METHOD AND SYSTEM FOR CLEANING A WATER SYSTEM

TECHNICAL FIELD OF THE INVENTION The object of the invention is a method and a system for cleaning a water system according to the preambles of the independent claims presented further below. The invention especially relates to a new way of removing solid material from a flowing water system, such as a ditch.

PRIOR ART

For example agriculture and peat production produce unwanted materials in water systems, such as solid material, nutrients and dissolved organic materials. When not cleaned these may cause eutrophication of the water system, siltation of the bottom, changes in the species variation in the water system or clouding of the water system. A large number of different purification methods have been developed. There is however still a need to provide a simple, easy-to-use and at the same time efficient way of cleaning a water system, which is applicable to flowing water systems, for example ditches.

One known way to remove solid materials from a flowing water system is to place a dam or another obstacle, which slows the flowing, across a ditch or brook. Solid material is accumulated behind the delay element, which solid material can at regular intervals be removed for example by pumping or by dredging with an excavator. Known solutions are often costly. Pumps and other actuators demand service in order to work. A work machine suited for dredging is often difficult to get beside the dam.

OBJECT AND BRIEF DESCRIPTION OF THE INVENTION . It is an object of the present invention to reduce or even eliminate the above- mentioned problems appearing in prior art.

It is especially an object of the present invention to provide a simple, easy-to-use and at the same time relatively efficient way of cleaning a water system.

It is especially an object of the present invention to provide an arrangement, wherewith solid material can be removed from a flowing water system such as ditches, brooks and rivers.

In order to realise the objects mentioned above, among other things, the method and the system for cleaning a water system according to the invention are characterised by what is presented in the characterising parts of the enclosed independent claims.

The embodiment examples and advantages mentioned in this text relate, where applicable, to both the method and the system according to the invention, even if this is not always specifically mentioned.

Typically when cleaning a water system in accordance with the invention

- a filter is held in the water system, which filter has a filter volume equipped at least partly with walls of filter cloth, whereby a part of the filter cloth is held at the bottom of the water system at least essentially in the direction of the bottom, whereby solid material is sedimented onto it, - water from the flowing water system is guided into the filter volume and out thereof through the filter cloth,

- solid material in the water system is collected into the filter volume,

- the solid material is removed from the water system in such a way that the filter is lifted out from the water system, so that the solid material mainly stays in the filter volume of the filter, and water runs out from the filter volume through the cloth of the filter.

Typically a water system is cleaned according to the invention with a system, which comprises - a filter, which has a filter volume for solid material remaining in the filter, whereby at least a part of the walls of the filter volume are of filter cloth.

A typical filter according to the invention is arranged to be lifted out of the water so that the solid material at least mainly stays in the filter volume of the filter and at the same time water runs out of the filter volume through the cloth of the filter.

By water system is in this text meant especially a flowing water system such as a ditch, a brook or a river. The invention is suited for use also in other water systems.

The filter according to the invention can comprise many kinds of filter cloth. The mesh of the filter cloth is such that water can pass through it, but solid material in the water system, which is meant to be removed, can at least not completely pass through the cloth. At least a part of the filter cloth is in a normal running situation arranged to form a portion, which is essentially transverse to the flowing direction of the water system, the purpose of which portion is to halt the solid material. By essentially transverse is here meant for example a filter cloth, which in a ditch is essentially vertical and arranged transverse to the ditch.

The fact that the filter has a filter volume means that the solid material halted by the filter is sedimented at least partly into or onto the filter, i.e. in the filter volume. Typically the filter has a portion, which is essentially horizontal or essentially in the direction of the bottom of the water system. A planar filter cloth can for example be arranged in the water system so that the part of it on the upstream side rests on the bottom of the water system, suitably attached to the bottom, and the end of the filter cloth on the downstream side is lifted upright, to be transverse against the general flow direction of the water system.

In an embodiment of the invention the filter volume is pouch-like and it has an opening and the water is arranged to flow into the filter volume through the opening. The filter can be formed to be pouch-like, i.e. to comprise at least a bottom part and sides attached thereto, which sides surround the pouch-like filter volume. At least one aperture, i.e. the opening of the filter, leads into the pouch- like filter volume. Thus the water is typically arranged in through the opening and to flow into the pouch-like filter volume. Typically the pouch-like filter is placed in

the water system on its side, i.e. so that the opening of the pouch is essentially vertical and transverse in relation to the general flow direction of the water system. At least one side of the pouch is thus typically on the bottom of the water system or at least essentially in its direction. The bottom part of the pouch is thus typically downstream from the opening, at a distance, which is the length of the side walls of the pouch.

A pouch or bag, which is nowadays used for other purposes on the market, for example a so-called bulk bag, i.e. flexible intermediate bulk container, FIBC, can function as the filter according to the invention. Thus the opening of the bag can function as said opening of the filter and the volume of the bag as said filter volume. The bag can be manufactured of mainly fibre cloth, for example glass fibre cloth. The volume of the bag can be for example 0.5-3 m ³ or 1-2 m ³ . The cross-section of the bag in the direction of the opening can be for example a circle or a rectangle. The largest diameter of the bottom part or the opening can be for example 0.5-2 m or 0.75-1.5 m. The length of the side walls of the bag can be for example 0.5-3 m or 1-2 m. The bags on the market nowadays are durable and suitably sized for the cleaning of most ditches or other flowing water systems. Due to their ready lifting loops for example the so-called bulk bags are excellently suited for use in the method according to the invention, where the bag is lifted out from the water system when needed.

It has now surprisingly been discovered that no expensive and often complicated devices are needed for removing solid material from a water system. With the aid of the invention the removal of solid material from the water system is easy and inexpensive. The filter system according to the invention is reliable. It is easy to completely remove from its place when necessary, for example during winter or maintenance work. If bags, which are readily available on the market, are used as the filter, the emptying and renewing of the filter is very easy and inexpensive.

In an embodiment of the invention another filter cloth is arranged inside the bag, the mesh of which is smaller than the mesh of the bag. The selection of the

second filter cloth can impact the quality of solid material removed from the water system.

In an embodiment of the invention, when the filter has been lifted out of the water system, it is at least mainly emptied from solid material and then returned to the water system to collect solid material. For example various known fibre cloth materials can well endure long-time use.

In an embodiment of the invention the filter is lifted by its edges. Suitable lifting locations may have been arranged in the edges of the filter, by which the lifting is easy. In an embodiment of the invention there are lifting means, such as rings, loops or hooks, in the edges of the opening of the filter volume of the filter or in the vicinity of the edges, for making the lifting easier. The filter can be lifted out of the water system with many different devices, for example a chain, rope, cable wire or the like, attached to the lifting boom of a tractor or another work machine, can be attached to the filter at suitable lifting locations.

In an embodiment of the invention the filter is attached to a support, for example poles, attached to the edges of the water system, such as the ditch, or to the bottom of the water system. The poles or other supports are thus typically attached to the edges or the bottom of the water system firmly and essentially immovably. Attaching means which can be opened and closed, such as a slot, have in an embodiment been arranged between the poles or other supports and the filter, to which slot the opening of the filter can be attached. The filter can, for example around its opening, have a counterpart, which fits the attaching means in the support. The attaching can be secured with various connectors, for example a so-called bayonet catch. It is also possible to attach the filter to the support with ropes, cable wires or the like, for example directly onto a solid attaching point in the edges of a ditch or another water system.

In an embodiment of the invention a dam arranged in the water system functions as the support for the filter, with the aid of which dam water is guided into the filter volume of the filter according to the invention. The dam can be manufactured from

an essentially non-water permeable material, for example concrete, plywood or wood. The dam can be arranged to cover, with the exception of the opening of the filter, the entire water system, such as the ditch. Thus all the water flowing in the water system is filtered.

In an embodiment of the invention the amount of water flowing into the filter is controlled by altering the size of the opening. Closing means have thus possibly been arranged in connection with the filter for altering the size of the opening. The closing means have in one embodiment of the invention been attached to the support, where the filter is also attached, for example to the dam.

In an embodiment of the invention the size of the opening is altered with the aid of a closer placed in front of the opening, which closer can be moved between different positions. The closer can for example be a board, hatch or the like, which is moved supported by rail elements such as rails or slots. The closer can also be a turnable hatch or the like, for example hinged to be turnable around a vertical or horizontal axis.

In an embodiment of the invention the height of the surface of the water system or the volume of the flow is measured and the position of the closing means of the opening is controlled according to the height of the surface of the water system or the volume of the flow. The meter for the height of the surface of the water system or the meter, which measures the volume of the flow, can be connected to the closing means of the opening automatically, whereby the size of the opening is controlled automatically according to the height of the surface of the water system or the volume of the flow. The meter for the height of the water system can for example be a swimmer valve, whereby when the surface of the water rises, the swimmer valve, i.e. the float, rises upwards, and with a suitable swimmer mechanism the closer closes the opening of the filter as a function of the height of the water surface. In some applications of the invention the passing of the water into the filter is limited or it is completely prevented during high water or a large flow. By closing the opening, the washing away of solid material from the filter volume, for example due to flood water, can be prevented.

In an embodiment of the invention a water purification chemical is fed into the water system at the filter. In an embodiment a container for a water purification chemical and a dosing device for feeding the water purification chemical from the container into the water system have thus been arranged in connection with the filter. For example ferrous sulphate or another chemical coagulant can be dosed in a suitable manner to promote the sedimentation of nutrients, for example phosphor, into the filter according to the invention. If the properties of the water system, for example the surface height, the flow, the amount of solid material or the amount of some specific ingredient are measured with a suitable meter, the dosing of the chemical can be linked to the values received from the meter.

BRIEF DESCRIPTION OF THE FIGURES

The invention is described in more detail below with reference to the enclosed schematic drawing, in which

Figure 1 shows an embodiment of the invention installed into a ditch and seen from above,

Figure 2 shows the embodiment of figure 1 seen from the side, Figure 3 shows a second embodiment of the invention installed into a ditch and seen in the direction of the ditch,

Figure 4 shows a third embodiment of the invention installed into a ditch and seen from the side, Figure 5 shows a fourth embodiment of the invention installed into a ditch and seen in the direction of the ditch, and Figure 6 shows a fifth embodiment of the invention installed into a ditch and seen from the side.

DETAILED DESCRIPTION OF THE EXAMPLES OF THE FIGURES Corresponding parts in different embodiments have for the sake of clarity been marked with the same reference numbers in the figures. The flowing of the water is marked with arrows.

Figures 1 and 2 show a system 1 according to the invention for cleaning a water system, which system comprises a filter cloth 2. The shape of the filter cloth 2 is essentially rectangular. In figure 1 the filter cloth 2 is shown with a dotted line. The first end 3 of the filter cloth rests with the aid of weights 4 on the bottom 6 of the ditch 5, essentially in the direction of the bottom. At a distance, for example 1-5 m, downstream from the first end 3 is the second end 7 of the filter cloth, which second end is attached to a float 8. With the aid of the float the second end 7 is kept near the water surface 9 of the ditch. In the example in figures 1 and 2 the float 8 is elongated and placed transverse to the ditch. Many alternative solutions for the structure of the float can of course be imagined. Weights 4 have been attached to the filter cloth 2 also near its second end 7, in order to help the second end 7 of the cloth 2 to stay approximately vertical. In figure 2 is seen how the middle part of the cloth has folds 10 approximately underneath the float 8. In this way there is enough filter cloth to reach the surface even when the height of the water surface 9 varies somewhat. Additional floats 11 essentially in the direction of the ditch, which stabilize the float 8, have been arranged in connection with the float 8, near the water surface 9.

The water in the ditch 5 can travel through the second end 7 of the vertical filter cloth, which is transverse in relation to the main flow direction of the water. At least not all of the solid material travelling with the water can pass through the filter cloth, but solid material is sedimented onto the part of the filter cloth, which rests on the bottom. This space 12 is in this application called the filter volume of the filter.

At the edges of the filter cloth 2 has been arranged means 13, which make the lifting of the filter cloth from the water system easier. Floats can be arranged for example in the first end 3 of the filter, which floats can be filled with air if desired. Thus, when the filter 2 is lifted out of the water system, the floats 13 can first be filled with air, whereby the edges of the filter cloth rise to the surface. The float may go around all the edges of the cloth 2. The means 13 can also be loops or hooks arranged in the edges of the cloth 2.

The bottom dam 14 is drawn visible in figure 2. The system 1 according to the invention works well with a bottom dam 14 or a corresponding device, which slows the flow of water. Solid material travelling with the water system is sedimented into the filter volume 12 of the filter according to the invention. According to the invention the solid material is easy to remove from the water system. Thus dredgings upstream from the bottom dam can be made less frequent. A bottom dam 14 or the like is easy to arrange to support the filter system 1 according to the invention.

In figure 3 is shown an embodiment of the invention installed in a ditch and shown in the direction of the ditch. In the figure is seen a dam 15 built across the ditch, the edges of which dam are sunk into the ground 16 surrounding the ditch. The triangular edges of the dam 15 underneath the ground are shown with dotted lines. A flow opening 17 has been formed in the dam 15. The dam can be manufactured in many different ways, but one simple way is to manufacture it out of plywood, such as waterproof plywood, or some other board-like material, the edges of which are sealed against the edges of the water system, such as the ditch. In the situation in the figure the water surface 9 reaches close to the upper edge of the flow opening 17. The filter according to the invention can be attached to the edges of the flow opening 17. For example if the filter is bag-like and equipped with an opening, the flow opening can be arranged to be approximately of the same size as the opening. Thus the attaching of a bag-like filter formed for example from a so-called bulk bag to the dam is relatively easy. With the aid of the dam 15 as much as all the water in the water system can be guided into the flow opening 17 and thus into the filter. In figure 3 is seen with dotted lines the edges of the opening 19 of the filter arranged behind the dam 15. The water flowing from the flow opening 17 thus goes in through the opening 19 and into the bag-like filter. One filter 18 and solution for arranging the filter 18 in connection with the dam 15 is shown in figure 4.

Figure 4 shows a system 1 , where a bag-like filter 18 has been attached by its opening 19 to a dam 15. Around the opening 19 has been arranged a plate-like flange or collar 20, which is easy to attach with attaching means 21 tightly to the

dam 15 at the flow opening 17. In the example in the figure the opening 19 of the filter, i.e. the opening of the inner edge of the collar 20, is larger than the flow opening 17 in the dam, so all the water flowing from the flow opening 17 easily goes into the filter 18. The attaching of the filter 18 to the dam can be done in many different ways, so it has not been described here in further detail. For example between the dam 15 and the attaching means 21 can be arranged a slot 23, wherein the collar 20 can be slid in a detachable manner.

The bag-like filter in figure 4 is for example a so-called bulk bag available on the market, to the opening of which has been attached a flange or collar 20. The collar

20 has been arranged upstream in the ditch 5 and the bottom 24 of the bag essentially vertically downstream in the ditch. One side 25 of the bag rests due to the effect of weights 4 on the bottom 6 of the ditch, essentially in the direction of the bottom. The other side 26 of the bag is, carried by floats 27, near the water surface 9, essentially in the direction of the surface. A filter volume 12 is formed inside the bag, where solid material travelling with the water is sedimented. The sedimented solid material is shown with a dotted line 28. To the dam 15 in figure 4 has above the surface, downstream from the dam, been attached a dosing container 29 for a chemical coagulant, for example ferrous sulphate. The dosing of the chemical is controlled by controlling the position of the closer 30.

When the filter 18 is emptied, the collar 20 of the opening is first detached from its attaching means 21. The collar 20 or a spot near it is grabbed and it is lifted for example with the lifting boom of a tractor. Lifting loops can for example have been arranged in the collar 20 to make it easier to grab it. When lifting close to the opening, the solid material in the filter volume 12 mainly remains in the filter 18. The water in the filter can first be drained through the filter cloth into the ditch before the bag is emptied for example into the trailer of a tractor or into a field. The empty filter bag is returned to its place or exchanged for a new one.

A flood may cause solid material to be washed away from the filter 18 or even cause the filter 18 to detach from its attaching means. Figures 5 and 6 show two

solutions for limiting the amount of water flowing into the filter 18 when the water surface 9 rises.

Figure 5 shows a system 1 , where a closing solution has been attached to the flow opening 17 in the dam, in a dam 15 corresponding to the one shown in figures 3 and 4. Essentially vertical guiding rails 30 have been attached to the dam, on its upstream side. A closing hatch 32 has been arranged into them to move along a vertical path on pegs 31. The size of the closing hatch is slightly larger than the flow opening 17. In its lower position the closing hatch 32 completely covers the flow opening 17. In its upper position the closing hatch 32 is completely away from in front of the flow opening 17. The rails are placed so close to the dam 15, that the closing hatch in the lower position at least essentially prevents the water from flowing through the flow opening 17. In the figure is schematically shown how a so-called swimmer device 33 has been connected to the closing hatch. The swimmer has a lever 35, which turns around an axis 34, which is supported on the dam. On one side of the axis 34 the lower end 36 of the lever is attached to the closing hatch 32. On the other side of the axis 34 there is at the top end 37 of the lever a float 38, which floats on the water surface 9. When the water surface 9 rises, the lower end 36 of the lever sinks lower and at the same time the closing hatch 32 closes. In the situation in figure 5 the water surface 9, has risen close to the upper edge of the dam 15, and the closing hatch 32 is almost in its lower position.

Figure 6 shows a system 1 seen from the side, where a bag-like filter 18 is arranged detachably between two poles 39 struck down into the bottom of a ditch 5. Unlike in the solutions shown above, in figure 6 the swimmer device 33 directly adjusts the size of the opening 19 of the bag. The lower end 36 of the lever 35 has now been attached directly to the upper edge 40 of the opening 19. The upper edge 40 thus moves up or down along with the water surface 9. The lower edge 41 of the opening has been arranged to be approximately in its place, for example due to weights 4, which hold the bag on the bottom. Thus when the water surface 9 moves, the size of the opening 19 of the bag changes and thus the amount of water flowing into the filter 18 varies. The solution shown in figure 6 does not need

a dam or a corresponding structure to support it. The poles 39 must of course be supported sufficiently to withstand the stress of the flowing water. In figure 6 are seen the lifting loops 13, arranged near the edge of the opening, by which the filter is easy to lift when emptying it.

The figures show only some embodiments according to the invention. Facts of secondary importance with regards to the main idea of the invention, facts known as such or apparent for a person skilled in the art, such as all support structures possibly required by the invention, are not separately shown in the figures. For example the lever arrangements shown in figures 5 and 6 are only examples of solutions, which can be substituted with various automations. It is apparent to a person skilled in the art that the invention is not limited exclusively to the examples described above, but that the invention can vary within the scope of the claims presented below. The dependent claims present some possible embodiments of the invention, and they are not to be considered to restrict the scope of protection of the invention as such.