pumped via a pump and a hose (not shown) onshore to a permanent or temporary disposal site. Alternatively the cut material may be temporarily stored onboard the craft and brought ashore by the craft. Another alternative is that the cut material in a per se known way such as by hoisting, grabbing or pumping is brought across into another auxiliary craft such as a barge .

The craft 1 is in one embodiment equipped with a water jet for propulsion and hydraulic operation of equipment like the drum 21, mill and pumps (not shown) . A diesel unit (not shown) is the power source. It is possible to use other al- ternatives for propulsion and operation of equipment, which is well known for a person versed in the art.

In the example removal of aquatic plants with a root is described. Other aquatic plants having other or no attachment organs may be removed in the same manner. The invention is not limited to use in limnic environments but will also be possible to use for removal of seaweed and kelp. The use of the invention is further not limited to removal of aquatic plants having intact roots or attachment organs. Drifting aquatic plants in the water surface area or just below the water surface may also be removed with the use of an apparatus according to the invention.

Claims

P a t e n t c l a i m s

1. Cleaning device (2) for removing of aquatic plants (9) from their habitat (92) wherein the cleaning device

(2) is allocated to a movable structure (1) , c h a r a c t e r i s e d i n that the cleaning device (2) includes at least one rotatable, motor driven drum (21) provided with at least one protruding finger

(3) arranged to engage the aquatic plants (9) and the protruding finger (3) is designed to hold on to the aquatic plants (9) while they are being removed from the habitat (92) .

2. Cleaning device (2) according to claim 1, c ha r a c t e r i s e d i n that the drum (21) in its working position is positioned at a distance from a bot- torn .

3. Cleaning device (2) according to claim 1, c h a r a c t e r i s e d i n that the drum (21) in its working position is rotatable about the horizontal axis.

4. Cleaning device (2) according to claim 1, c h a r - a c t e r i s e d i n that the protruding finger (3) is fixedly arranged relative to the drum (21) .

5. Cleaning device (2) according to claim 1, c h a r a c t e r i s e d i n that the protruding finger (3) is displaceable in its longitudinal direction relative to the drum (21) .

6. Cleaning device (2) according to claim 1, c h a r a c t e r i s e d i n that the cleaning device (2) is further provided with a cleaning apparatus (22) arranged to remove aquatic plants (9) from the drum (21) and the finger (3) .

7. Cleaning device (2) according to claim 6, c h a r a c t e r i s e d i n that the cleaning apparatus (22) is a stripper.

8. Cleaning device (2) according to claims 1 to 5, c ha r a c t e r i s e d i n that

- a finger (3) lying movably in a guide tube (32) attached to the drum (21) ;

- the finger (3) via a connecting element (33) through a slot (34) in the guide tube (32) is attached to a sleeve (35) whose central axis is horizontal and perpendicular to the finger (3) ;

- a horizontal shaft (4) is supported in the sleeve (35) and at each end allocated a guide element (41) positioned in a guide channel (42) ; - the guide channels (42) are attached to the stationary end pieces (25) of the cleaning device (2);

- the guide channels, (42) are in one portion designed to bring the end portion (36) of the finger (3) approximately flush with the shell plate (26) of the drum (21) , alternatively to bring the end portion (36) of the finger (3) inside the shell plate (26) of the drum (21) .

9. Method for picking up and removing of aquatic plants with appurtenant attachment organs from their habitat, c h a r a c t e r i s e d i n that a movable structure (1) allocated to a cleaning device (2) according to claim 1, arranged to engage aquatic plants (9) , holds on to the aquatic plants (9) and applies to these a force having at least a vertical force compo- nent .

10. Method according to claim 9, c h a r a c t e r i s e d i n that the cleaning device (2) applies a force to the aquatic plant (9) by means of a rotating drum (21) .