A method and a system for filtering a suspension

Abstract

A system and a method for filtering a predetermined molecule entrained as a 3D-complex in a liquid comprising a filter forming solid all forming a filter forming suspension, the system having a filter chamber into which the filter forming suspension is fed and drained to form a filter with inclusions of the 3D-complex, where after a cleansing liquid is fed to a neighbouring liquid chamber and fed evenly through the filter to cleanse the filter and subsequently dissolve the complex to retrieve the product or target molecule.

Claims

1. A system (10) for filtering a suspension, the apparatus comprising: a filter chamber (12) comprising a first inlet (121), a liquid chamber (14) comprising a second inlet (141), a liquid distributor element (18) having a first and a second, opposing, surfaces, the first surface forming part of the filter chamber and the second surface forming part of the liquid chamber, and a flow system (122, 142), the filter chamber additionally having a surface portion formed by a filter element (16), the flow system being capable of delivering a filter forming suspension, comprising the suspension, to the filter chamber and a liquid to the liquid chamber, characterized in that the liquid distributor comprises a plurality of through-going channels and is configured to distribute liquid from the liquid chamber into the filter chamber with the same amount of liquid per unit area of the second surface.

2. The system according to claim 1, wherein the flow system comprises: a first flow channel (122) extending from a first entrance to the first inlet and a second flow channel (142) extending from a second entrance to the second inlet.

3. The system according to claim 1, wherein the flow system comprises a flow channel and a valve (144) configured to alter between allowing liquid from the flow channel to enter the liquid chamber and preventing liquid from the flow channel from entering the liquid chamber.

4. The system according to claim 1, wherein, along a predetermined direction: the liquid chamber is positioned before the liquid distributor, the liquid distributor is positioned before the filter chamber, and the filter chamber is positioned before the filter element.

5. The system according to claim 1, wherein the filter chamber has a flat shape with a height which is lower than a depth and a width thereof.

6. The system according to claim 1, the system comprising a plurality of filter units each having: a filter chamber comprising a first inlet, a liquid chamber comprising a second inlet, a liquid distributor element having a first and a second, opposing, surfaces, the first surface forming part of the filter chamber and the second surface forming part of the liquid chamber, where the filter chamber additionally has a surface portion formed by a filter element, where the flow system is capable of delivering a filter forming suspension to each filter chamber and a liquid to each liquid chamber.

7. A method of operating the system of claim 1, the method comprising the steps of: feeding a filter forming suspension, comprising liquid and a solid component, into the filter chamber via the flow system and the first inlet, allowing liquid from the filter chamber to escape via the filter element, the filter element retaining at least part of the solid component, feeding a liquid from the flow system into the second inlet, into the liquid chamber, through the liquid distributor element, through the retained solid component and through the filter element.

8. The method according to claim 7, wherein the step of feeding the filter forming suspension comprises feeding the filter forming suspension through a first flow channel from a first entrance to the first inlet and wherein the step of feeding the liquid comprises feeding the liquid through a second flow channel extending from a second entrance to the second inlet.

9. The method according to claim 7, wherein the step of feeding the filter forming suspension comprises feeding the filter forming suspension through a flow channel to the filter chamber while a valve prevents filter forming suspension from entering the liquid chamber, and wherein the step of feeding the liquid comprises feeding the liquid through the flow channel while the valve allows the liquid to enter the liquid channel.

10. The method according to claim 7, wherein the step of feeding the liquid comprises feeding the liquid: into the liquid chamber, from the liquid chamber through the liquid distributor and into the filter chamber, through the filter chamber and into and through the filter element, where the feeding through the liquid distributor, the filter chamber and the filter element is a feeding along a predetermined, general direction.

11. The method according to claim 7, wherein the filter chamber has a flat shape with a height which is lower than a depth and a width thereof.

12. The method according to claim 7, wherein the system comprises a plurality of filter units each having: a filter chamber comprising a first inlet, a liquid chamber comprising a second inlet, a liquid distributor element having a first and a second, opposing, surfaces, the first surface forming part of the filter chamber and the second surface forming part of the liquid chamber, where the filter chamber additionally has a surface portion formed by a filter element, wherein: the step of feeding the filter forming suspension comprises feeding the filter forming suspension to all filter chambers, the allowing step comprises allowing liquid from all filter chambers to escape via the respective filter elements, each filter element retaining at least part of the solid component fed to the respective filter chamber, the step of feeding the liquid comprises feeding the liquid to all liquid chambers, through the respective liquid distributor elements, through the retained solid component and through the respective filter element.

13. The method according to claim 7, further comprising the step of preparing the filter forming suspension from at least: a pre-determined molecule, a complex forming element forming, with the molecule, a 3D complex of a minimum volume or size, and a solid material forming, when drained, a filter structure with a pore size.

14. The method according to claim 13, wherein the step of feeding the filter forming suspension comprises feeding a mixture of the solid material and the 3D complex to the filter chamber and wherein the step of allowing the liquid to escape comprises the solid material retaining at least of the 3D complex in the filter structure.

15. The method according to claim 14, wherein the step of feeding the liquid comprises initially feeding a first liquid and subsequently feeding a second liquid dissolving the 3D complex and flushing the molecules from the filter.

16. The method according to claim 7, wherein the solid component is filtering particles and wherein the step of feeding he filter forming suspension and the allowing step results in the filter chamber being at least 95% filled by the filtering particles.

Description

[0093] In the following, preferred embodiments are described with reference to the drawing, wherein:

[0094] FIG. 1 illustrates a first embodiment of the present invention,

[0095] FIG. 2 illustrates a second embodiment of the invention and

[0096] FIG. 3 illustrates a plurality of units connected in parallel.

[0097] In FIG. 1, a system or a filtering unit 10 is seen having a filter chamber 12 and a liquid chamber 14. A lower, in this illustration, side of the liquid chamber 14 is formed by a liquid distributor element 18 also forming the top of the filter chamber. The opposite, lower, side of the filter chamber is formed by a filter element 16.

[0098] In addition, a first flow channel 122 is provided for providing a filter forming suspension through an inlet 121 into the chamber 12. A second flow channel 142 is provided for feeding a liquid through an inlet 141 into the liquid chamber 14.

[0099] An output 161 is provided for allowing liquid escaping the filter chamber 12 via the filter element 16 to escape the unit to a waste channel 162.

[0100] A separate waste output may be used for this, or one of the first and second flow channels may be used.

[0101] Multiple inlets may be provided for the filter chamber and/or liquid chamber, such as for different liquids/suspensions or for ensuring a swift delivery of the liquid/suspension. Also, for the filter chamber, multiple inlets may be desired in order to ensure that the filter chamber is filled or sufficiently filled with the suspension. It is desired that the filter chamber is completely filled or at least 90% filled, such as 95% filled by the suspension and/or the filtering particles.

[0102] The operation of the unit may be as follows:

[0103] A set-up of this type is especially well suited for the so-called Diatomaceous Earth (also called DE or kieselgur) Filtration, where shells from of fossilized remains of diatoms, a type of hard-shelled protist (chrysophytes) are used as the particles for the filter.

[0104] The filter, also called a filter cake, is formed in the filter chamber 12 by suspending a particle shaped solid, preferably kieselgur, also called a filter aid in a liquid and feeding the suspension, being a filter forming suspension, into the filter chamber. The liquid will be allowed to escape the filter chamber via the filter. Thus, the filter is configured to allow liquid to escape while retaining at least a portion of the solid therein. The retained particle shaped solid then will form a matrix creating a filter.

[0105] Thus, it is preferred that the filter element has openings toward the filter chamber which have a lowest dimension (as they may be slot shaped) which is no more than 130% of a mean diameter of the particles (such as each particle's volume is converted into a sphere), such as no more than 110% of the mean diameter, such as no more than 100% of the mean diameter, such as no more than 90% of the mean diameter, such as no more than 75% of the mean diameter, such as no more than 50% of the mean diameter.

[0106] Clearly, as the filter particles may be made of a natural material, the shape and size thereof may not be known or easily determined (see fx photo 1 of Diatomaceous Earth Filtration by Tjebbe van der Meer, Benjamin Minow, Bertille Lagrange, Franziska Krumbein and Francouis Rolin, BioProcess International, September 2014, pp 25-28). Thus, a test may be made where a sample of the desired powder it provided on the filter element and the amount or percentage thereof passing the filter element may be determined. If a predetermined percentage or more (by weight) passes the filter element, the filter element openings should be made smaller.

[0107] On the other hand, the liquid distributor element is also configured to not allow the filter particles from travelling through it and into the liquid chamber. Then, the openings in the liquid distributor element may be as those mentioned for the filter element.

[0108] In addition, the best and fastest draining of the filter is obtained if the filter element has sufficiently many openings or a sufficiently large percentage of its surface as openings. The openings have a size requirement but not a number requirement. Thus, the filter may be provided with as many openings as possible, as long as the openings have the required size. A factor weighing toward fewer openings is the fact that the liquids and filter forming suspension may be provided under pressure so that a certain strength may be required by the filter elementand the liquid distributing element.

[0109] The filter may be cleansed by feeding a liquid to the liquid chamber, through the liquid distributor element and through the filter. The liquid distributor element is configured to create an at least substantially even flow of liquid through the filter. Usually, the liquid distributor element comprises a number of channels or openings therein ensuring that the liquid is fed more or less evenly to the filter through the openings. In a preferred embodiment, the amount or cross section of the openings is the same over the area of the liquid distributor element. Preferably, the openings of the liquid distributor element are equally spaced, such as provided in a repeating pattern, so that when the liquid is fed into the liquid chamber at a certain pressure, the same amount of liquid will be transported through the liquid distributor element per area of the liquid distributor element.

[0110] Then, a 3D complex of a sufficient size may be added to the filter forming suspension. Thus, it will be fed to the filter chamber and distributed within the solid particles of the filter and will remain within the filter when drained if the size of the particle/cell/complex is sufficiently large to not be able to travel with the liquid through the filter and out via the filter element.

[0111] Thus, preferably, the diameter (if the volume is converted into a sphere) of the particle/cell/complex is at least 5%, such as at least 10%, such as at least 15%, such as at least 20%, such as at least 25%, such as at least 35%, such as at least 50% of a mean diameter of the particles of the filter forming suspension. Then, the channels formed between neighbouring or engaging/abutting filter particles will be sufficiently narrow to prevent such particle/cell/complex to travel through it and thus through the formed filter.

[0112] Clearly, the filter forming suspension may additionally have therein unwanted elements, such as impurities. In the situation where these are either liquids or have sizes smaller than that of the cell/particle/complex, the particle size of the filter may be selected so that these impurities may travel between the particles and thus through the filter. Also, the openings of the filter element may be selected so that the impurities may travel through it. Thus, when draining the filter, at least a portion of the impurities may be removed from the filter.

[0113] Remaining impurities or other unwanted elements may then be removed by cleaning the filter. Flushing liquid is fed to the liquid chamber and through the liquid distributor element and thus through the filter toward the filter element. This flow of liquid will transport impurities, liquid remnants, small particles and the like through the filter and through the filter element.

[0114] Then, the output of the filter element may be monitored to see when the filter is sufficiently clean.

[0115] The 3D complexes may be dissolved or otherwise altered to liquid form or to a smaller size, whereby they may be transported through the filter and filter element and thus be collected.

[0116] In a preferred embodiment, a complex may be formed by a molecule of interest and a complex forming agent. The resulting complex has a 3D shape of a particular size of 800 nm m. When the filter particle material is e.g. Cellpure C25 or Cellpure C65, the resulting filter will retain the complex.

[0117] In general, the filter particle material may be selected based on a particular complex by preparing the filter suspension with a known percentage (by weight) of the complex, the liquid and the powder. Having filled the filter chamber and rinsed it, the retained complexes are dissolved (see below) and the resulting number of complexes determined. If this number (or percentage) of retained complexes exceed a desired threshold, the filter particles are of a sufficiently small size.

[0118] After rinsing, the complex may be dissolved by a dissolving liquid of a predetermined pH value. The dissolving of the complex results in a solution of the molecule and thus is able to travel through the filter together with the dissolving liquid.

[0119] Clearly, the material of the filter may be selected within wide ranges. Usually, it is desired that the filter material does not react with the 3D-complex nor the liquids used for the filter forming suspension, the flushing and the dissolving.

[0120] It is noted that the filter element and liquid distributor need not be at opposite sides of the filter chamber, but this is preferred, as it allows a uniform flow of the liquid though the filter and thus a uniform cleansing of the filter. Also, the general direction of the flow of the liquid need not be vertical. A horizontalor any other directionmay be used.

[0121] It is preferred that the filter chamber is rather flat, so that it has a shorter dimension and, perpendicular thereto, two dimensions which are larger. Then, the distance from the filter element to the liquid distributor element may be no more than 50%, such as no more than 25%, such as no more than 10% of a shortest extent or dimension of the surfaces of the filter element and liquid distributor element facing the filter chamber or forming part of the filter chamber.

[0122] In one situation, the filter chamber has a thickness in the range of 0.1-4 cm, such as 1-3 cm, such as around 1.5 cm.

[0123] FIG. 3 illustrates the present system with multiple units 11, comprising the filter chamber liquid chamber, liquid distributing element and filter element, which may share the flow channels 162, 142 and 122, such that a larger volume of the filter forming suspension may be handled at the time.

[0124] Also, a single flow channel may be used, as seen on FIG. 2, where only the flow channel 122 is seen. In this embodiment, the inlet 141 has a valve 144 configured to open and close the inlet 141. Then, when the filter forming suspension is fed through the channel 121, the valve 144 is closed to prevent filter forming suspension from entering the liquid chamber 14. When the liquid is fed through the channel 122, the valve 144 is open. Clearly, a valve may also be provided in the opening 121 to prevent liquid from entering the filter from that inlet.