Field of invention

The present invention relates to a filter system for purification of a fluid using aluminum silicate grains as defined in the preamble of claim 1 . The present invention also relates to a corresponding method and computer program for carrying out the method .

Background of invention

The following background information is a description of the background of the present invention, which does not neces sarily have to be a description of prior art .

Various types of filter systems have been developed to purify fluids such as e . g . waste water from industrial plants or contaminated water in lakes . Filtering systems with a filter media such as an aluminum silicate are known and can be used to remove both contaminations and organic material from the fluid . The ion exchange properties of aluminum silicate allow a wide variety of impurities and pollutant s in the fluid to be absorbed by the aluminum silicate and hence provide an effective purification . However, conventional filter systems using aluminum silicate are often complex and uneconomical .

SUMMARY OF INVENTION

One problem with conventional filter systems based on aluminum silicate is that their ef fectivenes s typically deteriorates over time due to e . g . organic substances in the fluid creating a bio film growth which clogs the pores in the filter media .

Consequently, there is a need to provide an improved filter system which can reduce bio film growth such that the ef fectivenes s of the filter can be maintained for longer periods of time .

An ob j ective of the present invention is to provide a filter system for purification of a fluid that solve at least some of the above stated problems and/or disadvantages .

The above and further ob j ectives are achieved by the sub j ect matter of the independent claims . Further advantageous implementation forms of the present invention are defined by the dependent claims and other embodiment s .

According to an aspect of the invention, the above mentioned and other ob j ectives are achieved with a filter system for purification of a fluid according to the characteri zing portion of claim 1 . The filter system comprising :

- a filter arranged in a container, the filter comprising aluminum silicate grains ; and

- an inlet arrangement arranged to input the fluid into the container such that the fluid pas ses through the filter, whereby the fluid is ion exchanged and filtered by the aluminum silicate grains ; characterized by :

- the inlet arrangement comprising at least one acoustic wave creating arrangement arranged in contact with one or more of the fluid pas sing through the filter and the aluminum silicate grains , and arranged to let the fluid flow through it when being input into the filter ;

- the at least one acoustic wave creating arrangement being arranged to :

- interact with the fluid flowing through it , thereby creating acoustic waves ; and

- trans fer, by the contact , the created acoustic waves into the filter, the acoustic waves causing at least a portion of the aluminum silicate grains to move relative to their neighboring grains .

The at least one acoustic wave creating arrangement being in contact with one or more of the fluid pas sing through the filter and the aluminum silicate grains in this document means that the acoustic waves may be trans ferred/ conveyed/propagated/ spread from the at least one acoustic wave creating arrangement to the grains , via direct or indirect contact , pos sibly being a physical contact . Thus , the contact may provide a direct trans fer of the acoustic waves from the at least one acoustic wave creating arrangement to the grains , or may provide an indirect trans fer, e . g . via a piping wall and/or the fluid, of the acoustic waves .

An advantage with the filter system according to this aspect of the invention is the created individual relative movement s of the silicate grains , between neighboring aluminum silicate grains in the filter . When the aluminum silicate grains move relative to each other, they are rubbed and polished against each other . Thereby, the growth of bio film on the aluminum silicate grains can be prevented or reduced and the effectivenes s of the filter media can be prolonged .

Especially, the growth of nitrate nitrogen from ammonium is mitigated and/or prevented .

A further advantage with this aspect of the invention is that movement s between the aluminum silicate grains are created by the fluid flowing though the filter . The number of moving part s in the filter system can thereby be reduced and the reliability of the filter system increased . Furthermore , the filter system provides a controlled and adjustable flow of fluid and contact time with the filter . A predictable and easily controlled filtering ef fect can thereby be provided .

According to an embodiment , the least one acoustic wave creating arrangement comprises at least one string arranged to be oscillated by the fluid flowing through the acoustic wave creating arrangement .

Hereby, a low complexity arrangement for creating the acoustic waves is provided, which creates the acoustic waves by it s interaction with the fluid being flowing through the inlet arrangement when being input into the filter . Neither energy supply nor external mechanical arrangement s are here needed for creating the acoustic waves .

According to an embodiment , the least one acoustic wave creating arrangement comprises a swirling arrangement upstream of the at least one string, the swirling arrangement comprising one or more surfaces arranged to deflect the fluid flowing through it such that the fluid is given a swirl .

The swirling arrangement causes irregularities in the fluid before it s interaction with the at least one string, which improves the creation of the acoustic waves . Further, the swirling arrangement provides for aeriation of the fluid, which also prevent s bio film growth .

According to an embodiment , the at least one acoust ic wave creating arrangement comprises at least one resonance arrangement , to which an end of at least one string is attached, the resonance arrangement being arranged for amplifying the acoustic waves created by the at least one string, and for being in contact with one or more of the fluid pas sing through the filter and the aluminum silicate grains of the filter .

The resonance arrangement improves the creation of acoustic waves and their trans fer into the filter . Especially, the amplitude/ intensity of the acoustic waves within the filter is increased, resulting in more grain movement s and more efficient polishing . The resonance arrangement being in contact with one or more of the fluid and grains in this document means that the acoustic waves may be trans ferred/ conveyed/propagated/ spread from the resonance arrangement to the grains , via direct or indirect contact , pos sibly being a physical contact .

According to an embodiment , the at least one string comprises one or more material in the group of :

- copper ; and

- nylon .

Both copper and nylon are suitable materials for creating acoustic waves by oscillation, and for trans ferring/ conveying/propagating/ spreading such acoustic waves through the at least one string .

According to an embodiment , the least one acoustic wave creating arrangement is at least partly arranged as part of a pipe of the inlet arrangement , such that first and second ends of the at least one string are attached to first and second opposite pipe walls , respectively . Hereby, the acoustic wave creating arrangement is arranged within the already present inlet arrangement and takes up no extra space in the filter system . Also, when positioned within the pipe providing fluid to the filter, the acoustic wave creating arrangement is positioned in directly in the flow of the fluid, thereby facilitating the interaction with the fluid .

According to an embodiment , the filter system comprises at least two acoustic wave creating arrangement s arranged as part s of at least two pipes of the inlet arrangement , respectively .

By utilizing multiple acoustic wave creating arrangement s , an increased relative movement of individual grains is provided . Multiple waves from multiple point s of origin, and pos sibly with dif fering frequencies , are hereby trans ferred into the filter, causing increased and irregular movement s of the grains .

According to an embodiment , the inlet arrangement comprises at least one pipe arranged to input the fluid adj acent to a bottom of the container such that the fluid pas ses through the filter from a bottom towards a top of the filter .

An advantage with this embodiment of the invention is that the filtering of the fluid is easily controlled . Also, the fluid is in contact with the aluminum silicate grains during a well defined and also easily controllable contact time when it pas ses through the filter from the bottom towards the top . The filtering proces s hereby becomes predictable and al so controllable . According to an embodiment , the at least one pipe comprises one or more noz zles , of which at least one noz zle i s arranged adj acent to a bottom of the container when in use .

An advantage with this embodiment of the invention is that the above mentioned fluid flow from the bottom towards the top of the container is accomplished .

According to an embodiment , the at least one acoust ic wave creating arrangement is part of a filtering influencing arrangement , the filtering influencing arrangement being arranged for controlling the input of fluid such that irregular current s in the fluid pas sing through the filter and the relative movement s of at least a portion of the aluminum silicate grains are caused .

Thus , the filtering influencing arrangement may here provide acoustic waves and/or pulsed fluid being input into the filter, which causes the relative movement s silicate grains and thereby prevent s bio film growth .

According to an embodiment of the present invention , the filter system comprises a filtering influencing arrangement configured to control the input of fluid such that it is pulsed, by providing variations of one or more of a pres sure and a flow of the fluid being input , such that the relative movement s of the at least a portion of the aluminum silicate grains are caused and/or increased .

An advantage with this embodiment of the invention is that the pulsed input of fluid is a simple way of creating the irregular current s and thus individual vibrations of the grains , which adds very little to the complexity of the system . Furthermore , by controlling variations of the pres sure and/or flow of the input of fluid, the filtering influencing arrangement can provide optimized pulses for a specific filtering use case , i . e . the pulses may be adapted based on characteristics of the fluid to be purified and/or the aluminum silicate grains . Thereby, the filtering system can provide a flexible filtering and is able to handle a large variety of pollutions .

According to an embodiment of the present invention , the filtering influencing arrangement comprises at least one compres sor arranged for varying a pres sure of the f luid being input to create the pulsed input of fluid .

An advantage with this embodiment of the invention is that a compres sor easily and at low cost provides the pulsed fluid input .

According to an embodiment of the present invention , the filtering influencing arrangement comprises a pump arranged for varying a flow of the fluid being input to create the pulsed input of fluid .

An advantage with this embodiment of the invention is that that a pump easily and at low cost , and with little complexity addition, provides the pulsed fluid input .

According to an embodiment of the present invention , the filtering influencing arrangement comprises at least one valve arranged for varying a flow of the fluid being input to create the pulsed input of fluid . An advantage with this embodiment of the invention is that the pulsed fluid input is provided with a simple and low cost solution .

According to an embodiment of the present invention , the pulsed input of fluid comprises one or more pulses defined by one or more in the group of :

- a magnitude of the pres sure of the fluid;

- a magnitude of the flow of the fluid;

- a length in time of the one or more pulses ; and

- a frequency of an occurrence of the one or more pulses .

An advantage with this embodiment of the invention is that a large number of pulse variations may be achieved by altering one or more of these pulse parameters , whereby the individual relative movement s /vibrations may be tailored for the specific fluid conditions .

According to an embodiment of the present invention , the filtering influencing arrangement is configured to control an aeriation of the fluid being input into the container, such that the relative movement s of the at least a portion of the aluminum silicate grains are caused and/or increased by the aeriation .

An advantage with this embodiment of the invention is that the addition of air or oxygen further mitigates and/or prevent s the growth of bio film on the aluminum silicate grains . The addition of air or oxygen further reduces the biological oxygen demand 7 days (BOD7 ) value , i . e . the amount of oxygen needed for microorganisms to degrade organic material in water within seven days . According to an embodiment of the present invention , the aeriation is provided by inputting into the fluid one or more in the group of :

- oxygen ;

- compres sed oxygen ;

- air ; and -compres sed air .

An advantage with this embodiment of the invention is that the aeriation can be adapted to be optimized for the specific organic substances being present in the fluid .

According to an embodiment of the present invention , the filtering influencing arrangement is configured to control one or more of the creation and trans fer of acoustic waves into the fluid and the pulsed input of fluid into the filter based on one or more parameters in the group of :

- a rainfall ;

- a type of pollution in the fluid;

- a concentration of pollution in the fluid;

- a conductivity of the fluid;

- a granular size of the aluminum silicate ;

- a viscosity of the fluid; and

- a turbidity of the fluid .

An advantage with this embodiment of the invention is that the creation of the relative movement s /vibrations may be the optimized for the specific organic substances being present in the fluid . Furthermore , the filtering result and li fe time of the filter media can be calculated in advance . According to an embodiment of the present invention , the aluminum silicate grains comprise one or more in the group of :

- natural zeolite grains ; and

- artificial zeolite grains .

An advantage with this embodiment of the invention is that essentially any zeolite grains may be used as filter media in the filter .

According to an embodiment of the present invention , the filter system further comprises a fluid tank coupled to the inlet arrangement , whereby the fluid tank is arranged to store fluid and to provide the fluid to the inlet arrangement .

An advantage with this embodiment of the invention is that the use of the fluid tank secures supply of fluid for the compres sor and/or pump, such that they do not run out of fluid . Thereby, a continuous flow of fluid may be ensured .

According to another aspect of the invention, the above mentioned and other ob j ectives are achieved with a method for purification of a fluid using a filter system; the filter system comprising :

- a filter arranged in a container, the filter comprising aluminum silicate grains ;

- an inlet arrangement ; and

- at least one acoustic wave creating arrangement comprised in the inlet arrangement , arranged in contact with one or more of fluid pas sing through the filter and the aluminum s ilicate grains , and arranged to let the fluid flow through it when being input into the filter ; the method comprising : - inputting the fluid into the container by usage of the inlet arrangement such that the fluid pas ses through the filter, whereby the fluid is ion exchanged and filtered by the aluminum silicate grains ;

- interaction of the acoustic wave creating arrangement with the fluid, thereby creating acoustic waves ; and

- trans ferring, by the contact , the created acoustic waves into the filter, the acoustic waves causing at least a portion of the aluminum silicate grains to move relative to their neighboring grains .

The method may be adapted in accordance with the above- mentioned embodiment s of the filter system . The advantages of the method are the same as the advantages of the corresponding embodiment s of the filter system .

According to an aspect of the invention, the above mentioned and other ob j ectives are achieved with a control unit arranged to control the filter system to carry out the method according to any embodiment of the method aspect .

According to further aspect s of the present invention, the herein described methods are implemented by use of computer program product s comprising instructions which, when the programs are executed by a computer, such as e . g . a herein mentioned control unit , cause the computer to carry out the steps of the methods according to any one of the herein described embodiment s .

According to further aspect s of the present invention, the herein described methods are implemented by use of computer- readable storage media that , when executed by a computer, such as e . g . a herein mentioned control unit , causes the computer to carry out the steps of the methods according to any one of the herein described embodiment s .

Further applications and advantages of the present invention will be apparent from the following detailed description .

BRIEF DESCRIPTION OF THE DRAWINGS

Embodiment s of the invention are described in more detail with reference to attached drawings illustrating example s of embodiment s of the invention in which :

Figure 1 shows a filter system according to an embodiment of the invention ;

Figure 2 shows an inlet arrangement according to an embodiment of the invention ;

Figure 3 shows an acoustic wave creating arrangement according to an embodiment of the invention ;

Figure 4 shows a filtering influencing arrangement according to various embodiment s of the invention ;

Figure 5 shows pos sible locations for part s of a filtering influencing arrangement according to various embodiment s of the invention ; and

Figure 6 shows a method for a filter system according to an embodiment of the invention .

DETAILED DESCRIPTION OF INVENTION

According to embodiment s of the invention a filter system 100 for purification of a fluid is provided . Fig . 1 schematically shows the filter system 100 according to an embodiment of the invention . The filter system 100 comprises a filter 110 arranged in a container 120 . The filter 110 comprises aluminum silicate grains 112 , i . e . the filter media of the f ilter 110 comprises grains of one or more types of aluminum s ilicates . The aluminum silicate grains 112 may be natural and/or artificial zeolite grains. When natural zeolite grains are used, the natural zeolite may e.g. be clinoptilolite, which can effectively purify a wide range of polluted fluids. The size of the aluminum silicate grains 112 may be adapted to the filtering use case, as will be further described below.

The filter system 100 further comprises an inlet arrangement 130 arranged to input the fluid to be purified into the container 120. The fluid 111 flows through the inlet arrangement 130 and is input into the container 120 such that the fluid 111 passes through the filter 110 and is ion exchanged and filtered by the aluminum silicate grains 112 in the filter 110. In other words, the fluid 111 flows through and around the aluminum silicate grains 112, which absorbs impurities and pollutants in the fluid. Once purified, the fluid 111 is output through an outlet arrangement 150. The flow of the fluid 111 through the filter system 100 shown in Fig. 1, i.e. the flow through the inlet arrangement 130, the filter 110 and the outlet arrangement 150, is indicated with dashed arrows .

According to the embodiment shown in Fig. 1, the inlet arrangement 130 is arranged to input the fluid 111 adjacent or close to a bottom 122 of the container 120 such that the fluid 111 passes through the filter 100 from a bottom 114 towards a top 116 of the filter 110, i.e. the fluid 111 raises up through the filter 110. When the fluid 111 reaches the level of the outlet arrangement 150, which is arranged above the filter 110, i.e. above the filter media 112, e.g. adjacent to a top 124 of the container 120, the purified fluid 111 is output . With reference to Fig. 1, the level of the fluid Lfi _U id in the container 120 may hence be above the filter 110, i.e. above an upper/top surface of the filter media 112. The inlet arrangement 130 may be arranged to input the fluid 111 adjacent to the bottom 122 of the container 120 with one or more nozzles 132 arranged adjacent to the bottom 122 of the container 120 when in use. According to an embodiment, the inlet arrangement 130 is arranged to input the fluid 111 below a lower/bottom surface of the filter media 112, adjacent to the bottom 122 of the container. Thus, at the bottom 122 of the container, there may be a volume without /absent of filter media 112. Correspondingly, at the top 124 of the container, there may be a volume without /absent of filter media 112. The passing of the fluid 111 through the filter 110 from the bottom 114 towards the top 116 provides for a well defined and also controllable contact time between the fluid 111 and the aluminum silicate grains 112 in the filter 110.

Fig. 2 schematically shows an inlet arrangement 130 according to an embodiment of the invention. The inlet arrangement 130 comprises an inlet 134 for receiving the fluid 111 to be purified and one or more nozzles 132, e.g. four nozzles 132 as illustrated in Fig. 2, for outputting the fluid 111 into the filter 110. When in use in the container 120, the inlet 134 is at least partly arranged adjacent to the top 124 of the container 120, while the nozzles 132 are arranged adjacent to the bottom 122 of the container 120, as explained above. The inlet 134 may hence be arranged higher than/above the nozzles 132, such that the fluid 111 received by the inlet 134 falls down, for example essentially vertically, through the inlet arrangement 130 towards the nozzles 132 due to gravity. The nozzles 132 may be distributed over a bottom area of the container 120, e.g. in a respective quarter of the bottom area of the container 120 when four nozzles 132 are used. In this way, the fluid 111 to be purified can be essentially evenly distributed in the void under the filter media 112, and thereby over the bottom 114 of the filter 110, i.e. can be evenly distributed over the lower/bottom surface of the filter media 112, and may be in contact with the aluminum silicate grains 112 during a well-defined contact time when it raises up through the filter 110. Also, by using gravity, essentially no additional components need to be added to the system for distributing the fluid 111 over the bottom 114 of the filter.

Although the shown inlet arrangement 130 comprises four nozzles 132, the inlet arrangement 130 may comprise essentially any number of nozzles 132, and the nozzles 132 may also be arranged differently than shown in the figures, without deviating from the scope of the invention. For example, one or more nozzles 132 may be arranged adjacent to the bottom 122 of the container 120 and/or one or more nozzles 132 may be arranged at a middle, a side or a top of the container 120. Also, the nozzles 132 may be distributed differently over the bottom area of the container 120 than shown in the figures.

The filter system 100 further comprises at least one acoustic wave creating arrangement 160 arranged in pcontact with the fluid 111 passing through the filter media 112 and/or the aluminum silicate grains 112 of the filter 110, As schematically illustrated in Fig. 1. The at least one acoustic wave creating arrangement 160 is arranged to have the fluid 111 being input into the filter 110, i.e. the fluid 111 flowing through the inlet arrangement 130, flow through it. Thus, the fluid 111 flows through the at least one acoustic wave creating arrangement 160 on its way into the filter 110 as shown in Figs . 1 and 2.

The at least one acoustic wave creating arrangement 160 is arranged such that the input fluid flowing through it creates acoustic waves. Thus, the fluid 111 flowing through the at least one acoustic wave creating arrangement 160 interacts with the at least one acoustic wave creating arrangement 160 such that vibrations causing acoustic waves are created by physical and/or mechanical vibrations occurring in the at least one acoustic wave creating arrangement 160. Since the at least one acoustic wave creating arrangement 160 is arranged in contact with the fluid 111 in the filter 110 and/or the filter media 112, the created acoustic waves are transferred into the filter 110.

The acoustic waves hereby transferred into the fluid 111 and/or the filter media 112 causes at least a portion of aluminum silicate grains 112 to move relative to their neighboring grains 112. The grains of the filter media 112 are moved/vibrated, in an otherwise non-moving/stationary filter 110, such that they are polished against each other. Thus, the filter media 112 as a whole is essentially stationary, i.e. not dislocated by the acoustic waves, although individual grains are caused to move in relation to surrounding grains, and are thereby caused to be polished against these surrounding grains. The filter media 112 as a whole is, in other words, essentially stationary in relation to the fixed parts of the filter system 100, i.e. in relation to the container 120 and/or the inlet arrangement 120, whereas the individual grains are caused to move in relation to both the fixed parts of the filter system 100 and to adjacent and/or neighboring grains . As schematically illustrated e.g. in Figs. 1 and 2, the at least one acoustic wave creating arrangement 160 is, according to an embodiment, at least partly arranged as part of a pipe of the inlet arrangement 130. According to various embodiments, at least two, e.g. four, acoustic wave creating arrangements 160, are arranged as parts of at least two, e.g. four, pipes of the inlet arrangement 130, respectively.

According to an embodiment schematically illustrated in Fig. 3, the least one acoustic wave creating arrangement 160 comprises at least one string 161. The first and second opposite ends of the string 161 may then be attached to opposite pipe walls 135, 136, such that the string 161 extends across the pipe, i.e. across a cross section of the pipe of the inlet arrangement 130.

The one or more string 161, exemplified by two strings 161 in Fig. 3, are arranged to be set in vibration by the fluid 111 flowing through the acoustic wave creating arrangement 160. The at least one string 161 may comprise a material suitable for transferring/conveying/propagating/spreading acoustic waves, for example copper and/or nylon.

Thus, the one or more strings 161 interact with the flowing input fluid 111 such that the one or more strings 161 are set in motion, i.e. are caused to oscillate/vibrate/swing, by the interaction with the fluid 111. Hereby, i.e. by the caused oscillat ion/vibrat ion/movement of the at least one string 161, acoustic waves are created. The one or more strings 161 are arranged for being in contact with the fluid 111 and/or the filter media 112 of the filter 110, e.g. by being attached to one or more pipe walls 135. Hereby, the acoustic waves being created by the at least one string 161 are transferred/conveyed/propagated/spread into the filter media 112 via the contact with the fluid 111 and/or filter media 112 in the filter 110, causing the small relative movements of individual grains, as explained above. According to various embodiments, the one or more strings 161 may either be in direct physical contact with the fluid 111 and/or filter media 112 themselves, e.g. by extending through a pipe wall 135, or may be attached to the inside of the pipe wall 135, such that the acoustic waves are transferred/conveyed/propagated/spread into the filter media 112 via the pipe wall 135. A contact useful for transferring acoustic waves from the one or more strings 161 and the grains and/or the fluid 111 is thus provided .

In Fig. 3, the acoustic wave creating arrangement 160 comprises two strings 161. However, according to various embodiments, essentially any number of strings may be implemented in the acoustic wave creating arrangement 160. For example, one or more strings 161 may be arranged essentially horizontally across the acoustic wave creating arrangement 160, i.e. between first and second ends positioned on essentially equal vertical levels on opposite pipe walls 135, 136 of the pipe carrying the fluid 111. One or more strings may also be arranged vertically diagonal, such that the first and second ends of the string are attached to the pipe wall on positions having differing vertical levels.

Further, groups of such one or more strings 161 may be arranged at different levels of the pipe, e.g. at different vertical levels. As a non-limiting example, eight strings 161 may be included in pairs of two at four levels in the acoustic wave creating arrangement 160. Of course, any number of strings arranged in a suitable way may be included in the acoustic wave creating arrangement 160 for creating the acoustic waves.

According to an embodiment schematically illustrated in Fig. 3, the least one acoustic wave creating arrangement 160 comprises a swirling arrangement 165 arranged upstream of the at least one string 161. The swirling arrangement 165 comprising one or more deflecting surfaces, such as e.g. one or more fins, screens, propellers or shields, arranged to deflect the fluid 111 flowing through it, thereby giving the fluid a swirl 166.

For example, the fluid 111 may flow essentially vertically when entering the swirling arrangement 165. After hitting the one or more deflecting surfaces, the flow of the fluid 111 is at least partly deflected from its initial vertical path, such that a swirling water flow is created, e.g. having an at least partly non-vertical flow direction. Possibly, the fluid 111 is given an at least partly circular flow direction by the swirling arrangement 165. Hereby, the interaction of the water and the downstream arranged at least one string 161 is intensified, creating acoustic waves with higher/greater amplitudes. Also, the swirling arrangement 165 causes more irregularities in the input fluid 111 in general and/or aeriation of the fluid, which results in more relative movements of individual grains and reduced bio film growth.

According to an embodiment schematically illustrated in Fig. 3, the at least one acoustic wave creating arrangement 160 comprises at least one resonance arrangement 162. To each resonance arrangement 162, at least one end of at least one string 161 is attached. For example, each the first and second ends of a string 161 may be attached to a first and second resonance arrangements 162, respectively. The resonance arrangement 162 is arranged attached to the pipe wall 135 for amplifying the acoustic waves created by the at least one string 161, and for being in contact with the fluid 111 and/or the filter media 112 of the filter 110. Hereby, the acoustic waves being created by the at least one string 161 and being amplified by the at least one resonance arrangement 162 are efficiently transferred into the filter 110. Thus, the resonance arrangement 162 is, by its contact with one or more of the fluid 111 and the grains, arranged for transferring/conveying/propagating/spreading acoustic waves to the grains and/or the fluid, either directly or indirectly.

The resonance arrangement 162 may comprise a material suitable for conveying acoustic waves, for example copper. According to an embodiment, the geometrical shape and/or size of the resonance arrangement 162 are adapted to the frequency to be created by the acoustic wave creating arrangement 160, such that the amplitude of the acoustic wave is amplified. Thus, the resonance arrangement 162 may be arranged such that its f undamental/eigen frequency corresponds essentially to the frequencies of the created acoustic waves. In other words, the resonance arrangement 162 may be arranged to resonate with the created acoustic waves. The resonance arrangement 162 may comprise at least one fastening device, such as e.g. at least one nut or the like, arranged for attaching at least one string end to the resonance arrangement 162 and/or to the pipe wall .

Also, the at least one string 161 may, according to an embodiment, be arranged, e.g. by choice of its material, thickness, length and/or tension, to create acoustic waves having a suitable and controllable frequency. This frequency may, according to an embodiment, be adapted to the f undamental/eigen frequency of the resonance arrangement 165. Thus, the at least one string 161 and/or the resonance arrangement 165 may be designed to, e.g. be tuned to, be suitable for creating, amplifying and transferring one or more certain frequencies suitable for preventing bio film growth.

If more than one string 161 is utilized in one acoustic wave creating arrangement 160, acoustic waves are transferred into the filter 110 from multiple locations. Correspondingly, if more than one acoustic wave creating arrangement 160 is used, acoustic waves are also transferred into the filter 110 from multiple locations. Such multiple origin acoustic waves, possibly also having different frequencies, will then interfere with each other, thereby causing differing acoustic waves in different parts of the filter 110. Hereby, individual movements of grains relative their neighbors are provided and/or intensified.

The at least one acoustic wave creating arrangement 160 may be comprised in a filtering influencing arrangement 140 configured to control the input of the fluid 111 such that acoustic waves and/or irregular currents in the fluid passing through the filter 110, and the relative movements of at least a portion of the aluminum silicate grains 112, are caused. The filtering influencing arrangement 140 may be connected/coupled to, or arranged in, the inlet arrangement 130, as explained above. The filtering influencing arrangement 140 may also be connected e.g. to an inlet 134 of the inlet arrangement 130 and provide the fluid to be purified to the inlet arrangement 130, as indicated in Fig. 1. Acoustic waves and/or irregular currents (described in detail below) in the fluid 111 created by the filtering influencing arrangement 140 cause relative/individual movements/vibrations of at least a portion of the aluminum silicate grains 112. The individual movements/vibrations may comprise movements of individual grains relative to their neighboring grains, such that the grains are polished against each other. Thus, a grain moving/vibrat ing individually moves slightly different than its neighboring grains. The grains moving/vibrating due to the acoustic waves and/or irregular currents are hence rubbed against each other, and any growth on the surface of the grains such as e.g. a bio film may thereby be removed or reduced. Also, the individual movements/vibrations may prevent that such a growth begins at all. The individual movements/vibrations of the grains, i.e. the relative movements between them, i.e. in relation to neighboring grains, may be small, e.g. microscopic and/or small relative to a diameter of the grains .

According to some embodiments, the filtering influencing arrangement 140 is configured to control the input of fluid such that it is pulsed, i.e. such that fluid 111 is input into the container 120 and the filter 110 in one or more pulses. The pulsed input of fluid creates the irregular currents in the fluid 111 passing through the filter 110 and hence causes and/or increases/intensif ies the relative/individual movements/vibrations of at least a portion of the aluminum silicate grains 112 in the filter 110. The filtering influencing arrangement 140 may control the input of fluid to be pulsed by providing variations of one or more of a pressure and a flow of the fluid being input. The filtering influencing arrangement 140 may e.g. increase or decrease the pressure and/or flow of the fluid being input, either in one step to create one pulse, or periodically and/or aperiodically to create a series of pulses.

The variations of the pressure and/or flow of the fluid being input may be provided in a number of different ways. With reference to Fig. 4, the filtering influencing arrangement 140 may, in addition to the acoustic wave creating arrangement 160, e.g. comprise one or more compressors 142, one or more pumps 144, and/or one or more valves 146, by use of which the filtering influencing arrangement 140 may control the input of fluid to be pulsed. Each of the one or more compressors 142, the one or more pumps 144, and/or the one or more valves 146 may be connected/coupled to the inlet 134 of the inlet arrangement 130 or may at least partly be arranged inside the inlet arrangement 130.

Fig. 5 schematically shows non-limiting examples of possible locations of the filtering influencing arrangement 140 in relation to the inlet arrangement 130, such as e.g. adjacent to the inlet 134, at the top of the inlet arrangement 130 or adjacent to the nozzles 132. The one or more compressors 142, the one or more pumps 144, and/or the one or more valves 146 may be arranged and/or controlled separately or in combination and/or coordination to create the pulsed input of fluid. As shown in Fig. 5, the filtering influencing arrangement 140 may at least partly be arranged in various parts of the inlet arrangement 130. At least the acoustic wave creating arrangement 160, when being part of the filtering influencing arrangement 140, and also other parts of the filtering influencing arrangement 140 may, according to some embodiments, also be arranged in or at the container 120. Actually, except for the acoustic wave creating arrangement 160 , the other part s of the filtering influencing arrangement

140 may, according to the herein presented various embodiment s , be arranged es sentially anywhere within the filter system 100 where it is able to cause the irregular current s in the fluid and/or filter 110 .

The at least one compres sor 142 may be arranged for varying the pres sure of the fluid being input to create the pulsed input of fluid, while the at least one pump 144 and/or the at least one valve 14 6 may be arranged for varying the flow of the fluid being input to create the pulsed input of fluid . By controlling the one or more compres sors 142 , the one or more pumps 144 , and/or the one or more valves 14 6 , the f iltering influencing arrangement 140 may hence vary the pres sure and/or flow of the fluid being input such that it is input in one or more pulses , thereby creating the irregular current s and thus also the individual vibrations of the grains .

The at least one compres sor 142 may, according to an embodiment , be arranged for providing individual pulsing of fluid being input by two or more pipes , respectively . Thus , the fluid flow is here adapted individually for each of the at least two pipes inputting the fluid 111 into the filter 110 . Sequential individual pulsing in the two or more pipes according to a pulse pattern may also be provided . Such pulsing result s in more variations regarding the timing, frequency and amplitude of the created acoustic waves . Essentially all sort s of irregularity caused by such pulsing creates and/or increases the relative movement s of the grains .

The one or more pulses comprised in the pulsed input of fluid controlled by the filtering influencing arrangement 140 may be defined by one or more in the group of : - a magnitude of the pres sure of the fluid 111 ;

- a magnitude of the flow of the fluid 111 ;

- a length in time of the one or more pulses ; and

- a frequency of an occurrence of the one or more pulses .

The filtering influencing arrangement 140 may control the variations of the pres sure and/or flow of the input of fluid to provide optimized pulses for a specific filtering use case . In other words , the above-mentioned properties of the pulses may be adapted based on characteristics of the fluid to be purified and/or the aluminum silicate grains 112 , such that an optimized purification is provided .

The filtering influencing arrangement 140 may further be arranged to utilize gravity for creating a flow of the input of the fluid . The flow of the input fluid due to gravity may be provided, in use , by arranging the inlet 134 of the inlet arrangement 130 vertically higher than the one or more noz zles 132 of the inlet arrangement 130 , i . e . by a dif ference in height between the inlet 134 and the one or more noz zles 132 ( as shown in e . g . Fig . 2 ) . The filtering influencing arrangement 140 may utilize gravity in combination with any of the herein described methods for creating and/or increasing variations and/or pulses in the input fluid .

The filter system 100 may further comprise a fluid tank coupled to the inlet arrangement 130 . The fluid tank may be arranged to store fluid and to provide the fluid to the inlet arrangement 130 . In this way, a continuous flow of fluid to the inlet arrangement 130 may be ensured .

In embodiment s , the filtering influencing arrangement 140 is configured to control an aeriation of the fluid being input into the container, whereby the aeriation creates , or contributes to the creation of , the irregular currents and relative grain movement s . The aeriation may thus be used together with the above-mentioned acoustic waves and/or pulsed input of fluid for creating and/or enhancing the irregular current s and relative movement s .

The aeriation may be provided by inputting into the fluid a gas such as one or more in the group of oxygen, compres sed oxygen, air and compres sed air . Thus , the filtering influencing arrangement 140 may control the input of the gas into the input of fluid such that the fluid is aeriated . The aeration creates bubbles in the fluid 111 which in turn creates or increases the irregular current s and individual vibrations . The aeration further reduces the BOD7 value as the fluid is oxygenated .

Acoustic waves may, according to an embodiment , further be provided into the filter 110 using a speaker or other low frequent sound generating device arranged adj acent to or in contact with the inlet arrangement 130 and/or filter 110 , e . g . included in the filtering influencing arrangement 140 . Such a device for creating sound/acoustic waves , may according to various embodiment s , also be located for example within the container 120 or adj acent to, and in contact with, the container 120 . The speaker or other low frequent sound generating device is then arranged for trans ferring/ conveying/propagating/ spreading acoust ic waves to the grains and/or the fluid .

For all of the herein described means used to create the individual vibrations of the aluminum silicate grains 112 , the characteristics of the relative/individual movement s/vibrations may be controlled by acoustic wave creating arrangement 160 and/or the filtering influencing arrangement 140 based on the filtering use case, e.g. based on properties of the aluminum silicate grains 112 and/or the fluid to be purified. In various embodiments, the filtering influencing arrangement 140 and/or acoustic wave creating arrangement 160 may be configured to control the creation and transfer of acoustic waves into the fluid and/or the pulsing of the input fluid based on one or more parameters in the group of :

- a rainfall;

- a type of pollution in the fluid;

- a concentration of pollution in the fluid, e.g. a weight and/or volume of pollution in the fluid;

- a conductivity of the fluid;

- a granular size of the aluminum silicate;

- a viscosity of the fluid; and

- a turbidity of the fluid, i.e. a cloudiness or a haziness of the fluid caused by large numbers of individual particles.

By considering these parameters, the acoustic wave creating arrangement 160 and/or the filtering influencing arrangement 140 may control creation of acoustic waves and/or the input of the fluid to provide relative/individual movement s/vibrations with desired characteristics. The acoustic wave creating arrangement 160 and/or the filtering influencing arrangement 140 may further be adapted over time to compensate for changes in one or more of the parameters during the filtering of the fluid. For example, the filtering influencing arrangement 140 may e.g. continuously, periodically, or at irregular intervals check the current values of one or more parameters and update the control of the input of the fluid and/or the creation of acoustic waves based on the current values .

To cause and/or further increase movement s and/or individual vibrations among the aluminum silicate grains 112 in the filter 110 , the container 120 it self may be configured to move or vibrate . The container 120 may e . g . be arranged on a vibrating plate which causes vibrations of the container 120 , which reproduces /are trans ferred into the filter 110 inside the container 120 . The container 120 may further be arranged to be suspended such that it can easily be moved vertically and/or horizontally to create movement s and/or vibrations of the container 120 , and hence of the filter 110 inside the container 120 .

According to embodiment s of the invention a method 200 for purification of a fluid using a filter system 100 i s provided . As described with reference to Figs . 1 and 2 , the f ilter system 100 comprises a filter 110 comprising aluminum silicate grains 112 arranged in a container 120 , an inlet arrangement 130 and at least one acoustic wave creating arrangement 1 60 comprised in the inlet arrangement 130 .

A flow chart of the method 200 is shown in Fig . 6 and includes the steps of :

- inputting 202 the fluid into the container 120 by usage of the inlet arrangement 130 such that the fluid 111 passes through the filter 110 , whereby the fluid 111 is ion exchanged and filtered by the aluminum silicate grains 112 ; and

- interaction 204 of the acoustic wave creating arrangement 1 60 with the fluid 111 being input into the filter 110 , thereby creating acoustic waves ; and

- trans ferring 20 6 , by the contact of the at least one acoustic wave creating arrangement 1 60 with one or more of the fluid 111 pas sing through the filter 110 and the aluminum silicate grains 112 , the created acoustic waves into the filter 110 . The acoustic waves then cause at least a portion of the aluminum silicate grains 112 to move relative to their neighboring grains 112 , as explained above .

According to embodiment s of the invention, the filter system

100 may comprise or be connected to a control unit arranged to control the filter system 100 to carry out the method 200 . The control unit may hence be arranged/ conf igured/programmed with instruction to control the filter system 100 to perform the steps of any of the herein described embodiment s . The herein described filter system 100 , method 200 and control unit are not limited by the above-mentioned embodiment s . The filter system 100 , method 200 and control unit are instead limited by the independent claims .