Method for filtering solids from plasma-derived solution

Abstract

A method (100) of filtering solids (41) from a plasma-derived solution (44) is disclosed. The method (100) includes feeding a solution (44) into a hollow fiber filter (12) at a feed velocity, the hollow fiber filter (12) including a plurality of hollow fibers (38), each hollow fiber (38) including a membrane (36) defining an elongate hollow fiber channel (32). The method (100) further includes filtering (104) the solution (44) using the hollow fiber filter (12) to produce a permeate (46) and a retentate (45), the permeate (46) passing through the pores (37) of the membrane (36) under transmembrane pressure, and the retentate (45) flowing out from the respective outlets of the elongate hollow fiber channels (32), where the permeate (46) has a reduced solids content relative to the solution (44) fed to the hollow fiber filter (12).

Description

Technical Field

[0001] The present disclosure relates generally to a method of filtering solids from a liquid, and more particularly to a method of filtering solids from a plasma-derived solution. Background Art

[0002] The increasing understanding of the functions of plasma proteins and the defects involved in various hematological disorders, coupled with improvements in the storage of the major protein components of human blood, has led to the increasing utilization of specific subfractions of human blood rather than whole blood for therapeutic purposes, particularly the cellular components (red cells, platelets, and white cells) and the plasma protein components (albumin, fibrinogen, and globulins, including euglobulins, pseudoglobulins, alpha-globulins, beta-globulins, and gamma-globulins, such as immunoglobulin G (IgG)).

[0003] The plasma protein fraction of human blood is of great value to the pharmaceutical industry in particular for the production of drugs to treat disorders of fibrinogenesis, fibrinolysis and coagulation, as well as immunodeficiencies such as hemophilia, von Willebrand disease and fibrinogen deficiency.

[0004] Plasma fractions are formed by plasma fractionation processes such as the Cohn process, Kistler and Nitschmann processes or variations of these processes. These industrial-scale cryogenic ethanol fractionation methods enable the extraction of multiple plasma proteins from a single plasma source. These processes typically involve thawing frozen plasma (batch sizes range from 1000kg to 15000kg) to form an albumin-rich cryosupernatant and a cryoprecipitate. The cryoprecipitate contains valuable coagulation factors that are subsequently separated from the cryosupernatant. In the Cohn process or the Kistler and Nitschmann processes, the cryoprecipitate can optionally be exposed to an initial lower ethanol (usually 8%) precipitation stage to remove fibrinogen. Likewise, the precipitate (Fraction I) is also removed and can be used to make other products such as fibrinogen. Adsorption steps using ion exchange or affinity resins are also optionally performed in either of the two intermediate fractions to extract other proteins (such as prothrombin complex, antithrombin III, C1 esterase inhibitor). Subsequently, albumin is extracted from supernatant I by increasing the ethanol concentration to about 25% at about pH 6.9 for the Cohn method and to about 19% at about pH 5.85 for the Kistler and Nitschmann methods, the immunoglobulins are precipitated (fraction (I+)II+III or precipitate A), while albumin remains in solution (supernatant (I+)II+III or filtrate A). Albumin is then separated from the majority of other plasma impurities (primarily alpha and beta globulins) by further addition of ethanol to a final ethanol concentration of about 40% (fraction IV). In the final step, albumin itself is precipitated near its isoelectric point. The precipitated paste (fraction V) can be stored frozen prior to further processing. It is important to recognize that these processes are somewhat adaptable and have been optimized over many years to fit each manufacturer's portfolio. An example of this is, for example, the Fraction (I+) II+II step may or may not be followed by an additional Cohn fractionation step (Fraction IV-1) used to extract alpha-1-antitrypsin. Another example is the use of Fraction IV-4 derived from Fraction II+III or Fraction I+II+III to extract hemopexin.

[0005] In order to further process the plasma fraction to obtain the desired protein components, larger solid impurities need to be purified or separated from the plasma fraction by a separation process. A filter press is usually used to separate the solid and liquid phases. The filtration process takes place in the filter plates of the filter press, where several filter plates are connected to each other to form a filter plate assembly. Pressure is applied to the filter plate assembly by means of a closing cylinder, usually a hydraulic closing cylinder, in order to ensure the necessary tightness between the individual filter plates. Each filter plate has a filter area covered with a filter medium, wherein the resuspended plasma component to be filtered is pressed into the filter chamber formed between two filter plates and abuts against the filter medium. Applying the product to the filter press allows the liquid to pass through the filter medium, while the solids are retained on the filter medium. The filtrate retentate between the filter medium and the filter area is then carried away, while the filter cake is left in the filter chamber. When the filter plates are separated from each other, the solids forming the filter cake are harvested from the filter press.

[0006] However, filter press operation is labor-intensive and time-consuming. In addition, filter presses have a large footprint and therefore require a large amount of space for storage and operation.

[0007] Any discussion of documents, acts, materials, devices, articles or the like contained in this specification is not to be taken as an admission that any or all of these matters form part of the prior art base or were general knowledge in the field relevant to the present disclosure as it existed before the priority date of the appended claims. Summary of the invention

[0008] In one aspect of the present disclosure, a method for filtering solids from a solution derived from plasma is provided, the method comprising: feeding the solution to a hollow fiber filter at a feed rate, the hollow fiber filter comprising a plurality of hollow fibers, each hollow fiber comprising a membrane defining an elongated hollow fiber channel; and filtering the solution using the hollow fiber filter to produce a permeate and a retentate, the permeate passing through pores of the membrane under a transmembrane pressure, the retentate flowing out from corresponding outlets of the elongated hollow fiber channels, wherein the permeate has a reduced solid content relative to the solution fed to the hollow fiber filter.

[0009] In some embodiments, the method further comprises recycling the retentate into solution for resupply to the hollow fiber filter.

[0010] The supply speed of solution can be limited by the transverse flow velocity of solution, and the transverse flow velocity is the linear velocity of the flow tangent to the hollow fiber membrane surface. For example, the transverse flow velocity can be about 0.6m / s to about 4m / s. The hole of membrane can have an average pore size of about 0.1 micron to about 4 microns. Transmembrane pressure can be from about 20 kPa to about 300 kPa.

[0011] The method may further include measuring the permeate output of the system. This helps to evaluate the performance of the system and determine when the filter performance has declined, and allows for timely corrective measures. In some embodiments, the method may include measuring the flow rate of the permeate during filtration. In some embodiments, the method may include measuring the permeate flux during filtration. The permeate flux may be at least 3 liters per square meter of hollow fiber filter per hour.

[0012] In some embodiments, the method includes multiple filtering steps. In these embodiments, the method also includes supplying a backwash solution through the hollow fiber filter between the filtering steps. The backwash solution may include a buffer solution. Alternatively or additionally, the backwash solution may also include a permeate. The volume of the backwash solution supplied to the hollow fiber filter between the filtering steps is provided in a ratio of from 1:6 to 1:1 to the volume of the permeate obtained during the filtering step before backwashing.

[0013] The plasma-derived solution may have a conductivity of about 2 mS / cm to about 40 mS / cm.The solution may be at a temperature of about 4°C to about 37°C.

[0014] In one embodiment, the plasma-derived solution may have a conductivity of about 2 mS / cm to about 8 mS / cm when measured at room temperature. In another embodiment, the plasma-derived solution may have a conductivity of about 8 mS / cm to about 15 mS / cm when measured at room temperature. In another embodiment, the plasma-derived solution may have a conductivity of about 25 mS / cm to about 40 mS / cm when measured at room temperature.

[0015] The solution may include a plasma component. The solution may include a buffer. The buffer may include sodium acetate or phosphate. The solution may have an extraction ratio of about 1:2 to about 1:10 per kilogram of plasma component to about 1 kilogram of buffer.

[0016] The solution may include hemopexin, albumin or immunoglobulin G. The method further includes adding caprylic acid to the permeate for defatting the permeate. The solution may include a filter aid. The solution may have a pH between about 4 and about 9.

[0017] The recovery of the permeate may be at least 30%, at least 50%, at least 75%, or at least 90%.The turbidity of the permeate may be less than about 400 nephelometric units.

[0018] Throughout the specification, the word "comprise" or variations such as "comprising" will be understood to imply the inclusion of stated elements, integers or steps, or groups of elements, integers or steps, but not the exclusion of any other elements, integers or steps, or other groups of elements, integers or steps. BRIEF DESCRIPTION OF THE DRAWINGS

[0019] Embodiments of the present disclosure will now be described, by way of example only, with reference to the accompanying drawings:

[0020] Figure 1a An embodiment of a filtration system is shown, which includes a hollow fiber filter, shown in a filtering configuration;

[0021] Figure 1b Shows Figure 1a An embodiment of the invention is shown in a backwash configuration;

[0022] Figure 2 shows an exploded perspective view of the hollow fiber filter shown in FIG. 1 , the hollow fiber filter having channels in the form of hollow fibers;

[0023] Figure 3 is a perspective view of a hollow fiber;

[0024] Figure 4A-4D Shows Figure 3 A schematic diagram of the pores of a hollow fiber is shown, and the fouling mechanism of the pores is illustrated;

[0025] Figure 5 A flow chart showing an embodiment of a method for removing solids from a plasma fractionation solution to produce a permeate using the hollow fiber filter shown in FIG1 ;

[0026] Figure 6 yes Figure 5 A flow chart of another embodiment of the method shown;

[0027] Figure 7 The solution is shown Figure 5 When the method shown is used, the experimental results of the permeate flow rate relative to time at different TMP values ​​are shown;

[0028] Figure 8 The solution is shown Figure 5 When the method shown is used, the experimental result diagram of the permeate mass relative to time at different TMP values;

[0029] Fig. 9 The solution is shown Figure 5 When the method shown is used, the experimental results of the permeate flow rate relative to time at different TMP values ​​are shown;

[0030] Fig.10 The solution is shown Figure 5 When the method shown is used, the experimental result diagram of the permeate mass relative to time at different TMP values;

[0031] Fig.11 The solution is shown Figure 6When the method shown is used, the experimental result diagram of the mass of the permeate after backwashing relative to the time under different TMP values ​​and pump speed conditions;

[0032] Fig.12 The solution is shown Figure 6 When the method is shown, the protein permeation rate is plotted against the accumulated permeate volume at different TMP values ​​and pump speeds;

[0033] Fig.13 The solution is shown Figure 6 When the method shown is used, the experimental result diagram of the average permeate flow rate relative to the accumulated backwash volume at different backwash frequencies;

[0034] Fig.14 The solution is shown Figure 6 When the method is shown, the experimental result diagram of the average permeate flow rate relative to the time after each backwashing for different times of backwashing cycles;

[0035] Fig.15 The solution is shown Figure 6 The bar graph of the experimental results of average permeate flow rate versus backwashing times when the method shown is used;

[0036] Fig.16 The solution is shown Figure 6 The experimental results of average permeate flow rate versus time when the method shown is used;

[0037] Fig.17 The solution is shown Figure 5 When the method is shown, a comparison chart of protein permeation rate versus permeate component volume for albumin and a comparative hemopexin;

[0038] Fig.18 The solution is shown Figure 6 The experimental results of the permeate flow rate versus time for different numbers of backwash cycles are shown in the method shown;

[0039] Fig.19 The solution is shown Figure 6 The experimental results of steady-state permeate flow rate versus backwash cycle number when the method shown is used;

[0040] Fig. 20 The solution is shown Figure 5 When the method shown is used, the experimental results of the permeate mass relative to time at different TMP growth rates are shown;

[0041] Fig.21 The solution is shown Figure 5When the method is shown, a graph of protein permeation rate versus volume of the permeate fraction for a hemopexin extract at different pH levels of the solution;

[0042] Fig. 22 A plot of permeate flow rate versus time at different TMP values ​​is shown in comparison with a theoretical cake formation fouling model;

[0043] Fig.23A shows a plot of permeate flow rate versus time during the early stages of the experiment compared to theoretical partial blockage, internal blockage, and cake formation fouling models;

[0044] Fig. 23B shows a plot of permeate flow rate versus time at a later stage of the experiment compared to theoretical partial blockage, internal blockage, and cake formation fouling models;

[0045] Fig.24 Shown is a plot of permeate flow rate versus time compared to a theoretical partial blocking and cake formation fouling model. DETAILED DESCRIPTION

[0046] General

[0047] Throughout this specification, references to a single step, ingredient, group of steps, or group of ingredients should be understood to cover both one and a plurality of such steps, ingredients, groups of steps, or groups of ingredients, unless specifically stated otherwise or the context requires otherwise. Thus, as used herein, the singular forms "a," "an," and "the" include plural aspects unless the context clearly dictates otherwise. For example, reference to "a" includes the single as well as two or more; reference to "an" includes the single as well as two or more; reference to "the" includes the single as well as two or more, etc.

[0048] Unless otherwise specifically stated, each example of the present disclosure described herein shall apply mutatis mutandis to each other example. The scope of the present disclosure is not limited by the specific examples described herein, which are provided for illustration only. Functionally equivalent products, compositions, and methods are clearly within the scope of the disclosure described herein.

[0049] The term "and / or", such as "X and / or Y", should be understood to mean "X and Y" or "X or Y", and should be used to provide clear support for both meanings or either meaning.

[0050] Unless otherwise defined, all technical and scientific terms used herein have the same meaning as those commonly understood by those of ordinary skill in the art to which the invention belongs. Although methods and materials similar or equivalent to those described herein can be used in the practice or testing of the present invention, suitable methods and materials are described below. In the event of a conflict, the present specification (including definitions) shall prevail. In addition, the materials, methods, and examples are illustrative only and are not limiting.

[0051] As used herein, the term "approximately" means within 5%, more preferably within 1%, of a given value or range. For example, "about 3.7%" means from 3.5% to 3.9%, preferably from 3.66% to 3.74%. When the term "about" is associated with a numerical range, such as "about X% to Y%", the term "about" is intended to modify the lower (X) value and the upper (Y) value of the range. For example, "about 20% to 40%" is equivalent to "about 20% to about 40%".

[0052] Specific aspects

[0053] The term "recovery" or "percent recovery" is used to refer to the concentration of a protein (e.g., hemopexin, albumin, IgG, or any other desired protein) in the permeate 46 as a percentage of the maximum possible concentration of the protein in the permeate 46, taking into account the mass difference between the permeate 46 and the solution 44. For example, the concentration can be measured using reverse phase high performance liquid chromatography (RP-HPLC) or nephelometry or ultraviolet spectroscopy. The maximum possible concentration of the protein in the permeate 46 can be calculated using the following formula:

[0054]

[0055] in: is the maximum protein concentration in the permeate 46 (g / L)

[0056] is the mass of the extract or solution 44 (kg)

[0057] is the final permeate mass (kg)

[0058] is the concentration of the extract or solution 44 (g / L)

[0059] The recovery rate can be used as a performance indicator, wherein the operating parameters of the hollow fiber filter 12 are changed to achieve the desired recovery rate. It should be understood that the desired recovery rate will vary depending on various factors, such as the composition of the feed solution 44, the number of backwash cycles. The characteristics and / or operating conditions of the hollow fiber filter 12 and the inclusion of one or more additional separation / filtration processes can be selected to provide the desired recovery rate and clarity.

[0060] The term "permeate flow rate" is defined as the mass of permeate 46 flowing out of the hollow fiber filter 12 through the permeate line 24 per unit time and is expressed in grams per minute (g / min). It should be understood that any suitable unit may be used, such as pounds of permeate per hour. The permeate flow rate may be used as a performance indicator for the method 100, wherein a higher permeate flow rate generally indicates improved productivity and filter performance (e.g., the filter is not blocked, fouled, or clogged with solids). The characteristics and / or operating conditions of the hollow fiber filter 12 and the characteristics of the solution 44 may be selected to provide a desired permeate flow rate.

[0061] The term "flux" or "permeate flux" is defined as the total volume of permeate 46 filtered per unit surface area of ​​the hollow fiber filter 12 per unit time, expressed as liters of permeate 46 per square meter of the filter per hour (L / m² / h). It should be understood that any suitable unit may be used, such as gallons of permeate 46 per square foot of the filter per second. Flux may be used as a performance indicator for the method 100, where a higher flux indicates improved productivity and filter performance (e.g., the filter is not blocked / fouled or clogged with solids). As with the permeate flow rate, the characteristics and / or operating conditions of the hollow fiber filter 12 and the properties of the solution 44 may be selected to provide a desired flow rate.

[0062] The term "bound hemopexin" or "percent bound hemopexin" is defined as the weight percent of hemopexin that is bound to native heme in the solution 44, retentate 45, or permeate 46, rather than that obtained as free hemopexin. This can be measured, for example, using size exclusion-high performance liquid chromatography (SEC-HPLC).

[0063] The term "protein permeability" or "protein permeability percentage" is defined as the concentration of a protein (e.g., hemopexin, albumin, IgG, or any other desired protein) in the permeate 46 as a percentage of the concentration of that protein in the retentate 45, which can be measured, for example, by protein A280, etc.

[0064] Process for removing solids from solutions derived from plasma

[0065] See first Figure 1a and Figure 1b , a filtration system 10 is shown, which includes a hollow fiber filter 12. A supply tank 14 is connected to the inlet of the hollow fiber filter 12 through supply lines 20a, 20b, a supply pump 16, and a supply valve 27. The retentate outlet of the hollow fiber filter 12 is connected to the supply tank 14 through a retentate line 22 and a retentate valve 29, and the permeate outlet of the hollow fiber filter 12 is connected to the permeate tank 18 through a permeate line 24 and a permeate valve 31. A supply pressure gauge 26, a retentate pressure gauge 28, and a permeate pressure gauge 30 are respectively provided on the supply lines 20a, 20b, the retentate line 22, and the permeate line 24. A backwashing circuit is also provided, which includes a backwashing tank 49, backwashing lines 51a, 51b, a backwashing valve 57, a backwashing pump 55, and a backwashing pressure gauge 53. In an alternative embodiment, a fluid supply line (not shown) connecting the permeate tank 18 and the backwashing circuit may be provided.

[0066] Figure 2 An embodiment of a hollow fiber filter 12 is shown. The hollow fiber filter 12 includes a filter housing 33 and a plurality of hollow fibers 38 positioned within the housing. Figure 3 As best shown, each hollow fiber 38 includes a membrane 36 that defines an elongated hollow fiber channel 32. The hollow fibers may be any hollow fibers suitable for performing solid / liquid separation. Figure 3 , the hollow fibers may include a porous support 35 and a wall 34 surrounding the porous support 35. The wall 34 includes a membrane 36 having pores 37 characterized by a pore size. The hollow fibers 38 are secured to the end caps 40 and 42 of the hollow fiber filter 12 ( FIG. 1 ). The hollow fibers 38 may be formed of any suitable material, for example, the hollow fibers 38 may be formed of a ceramic or polymer material. In one embodiment, the hollow fibers 38 are formed of silicon carbide. It should be understood that the channels 32 of the hollow fiber filter 12 may alternatively be formed as through holes in a porous material that acts as a membrane 36, rather than having discrete hollow fibers 38.

[0067] The total filtration area of ​​the hollow fiber filter 12 is defined by the sum of the membrane 36 areas of all hollow fibers 38. Although primarily described with respect to a single filtration unit, it should be understood that the system may include multiple individual hollow fiber filtration units connected in parallel and / or in series, particularly to increase the scale of operation and the volume of solution that can be filtered.

[0068] In one embodiment, the method can be performed using a single hollow fiber filtration unit. The filtration area of ​​a single hollow fiber filtration unit according to the present disclosure can be from about 0.1 m² to about 10 m². For example, the filtration area of ​​a single unit can be about 0.05 m², about 0.1 m², about 0.15 m², about 0.2 m², about 0.25 m², about 0.3 m², about 0.35 m², about 0.4 m², about 0.45 m², about 0.5 m², about 0.6 m², about 0.7 m², about 0.8 m², about 0.9 m², about 1 m², about 1.1 m², about 1.2 m², about 1.3 m², about 1.4 m², about 1 The filtration area of ​​a single hollow fiber filter unit can be within the range of any two of the filtration areas listed above.

[0069] In some embodiments, the method can use two or more separate hollow fiber filter units running in parallel. Each separate hollow fiber filter unit has a filtration area as defined above. The separate hollow fiber filter units running in parallel can all have the same filtration area, or the filtration areas of some or all of the separate filter units can be different. It should be understood that the total filtration area for the system will be limited by the sum of the filtration areas of each separate unit.

[0070] The length of hollow fiber 38 can be any suitable length. Typically, although not necessarily, passage 32 has a substantially circular cross section. The diameter of passage 32 can be from about 2mm to about 20mm, such as about 2mm, about 3mm, about 4mm, about 5mm, about 6mm, about 7mm, about 8mm, about 9mm, about 10mm, about 11mm, about 12mm, about 13mm, about 14mm, about 15mm, about 16mm, about 17mm, about 18mm, about 19mm or about 20mm. In one embodiment, the diameter is 3.2mm. It should be appreciated that passage 32 can have other cross-sectional shapes, such as elliptical or polygonal.

[0071] During filtration, the feed valve 27, the retentate valve 29, and the permeate valve 31 are opened, and the feed pump 16 is used to pump the solution 44 from the feed tank 14 through the end cap 40 of the hollow fiber filter 12 into the elongated hollow fiber channels 32. During filtration, the backwash valve 57 is closed. Particles in the solution 44 that are smaller than the pore size of the hollow fiber membrane 36 are driven by the transmembrane pressure (TMP) to pass through the hollow fiber membrane 36 and flow through the permeate line 24 as permeate 46 for collection in the permeate tank 18. The remainder of the solution, the retentate 45, flows through the elongated hollow fiber channels 32 to the retentate line 22 for recirculation 105 to the feed tank 14. Recirculation of the retentate 45 and filtration of the solution 44 can continue until the desired volume or recovery rate of the permeate 46 is achieved.

[0072] As filtration proceeds, fouling of the hollow fibers 38 may occur, wherein the pores 37 of the membrane 36 become blocked by solids 41, which in turn may reduce the efficiency of the filter. This may manifest as a decrease in permeate flow or permeate flux, or a change in transmembrane pressure (TMP).

[0073] The four main mechanisms of scaling or plugging include: complete pore blockage, in which solid particles completely cover and block the pores37 ( Figure 4A ); Standard / internal blocking mode, where solid 41 collects on inner wall 48 of hole 37 ( Figure 4B ); intermediate / partial blocking mode, where particles accumulate on the membrane surface and block part of the pores37 ( Figure 4C ); and cake filtration / formation mode, where particles aggregate and cover the membrane surface ( Figure 4D ), thereby forming a filter cake with low permeability on the hollow fiber membrane 36 ( Figure 4D ). These models are defined by the following formulas [Brião, VB, Seguenka, B., Zanon, CD, &Milani, A. (2017). Cake formation and the decreased performance of wheyultrafiltration. Acta Scientiarum. Technology, 39(5), 517-524]:

[0074] in, , , and is a constant of the model

[0075] is the critical flow rate, which should not be exceeded to avoid scaling

[0076] is the permeate flow rate after time t

[0077] is the initial permeate flow rate

[0078] is the membrane surface porosity of the cleaned membrane 36

[0079] is the surface area of ​​the membrane

[0080] is the area of ​​the blocked membrane per unit permeate volume

[0081] α is a parameter that characterizes the scaling potential of the solution

[0082] is the resistance of the cleaned membrane

[0083] The filtration process may be periodically paused, or the feed rate may be moderately reduced, to allow the hollow fiber filter to be backwashed to remove scale and unclog the pores by pushing a backwash solution 47 (e.g., buffer and / or permeate) through the filter 12 from the permeate side, thereby clearing the fouled membrane 36.

[0084] See also Figure 5 , an embodiment of a method 100 for filtering solids 41 from a plasma-derived solution 44 is provided. The method 100 includes feeding 102 the solution 44 to a hollow fiber filter 12 at a feed rate, the hollow fiber filter 12 including a plurality of hollow fibers 38, each hollow fiber 38 including a membrane 36 defining an elongated hollow fiber channel 32. The method 100 also includes filtering 104 the solution 44 using the hollow fiber filter 12 to generate a permeate 46 and a retentate 45, the permeate 46 passing through the pores 37 of the membrane 36 at a transmembrane pressure (TMP), and the retentate 45 flowing out of the corresponding outlet of the elongated hollow fiber channel 32, wherein the permeate 46 has a reduced solid content relative to the solution 44 fed to the hollow fiber filter 12.

[0085] The step 102 of supplying the solution can be performed using a pump 16 (e.g., a centrifugal pump). The supply rate of the solution 44 can be defined by a cross flow velocity, wherein the volume flow rate is a function of the cross flow velocity and the cross-sectional area of ​​the fiber channel. The cross flow velocity of the supply can be from about 0.6 m / s to about 4.0 m / s. In some embodiments, the lateral flow velocity may be about 0.6 m / s, about 0.7 m / s, about 0.8 m / s, about 0.9 m / s, about 1.0 m / s, about 1.1 m / s, about 1.2 m / s, about 1.3 m / s, about 1.4 m / s, about 1.5 m / s, about 1.6 m / s, about 1.7 m / s, about 1.8 m / s, about 1.9 m / s, about 2.0 m / s, about 2.2 m / s, about 2.4 m / s, about 2.6 m / s, about 2.8 m / s, about 3.0 m / s, about 3.2 m / s, about 3.4 m / s, about 3.6 m / s, 3.8 m / s or about 4.0 m / s.

[0086] The supply rate is related to the pump speed by the formula:

[0087]

[0088] in: , There are two different supply speeds (L / min)

[0089] , are the two corresponding pump speeds (rpm)

[0090] The pump speed may be set on the pump 16 using either rpm or Hertz (Hz) units, the latter of which may be converted to rpm by multiplying by 60.

[0091] The average pore size 39 can be between about 0.1 microns and about 4 microns, for example, about 0.2 microns to about 1 micron. In some embodiments, the pore size 39 can be about 0.05 microns, about 0.1 microns, about 0.15 microns, about 0.2 microns, about 0.25 microns, about 0.3 microns, about 0.35 microns, about 0.4 microns, about 0.45 microns, about 0.5 microns, about 0.55 microns, about 0.6 microns, about 0.65 microns, about 0.7 microns, about 0.75 microns, about 0.8 microns, about 0.85 microns, about 0.9 microns, about 0.95 microns, about 1 micron, about 1.25 microns, about 1.5 microns, about 1.75 microns, about 2 microns, about 2.5 microns, about 3 microns, about 3.5 microns, or about 4 microns. It should be understood that the desired pore size can vary depending on the properties of the solution to be treated and the desired final properties of the permeate.

[0092] It should be understood that the pores 37 can be distributed in a homogeneous, uniform or substantially uniform manner on the membrane 36, such that the distances between the pores 37 are substantially equal. It should also be understood that the pores 37 can be distributed in an inhomogeneous or non-uniform manner, such that the distances between some pores 37 are smaller or larger than the distances between other pores 37.

[0093] TMP is defined by the following formula:

[0094]

[0095] in is TMP (kPa)

[0096] is the inlet pressure (kPa), such as the supply pressure gauge 26

[0097] is the outlet pressure (kPa), such as the retentate pressure gauge 28

[0098] is the permeate pressure (kPa), for example, the permeate pressure gauge is 30

[0099] The TMP can be varied by adjusting one or more of the supply valve, the retentate valve, and / or the permeate valve, in combination with other operating parameters that can vary the inlet pressure and / or the outlet pressure. The TMP can be between about 10 kPa and about 300 kPa, for example, between about 20 kPa and 300 kPa. In some embodiments, the TMP can be set to about 10 kPa, about 20 kPa, about 25 kPa, about 30 kPa, about 35 kPa, about 40 kPa, about 45 kPa, about 50 kPa, about 55 kPa, about 60 kPa, about 65 kPa, about 70 kPa, about 75 kPa, about 80 kPa, about 85 kPa, about 90 kPa, about 95 kPa, about 100 kPa, about 105 kPa, about 110 kPa, about 115 kPa, about 120 kPa, about 125 kPa, about 130 kPa, about 131 kPa, about 132 kPa, about 133 kPa, about 134 kPa, about 136 kPa, about 137 kPa, about 138 kPa, about 139 kPa, about 140 kPa, about 141 kPa, about 142 kPa, about 143 kPa, about 144 kPa, about 145 kPa, about 146 kPa, about 147 kPa, about 148 kPa, about 149 kPa, about 150 kPa, about 151 kPa, about 152 kPa, about 153 kPa, about 154 kPa, about 156 kPa, about 157 kPa, about 158 ​​kPa, about 159 kPa, about 160 kPa, about 161 kPa, about kPa, about 125 kPa, about 130 kPa, about 135 kPa, about 140 kPa, about 145 kPa, about 150 kPa, about 160 kPa, about 170 kPa, about 180 kPa, about 190 kPa, about 200 kPa, about 210 kPa, about 220 kPa, about 230 kPa, about 240 kPa, about 250 kPa, about 260 kPa, about 270 kPa, about 280 kPa, about 290 kPa or about 300 kPa. The TMP can be set in the range between any two of the pressures listed above.

[0100] In some embodiments, solution 44 includes plasma components, such as component (I+)II+III including IgG, component IV-4 including hemopexin, and component V including albumin. It will be appreciated by those skilled in the art that solution 44 is not limited to the use of plasma components, which are not limited to the above components and may include any suitable plasma components, such as any of the plasma components described in the background section. It will also be appreciated by those skilled in the art that solution 44 may be derived from blood from other sources, such as animal blood, for example, bovine blood.

[0101] The use of different plasma components may require the selection of different operating parameters of the hollow fiber filter 12 in order to obtain higher recovery, higher permeate flow rate, higher permeate flux and / or lower turbidity of the permeate 46. In addition, under the same operating parameters, some plasma components may have higher recovery and lower turbidity than other plasma components. For example, as seen in the Examples section, the use of Fraction IV-4 including hemopexin can provide higher recovery and lower turbidity.

[0102] The temperature of solution 44 can be any suitable temperature for the solution components. In one embodiment, the solution is maintained at a temperature in the range of about 4° C. to about 37° C. In some embodiments, the temperature of the solution is less than about 25° C.

[0103] Preferably, the conductivity of the solution is about 2 mS / cm to about 40 mS / cm. For example, the conductivity of the solution can be about 2 mS / cm, 3 mS / cm, 4 mS / cm, 5 mS / cm, 6 mS / cm, 7 mS / cm, 8 mS / cm, 9 mS / cm, 10 mS / cm, 11 mS / cm, 12 mS / cm, 13 mS / cm, 14 mS / cm, 15 mS / cm, 16 mS / cm, 17 mS / cm, 18 mS / cm, 19 mS / cm, 20 mS / cm, 21 mS / cm, 22 mS / cm, 23 mS / cm, 24 mS / cm, 25 mS / cm, 26 mS / cm, 27 mS / cm, 28 mS / cm, 29 mS / cm, 30 mS / cm, 31 mS / cm, 32 mS / cm, 33 mS / cm, 34 mS / cm, 35 mS / cm, 36 mS / cm, 37 mS / cm, 38 mS / cm, 39 mS / cm, 40 mS / cm, 41 mS / cm, 42 mS / cm, 43 mS / cm, 44 mS / cm 1mS / cm, 22mS / cm, 23mS / cm, 24mS / cm, 25mS / cm, 26mS / cm, 27mS / cm, 28mS / cm, 29mS / cm, 30mS / cm, 31mS / cm, 32mS / cm, 33mS / cm, 34mS / cm, 35mS / cm, 36mS / cm, 37mS / cm, 38mS / cm, 39mS / cm, or 40mS / cm. Although the conductivity of the solution is typically measured at room temperature, it should be understood that the conductivity can also be measured at a given temperature of the solution supplied to the hollow fiber filter. In one embodiment, the conductivity of the solution derived from plasma can be about 8mS / cm to about 15mS / cm when measured at room temperature.

[0104] Solution 44 may also include a buffer. In these embodiments, the buffer is added to the plasma-derived product to form solution 44 prior to being fed to hollow fiber filter 12. The purpose of the buffer is to resuspend the plasma components (which are precipitates and may be mushy) so that solution 44 has a suitable viscosity for feeding into hollow fiber filter 12. Any suitable buffer may be used, for example, the buffer may include sodium acetate, water (such as water for injection (WFI)), or phosphates, such as disodium phosphate.

[0105] The conductivity of the solution can be adjusted as needed to achieve the desired conductivity. In the case where the solution contains a buffer solution, the concentration of the buffer solution can be adjusted to achieve the desired conductivity without significantly diluting the sample.

[0106] The ratio of plasma components to buffer used in solution 44 may affect the recovery, permeate flow rate and / or turbidity of permeate 46. This ratio is referred to as the extraction ratio of solution 44, which is defined as the ratio of kilograms of plasma components to kilograms of buffer. It should be understood that the extraction ratio can vary depending on the components of the plasma used and practical considerations, such as the space required to store and use the volume of buffer required for higher extraction ratios. For example, an extraction ratio of 1:1 or higher can be used, but for higher recoveries, an extraction ratio of at least 1:2 will be suitable. The maximum practical extraction ratio is 1:20, but it will be understood by those skilled in the art that the extraction ratio can exceed 1:20 if a specific recovery needs to be achieved and / or a specific plasma component needs to be resuspended.

[0107] Taking these factors into consideration, the extraction ratio of solution 44 may be from about 1:2 to about 1:10. However, the extraction ratio may be any suitable extraction ratio, for example, the extraction ratio may be about 1:1, about 1:1.5, about 1:2, about 1:2.5, about 1:3, about 1:3.5, about 1:4, about 1:4.5, about 1:5, about 1:5.5, about 1:6, about 1:6.5, about 1:7, about 1:7.5, about 1:8, about 1:8.5, about 1:9, about 1:9.5, about 1:10, about 1:1 0.5, about 1:11, about 1:11.5, about 1:12, about 1:12.5, about 1:13, about 1:13.5, about 1:14, about 1:14.5, about 1:15, about 1:15.5, about 1:16, about 1:16.5, about 1:17, about 1:17.5, about 1:18, about 1:18.5, about 1:19, about 1:19.5, about 1:20, or about 1:20.5.

[0108] In some embodiments, the pH of solution 44 is between about 4 and about 9. For example, the pH of solution 44 can be about 4, about 4.5, about 5, about 5.5, about 6, about 6.5, about 7, about 7.5, about 8, about 8.5, or about 9.

[0109] In some embodiments, solution 44 includes a filter aid. In these embodiments, the filter aid is from a plasma fractionation process. The filter aid can be any suitable filter aid, for example, the filter aid can be cellulose-based or silica-based.

[0110] The method 100 can provide a permeate 46 having a recovery of at least 30%. In some embodiments, the method can provide a permeate 46 having a recovery of at least 30%, at least 50%, at least 75%, or at least 90%.

[0111] Improving the recovery will allow for less protein loss, which means less product remains in the retentate. The operating parameters (such as feed rate, pore size and / or transmembrane pressure) and the parameters of solution 44 can be selected to improve the recovery. It should be understood that the recovery of permeate 46 can be at least about 20%, at least about 25%, at least about 30%, at least about 35%, at least about 40%, at least about 45%, at least about 50%, at least about 55%, 60%, at least about 62.5%, at least about 65%, at least about 67.5%, at least about 70%, at least about 72.5%, at least about 75%, at least about 77.5%, at least about 80%, at least about 82.5%, at least about 85%, at least about 87.5%, at least about 90%, at least about 92.5%, or at least about 95%.

[0112] The method 100 can be performed such that the turbidity of the permeate 46 is less than about 400 nephelometric turbidity units (NTU). In some embodiments, lower turbidity of the permeate 46 can be a general indicator of improved solids removal, and thus lower turbidity of the permeate 46 is desirable. Operating parameters (such as pore size) and parameters of the solution 44 can be selected to reduce turbidity. It should be understood that the turbidity of the permeate 46 can be less than about 600 NTU, less than about 550 NTU, less than about 500 NTU, less than about 450 NTU, less than about 400 NTU, less than about 375 NTU, less than about 350 NTU, less than about 325 NTU, less than about 300 NTU, less than about 275 NTU, less than about 250 NTU, less than about 225 NTU, less than about 200 NTU, less than about 175 NTU, less than about 150 NTU, less than about 125 NTU, less than about 100 NTU, less than about 75 NTU, less than about 50 NTU or less than about 25 NTU.

[0113] In some embodiments, such as where solution 44 comprises IgG, method 100 further comprises adding caprylic acid to solution 44 for defatting solution 44. In other embodiments, caprylic acid is added to permeate 46 for defatting permeate 46. When caprylic acid is used, calcium phosphate may be added to solution 44 or permeate 46 to neutralize any excess caprylic acid.

[0114] For example, Figure 6 As shown, the method 100 may also include backwashing 106 the hollow fiber filter 12. Backwashing 106 includes closing the permeate valve 31 while opening the backwash valve 57, the feed valve 27, and the retentate valve 29. A backwashing solution 47 (e.g., a buffer, preferably the same buffer as used in the solution 44) is pumped into the permeate side of the hollow fiber filter 12 through the buffer lines 51a, 51b using the backwash pump 55, thereby flushing the pores 37 of the membrane 38 to remove scale and blockages. The backwashing solution 47, carrying the solids flushed from the membrane, flows through the longitudinal channels 32 and the retentate line 22. The backwashing solution 47 and the flushed solids are recycled to the feed tank for further filtration.

[0115] Backwashing 106 may be performed before supplying 102 and / or after filtering 104. Backwashing may be performed at certain time intervals using a certain volume of backwash solution 47 for the backwash cycle, for example, at a rate of at least 500 mL of backwash solution 47 per 2 L of permeate 46 produced. In some embodiments, the volume of backwash solution per unit volume of permeate may be about 100 mL per 2 L, about 150 mL per 2 L, about 200 mL per 2 L, about 250 mL per 2 L, about 300 mL per 2 L, about 350 mL per 2 L, about 400 mL per 2 L, about 450 mL per 2 L, about 500 mL per 2 L, about 550 mL per 2 L, about 600 mL per 2 L, about 650 mL per 2 L, about 700 mL per 2 L, about 750 mL per 2 L, about 800 mL per 2 L, about 850 mL per 2 L, about 900 mL per 2 L, ...0 mL per 2 L, about 1000 mL per 2 L, about 100 About 950mL per 2L, about 1L per 2L, about 1.1L per 2L, about 1.2L per 2L, about 1.3L per 2L, about 1.4L per 2L, about 1.5L per 2L, about 1.6L per 2L, about 1.7L per 2L, about 1.8L per 2L, about 1.9L per 2L, about 2L per 2L, about 2.5L per 2L, about 3L per 2L, about 100mL per L, about 150mL per L, about 200mL per L, about 250mL per L, about 300mL per L, about 350mL per L, about 400mL per L, about 400mL per L 50mL, about 500mL per L, about 550mL per L, about 600mL per L, about 650mL per L, about 700mL per L, about 750mL per L, about 800mL per L, about 850mL per L, about 900mL per L, about 950mL per L, about 1L per L, about 1.1L per 1L, about 1.2L per L, about 1.3L per L, about 1.4L per L, about 1.5L per L, about 1.6L per L, about 1.7L per L, about 1.8L per L, about 1.9L per L, about 2L per L, about 2.5L per L, or about 3L per L.

[0116] In some embodiments, at least two backwash cycles are performed during method 100. In some embodiments, the number of backwash cycles performed can be 1, 2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15, 16, 17, 18, 19, 20, about 25, about 30, about 35, about 40, about 45, about 50, or more. In some embodiments, the method can be a continuous process with continuous cycling between filtering and backwashing.

[0117] Where backwash 106 is included in method 100, in addition to operating parameters of hollow fiber filter 12 (e.g., feed rate, pore size and / or TMP) and parameters of solution 44, operating parameters of the backwash (e.g., backwash interval and number of backwash cycles) may be selected to achieve a desired recovery and / or turbidity of permeate 46. The recovery and / or turbidity of permeate 46 may be evaluated after one or more backwash cycles.

[0118] In some embodiments, the method further comprises measuring the permeate flow rate during the filtration process.Operation parameters (such as feed rate, pore size and / or TMP) and parameters of solution 44, as well as backwash intervals and / or backwash cycle times, may be selected to achieve a desired permeate flow rate.

[0119] In some embodiments, the method further comprises measuring the permeate flux during the filtration process.Operation parameters (such as feed rate, pore size and / or TMP) and parameters of solution 44, as well as backwash interval and / or number of backwash cycles can be selected to achieve a desired permeate flux.

[0120] In some embodiments, the permeate flux may be about 0.5 L / m² / h, about 1 L / m² / h, about 2 L / m² / h, about 2.5 L / m² / h, about 3 L / m² / h, about 3.5 L / m² / h, about 4 L / m² / h, about 4.5 L / m² / h, about 5 L / m² / h, about 5.5 L / m² / h, about 6 L / m² / h, about 6.5 L / m² / h, about 7 L / m² / h, about 7.5 L / m² / h, about 8 L / m² / h, about 8.5 L / m² / h, about 9L / m² / h, about 9.5L / m² / h, about 10L / m² / h, about 10.5L / m² / h, about 11L / m² / h, about 11.5L / m² / h, about 12L / m² / h, about 12.5L / m² / h, about 13L / m² / h, about 13.5L / m² / h, about 14L / m² / h, about 14.5L / m² / h, about 15L / m² / h, about 15.5L / m² / h, about 16L / m² / h, about 17L / m² / h 6.5L / m² / h, about 17L / m² / h, about 17.5L / m² / h, about 18L / m² / h, about 18.5L / m² / h, about 19L / m² / h, about 19.5L / m² / h, about 20L / m² / h, about 21L / m² / h, about 22L / m² / h, about 23L / m² / h, about 24L / m² / h, about 25L / m² / h, about 30L / m² / h, about 35L / m² / h, or about 40L / m² / h, about 5 The permeate flux may be within a range between any two of the above values.

[0121] The permeate flow rate and / or permeate flux may be monitored to provide an indication of filter performance over time. Once filtration of the solution begins, the permeate flow rate will quickly reach a steady state, such as one of the above-mentioned flow rates. As filtration proceeds and more fouling of the pores occurs, the permeate flow rate may drop from the steady state permeate flow rate. Once the permeate flow rate has dropped below a critical flow rate value (which may be a percentage of the steady state flow rate), filtration may be stopped and a backwashing step may be performed. Flux may be similarly monitored to assess filter performance.

[0122] The method 100 may also include additional filtration of the permeate, such as using a depth filter, a membrane filter, or a combination thereof. However, those skilled in the art will appreciate that other filtration media and techniques, such as filter paper, glass microfiber filters, pre-filters, etc., may be used in addition to or in place of depth filters and / or membrane filters. It should also be understood that the permeate or the permeate after filtration using a depth filter and / or a membrane filter constitutes the plasma product produced using the method 100.

[0123] Where additional filtration is included in method 100, in addition to the operating parameters of hollow fiber filter 12 and the parameters of solution 46, the characteristics and operation of the filter, such as filter type, filter pore size and / or cut-off rating, may be selected to achieve a desired recovery and / or turbidity of the filtered permeate.

[0124] Advantageously, the use of hollow fiber filter 12 in method 100 can remove solids from solution 44 to an extent comparable to prior art techniques (e.g., filter presses), while providing a reduced footprint and a faster overall process. It should be appreciated that the operation of hollow fiber filter 12 is also less labor intensive than a filter press and does not require emptying of individual filter plates, which increases the overall processing time.

[0125] In some embodiments, the use of hollow fiber filter 12 in method 100 can provide a recovery rate of at least 60%, such as at least 75% or even at least 90%, thereby providing a recovery rate comparable to or better than using a filter press. In some embodiments of the method 100, the permeate flux can be at least 30 L / m² / h, which is a value comparable to the permeate flux value of a filter press, thus indicating that the method 100 can be as efficient and fast as filtering using a filter press, while providing the above-mentioned advantages of reduced floor space and labor.

[0126] It should be understood that the permeate 46 produced using the hollow fiber filter 12 constitutes the plasma product produced using the method 100 .

[0127] Those skilled in the art will appreciate that numerous changes and / or modifications may be made to the above embodiments without departing from the broad overall scope of the present disclosure. Therefore, the present embodiments should be considered in all aspects as illustrative and not restrictive.

[0128] Example

[0129] The following examples should be understood as being illustrative only. Therefore, the following examples should not be understood as limiting the embodiments of the present disclosure in any way.

[0130] Figure 7-Figure 24Results of experiments conducted with respect to various embodiments of the method 100 of removing solids 41 from a solution 44 are shown.

[0131] Example 1 - Effect of different TMPs

[0132] Figure 7 and Figure 8 The effect of different TMPs on the permeate flow and permeate quality of a hemopexin extract (Fraction IV-4) with an extraction ratio of 1:10 (3.64 kg Fraction IV-4: 36.4 kg, 40 mM disodium phosphate) fed to a filter with a pore size of 0.6 μm and a filter area of ​​0.2 m 2 The ceramic hollow fiber filter 2 was placed inside the filter and a water bath with a copper cooling coil (not shown) was used to maintain the supply tank temperature below 25° C. For every 2 L of collected permeate, 2 L of buffer was also used for backwashing, and the pump speed was set to 30 Hz (about 60 L / min-80 L / min).

[0133] Figure 7 The experimental results of permeate flow rate versus time for different TMP values ​​recorded by the data logger are shown in graph 700. At all applied transmembrane pressures, the permeate has a high initial flow rate, but quickly reaches a steady-state flow rate of 100 g / min-150 g / min after about 3 minutes (permeate flux of about 45 L / m² / h-75 L / m² / h).

[0134] Figure 8 The experimental results of permeate mass versus time for different TMP values ​​recorded by the data logger are shown in graph 800. These results show that, in general, higher TMP values ​​result in higher initial permeate fluxes, although the permeate fluxes for all conditions reach similar plateaus over time. The initial flux for 40 kPa TMP is higher than that for 80 kPa TMP, which may be due to the 40 kPa condition being performed first, so that the fouling of the filter membrane is the least at this time.

[0135] Fig. 9 and Fig.10 The effect of different TMP values ​​on the permeate flow rate and permeate quality of a hemopexin extract (fraction IV-4) with an extraction ratio of 1:2.5, fed to a ceramic hollow fiber filter with a pore size of 0.6 microns, a filter area of ​​0.2 m², and a feed tank temperature maintained below 25°C using a water bath, is shown. For every 2 L of permeate collected, 2 L of buffer was also used for backwashing.

[0136] Fig. 9Graph 900 showing experimental results of permeate flow rate versus time for different TMP values ​​recorded by a data logger, Fig.10 The experimental results of permeate mass versus time for different TMP values ​​recorded by the data logger are shown in Figure 1000. At all applied transmembrane pressures, the initial permeate flux is high, but quickly reaches a steady-state flux of 150 g / min-200 g / min after about 0.8 minutes (permeate flux is about 45 L / m² / h-75 L / m² / h). Compared with the above experiment with a 1:10 extraction ratio, the permeate flux decreases more rapidly, while the final stable permeate flux is similar. Figures 900 and 1000 show that there is no significant difference in the initial permeate flux under different TMP conditions. In addition, it seems that higher TMP values ​​(140 kPa and 160 kPa) may produce lower initial fluxes, so lower TMP values ​​(≤120 kPa) can be used in the case of a 1:2.5 extraction ratio.

[0137] Figures 900 and 1000 were averaged from 4-5 experiments and it was found that the initial flux varied when run at the same TMP. This variation may be due to the continuous manual adjustment of the permeate valve to control the TMP at the beginning of the experiment. It was also found that a cake / gel layer may form during the initial transient period of filtration. The formation of the cake resulted in a decrease in the permeate flux and a reduction in protein permeation, which could not be solved by higher TMP values.

[0138] Table 1 below summarizes the results of the above hemopexin experiments and provides a comparison of the results between the 1:2.5 hemopexin extract and the 1:10 hemopexin extract. The results show that after filtration of both hemopexin extracts, the total recovery of hemopexin was 71%, indicating that a recovery of over 70% can be achieved using lower extraction ratios for hemopexin.

[0139] Table 1: Results for mass, concentration and recovery of hemopexin extract (feed) and final permeate.

[0140] Example 2 - Effects of Changing Pump Speed

[0141] Fig.11 and Fig.12The effect of varying the pump speed for different TMP values ​​is shown. Experiments were performed using a hemopexin extract (Fraction IV-4) with an extraction ratio of 1:10 (3.64 kg Fraction IV-4: 36.4 kg, 40 mM disodium phosphate) fed to a ceramic hollow fiber filter with a pore size of 0.25 microns, a filter area of ​​0.2 m², and the feed tank temperature was maintained below 25°C using a water bath.

[0142] Fig.11 The experimental results graph 1100 of permeate mass versus time for different pump speeds at different TMP values ​​is shown. This process was performed until 3 liters of permeate were recovered, and backwashing was performed between each process. Compared to the previous example, the initial high permeate flow rate was not present. In addition, the higher the pump speed and / or TMP, the higher the permeate flow rate.

[0143] Fig.12 A graph 1200 of the percentage of protein permeate versus cumulative permeate volume for different pump speeds at different TMP values ​​is shown. The percentage of protein permeate was initially high (about 80%), but gradually decreased to a steady state of about 40% at 30 kPa TMP, regardless of pump speed. The gradual increase in TMP did not result in a further decrease in protein permeate, and the pump speed had no significant effect on the initial rate of decrease in protein permeate. Therefore, the results indicate that low TMP and high pump speed do not prevent cake formation on the membrane. However, this also suggests that backwashing for every 0.5 L of permeate produced can potentially address low protein permeate to maintain an overall protein permeate greater than 50%.

[0144] Example 3 - Effect of Backwash Volume

[0145] Fig.13 The effect of backwash volume on the average permeate flow rate is shown, and the results of hemopexin concentration and recovery are shown in Table 1. In this experiment, the same hemopexin extract as in Example 2 was used and fed to a ceramic hollow fiber filter with a pore size of 0.6 microns, a filter area of ​​0.2 m², and a transmembrane pressure of 110 kPa. The same water bath was used as in the previous example.

[0146] Fig.13A graph 1300 showing average permeate flow rate versus cumulative backwash volume is shown. For approximately the first 19 liters of cumulative backwash, 500 ml of buffer was used for every 2 liters of collected permeate to concentrate the solution to half the volume. Thereafter, 1 liter of buffer was used for every 1 liter of permeate. The large variation in average permeate flow rate may be due to the time spent backwashing and the opening and closing of the valve between backwash cycles. However, the average flow rate was generally relatively stable at 150 g / min-250 g / min for both backwash conditions. Therefore, under these conditions, a backwash volume of 500 ml was sufficient to clean the filter membrane.

[0147] During this experiment, hemopexin conjugates were measured using SEC-HPLC and hemopexin concentrations were measured using RP-HPLC. Table 1 shows the weight, total hemopexin concentration, percentage of hemopexin complexes and recovery in the hemopexin extracts, final retentate and final permeate before feeding or filtration.

[0148] Example 4 - Use of albumin and IgG extracts and the impact of backwashing

[0149] Figure 14-17 The effect of backwashing on the albumin extract (fraction V) is shown. Figure 18-Figure 19 The effect of backwashing on the IgG extract (fractions I+II+III) is shown.

[0150] and Figure 14-17 The results shown in the experiment were related to an extraction ratio of 1:2 (6.7 kg of component V: 13.3 kg of 10 mM sodium acetate), using a 0.25 μm pore size, 0.2 m 2 The filter area was 1000 mm / s. The pump rate was set to 35 Hz (supply rate was about 90 L / min) and the TMP was set to 100 kPa. 1 L of buffer was used for backwashing for every 1 L of permeate produced. A water bath with a copper cooling coil was used to maintain the supply tank temperature below 25 °C.

[0151] Fig.14 A graph 1400 showing average permeate flow rate (based on 2 processes) versus time after different numbers of backwashes are performed is shown. In the early stages of filtration (i.e., before the third backwash), the permeate flow rate shows a clear downward trend over time. During this stage, the initial permeate flow rate is greater than 400 g / min, and within a 20 minute time span, the flow rate gradually decreases to about 80 g / min, and then the next backwash is performed at this time. However, in the later stages of filtration, the initial high permeate flow rate becomes less obvious, and the permeate flow rate almost immediately reaches a stable flow rate of about 60 g / min.

[0152] Fig.15 A graph 1500 of average permeate flow rate (based on 2 passes) versus backwash number is shown to investigate the change in flow rate between backwash cycles. Flow rate results for early filtration runs (0 and 1 backwash performed) are omitted as they behave significantly differently than the other results. During the experiment, the average permeate flow rate remained constant at 55 g / min-65 g / min. This is equivalent to a permeate flux of 18 L / m² / h. This flow rate is significantly lower than the average flow rate observed in Example 2 (approximately 200 g / min) under the same operating conditions.

[0153] Fig.16 A graph 1600 of average permeate flow rate versus time for an extended filtration without backwashing for 90 minutes is shown to investigate the permeate flow rate trend over a longer period of time. The results show that the permeate flow rate remains stable at 50 g / min-60 g / min, which is consistent with Fig.14 and Fig.15 This is consistent with the average permeate flow rate observed in the

[0154] Fig.17 A graph 1700 of protein permeation versus permeate fraction is shown, where protein permeation is measured at specific permeate fractions compared to the hemopexin extract in Example 2. It is observed that protein permeation is generally higher with the hemopexin extract than with the albumin extract.

[0155] Table 2 shows the mass, total albumin concentration and recovery in the albumin extract, final retentate and final permeate before feeding or filtration. The albumin concentration was measured by turbidimetry. The turbidity of the final permeate was 4.63 NTU.

[0156] Table 2: Results of quality, concentration and recovery of albumin extract, final retentate and final permeate

[0157] and Figure 18-Figure 19 The experiments for which the results are shown were conducted at an extraction ratio of 1:4.5 (3.6 kg fractions I+II+III: 16.4 kg, 0.22 M sodium acetate) using a ceramic hollow fiber filter with a pore size of 0.25 micron and a filter area of ​​0.2 m². The pump speed was set at 32 Hz (approximately 80 L / min feed rate) and the TMP was set at 80 kPa. 1 L of buffer was used for backwashing per 1 L of permeate produced. The temperature of the feed tank was maintained below 25°C using a water bath with a copper cooling coil.

[0158] Fig.18A graph 1800 of permeate flow rate versus time after various numbers of backwashes are performed is shown. The decay of the permeate flow rate is similar to the results for the albumin extract. In the early stages of filtration, the initial permeate flow rate is high (i.e., greater than 200 g / min), and the permeate flow rate gradually decreases over time. In the later stages of filtration (i.e., after the fifth backwash), the initial high permeate flow rate becomes less pronounced, and the permeate flow rate reaches a steady-state flow rate almost immediately.

[0159] Fig.19 A graph 1900 of the steady state permeate flow rate versus the number of backwashes performed is shown. Unlike the previous filtration experiments with the hemopexin extract and the albumin extract, the steady state flow rate decreased during the experiment. This indicates that the membrane of the hollow fiber filter was blocked by fouling and that the backwashing was unable to remove the blockage. During the experiment, a back pressure of 5 bar was applied on the permeate side during the backwash, which is higher than the typical 4 bar back pressure in other experiments. However, this still did not provide a more effective backwash. This is most likely because the fouling is strongly adsorbed to the membrane.

[0160] Example 5 - Effects of Changing the TMP Step-Up Rate

[0161] Fig. 20 A graph 2000 of permeate mass versus time for a fast increase or fast ramp up of TMP and a slow increase or slow ramp up of TMP to 100 kPa using a ceramic hollow fiber filter having a pore size of 0.25 microns and a filter area of ​​0.2 m² is shown. The pump rate was set to 35 Hz (supply rate of approximately 90 L / min) and the supply tank temperature was maintained below 25°C using a water bath with a copper cooling coil. The fast increase reached 100 kPa in 10 seconds and the slow increase reached 100 kPa in approximately 30 seconds. There was no significant difference in permeate flow between the slow and fast ramp ups.

[0162] Example 6 - Effect of Changing Solution pH

[0163] Fig.21A graph 2100 of hemopexin permeability versus permeate volume for solutions at different pH levels is shown. The experiment was performed using a hemopexin extract (fraction IV-4) at an extraction ratio of 1:10 (3.64 kg fraction IV-4: 36.4 kg, 40 mM disodium phosphate), the hemopexin extract was fed to a ceramic hollow fiber filter having a pore size of 0.25 microns, a filter area of ​​0.2 m², and the feed tank temperature was maintained below 25°C using a water bath. The transmembrane pressure was set to 30 kPa and the pump speed was set to 35 Hz (feed rate of approximately 90 L / min). Graph 2100 shows that pH has little effect on the transmembrane permeation of hemopexin.

[0164] Example 7 - Fouling Model Study

[0165] Figure 22-Figure 24 Results of a study showing how experimental data for hemopexin, IgG, and albumin extracts compare to theoretical results for the standard / internal blocking model, the intermediate / partial blocking model, and the cake filtration / formation model.

[0166] Fig. 22 A graph 2200 of permeate flow rate versus time is shown to compare the smoothed experimental permeate flow rate curve to a theoretical curve generated by a filter cake fouling model that best fits the experimental results. Using the hemopexin extract under the same conditions as Example 1 at different TMP values, the similarity between the experimental and theoretical curves indicates that for this experiment, the rapid decrease in permeate flow rate was most likely due to filter cake formation.

[0167] Fig.23A and Fig. 23B Graphs 2300a and 2300b of permeate flow rate versus time are shown, respectively, to compare the smoothed permeate flow rate curve from using an albumin extract as in Example 4 with theoretical curves generated by the cake fouling model, the partial fouling model, and the internal fouling model. Fig.23A The experimental results of Example 4 in the early stage of the experiment (after the first backwashing) are shown. Fig. 23B The experimental results of Example 4 at the end of the experiment (after the thirteenth backwash) are shown. It seems that the same fouling mechanism, namely partial fouling, caused the permeate flow curve performance in the early and late stages of the experiment. The partial fouling mechanism indicates that the foulants adhere to both the membrane surface and the membrane pores (such as Figure 4C ). Blockage and unblocking of pores can occur dynamically, and backwashing between filtrations may remove only a small portion of the dirt attached to the membrane. As a result, the steady-state permeate flow rate gradually decreases in the early stages of filtration and becomes relatively stable in the later stages of filtration.

[0168] Considering that the protein permeability in this experiment was only 20%-40%, and the albumin concentration in the feed tank was high as shown in Table 2, it is likely that a gel layer also formed on the top of the filter membrane. However, this gel layer did not have a major effect on the attenuation of the permeate flow. Literature has shown that albumin has a stronger adsorption on silicon carbide materials and ceramic membranes are fouled by albumin at a faster rate when the solution pH level is lower (3-5) than the neutral pH used in this experiment.

[0169] Fig.24 A graph 2400 of permeate flow rate versus time is shown to compare the smoothed experimental permeate flow rate curve from using an IgG extract as in Example 4 with a theoretical curve generated by a filter cake fouling and partial blocking model (the theoretical curve is closest to the experimental results). It is possible that both pore blocking mechanisms are involved in the decay of the permeate flow rate, but the reduction in steady-state permeate flow rate is most likely due to partial pore blocking. Partial blocking occurs when the size of the contaminant is larger than the pore size, preventing the contaminant from entering the pores and becoming attached to the membrane surface, which partially blocks the membrane pores. In filtering the IgG extract, the contaminant is likely to be lipid / lipoprotein aggregates, whose average size is larger than the 0.25 micron membrane pore size used in this experiment.

Claims

1. A method for filtering solids from a solution derived from plasma, the method comprising: supplying a solution at a supply rate to a hollow fiber filter comprising a plurality of hollow fibers, each hollow fiber comprising a membrane defining an elongated hollow fiber channel; and The solution is filtered using the hollow fiber filter to produce a permeate that passes through the pores of the membrane under a transmembrane pressure and a retentate that flows out of corresponding outlets of the elongated hollow fiber channels, wherein the permeate has a reduced solids content relative to the solution supplied to the hollow fiber filter.

2. The method of claim 1, further comprising recycling the retentate into the solution for feeding into a hollow fiber filter.

3. The method according to claim 1 or 2, wherein the feed rate is defined as a lateral flow rate of about 0.6 m / s to about 4.0 m / s.

4. The method of any of the above claims, wherein the pores of the membrane have an average pore size of about 0.1 microns to about 4 microns.

5. The method according to any one of the above claims, wherein the transmembrane pressure is from about 20 kPa to about 300 kPa.

6. The method of any one of the preceding claims, further comprising measuring the permeate flux during filtration.

7. The method of claim 6, wherein the permeate flux is at least about 3 liters per hour per square meter of hollow fiber filter area.

8. A method according to any one of the preceding claims, wherein the method comprises a plurality of filtration steps, wherein the method further comprises feeding a backwash solution through the hollow fiber filter between filtration steps.

9. The method of claim 8, wherein the backwash solution comprises a buffer solution.

10. The method of claim 8 or 9, wherein the backwash solution comprises permeate.

11. The method according to any one of claims 8 to 10, wherein the volume of the backwash solution supplied to the hollow fiber filter between filtration steps is provided in a ratio of about 1:6 to about 1:1 to the volume of the permeate obtained during the filtration step before backwashing.

12. The method of any of the preceding claims, wherein the solution has a conductivity of about 2 mS / cm to about 40 mS / cm.

13. The method of any of the preceding claims, wherein the solution has a conductivity of about 8 mS / cm to about 15 mS / cm.

14. The method of any of the above claims, wherein the solution is at a temperature of about 4°C to about 37°C.

15. The method of any of the preceding claims, wherein the solution comprises a plasma component.

16. The method of any one of the preceding claims, wherein the solution comprises a buffer.

17. The method of claim 16, wherein the buffer comprises sodium acetate or phosphate.

18. The method of claim 16 or 17, wherein the solution has an extraction ratio of kilogram plasma component to kilogram buffer of about 1:2 to about 1:

20.

19. The method of any of the preceding claims, wherein the solution comprises hemopexin.

20. The method of any one of claims 1-19, wherein the solution comprises albumin.

21. The method of any one of claims 1-19, wherein the solution comprises immunoglobulin G.

22. The method according to claim 21, further comprising adding caprylic acid to the permeate for degreasing the permeate.

23. The method of any one of the preceding claims, wherein the solution comprises a filter aid.

24. The method of any of the above claims, wherein the pH of the solution is between about 4 and about 9.

25. The method of any one of the preceding claims, wherein the permeate recovery is at least 30%.

26. A method according to any one of the preceding claims, wherein the recovery of the permeate is at least 50%.

27. A method according to any one of the preceding claims, wherein the permeate recovery is at least 75%.

28. The method of any one of the preceding claims, wherein the permeate recovery is at least 90%.

29. The method of any of the above claims, wherein the permeate has a turbidity of less than about 400 nephelometric units.

30. A plasma product produced using the method of any one of the preceding claims.

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