The invention relates to a filtering system. More specifically, the invention relates to a filtering system suitable for cleaning water originating from sewer systems, aquaria and/or other sources. Regular filtering systems are generally designed to filter solid materials from the exiting water, wherein the dissolved compounds remain in solution. In recycle streams, this can lead to a build-up of dissolved compounds which can finally reach levels that can pollute the downstream source, e.g. the aquarium in

question .

Accordingly, it is an object of the invention to mitigate or solve the above described and/or other problems of currently available filters, while maintaining and/or improving the advantages thereof. More specifically, an object of the invention can be to improve the cleaning action of filters used in aquaria and other such systems. These objectives are achieved by a filtering system suitable for or configured to filtering and purifying liquid, for example, water originating from an aquarium attached to a cleaning unit, said cleaning unit comprising a light source, a growth chamber, and exchangeable elements such as slats, wherein the light source is placed in the vicinity of the growth chamber and is configured to illuminate the interior of the growth chamber, wherein the exchangeable elements can be installed in the growth chamber and wherein the

exchangeable elements comprise a surface structure

configured to accommodate attachment for algae.

By this arrangement, enhanced cleaning of the water can be obtained, as the algae will filter out several nutrients such as: phosphates, nitrates, sulphates,

carbonates, ammonium, potassium, and/or other dissolved ions, salts and/or compounds, which ordinary filters do not separate. These elements and nutrients can be used for the growth of the algae in question. Furthermore, ordinary filters clean out particulate material, such as fish food, whereas in this system it can be returned to and consumed in the connected aquarium.

By making the elements exchangeable, they can be replaced without the need of shutting down the filtering unit. The element can be cleaned, meaning that a portion of the algae grown thereon can be removed, and hereafter the element can be re-inserted in the corresponding growth chamber. Alternatively, the elements such as slats can be pre-seeded in order to rapidly reach a well grown algae mass, sufficient for cleaning the water running through.

The exchangeable elements of the filtering system can comprise a course surface structure such as a fabric or a non-woven material attached thereto. This surface

structure can provide ample hold for algae to attach to, such that the algae are kept in the confined interior of the growth chamber.

The surface structure can comprise Velcro tape. This is a durable material, which can be reasonably water resistant for a prolonged period of time. The hooks or the loops of the Velcro can be pre-seeded in order to have specific dedicated types of algae selected. These algae can be selected on the type of aquarium culture of which the water needs cleaning.

The exchangeable elements, can be alternatively or additionally provided with a turf structure for the attachment and growth of algae.

The growth chamber can comprise a sliding groove configured for receiving the exchangeable element. Thus the exchangeable element can be slid in and maintained in position during operation. The groove or grooves thus can assist in the readily and practicable replacement of the slats .

At least a portion of the outside of the filtering system and/or the growth chambers can be provided with a reflective coating or a reflective foil. This reflective foil or coating enhances utilization of the light source thereby increasing the efficiency of algae growth.

The topside of the cleaning chambers can be left open. Thus the slats can be exchanged during operation without the need for shut down of the filter system. Another advantage of leaving the top side open is that the level of liquid inside the cleaning chambers can be adjusted by raising or lowering the cleaning chambers in relation to the water level of the aquarium.

The filtering system can comprise a supply conduit system including a pump and a control valve. Thus the water can be transported from the aquarium to the filtering system. The filtering system can be operated in a trickling down mode, where the water is pumped to the feed conduit and then left trickling along the slats and the algae grown thereupon. Alternatively, the filter system can be operated in a submerged mode, where the water level in the growth chambers is at a certain height such that the slats are partially or completely submerged.

The flow and the residence time of the water inside the filtering system can be adapted by reducing or increasing the power delivered to the pump and/or by

adjusting the control valve.

The light source can be a phosphorescent or fluorescent tube light, a series of light emitting diodes, a gas discharge lamp, a halogen tube light and/or any other light source. Dependent on the type of algae used or desired, the light intensity and the spectral properties such as specific wavelengths or wave length distribution and/or intensities can be selected. Thus the type of light can be an aid in the growth of very specific types or colonies of algae.

The exchangeable elements such as slats are provided with a surface structure configured to provide attachment of algae. This can be any kind of structure such as the hook or the loop portion of Velcro tape.

The elements can be pre-seeded with a specific culture or specific cultures of algae, which are selected in order to provide specific cleaning action adapted for specific aquarium environments. Thus, for instance less rapid growing, though efficient cleaning algae can be used as well.

A further aspect of the invention is an aquarium system comprising a filtering system as described

hereinabove. In this system, a discharge conduit of the filtering system can be connected to the aquarium, such that growth chambers can form a communicating vessel with the aquarium and the water level in the growth chambers can be adjusted by raising or lowering the filtering system.

In order to further elucidate the invention, exemplary embodiments will be described with reference to the drawing. In the drawing:

figure 1 represents a schematic representation of a processing flow diagram of the method according to the invention ;

Figure 2 represents a schematic cross sectional side view of the filter according to the invention;

Figure 3A represents a schematic perspective view on the growth chambers according to an aspect of the

invention ; Figure 3B represents a schematic perspective view of an exchangeable element according to a further aspect of the invention;

Figure 3C represents a schematic perspective cut out view of a portion of a structure on a slate according to figure 3B;

Figure 4 represent a schematic perspective view of a combination of the filtering system according to the invention and an aquarium;

Figure 5 represents a schematic cross sectional top view along line B-B of the filtering system according to the invention.

Figure 6 represents a schematic cross sectional top view along line B-B of an alternative embodiment of the invention.

The figures represent specific exemplary embodiments of the invention and should not be considered limiting the invention in any way or form. Throughout the description and the figures the same or corresponding reference numerals are used for the same or corresponding elements .

The expression "translucent" used herein is to be understood as, though not to be considered limited to any material through which light can travel, such that at least a portion of the light entered on a first side will exit on a second side. It is advantageous that the translucent material is chosen such that the maximum amount of light entered in the translucent material exits the material again .

The expression "in the vicinity of" used herein is to be understood as, though not to be considered limited to that the light source is placed as close to the growth chambers as possible, in order to have as little light as possible escaping without entering the growth chambers.

The expression "slat" used herein is to be understood as, though not to be considered limited to a thin flat strip of any material.

Figure 1 represents a schematic flow diagram of a first embodiment of the invention. In this flow diagram water with a relative high content of nutrients exits in step I an aquarium and is brought to the filter, wherein the redirected water flows in step II over Velcro tape covered exchangeable elements such as slats. On the elements, algae can grow and can absorb the nutrients from the water as is represented in step III. In order to have the algae growing, a high intensity light source is positioned in close

vicinity of the slats as is represented by step V. In step IV, the water exits the filter and can return to the

aquarium. In order to service the filter the slats can be replaced or exchanged. The algae can be harvested by e.g. cutting the algae mass from the exchangeable element as is represented by step VI.

In figure 2 a schematic drawing of the filter is represented in more detail. Water arriving from aquarium 2 enters the filter 1 at an inlet 3. At the inlet 3 the water can be distributed in two chambers 4, 5. In the chambers 4, 5 slats 6 and 7 are inserted on which Velcro tape is

attached. The Velcro tape has little hooks 9 on which algae 10 can grow as is shown in figure 3C.

The chambers 4, 5 can be upright chambers with an outlet 11 at the bottom side and an open top side 12. From the open top side 12 the exchangeable elements 6, 7 can be entered in the chambers 4, 5 respectively as is shown in figure 3A. In figure 3B, a schematic perspective view of an exchangeable element is depicted. This element can be a plate like piece of material such as a slate. On the

exchangeable element, a structure can be arranged for providing hold for the algae to be grown thereon.

In figure 3C, a schematic perspective view of an example of such a structure is presented. In figure 3C, the hook portion of Velcro tape is used to provide a structure, which can accommodate the attachment of the algae to grow thereon.

In figure 4 a schematic arrangement of an aquarium and a filter is depicted. The aquarium 2 is in fluid

connection with the filter 1 by means of a dip pipe 13, a pump 14 and a header 15. The header 15 is split at the entrance of the filter in two inlets 16, 17 which enter the chambers 4, 5 respectively. At the lower side of the

chambers 4, 5 of the filter 1 a conduit 18 connects the outlet of the filter 1 with the aquarium 2.

By arranging the filter 1 and the aquarium 2 on substantially the same height, the fluid level A in the aquarium 2 and the fluid level S in the filter 1 will substantially be the same. By changing the speed of the pump 14 or by adjusting control valve 19, the amount of water to be filtered can be adjusted.

In between the two chambers 4 and 5 a light source

20 is arranged. This light source 20 can be for instance a fluorescent tube, or any other suitable light source. The chambers 4 and 5 can be provided with longitudinal grooves

21 and 22 respectively wherein the light source 20 can fit. By providing the chambers 4 and 5 with the longitudinal grooves 21 and 22, the chambers can substantially fully embrace the light source 20, as can be seen in figure 3A or in figure 5. Thus the amount of light that is not received by the algae mass can be reduced.

Figure 5 depicts a cross sectional top view of the filter 1 through line B-B. In this figure, the chambers 4 and 5 are provided with a hinge 23 which can hinge open the two chambers 4 and 5 in order to replace or service the light source 20. The slats 6 and 7 can be inserted in chambers 4 and 5 respectively by means of sliding grooves 24, 25, 26 and 27. These sliding grooves will maintain the slats 6 and 7 in the correct position.

On the outside of the chambers 4 and 5, a reflective coating or foil can be attached, in order to reflect any light that is not directly caught by the algae. By this reflective foil or coating the effectiveness of the filter can be increased.

By the arrangement as described herein-above an algae turf scrubber (ATS) is obtained that utilises

artificial light and algae grow to sequester nutrients and carbon dioxide from the water supply. The ATS can be used as an extremely efficient way to filter nutrients from fresh, brackish or salt water.

Depending on the conditions of the water that is to be filtered, specific algae will eventually start to grow. In order to speed up the algae growth, the slats with the Velcro tapes can be pre-seeded with specific types of algae. The Velcro that is used on the slats of the ATS provides ample hold for the algae to attach. If the unit starts to overgrow with algae the slats can be removed and the amount of algae grown thereon can be diminished by removing the excess algae.

In a further development, as is depicted in figure 6, a knife 30 arranged such that it slides vertically along the algae surface in slits 28, 29 and can be moved alongside the surface of slate 6. By moving this knife up and/or down, the algae grown on the slate can be cut off. This knife can for instance be attached to magnets 31 and 32, which can magnetically be coupled with other magnets 33 and 34 which can be arranged on the outside of the chamber 4 and/or 5. Thus the algae can be cut off without removing the algae from the chambers .

When the ATS is used in an aquarium system, the ATS can enhance the filtration or can be used as primary filter. The ATS unit can remove chemicals from the water such as inorganic nitrate, inorganic phosphate, ammonia, metals and carbon dioxide from the water. Furthermore, the ATS unit adds oxygen to the water.

By removing the inorganic nitrate and inorganic phosphate, the algae in the aquarium itself can be reduced. Contrary to ordinary filters, the ATS does not filter out food in suspension and allows this to re-enter the aquarium for consumption.

The invention is to be understood not to be limited to the exemplary embodiments shown in the figures and described in the specification. For instance the filter unit can also comprise more shunted compartments and/or compartments in series. Herein the same or different algae species or colonies may be applied in order to obtain an optimal cleaning of the water running through.

In an alternative embodiment, the light source may be placed or positioned inside the growth chambers. In which case the growth chamber need not necessarily be translucent and can be for instance completely covered by a reflective foil, layer or coating.

These and other modifications are considered to be variations that are part of the framework, the spirit and the scope of the invention outlined in the claims.