Field of the invention

The present invention relates to treatment processes of solutions, especially wastewaters and natural waters. It is based on a structural innovation and the principles of electrocoagulation.

Background of the invention

Electrocoagulation (EC) is an electrochemical technique, which has been used for a long time in water and wastewater treatment. Generally, such wastewaters are generated within various industrial processes. Electrocoagulation can be used for removing suspended solid particles and heavy metals, and also grease and oil from the water which is to be treated.

EC is a technique where different components present within a suspension can be separated from each other. This is achieved by placing an anode and a cathode near to each other within a solution volume, and then applying an electric current between these two electrodes in the volume of the aqueous solution. The electrodes are typically metal plates made from aluminium, iron or stainless steel. The anode material will dissolve into the solution, and these metal cations will then act as coagulation agents within the aqueous solution. The dissolved metal cations will change the surface charge of the particles within the suspension. This effect leads into an agglomeration process, where the suspended material will form larger particles, i.e. agglomerated pieces of matter commonly called floes, which can then be readily separated from the solution.

In addition to the anodic reactions, hydroxide ions (OH ^" ) and microbubbles of H ₂ are simultaneously released at the cathode. These hydrogen bubbles will adhere into the agglomerates and help them to rise towards the surface of the solution. This process is called electroflotation. When the suspended and agglomerated matter has separated into a particular place in an EC system, such as on the surface of the aqueous solution, it may be removed mechanically (or by some other means) from the solution container. The resulting solution (supernatant) will have a substantially reduced contaminant concentration, which means that the electrocoagulation chamber acts as a wastewater purifier. The EC-treated water may be discharged where found appropriate, such as being fed back to the nature. In prior art, electrocoagulation has commonly been used in several kinds of water purifying and/or water disinfection arrangements.

Publication WO 2015/18751 1 (Gilmore) discloses an electrocoagulation chamber which comprises of vertical electrode plates. The liquid is fed into the chamber from the inlet "30" below, through a pressurized container, and the liquid is further directed up between the electrode plates where a normal atmosphere prevails. After the electrocoagulation process between the plates, the liquid goes upwards and falls over the edge into an inter-wall volume "37".Typically, the EC sludge/foam rises to the surface of the liquid, and in Gilmore, this foam contained extra liquid flows over the edge to the cylindrical inter-wall volume and exits the housing through a chute "38".

Hungarian patent application no. 4217/89 (HUT631 19) discloses an electroflota- tion cell for treating wastewater. The reaction space comprises of vertical plate- type anodes and cathodes arranged in parallel, and connected to a direct current (DC) source. The minus and plus plates are placed alternately. The lower ends of the electrode plates are provided with a plurality of holes. The wastewater swirls down and up in each of the intermediate gaps between the plates. The excess foam flows up onto the top of the liquid surface and goes out of the electroflotation chamber along a tilted route "4" into an external "foam container 12". The foam and the liquid seem to exit the device from the same outlet.

One of the main problems of the prior art is that many of the presently available devices have a non-continuous (batch) working principle. This means that the solution or wastewater to be treated is first added into the purifying chamber, after which electrical current is applied in order to start the electrocoagulation process. After the electrocoagulation process is finished, the EC-treated water is removed from the chamber. This kind of singular usage principle/mode means that the amount of wastewater to be treated in a given time is relatively small.

Furthermore, the effectiveness of the method and the complexity of the devices have also been a problematic issue in the prior art arrangements. Brief description of the drawings

Figure 1 a illustrates a first embodiment of the water treatment device, shown as a side view, and at the start of the insertion with the water to be treated, Figure 1 b illustrates the first embodiment of the water treatment device, shown as a side view, and during the continuous operation with the water flow,

Figure 1 c illustrates a second embodiment of the water treatment device, provided also with a non-active plate or clarifier, shown as a side view, Figure 2 illustrates a third embodiment of the invention, provided with three electrode pairs (anode and cathode) and two non-active plates for the water flow, shown as a top view, and also presenting the movement directions of the agglomerated substances and EC foam/sludge,

Figure 3 illustrates a fourth embodiment of the invention as a side end view, show- ing a scraping means on top of the device for removing the agglomerated substances and foam from the surface of the treated water into a chute,

Figure 4 illustrates an example of the locations where the electrical connections into the water treatment device can be made,

Figure 5a illustrates a single-grooved exemplary structure of a groove element, Figure 5b illustrates a double-grooved exemplary structure of a groove element,

Figure 5c illustrates a top view of the exemplary device, where a pair of active plates (= a cathode and an anode plate) are connected in the inner surface of the housing through a U-shaped double-grooved element,

Figure 6a illustrates an example of a water through-hole in an upper part of a met- al plate which also acts as a handle creation means, and

Figure 6b illustrates a pair of metal plates fixed into a single movable element where another plate is like the plate in Figure 6a, and the plates are fixed together with two supporting sections.

Detailed description of the invention The present invention introduces a device for treating continuously an incoming flow of wastewater, or any other kind of suspension or aqueous solution which needs to be purified. By purification it is meant that solid materials and other liquid or gel-based materials such as grease and oil, are removed from the wastewater. Purification may also include removing bacterial organisms from the aqueous solu- tion. The wastewater treating device incorporates both mechanical and electro- chemical characteristics. The electrochemical action is performed through electrocoagulation. Electrocoagulation means here effecting electrolytic reactions through supplying electric current into pairs of metal plates. These electrolytic reactions comprise anodic dissolution and cathodic microbubble and OH- formation. In the following Figures, the structural properties of the device are illustrated according to certain embodiments of the invention.

Figure 1 a illustrates a first embodiment of the invention. The device has a housing 10 which may be made from metal, plastic, ceramic or other impermeable hard material. The housing 10 has a rectangular shape. The housing 10 is furthermore a covered or coverless rectangular box made of hard material, such as metal or plastic. The size of the housing 10 and the accurate dimension ratio between the length, height and width of the housing can be selected based on the application area and the desired amount of treated water per time unit. The housing 10 has an inlet 15a for the aqueous solution and an outlet 15b for the treated water. These inlets may be provided with input and output pipes made of e.g. metal, plastic or rubber which lead into the actual wastewater source container and treated water container, for instance. The heights of the inlet 15a and the outlet 15b within the vertical end walls of the housing 10 is not relevant in relation to the bottom level of the housing 10; the only restriction is that these pipings should preferably locate somewhere else than at the top of the housing 10 where the solution surface will eventually form during the use of the device.

The interior of the housing 10 is provided with vertically placed rectangular and electrically conductive plates, such as metal plates. These plates are functioning as cathode and anode pairs, and in this example, there are four such pairs of plates 1 1 a-b, 12a-b, 13a-b and 14a-b. The plates are impermeably connected or fixed to the inner vertical walls of the housing 10. When looked at from the direction of the wastewater inlet 15a, the first vertical plate 1 1 a will have a narrow gap between the lower edge of the plate 1 1 a and the bottom level of the housing 10. The top end of the plate 1 1 a will reach above the water surface level when the incoming water has been fed and the water surface level is settled. The second plate 1 1 b will locate a kind of step lower so that the lower edge of the plate 1 1 b is connected or fixed to the bottom level of the housing 10, while the top edge of the plate 1 1 b will end up locating just beneath the water surface (when the water is settled into the device). This means that water can flow over the top edge of this plate 1 1 b, meaning in the context of Figure 1 a that the wastewater flows from left to right.

The actual electrocoagulation process will occur between each pair of the metal plates such as between 1 1 a and 1 1 b. The gap width between the parallel plates 1 1 a and 1 1 b can be set to a distance value ranging from 3 mm to 25 mm. The gap width may also be set in between 3 to 12 mm to ensure a smaller needed current which enables the same effectiveness of the electrocoagulation process as the wider gap would do. In other embodiments, the distance value may be bigger than 25 mm, and this might be especially usable in very large scale applications. Figure 1 a shows the other pairs of plates as well, that is, a second pair of plates 12a-b, a third pair of metal plates 13a-b and a fourth pair of metal plates 14a-b. The electrocoagulation process will actively take place in each narrow gap between each pair of the plates, the reactions taking place on the surface of the plates. In one embodiment of the invention, the vertical locations of different pairs may differ for instance so that at least one plate of the plate group 1 1 a, 12a, 13a and 14a will locate in different height than the rest of the corresponding plates. The same applies with the plates fixed to the bottom of the housing, i.e. plates 1 1 b, 12b, 13b and 14b. In that embodiment, the top end of one or several plates 1 1 b, 12b, 13b and 14b will locate in different height than the other corresponding plates. The heights may thus differ regarding plates 1 1 b, 12b, 13b and 14b. When one or several of the top edges of the plates 1 1 a, 12a, 13a, 14a locate lower than the rest of these top edges, it may ease the processing of the sediment on top of the water surface. It may give a possibility to widen the scraping tool which can be used to remove the sediments on top of the device.

In another embodiment, the vertical locations of different pairs may be placed on the same level, regarding all the upper edges of the upper plates and correspondingly, regarding all the upper edges of the lower plates.

In one embodiment of the invention, the pairs of metal plates can be placed in a descending trend when looking at the vertical placement of the upper edges of the plates. This means that the upper edge level of plate 12a is a bit lower than the corresponding level of plate 1 1 a. Thus, the upper edges of all the plates 1 1 a, 12a, 13a, 14a will go down in a decreasing trend when looked at the geometry from left to right in Figure 1 a. The same applies to the group of the lower plates 1 1 b, 12b, 13b, 14b as well. This results in the fact that the treated water surface height in different sections of the apparatus will lower slightly when looked from left to right in the geometry of Figure 1 a. The benefit of this kind of arrangement is that it will ease to cleaning of the foam, floe and/or sludge material on top of the treated wa- ter surface.

The higher locating plates 1 1 a, 12a, 13a and 14a may act as anodes and the lower locating plates 1 1 b, 12b, 13b and 14b may then act as cathodes. This is achieved by connecting an electric current to all metal plates forming the pairs 1 1- 14. Of course, the electric current may be connected vice-versa, so that all the higher locating plates 1 1 a, 12a, 13a and 14a act as cathodes, and the lower locating plates 1 1 b, 12b, 13b and 14b act as anodes.

The lower locating plates 1 1 b, 12b, 13b and 14b may have a spike connected to it, and pointing upwards and thus, reaching above the water surface level. Such a spike can be used as a connection point to the electric current fed from outside the housing. The parts locating always above the water surface level may be directly connected to the electric current source, e.g. by clip-on electrodes directly con- nectable on top of the metal plates 1 1 a, 12a, 13a and 14a. With this kind of arrangement, the electric wires are not affected by the treated wastewater.

Figure 1 a shows a single time instant during the start of the water treating process where the inlet 15a has just been opened and the wastewater has just started to flow in as a pressurized water input. As it can be seen from the Figure, when the water level reaches the top level of the plate 1 1 b, it will flow over the plate 1 1 b and the water starts to fill the next wider gap between plates 1 1 b and 12a where no electrocoagulation takes place. In Figure 1 a the water level is rising in the second electrocoagulation reaction slot, between the plates 12a and 12b.

During the active working phase of the water treatment device, there should not emerge any water flow or dripping through any vertical seams of the plates and the inner surface of the housing. Also the lower edge seam between the plates 1 1 b, 12b, 13b and 14b and the lower surface of the housing 10 should be water- tight.

Figure 1 b illustrates the same device as in Figure 1 a but in an active water treatment stage. In this time, the device has been filled with incoming wastewater to be treated and the water has thus reached the final sub-part of the housing, in the right side of the plate 14b. Of course the number of pairs of plates is not restricted to four; actually the number of plate pairs can be any positive integer value. In this stage, the treated water pours out of the housing 10 through the outlet 15b, which may lead to a treated water storage or e.g. to place where the treated water is wanted to be fed at; e.g. directly back to the nature. The functioning of the device is in this stage continuous, meaning that there is a continuous and free flow of water through the device through the housing 10, making its use simple and enabling also very large volumes of water to be treated. In practice, the volumes of incoming water may even be unrestricted, acting as a continuously working treatment device for the wastewater e.g. for industrial processes. The water level during the active stage will be just over the top edge of the lower locating metal plates 1 1 b, 12b, 13b, 14b. The water flowing directions can be seen in Figure 1 b. The active electrocoagulation will take place in the narrow gaps between each plate pairs. In the active electrocoagulation area, both the water and the agglomerated pieces of suspended matter flow upwards, enabling a smooth water flow through the device. The foam and other suspended materials within water will form a coating on top of the water surface, while the cleaner water continues its flow through the device. In the end of this chain of electrocoagulation chambers, the treated water 18 in the end will be desiredly pure water, while all the other materials have been gathered on top of the water surface in different sub-sections of the device. These agglomerated solids, liquid-based contaminants and foam may be removed separately from the top of the water surface. This is discussed later in more detail. The top end of the housing 10 can be open as "a box without a cover" so that the electrical connections and also the removal of the other substances can easily be implemented. In one embodiment of the invention, the plates 1 1 a-b, 14a-b can be removed from the housing 10 by an upwards directed pulling movement. In such an embodiment, the plates can't be welded to the inner surface of the housing 10. The inner surface of the housing may be provided by an additional groove structure made e.g. by rubber. The plates may be located in these grooves so that the connection there would be water-tight. In yet another embodiment, the locations of the groove structures within the housing may be selected by the user. This means that in view of Figures 1 a-b the X-coordinates of the plates 1 1 a-b, 14a-b may be freely selected. This means that also the number of used plate pairs may be increased or decreased by adding or removing two groove structures per the plate pair. Of course, this effect might be created also with a single groove element, which com- prises two groove structures in a single groove element, where the distance between the two parallel groove structures is preferably between 3 ... 25 mm.

Figure 1 c illustrates yet another embodiment of the present invention, where there is an additional non-active plate 16 in the end of the water treating process so that the non-active plate 16 is fixed or connected to the bottom and the sides of the inner surface of the housing 10. In practice, this non-active plate 16 locates after the treated water has passed the last active plate which in this example is plate 13b. The reason why there is an additional non-active plate 16 is that it acts as a clarifier after the active treating phases between the pairs of the electrocoagulation plates 1 1 a-b, 12a-b, 13a-b. In this example, the housing 10 comprises three pairs of active electrocoagulation plates 1 1 a-b, 12a-b, 13a-b. There might alternatively be several non-active clarifier plates 16 placed consecutively along the treated water flow 18. The height of the non-active plate 16 may be noticeably less than the active plates in order to achieve smooth flow of the treated water. Other- wise, the embodiment of Figure 1 c works similarly as the embodiment in Figure 1 b.

The non-active plate 16 can also be located in the middle of the housing, meaning that there are active pairs of plates in both the incoming direction of the treated water and the outgoing direction of the treated water, when looked from the loca- tion of the non-active plate. In yet another embodiment, several non-active plates can be placed along the route of the treated water, either in a scattered manner along all the active pairs of plates, or as a group of consecutive non-active plates creating a larger clarifier region within the fluid volume of the apparatus.

Figure 2 illustrates a third embodiment of the wastewater treating device, and also showing the device directly on top of the device, taken directly from above. The housing 10 is a longitudinal and rectangular box without a cover. The left end wall of the housing 10 is provided with an inlet 15a for the incoming wastewater and the right end wall has the outlet 15b for the treated water to exit. The pairs of active electrocoagulation plates are here shown as three pairs of active plates 1 1 a- b, 12a-b and 13a-b. They are all connected to the side walls of the housing 10. The structure also comprises two non-active plates 16a, 16b acting as clarifiers for the treated wastewater. The incoming water will flow upwards (towards the "camera" in this view) in each of the narrower gaps between 1 1 a and 1 1 b, between 12a and 12b and between 13a and 13b. The water will flow downwards (meaning away from the camera in this image view) in the three left-most wider sub-volumes of the device; between the left end wall and plate 1 1 a, between 1 1 b and 12a, and between 12b and 13a. After the plate 13b, the water flow will clarify when it travels over the plates 16a and 16b, until the water reaches the outlet 15b in order to exit the housing 10. The solid and agglomerated materials such as droplets of solids and foam will rise on top of the surface and it will be visible in this top-view of the device. This embodiment arranges the removal of these solid and liquid waste components from the water 18 in showing the directions where the waste flow travels. The waste may be scraped with a physical scraper or any appropriate mechanical means from the top of the water surface. It may be an automated movement of the mechanical means or it may also be performed manually by a human user. The target is to gather the foam and solids and all other dirt into the chute 17. The lower vertical edge between the chute 17 and the housing 10 may be a bit lower so that the material may more easily enter the chute 17. The chute may be tilted so that the dirt material may flow out of the chute, and this is exemplified in the Figure 2 as the dirt material exits the chute 17 from the left-hand side end of the chute 17.

Regarding the exit direction of the materials within the chute, the solid and agglomerated materials can also flow on the chute 17 to the direction pointing to the right in Figure 2. A further option is to tilt the chute 17 downwards starting from the center part of the chute so that the left half of the chute 17 directs the material in the left part of the apparatus flowing to the left side, and the right half of the chute 17 directs the material in the right part of the apparatus flowing to the right side. In a yet further embodiment, a chute 17 can locate as adjacent to both long sides of the apparatus, resulting in two chutes 17 being used, one in the bottom part of Figure 2 and one in the top part of Figure 2, where the latter chute is placed in an opposite and parallel location compared to the first one.

The same structure with two chutes is further exemplified in Figure 3 where the view is taken along the horizontal line connecting the inlet 15a and the outlet 15b. The housing 10 comprises water 18 to be treated but the electrocoagulation plates are not shown in this illustration. Instead, an example of the scraping means 30 can be seen on top of the device. The scraping means 30 has spikes (as shown) or a scoop-shaped element (not shown) which are used to grab the suspended dirt material 32 on top of the water surface so that it will move towards the left-hand side or towards the right-hand side in this illustration. The grabbed or scooped dirt 32 will then flow over the left and right side edges of the housing 10 and it will drop into the chutes 17. Of course there can be a single dirt-grabbing movement or several consecutive automated movements only in one direction or in two opposite directions consecutively. In one example, the scraping movements can be activated after a given time period after the previous scooping movement. In one embod- iment, there is a chute 17 just along one side of the housing 10, like in Figure 2, and the scooping movement may be performed so that all the scraped material will move only in a single direction towards the single chute 17. Of course, the end(s) of the chute(s) may be provided with a pipe structure which conveys the dirt material to a desired location within the water treating process. The chute(s) may be tilted downwards from the center of the chute, like a shape of a ridge roof, or alternatively, from the either end(s) of the chute(s).

The movement of the scraping means is simplified in the Figure 3 to be just a horizontal movement of the element. It is also possible that the scraping means is a more complex structure which grabs the dirt material, lifts it onto a kind of convey- er belt type of transport means and it then transports the material into the chute or other kind of an exit pipe for the dirt material.

In Figure 3, the inlet and outlet location is exemplified with a round dashed line.

Figure 4 shows a view from the side of the housing and it emphasizes the way which electrical connections are created in the device. There are three pairs of active electrocoagulation plates 1 1 a-b, 12a-b, 13a-b visible in the Figure. The plates whose top edges will stay in the water in the normal continuous operation of the device, are plates 1 1 b, 12b and 13b. These plates are each provided with an electrode spike 42a, 42b, 42c, correspondingly. The reason for this spike is that the electrical feed signal should be somehow provided to both the anodes and cathodes, and the corresponding wires would last much better if not a part of the wires would locate in the wastewater. Therefore, the narrow spike will provide an electrode or additive connection point to the metal plate, which spike will always reach partly above the water surface. The upper edges of the other plates 1 1 a, 12a, 13a will already locate above the water surface while the device is in use, so there is no absolute need to attach spikes in those plates. The spikes may be formed from the same material as the metal plates or it can otherwise be formed from any other conductive material.

The electric current source 41 is connected to the anodes and cathodes like the Figure 4 shows. As already said above, the plates with spikes may be the cath- odes and in that case the plates without the spikes will be anodes. Alternatively, cathodes and anodes may be just the opposite. The order of the plates is not that relevant, and the main feature is that the current will flow through the wastewater between the anode/cathode pair of plates, when the current source 41 is switched on. While not shown in the Figure 4, the electrical current source 41 may comprise an electrically controllable or manually controllable switch, which can be used to start the electrocoagulation process and to switch it off, whenever desired.

As a further option regarding electric supply, there can be used several electric current sources for a single water treatment apparatus.

Figures 5a-c illustrate an alternative solution to welding the metal plates onto the inner surface of the housing 10. This alternative embodiment shows different kinds of groove-based elements, and these groove-based elements are meant as counter-parts to the single metal plates or pairs of the metal plates. Figure 5a shows a part of a single groove element 51 with a single-grooved structure, which may be manufactured at least partly from rubber or other elastic material. The material could comprise some adhesive component on top of it in order to enhance the grip to the contacting material. The width of the groove is essentially the same as the width of a single metal plate 1 1 a-b, 12a-b, ... . The height of the groove element 51 may be essentially the same as the height of the housing 10. Of course, the groove element 51 may be a U-shaped element so that it may be placed in the bottom of the inner surface of the housing 10 so that the wall sections will align with the left-hand vertical surface of the groove element 51 as shown in Fig. 5a. The resulting U-shaped groove element will not let the water to pass through the seams of the groove element and the walls and bottom of the housing 10.

Instead of a U-shaped groove element, the groove element may have a rectangu- lar shape. Referring to the metal plate embodiment where a hole separates a handle section in the metal plate (see Figures 6a-b), an alternative option is to have a rectangular groove element which coincides with the outer edge of the metal plate of Figure 6a. The actual metal plate may be the lower unified part of the metal plate, with less height than the height of the groove element. As a result, there is a hole between the groove element in its top horizontal part, and the metal plate itself. The groove element in its top horizontal part thus forms the handle from where the whole element can be grabbed (either manually or by a motorized tool) and risen away from the housing of the apparatus. The groove element of Figure 5a gives a possibility to tune the distances between an anode plate and a cathode plate in each pair of plates. This kind of groove element 51 may also be used for the non-active plate 16, 16a, 16b.

Figure 5b illustrates another type of groove element which has a double-grooved structure. In this kind of element, the distance between the parallel grooves will be set to the distance which is the desired distance between the active plates of a single electrocoagulation pair such as plates 1 1 a, and 1 1 b. Thus, in a useful embodiment this distance and also the groove distance within the element 52 is set between 3 ... 7 millimeters. Also the distances between 7 ... 25 millimeters are useful in some applications. The double-grooved element 52 can be formed as U- shaped or rectangularly shaped, and when placed in the bottom of the housing 10, it specifies a location for a single electrocoagulation pair where the active process will take place within the housing.

The groove element 52 of Figure 5b gives a possibility to tune the widths of the passive regions, e.g. the width between the plate 1 1 b and plate 12a in Figure 4.

Furthermore, the elements 51 and 52 from Figures 5a and 5b may be tilted in their outer edges so that there is not any 90° angle in the volume where the water passes. Alternatively, the edges of the metal plates may be provided with a beveled additional part which smooths the corners created in the intersections be- tween the metal plates and the housing inner walls. This has the advantage that the treated water with the dissolved solid materials does not sediment, i.e. get stuck in the inner corners of the apparatus that easily. In other words, the angles between element 51 (or 52) and the inner housing wall will be blunt and not 90 degrees. In case the metal plates are directly welded into the housing, and no groove elements are used, the beveled additional part makes the angles within the modified metal plate and between this plate and the housing wall as blunt, meaning more than 90 degrees. In one example, the beveled additional parts may result in inner angles of 135 degrees within the apparatus.

Figure 5c illustrates a view from the top of the device where a U-shaped double- grooved element 52 is in its place within the housing. After the groove element has been placed into the housing, the metal plates 1 1 a, 1 1 b can be inserted in the grooves by inserting them in the grooves from the top of the device in a vertical direction. The plates 1 1 a, 1 1 b will attach to the grooves so that this part of the structure will be impermeable to water. This may be ensured by inserting adhesive material such as glue in the inner surfaces of the grooves or on the outer edges of the plates in order to have a more intact structure. Naturally, this effect may be created through mechanical pressure such as it is the case with rubber, but also some external force creating means such as springs may be used to enhance the impermeability of this connection. With the structure of Figure 5c it is possible to retune the heights of different plates. Especially, it is possible to e.g. raise the plate 1 1 a upwards if somehow the water flowing beneath that plate is not sufficient. Also all plates 1 1 a-b, 12a-b, ... may be removed from the housing 10 in order to give the user a possibility to clean up the whole housing during a set interruption period in the use of the water treat- ing device.

In one embodiment of the invention, the incoming water flow speed (volume of incoming wastewater per time unit) can be specified and set to be used in the device inlet 15a. The tuning may be performed by a controller or an external computer which takes care of controlling the water treating process. Also the electrical current of the current source 41 may be controlled by the controller or an external computer in order to select an appropriate strength to the electrocoagulation process between the plates. This may vary because the incoming wastewater may have broadly variable characteristics. Also, the repetition rate of the scraping means movement can also be controlled through the computer. Alternatively, the system may provide a message to a user when the material 32 exceeds a certain limit. The user might then manually clean up the surface of the treated water. The quality of the incoming wastewater is one piece of source information which can be used to determine the above control parameters. Also the desired level in the power (effectiveness) of treating wastewater within the device, or the desired purity level in the outflowing water from outlet 15b can be used as a piece of source information when determining the above control parameters for the device.

In one embodiment, a single plate such as 1 1 a may be comprised of several pieces which may be placed adjacently to each other to create a single plate. The connections between the pieces may be done with 2-sided groove elements 51 so that a second groove will point 180 degrees to a different direction than the first groove does. In this way, the weights of a single piece of plate can be decreased, and in more largely scaled housing sizes, this will considerably ease the rising and lowering movements of the plates and treating of the housing itself. As an alternative structure to the one presented in Fig. 5c, the inner volume of the housing is provided with guiding sections which act as guiding locations for the plate stacks. The guiding sections can be short metallic pieces which are attached to the inner side surfaces of the housing. The adjacent guiding section can be placed in a distance which is the same as the depth of the element 52 (see Fig. 5b). In one embodiment, a pair of metal plates forms a single stack of plates which is placed between two guiding sections. One advantage of using guiding sections is that they protect the adjacent element (like metallic plate or a metallic groove element) from the effects of the treated wastewater, and also from the effects cre- ated with the electrocoagulation reactions on the surface of the active plates. In other words, the metal volume between the guiding sections not contacting the treated water will not dissolve and therefore the contact of the plates into the side walls of the housing remains stabilized. In one embodiment, the distance between the two guiding sections next to each other is between 25 mm ... 100 mm. In one embodiment the guiding section may be formed as a H-element in the inner volume of the housing, where the metal plate pairs can be placed as a matrix-type of formation along the housing inner volume. In this way, the weight of a single piece of a metal plate pair can be reduced, which results in easier removal of these units during the maintenance work. Going back to the embodiment of a single one-piece plate, a pair of metal plates may have a following structure, which is shown in Figures 6a and 6b. This kind of a metal plate pair structure can be applied in any of the previously discussed and illustrated embodiments. Enabling easier pulling possibilities for the metal plates out from the housing, each lower plate 1 1 b, 12b, 13b, 14b can have a structure shown in Figure 6a. The metal plate has a rectangular hole which formulates the top part of the plate. The hole creates a handle 61 where the user may take a grip during maintenance actions. The hole further acts as a gap in the plate during normal water treating operation where the treated water can flow through hole. Actually, the lower horizontal edge of the hole creates a top edge for the lower me- tallic part of the plate, and it thus acts the same way as the upper edge of the plates 1 1 b, 12b, 13b, 14b. The handle 61 can be grabbed by the operator or maintenance worker of the apparatus, and through a movement directly upwards, the metal plate can be removed from the housing or placed back into the housing. The groove structure as described above will make the vertical movement smooth and possible. The use of rubber within the groove structure will lessen the friction between the plate's side edges and the groove. Of course there might be used some lubricating substance which makes the same effect. If the used application and thus, the size of the water treatment apparatus is large, the handled plates may be placed side-by-side so that the planar metal sheet comprises several handled sections, such as in Fig. 6a or 6b, placed in an adjacent manner along the same plane. This will reduce the weight of a single section which is lifted with a single pulling movement. In other words for that embodiment, a metal plate on a single vertical plane comprises several plate sections which are attached together and the plate sections are each separately movable in a vertical direction from and into the housing 10. Figure 6b illustrates a structural example of creating a fixed double-plate element combining a metal pair of plates into a single movable element 62. Figure 6b exemplifies only the first pair 1 1 a, 1 1 b but of course the structure is applicable to any pair of metal plates within the apparatus. The two metal plates 1 1 a and 1 1 b can be fixed together with supporting sections 63a, 63b and in this example there are two such supporting sections rigidifying the pair of metal plates together. The height of the supporting section 63a, 63b can be freely selected and it may also be the same as the height of the plate 1 1 a, covering all its side edge. However, the width of the supporting section 63a, 63b means the same as the gap between the two plates where the effective electrocoagulation occurs. Therefore, as already defined above, the width of the supporting section 63a, 63b can be selected between values 3 ... 25 mm. The hole which separates the handle 61 in the right plate 1 1 b, also defines the path for the treated water to flow over the edge 64. When the treatment apparatus is empty and the plates need to be removed for maintenance purposes, the user can grab the handle 61 , and as a result, the whole pair of plates can be removed with a single pulling movement. Also it is a benefit that the plate gap remains fixed also after the pair of plates 1 1 a, 1 1 b has been lowered back into its place in the housing.

In one embodiment, the hole in plate 1 1 b can be formed from several separate holes e.g. by adding additional vertical and narrow support bars between the han- die 61 and the actual plate 1 1 b. This kind of structure would enhance the robustness of the structure but the effect to the flowing wastewater through the holes would still be a small one.

It is also possible to have the supporting sections in the top part of the plates only. Thereafter, the grooves where the side edges of the plates will make contact, may be fixed to the lower part of the housing only. The top end of the grooves will then coincide with the lower end of the supporting section. This makes the structure water-tight and robust, and easy to maintain also during the plate removal phase.

In one embodiment, the thickness of the active plates and the non-active plates are preferably over 1 millimeter. Because the invention is freely scalable to any sizes, there are no practical restrictions in the dimensions of the housing used in this invention. Just to mention a few practical exemplary apparatus sizes, a "handheld" apparatus may have width of approximately 15 cm, depth of approx. 15 cm and length of approx. 50 cm. A more efficient device with a larger water handling capabilities per time unit may have a width of 50 cm, depth of 50 cm and length of 1 m. An industrial application may be even larger, and in one example, the width of such an apparatus is approx. 1 ,60 m. The length of the device may be selected based on the level of "dirtiness" in the incoming water flow, because the length of the apparatus and the number of used metal plate pairs are in a strong correlation with each other. In one embodiment of the invention, the whole apparatus can be covered with a closure element, acting as "a roof to the housing of the wastewater treatment apparatus. The closure element may be provided with electrical connections or throughputs so that the cathode and anodes among all metal plates can be respectively connected to the electric supply. A separate computer, server or a controlling signal from a cloud service may act as a controlling means for the electrocoagulation process within the presented device according to the invention. The method steps and especially the controlling steps for the device may be implemented through a computer program, which may be stored in an appropriate medium such as a diskette or a hard drive. The pro- cessor of the computer can then execute the computer program, or appropriate commands among the computer program.

As a summary among different aspects of the same invention, the inventive concept comprises the device for treating natural water or wastewater using an electrocoagulation process. The inventive concept also comprises a corresponding method for treating natural water or wastewater using an electrocoagulation process. In other words, in the method, the following steps are performed:

- feeding water to be treated into a housing (10) through an inlet (15a), where the housing comprises one or more pairs of active rectangular electrode plates (1 1 a- b, 12a-b, 13a-b, 14a-b), whose side edges are fixed or connected to inner surfaces of the housing (10);

- supplying electric current from an external electric current source (41 ) to each of the pairs of active electrode plates (1 1 a-b, 12a-b, 13a-b, 14a-b), enabling elec- trocoagulation process between the plates within each pair of active rectangular electrode plates;

- outputting treated water from the housing (10) through an outlet (15b);

The method is characterized by that there are further the following method steps:

- fixing each pair of active rectangular electrode plates (1 1 a-b, 12a-b, 13a-b, 14a-b) with two supporting sections (63a, 63b) in order to form a fixed double- plate element (62) for each of the pairs of active rectangular electrode plates (1 1 a-b, 12a-b, 13a-b, 14a-b), wherein

- each pair of active rectangular electrode plates are vertically placed in a consecutive and parallel manner, and one pair of plates comprises of an anode plate and a cathode plate whose top edges are on a different height within a single pair of plates, and whose bottom edges are on a different height within a single pair of plates; so that

- the incoming water enters an active sub-volume defined between a pair of plates beneath a first plate (1 1 a, 12a, 13a, 14a) of the pair and pours out from the active sub-volume over a second plate (1 1 b, 12b, 13b, 14b) of the pair, which further enables a continuous flow of the treated water through the device from the inlet (15a) to the outlet (15b) through all sub-volumes during the operation of the device.

The inventive concept also comprises the corresponding computer program and medium for the computer program in order to execute appropriate method steps from the above when they are executed in a processor.

The present invention is suitable to treating wastewaters but it can also be used to treating natural waters such as river or lake freshwaters or even seawater. Wastewater may include all "grey waters" comprising sewage water, and also wastewater emerging from industrial processes (e.g. with additional harmful sub- stances). One option for the waters to be treated comprise water resulting from or used in mining industry, such as in bioleaching processes used in dedicated mines. A further option is to treat waters where an oil leak has contaminated a dedicated area of natural waters. Additional substances to be removed from the water can be salt (NaCI) from the sea water, or plastic from the oceans of the world. Furthermore, the treated water may be other kind of natural water comprising e.g. humic materials and other naturally present substances in natural freshwa- ters. Also living organisms such as bacteria and viruses can be eliminated with the presented apparatus.

By water treatment apparatus in the above description, it is generally meant that the apparatus is capable to treat any solution which has any additional mixed or dissolved material in the water in a homogenous or heterogeneous manner. By an active sub-volume it is meant the volume e.g. between the plates 1 1 a and 1 1 b where the active electrocoagulation will occur. By a passive sub-volume it is meant the volume e.g. between the plates 1 1 b and 12a which is preferably longer in the water flow direction than the gap width of each active sub-volume. The clari- fier plate(s) can be placed in the passive sub-volumes. A further advantage of the invention is that the apparatus itself does not contain any moving parts. This makes the structure more care-free, easier to move safely, and the lifetime of the apparatus becomes also longer than with a device with some moving parts.

The present invention is not restricted merely to the examples presented above, but it may vary within the scope of the claims.