Filter element for separation and concentration of liquid media

Abstract

FIELD: filters.SUBSTANCE: invention relates to installations for separating and concentrating liquid media and can find application in the manufacture of devices using semipermeable polymer membranes for the chemical, pharmaceutical, and biotechnological industries, as well as in water purification systems. A filter element is proposed for separating and concentrating liquid media from a polymer semi-permeable membrane placed between gaskets placed in a rigid polymer housing consisting of a cover and a base equipped with units for feeding a liquid medium, removing concentrate and filtrate in the form of through holes, the inner part of the cover of the rigid polymer housing is micro-relief in the form of repeating horizontal and vertical rows of volumetric fragments alternating in height, symmetrically located along a common diagonal, each of the volumetric fragments is made in the form of a solid-cast truncated quadrangular pyramid with a cylindrical protrusion with a curved upper base.EFFECT: increase in the efficiency of the filtration process, a reduction in the likelihood of the formation of stagnant zones, which in turn leads to an increase in the performance of the filter element and its service life.1 cl, 4 dwg

Description

[0001] The invention relates to installations for separating and concentrating liquid media and can find application in the manufacture of devices using semipermeable polymer membranes for removing high-molecular compounds, viruses, colloidal and dissolved substances of 3 kDa and above in size, including for the chemical, pharmaceutical, biotechnological industries, as well as in water purification systems, primarily small and medium volumes, operated in filter holders.

[0002] The simplest method for separating and concentrating liquid media, in particular, concentrating microorganisms using semipermeable membranes, is dead-end filtration, in which the liquid passes directly through the membrane, and microorganisms and other inclusions are collected by scraping or washing the membrane in the opposite direction. Dead-end filtration leads to the formation of a thick layer of inclusions (e.g., cells) on the semipermeable membrane, as a result of which the process takes a long time, which is why this method requires semipermeable membranes with a large surface area. More effective is filtration in the tangential flow mode over the membrane used for ultrafiltration, reverse osmosis and microfiltration (T. Brock. Membrane Filtration - translation from English. Moscow, Mir, 1987, pp. 306-307; Theodore H. Meltzer, Maik W. Jornitz. Filtration in the Biopharmaceutical Industry.- MARCEL DEKKER, Inc., 1998, pp / 501-503).

[0003] The design features of installations for tangential filtration involve the inclusion of turbulators (turbulizing elements) in the design, which increase the permeability of the membranes used, in various locations in the supramembrane space.

[0004] The following designs of turbulators for membrane devices are known in particular (published on the website chem.msu.ru):

[0005] - stirrers - make a circular motion;

[0006] - vibrating elements - perform oscillatory movements under the influence of the flow of oncoming liquid or from an external drive;

[0007] - ball elements - perform reciprocating movements under the action of gravity or by changing the direction of the fluid flow.

[0008] Flexible elements - for example, in the form of a ribbon attached at one end to a porous frame. As the medium moves, the element oscillates, which promotes flow turbulence near the membrane surface.

[0009] All the above mentioned turbulator designs cannot be used in the design of compact filter elements intended for the above mentioned purposes.

[0010] Development of new designs of turbulators with optimal geometry for membrane purification by tangential filtration remains one of the key tasks in the field under study.

[0011] A flat-chamber membrane element is known according to patent RU 2019279 (published September 15, 1994). It comprises a housing, a turbulator, and a drainage support with a substrate and a semipermeable membrane located on its surface. The turbulator is characterized by the fact that it is designed as a plate with a central opening for feeding the feed mixture and multi-start grooves located on the side facing the membrane in the form of an Archimedes spiral. A significant drawback of this known technical solution is that this design cannot provide a high degree of selectivity when used for separating small volumes.

[0012] Turbulator designs for membrane purification technologies using the cross-flow filtration method are known (Article “Printed Turbulators in a Cross-flow Microfiltration System for Removing Fine Particles” by Hung-Yan Tsai, Allen Huang et al., Department of Chemical Engineering, National Taiwan University, published in Journal of Memrane Science, www.elsever.com.locate / memsci).

[0013] The known solution describes three types of turbulators designed for microfiltration in the tangential filtration mode, which were placed in the channels of the microfiltration device to excite vortices in the flow and increase the cross-flow velocity, namely, round, diamond-shaped and elliptical.

[0014] A significant drawback of the known technical solution is the lack of specific geometric characteristics of these types of turbulators, in particular, in relation to the parameters of the filter element and the semi-permeable membrane - the fixed height of the turbulator location in the above-membrane space, which can lead to the emergence of so-called stagnant volumes and a decrease in the technical result achieved, as indicated below.

[0015] Turbulator meshes with a wide range of designs of different geometric shapes and thicknesses have found wide application in membrane technologies, actively used in reverse osmosis devices (risingsunmem.ru).

[0016] A membrane apparatus is known under Author's Certificate 1831799, published July 10, 1996. This membrane apparatus comprises a set of membrane elements constructed as a frame with permeate drainage channels, a drainage device consisting of two flexible meshes with membranes on either side of the frame, and intermediate elements equipped with flexible meshes on both sides. Due to the natural deflections of the apparatus during operation, the structure of the resulting sediment is disrupted and is removed from the apparatus as part of the washing liquid. Membrane regeneration is accomplished by reverse permeate flow. A disadvantage of this known device is the potential for stagnant zones to form, which reduces productivity and service life.

[0017] The closest technical solution to the claimed one is a filter element for separating and concentrating liquid media, as described in patent RU 2687906 (published May 16, 2019). According to the prototype solution, the filter element comprises a housing equipped with units for supplying the liquid medium, discharging the concentrate and filtrate, and a filter pack consisting of a polymer semipermeable membrane, a separator-drainage mesh, and a dividing frame. A disadvantage of the prototype solution is the possibility of stagnant zones forming during operation of the filter element, reducing its performance and service life.

[0018] The essence of the invention is as follows.

[0019] The technical problem, which the claimed invention is aimed at solving, is the development of a design of a filter element for separating and concentrating liquid media of a cartridge type, intended for separating and concentrating small-volume liquid media in the tangential filtration mode without the use of mesh turbulators, intended for repeated use; in fact, the technical problem was reduced to finding a new design of turbulator.

[0020] The technical result of the claimed invention is to increase the efficiency of the filtration process, reduce the likelihood of the formation of stagnant zones, which in turn leads to an increase in the performance of the filter element and its service life.

[0021] The technical result of the claimed invention is achieved by including in the composition of the filter element for separating and concentrating liquid media a polymer semi-permeable membrane placed between gaskets placed in a rigid polymer detachable housing consisting of a cover and a base equipped with units for feeding a liquid medium, removing concentrate and filtrate in the form of through holes, wherein the inner part of the cover of the rigid polymer detachable housing is made micro-relief in the form of repeating symmetrically located along a common diagonal of horizontal and vertical rows of alternating in height volumetric fragments, each of which is made in the form of a solid-cast truncated quadrangular pyramid with a cylindrical protrusion with a curved upper base, wherein the maximum height of the volumetric fragments corresponds to the height of the supramembrane space, and the number of volumetric fragments is from 180 to 220 per 1 cm 2polymer semipermeable membrane.

[0022] In a particular case of implementing the invention, the filter element for separating and concentrating liquid media is characterized in that the ratio of the heights of the alternating height volumetric fragments, each of which is made in the form of a solid cast truncated quadrangular pyramid with a cylindrical protrusion with a curved upper base, is 2:1.

[0023] The rigid polymer housing of the filter element is made detachable, consisting of a cover and a base, the inner part of its cover is made micro-relief in the form of alternating volumetric fragments of a given design and geometry, each of which is made in the form of a solid cast truncated quadrangular pyramid with a cylindrical protrusion with a curved upper base, performing the function of a turbulator in the filter element during its operation.

[0024] The best result in implementing the invention is achieved by maintaining the ratio of heights of alternating volumetric fragments of different heights, each of which is made in the form of a solid cast truncated quadrangular pyramid with a cylindrical protrusion with a curved upper base, amounting to 2:1 (hereinafter referred to as “high truncated pyramids” and “low truncated pyramids”).

[0025] Additional studies conducted by the applicant demonstrated that using the microrelief surface of the inner part of the rigid polymer filter element housing as a turbulator results in a more uniform distribution of the filtration flow across the surface of the semipermeable polymer membrane, significantly reducing the risk of stagnant zones. Furthermore, this filter element design ensures higher performance due to increased filtration flow and creates intense shear stress in the separated liquid medium, more effectively preventing sedimentation and fouling the membrane.

[0026] The filter element for separating and concentrating liquid media is shown in Fig. 1, where:

[0027] 1 - Liquid medium supply unit

[0028] 2 - Hard polymer case cover

[0029] 3 - micro-relief surface of the inner part of the cover of a rigid polymer housing (turbulator)

[0030] 4 - polymer semipermeable membrane

[0031] 5 - gasket

[0032] 6 - concentrate outlet unit

[0033] 7 - filtrate outlet unit

[0034] 8 - base of rigid polymer case.

[0035] Fig. 2 shows a horizontal section of the cover of a rigid polymer housing with a micro-relief surface of the inner part (turbulator).

[0036] Fig. 3 shows alternating height volumetric fragments of the micro-relief surface of the inner part of the cover of a rigid polymer housing (turbulator).

[0037] Fig. 4 shows individual volumetric fragments of the micro-relief surface of the inner part of the cover of the rigid polymer housing (turbulator), where

[0038] a - "high truncated pyramid"

[0039] b - "low truncated pyramid".

[0040] A specific implementation of the turbulator design can be illustrated by the following example.

[0041] The rigid polymer housing lid is made of polyurethane casting material using vacuum molding technology. The interior of the lid is microrelief-like, featuring repeating horizontal and vertical rows of alternating heights of solid-cast truncated quadrangular pyramids, symmetrically arranged along a common diagonal, with a cylindrical protrusion and a curved upper base. The calculation was based on a polymer semipermeable membrane area of ​​50 cm. 2 : the number of horizontal rows of "high truncated pyramids" per specified area was 144, vertical - 39; the number of horizontal rows of "low truncated pyramids" was 143, vertical - 38.

[0042] The “high truncated pyramid” had a square base measuring 0.71×0.71 mm, a height (excluding the cylindrical protrusion with a curved upper base) of 0.3 mm, a total height of the cylindrical protrusion of 0.1 mm, a diameter of the base of the cylindrical protrusion of 0.3 mm, and a radius of rounding of the curved upper base of 0.12 mm.

[0043] The “low truncated pyramid” had a square base measuring 0.71×0.71 mm, a height (excluding the cylindrical protrusion with a curved upper base) of 0.15 mm, a total height of the cylindrical protrusion of 0.05 mm, a diameter of the base of the cylindrical protrusion of 0.3 mm, and a radius of rounding of the curved upper base of 0.19 mm.

[0044] In the assembled filter element, the height of the “high truncated pyramids” (that is, the maximum height of the microrelief) corresponds to the height of the supramembrane space in such a way that the microrelief surface of the inner part of the cover of the rigid polymer housing comes into contact with the horizontal surface of the polymer semipermeable membrane through the cylindrical protrusions of the “high truncated pyramids” (in a specific design, the height of the supramembrane space corresponding to the actual height of the microrelief was 0.4 mm).

[0045] The claimed device operates as follows.

[0046] The liquid medium is supplied under pressure to the filter element through the liquid medium supply unit 1, located in the cover of the rigid polymer housing 2. The liquid medium, entering the space limited by the microrelief surface (turbulator) 3 of the cover of the rigid polymer housing 2, passes through the supramembrane space limited by the microrelief surface (turbulator) 3 and the polymer semi-permeable membrane 4, fixed by the gasket 5, penetrates through the polymer semi-permeable membrane 4, as a result of which the liquid medium is separated into a filtrate and a concentrate. The formed concentrate and filtrate are discharged through the concentrate outlet units 6 and filtrate 7, located in the cover 2 and the base 8 of the rigid polymer housing.

[0047] The recommended tangential flow rate is 40-60 ml / min: high tangential flow rate increases the mixing effect of the liquid medium in front of the polymer semipermeable membrane, which reduces the concentration gradient of the liquid medium at its surface.

[0048] The claimed device provides for cleaning the filter element after operation by rinsing the remains of the separated liquid medium using a buffer or already used filtrate.

[0049] The following materials and technologies can be used to implement the invention.

[0050] Polyurethane casting materials are used as the material of the rigid polymer housing.

[0051] Polyethersulfone membranes on a substrate, as well as membranes made of polysulfone, regenerated cellulose, and fluoroplastic can be used as semipermeable polymer membranes.

[0052] Organosilicon polymers are used as gasket material.

[0053] The undoubted advantage of the claimed filter element is the possibility of its effective use for concentrating and separating liquid media (proteins, peptides, nucleic acids, etc.) in small and medium quantities and its subsequent regeneration in the tangential filtration mode.

Claims

1. A filter element for separating and concentrating liquid media, consisting of a polymer semi-permeable membrane placed between gaskets placed in a rigid polymer housing consisting of a cover and a base equipped with units for feeding a liquid medium, removing concentrate and filtrate in the form of through holes, characterized in that the inner part of the cover of the rigid polymer housing is made microrelief in the form of repeating horizontal and vertical rows of volumetric fragments alternating in height, symmetrically located along a common diagonal, each of the volumetric fragments is made in the form of a solid-cast truncated quadrangular pyramid with a cylindrical protrusion with a curved upper base, wherein the height of the volumetric fragments with a maximum height corresponds to the height of the supramembrane space, and the number of volumetric fragments is from 180 to 220 per 1 cm 2 polymer semipermeable membrane.

2. A filter element for separating and concentrating liquid media according to paragraph 1, characterized in that the ratio of the heights of alternating volumetric fragments, each of which is made in the form of a solid cast truncated quadrangular pyramid with a cylindrical protrusion with a curved upper base, is 2:1.

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