Disposable device for filtering a large medium volume

Abstract

A single-use device for filtration of a large volume of medium including a plurality of single-use filter units, at least some of which, preferably all of which, are connected to each other by rigid pipes. The filter units include at least one prefilter and at least one main filter for virus filtration which is configured as a hollow fiber capsule.

Claims

1. A single-use filtration device for filtering a large volume of medium, comprising: a plurality of single-use filter units, at least some of which are connected to each other by rigid pipes, the filter units including a plurality of prefilters and a plurality of main filters for virus filtration which are configured as hollow fiber capsules; a common outlet pipe for the plurality of prefilters; at least one shut-off valve between the prefilters and the main filters in the common outlet pipe allowing a grouping of all of the plurality of main filters separate from the prefilters, the plurality of main filters having vent connections on their upper front sides opening into a common vent pipe which leads to an unfiltrate-side sterile air filter, configured so that test gas can be supplied via the sterile air filter through the common vent pipe to all of the plurality of main filters to jointly test integrity of the plurality of main filters.

2. The single-use filtration device according to claim 1, characterized in that a rigid pipe is provided between the at least one prefilter and the at least one main filter.

3. The single-use filtration device according to claim 1, characterized in that an inlet pipe to the at least one main filter is configured as a rigid pipe.

4. The single-use filtration device according to claim 1, characterized in that the at least one prefilter and the at least one main filter are connected in series.

5. The single-use filtration device according to claim 1, characterized in that the rigid pipes are formed by pressure-stable tubes having a defined diameter.

6. The single-use filtration device according to claim 1, characterized in that it has both a common inlet connection and a common outlet connection for the medium and is adapted to be integrated into a filtration branch by sterile connectors.

7. The single-use filtration device according to claim 1, characterized in that the filter units and the rigid pipes are arranged such that all prefilters and the main filters are each exposed to a flow in parallel.

8. The single-use filtration device according to claim 1, characterized in that the prefilters are designed for dead-end filtration and the main filters for cross-flow filtration.

9. The single-use filtration device according to claim 1, characterized in that some of the rigid pipes are formed by common housings of filter units.

10. The single-use filtration device according to claim 1, characterized in that at least one filter unit is configured as a multiple capsule having at least two identical or different filter elements installed in a common housing.

11. The single-use filtration device according to claim 10, characterized in that the filter elements are arranged so as to be exposed to a flow in parallel.

12. The single-use filtration device according to claim 10, characterized in that the filter elements are arranged so as to be sequentially exposed to a flow.

13. The single-use filtration device according to claim 10, characterized in that the multiple capsule includes at least one pleated filter element and one hollow fiber filter element.

14. The single-use filtration device according to claim 1, characterized in that a group of main filters and/or a group of prefilters, are each configured as a module.

15. The single-use filtration device according to claim 1, characterized in that a pressure-stable sight glass is integrated into the vent pipe and/or in that at least one indicator which reacts to water is arranged in the vent pipe and/or in that a protective filter for protecting the air filter is interposed between a vent connection and an inlet of the air filter.

16. The single-use filtration device according to claim 1, characterized in that a releasable vent valve is provided in the vent pipe or on the sterile air filter.

17. The single-use filtration device according to claim 1, characterized in that at least one filter unit, are oriented so as to be exposed to a flow from bottom to top.

18. The single-use filtration device according to claim 17, characterized in that at least one filter unit includes a lower unfiltrate inlet and a lower filtrate outlet, and an upper filtrate outlet and an upper vent connection.

19. The single-use filtration device according to claim 18, characterized in that valves are provided for blocking the lower unfiltrate inlets and for blocking the vent connections.

20. The single-use filtration device according to claim 1, characterized in that a flow-reducing element is provided at an outlet of a filter unit or a group of filter units to produce a differential pressure for a flushing process.

21. The single-use filtration device according to claim 1, characterized by a connection on a filtrate side of the device to which a filtrate-side sterile air filter can be connected through which gas can be pumped after completion of a filtration for discharging filtrate remaining in the device.

22. The single-use filtration device according to claim 1, characterized by a valve for blocking the vent pipe or the unfiltrate-side sterile air filter connected thereto.

23. The single-use filtration device according to claim 1, characterized in that pipes towards the filter units, away from the filter units or between the filter units are configured so as to be adapted to be separated in a sterile manner.

24. A method of performing an integrity test in a single-use filtration device for filtering a large volume of medium, the single-use filtration device comprising a plurality of prefilters, a plurality of main filters for virus filtration which are configured as hollow fiber capsules, and a common outlet pipe for the plurality of prefilters, a shut-off valve being provided between the prefilters and the main filters in the common outlet pipe, the plurality of main filters having vent connections on their upper front sides opening into a common vent pipe which leads to an unfiltrate-side sterile air filter, the method comprising steps of: grouping all of the plurality of main filters independently of the plurality of prefilters by closing the shut-off valve to shut off the plurality of main filters from the plurality of prefilters, and supplying a test gas via the sterile air filter through the common vent pipe to all of the plurality of main filters.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

(1) Further features and advantages of the invention will become apparent from the description below and from the attached drawings to which reference is made. In the drawings:

(2) FIG. 1 shows a perspective view of a single-use filtration device according to the invention;

(3) FIG. 2 shows a side view of the device of FIG. 1; and

(4) FIG. 3 shows a perspective view of a part of a single-use filtration device according to the invention with an additional air filter.

DETAILED DESCRIPTION OF THE INVENTION

(5) FIGS. 1 and 2 show a single-use filtration device 10 comprising a plurality of filter units 12, here in the form of filter capsules. The filter units 12 are held in position by a rigid holder 14 (rack) in a predetermined arrangement (grid).

(6) At least one unit of the filter units 12 is a hollow fiber capsule for virus filtration (hereinafter only referred to as main filter 12b for the sake of simplicity). At least one filter unit 12 is used for pre-filtration (hereinafter only referred to as prefilter 12a for the sake of simplicity). Preferably, the prefilters 12a contain pleated filter elements, although other configurations are also possible. Optionally, sterile filters can also be provided for a stepwise filtration.

(7) Preferably, the ratio of the number of prefilters 12a to main filters 12b is 1:1. Other ratios, in particular of 1:2, 2:1; 1:3, 3:1, may also be useful depending on the respective circumstances (size, arrangement of the filters etc.). The effective filter surfaces of the prefilters 12a and the main filters 12b can also be used for optimum filtration conditions, wherein the same preferred ratios apply.

(8) The single-use filtration device 10 has a common inlet connection 16 (unfiltrate side) and a common outlet connection 18 (filtrate side) for all filter units 12, so that it can be integrated into a filtration branch.

(9) Within the device 10, the filter units 12 are completely or at least largely connected to each other by rigid, pressure-stable pipelines having a defined diameter. The rigid pipelines ensure a uniform flow behavior without pressure fluctuations during operation. The course of the pipelines is determined by the intended operation of the single-use filtration device 10 (parallel and/or series connection of all or of specific filter units 12), wherein the pipelines have the necessary branches to the individual filter units 12. Where necessary, the pipelines are attached to the holder 14.

(10) In the example embodiment shown in FIGS. 1 and 2, prefilters 12a and main filters 12b of different sizes are arranged in the stable holder 14 (rack). In particular, the main filters 12b are each configured as upright filter capsules having an unfiltrate inlet 24 on the lower front side of the filter capsule and two filtrate outlets 26, 28 which are internally connected to each other and one of which is located at the lower end and one at the upper end of the filter capsule. Only one filtrate outlet is required for the filtration itself. The purpose of the additional, optional filtrate outlet will be explained later.

(11) The medium to be filtered flows from the inlet connection 16 through a common prefilter inlet pipe 34, which is configured as a rigid distribution tube having a defined diameter and branches to the prefilters 12a. The prefilter inlet pipe 34 distributes the medium in parallel to all prefilters 12a. After having passed through the prefilters 12a, the prefiltered medium is collected in a common prefilter outlet pipe 36, which in turn is configured as a rigid collecting tube having a defined diameter and branches to the prefilters 12a.

(12) The prefiltered medium passes from the prefilter outlet pipe 36 via a further rigid connecting pipe 38 to a common main filter inlet pipe 40, which is configured as a rigid distribution tube having a defined diameter and branches to the main filters 12b. The main filter inlet pipe 40 distributes the medium in parallel to all main filters 12b. After having passed through the main filters 12b, the filtered medium flows out of the lower filtrate outlets 26 and is collected in a common main filter outlet pipe 42, which in turn is configured as a rigid collecting tube having a defined diameter and branches to the main filters 12b. The filtrate finally flows out of the device 10 through the outlet connection 18.

(13) A common main filter outlet pipe (not shown here), which is configured as a rigid collecting tube having a defined diameter can also be provided for the upper filtrate outlets 28.

(14) The main filters 12b with their unfiltrate inlets 24 and the pipelines are oriented such that the flow passes through the main filters 12b from bottom to top, which ensures uniform hydrostatic conditions.

(15) Both the prefilters 12a and the main filters 12b are designed for dead-end filtration. However, it is also possible that the prefilters 12a are designed for dead-end filtration and the main filters 12b for cross-flow filtration. The longer service life of cross-flow filters compared to dead-end filters is important especially for virus filtration.

(16) The filter units 12 can be configured as multiple capsules. This means that several similar or different filter elements are accommodated in a common or in several rigidly connected housings. The filter elements within the multiple capsule can be exposed to a flow in parallel or sequentially, depending on their design. In particular, two or more hollow fiber capsules can be accommodated in one housing. In a further configuration, a multiple capsule is provided which has at least one pleated filter element and one hollow fiber filter element. The multiple capsules can generally be configured as a main filter 12b or as a prefilter 12a. A combination of prefilter 12a and main filter 12b within a multiple-capsule housing is also possible.

(17) The main filters 12b have vent connections 30 on their upper front side, which open into a common vent pipe 20. The vent pipe 20 is configured as a rigid collecting tube having a defined diameter and branches to the main filters 12b. The vent pipe 20 leads to a sterile air filter 22 (not shown in FIGS. 1 and 2), if necessary via a further (hose) pipe.

(18) The common vent pipe 20 may contain a pressure-stable sight glass upstream of the sterile air filter 22 in flow direction. The sight glass makes medium rising to the sterile air filter 22 visible for the user. This enables a visual check of the correct venting, so that the user, if necessary, can take appropriate measures in due time before the sterile air filter 22 may come into contact with any liquid and is therefore blocked. This can especially happen when liquid forms a kind of film on a nonwoven supporting the membrane of the sterile air filter 22. The sight glass can also be used to monitor the level in the filter unit(s) 12.

(19) For the same purposes, an indicator which reacts to water can be placed in the vent pipe 20 as an alternative or in addition to the sight glass. Such water contact indicators are available as adhesive tapes, which turn red on contact with water, or based on blue gel (silica gel), which turns pale pink. A further protective measure is a protective filter which is arranged in front of the sterile air filter 22 and which is configured as a flat filter without supporting nonwoven or similar. The air filter membrane of the protective filter can be made of polyvinylidene fluoride (PVDF), polyethylene (PE), hydrophobic polyethersulfone (PESU) or polytetrafluoroethylene (PTFE). Since the protective filter has no supporting nonwoven, the risk of blocking is minimized.

(20) The sterile air filter 22 can also be used as a test gas inlet within the scope of an integrity test, as will be described below.

(21) All or specific filter units 12, in particular the main filters 12b and the prefilters 12a, each form a module, so that an integrity test for an entire module can be performed inside the single-use filtration device 10, but also outside the single-use filtration device 10 (offline).

(22) Shut-off valves can be provided between the filter units 12, so that connections between specific filter units 12 can be shut off in a purposeful manner. This permits a purposeful sterile venting or a purposeful sterile integrity test of a single filter unit 12 or of a group of interconnected filter units 12, e.g. all prefilters 12a and all main filters 12b.

(23) When performing an integrity test, individual filter units 12, one or several groups of filter units 12 or all filter units 12 installed in the device 10 may be tested together.

(24) A test of all main filters 12b in one test step to save costs and time is preferred. For this purpose, test gas is supplied from the unfiltrate side through the vent pipe 20 via a sterile air filter 22 (see FIG. 3). For this test, only one valve on the prefilter outlet pipe 36 of the device 10 needs to be closed.

(25) When testing individual main filters 12b separately via the unfiltrate-side sterile air filter 22, valves (not shown) are provided for each vent connection 30 and for each unfiltrate inlet 24 to selectively block and unblock the connections or inlets. The valves are switched depending on the main filter 12b to be tested.

(26) If all filter units, including the prefilters 12a are to be tested, it is also possible to pump the test gas into the unfiltrate inlet connection 16 of the device 10 instead of introducing the test gas through the vent pipe 20. For this purpose, a sterile air filter is connected to the inlet connection 16 through which the test gas passes before it enters the filter units 12 through the unfiltrate inlets 24.

(27) It is also possible to test the filter units 12 together or individually by pumping the test gas via a sterile air filter through the upper filtrate outlets 28 into the single-use filtration device 10. For this purpose, all upper filtrate outlets 28 are connected to the test gas during a joint test, if necessary via a collecting tube connected to these outlets, or only to one of the upper filtrate outlets 28, while the remaining filtrate outlets 28 are closed by a valve (not shown). The lower filtrate outlets 26 must be closed by valves (not shown) depending on the type of test (common or individual test).

(28) The most important valves, preferably all valves required to operate the single-use filtration device 10 are located on the same side of the single-use filtration device 10, which provides an improved overview and simplified operability.

(29) Before performing an integrity test, it may be advantageous to flush the filter units 12, in particular the main filters 12b with a wetting medium at a differential pressure. This ensures sufficient wetting for the integrity test. In order to regulate only the inlet pressure, a flow-reducing element is provided at the outlet of the respective filter unit 12 or filter unit group, which allows only a low flow and thus creates a differential pressure. The respective flow-reducing element must be adapted to the size and number of filter units 12 to be flushed. For example, different resistances are required for a device having three, six or nine (main) filter units 12. Such a flow-reducing element is typically designed for a specific field of application, for example for a combination of four to six filter units 12 of a specific type. For a different number of such filter units 12 (e.g. two or seven), a correspondingly differently designed flow-reducing element must then be provided.

(30) One possibility for variable adjustment is to use hoses of different lengths at the outlet of the filter units 12 to be flushed. The resistance generated by the hose (friction of the liquid against the inner surface of the hose) can be adjusted by modifying the length of the hose. A further possibility to make the flow for a flushing process variable is to design the flow reducing element as a (proportional) valve, for example in the form of a pinch or diaphragm valve.

(31) FIG. 3 shows part of an embodiment of the single-use filtration device 10, in which only main filters 12b are shown for a better clarity. However, the unfiltrate-side sterile air filter 22 connected to the common vent pipe 20 via a hose pipe is illustrated here. After filtration, a vent valve provided in the vent pipe 20 or on the sterile air filter 22 can be released so that sterilized air can flow through the sterile air filter 22 to the filter units 12. It is thus possible that a part of the remaining unfiltrate can pass through the filter (elements) of the filter units 12 by its own weight due to the static pressure and can thus increase the filtrate quantity. This is promoted by the preferred vertical installation of the filter (elements) in the filter units 12.

(32) Furthermore, in the embodiment shown in FIG. 3, a further filtrate-side sterile air filter 32 is provided on an additional connection on the filtrate side of the device 10, more precisely on the main filter outlet pipe 42. Due to this filtrate-side sterile air filter 32, sterile gas can be pumped after completion of the filtration to discharge the filtrate remaining in the device 10 through the outlet connection 18. During the preceding filtration, the unfiltrate-side sterile air filter 32 is blocked by a valve, so that a fluid contact of the medium (product solution) with the filtrate-side sterile air filter 32 is excluded.

(33) In principle, each of the rigid, pressure-stable pipelines of the device 10 can be equipped with an sight glass. Therefore, it is for example possible to visually monitor levels and sufficient venting in the common prefilter inlet pipe 34 of the common main filter outlet pipe 42.

(34) It is necessary for all embodiments that the materials used in the single-use filtration device 10 (also for any flexible hose pipes etc.) can be sterilized, in particular by gamma radiation, heat or gassing, or can be autoclaved. The single-use filtration device 10 can thus be sterilized and packaged in a pre-assembled, i.e. ready-to-connect state, or first packaged and sterilized together with the packaging. After delivery to a customer, the entire single-use filtration device 10 can be installed there in an existing filtration branch using sterile connectors, i.e. it is immediately ready for use.

(35) In order to enable a proper disposal of the single-use filtration device 10, which includes a sterilization step in an autoclave, the filter units 12 are connected to each other in the device 10 such that they can be separated from each other without much effort. The separation is preferably performed in a sterile manner by the product Quickseal® (Aseptic Tube Sealing System) to avoid contamination. For disposal, the size and weight of the separated segments are selected so that they can be carried by one person and transferred to an autoclave. Each separated filtration segment has at least one valve that can be opened during autoclaving to prevent overpressure in the filtration segment during sterilization.

LIST OF REFERENCE NUMBERS

(36) 10 single-use filtration device 12 filter units 12a prefilter 12b main filter 14 holder 16 inlet connection of the single-use filtration device 18 outlet connection of the single-use filtration device 20 vent pipe 22 unfiltrate-side sterile air filter 24 unfiltrate inlet of a filter unit 26 lower filtrate outlet of a filter unit 28 upper filtrate outlet of a filter unit 30 vent connection of a filter unit 32 filtrate-side sterile air filter 34 prefilter inlet pipe 36 prefilter outlet pipe 38 connection pipe 40 main filter inlet pipe 42 main filter outlet pipe