CN114502262A

CN114502262A - Membrane structure for a bioreactor

Info

Publication number: CN114502262A
Application number: CN202080055700.4A
Authority: CN
Inventors: 詹姆斯·约翰·坦纳; 里斯·拉克兰·埃迪; 罗恩·约翰·肯尼迪
Original assignee: Envirostream Solutions Pty Ltd
Current assignee: Envirostream Solutions Pty Ltd
Priority date: 2019-08-05
Filing date: 2020-07-20
Publication date: 2022-05-13
Also published as: AU2020326454A1; CN112320924A; WO2021022319A1

Abstract

A crimpable sheet membrane structure for use in a bioreactor comprising: a sealing membrane layer defined by two adjacently positioned breathable, waterproof sheet-like membranes sealingly coupled to one another at or near their respective edges, the membrane layer including a top end and a bottom end with two outwardly facing sheet membrane surfaces therebetween, wherein one or more internal air channels are defined between the top and bottom ends of the membrane layer; the support layer is operatively coupled to one of the two sheet membrane surfaces, the support layer comprising a plurality of elongate resilient ribs arranged in a lattice configuration relative to the sheet membrane surface between top and bottom ends of the support layer so as to define one or more fluid permeable channels therebetween, wherein the sheet membrane surface is configured to retain a biofilm in an aqueous solution in use.

Description

Membrane structure for a bioreactor

Technical Field

The present invention relates to a sheet-like membrane structure, and more particularly, to a module of a crimpable membrane structure for supporting a biofilm to treat wastewater in a bioreactor.

Background

Conventional wastewater treatment plants use an activated sludge process based on biological oxidation of organic materials. Such systems require extensive use of aerators and large treatment tanks, resulting in high costs. Other bio-oxidation processes utilize the growth of a biofilm on a solid medium or membrane, wherein a gas permeable membrane divides the treatment tank into a liquid compartment and a gas compartment, wherein the biofilm is grown on the liquid side of the membrane. In such a process, oxygen is provided to the biofilm through the gas permeable membrane. Disadvantages of existing membrane-based wastewater treatment plants include bio-fouling due to high biofilm growth density, or inefficient operation if the biofilms are spaced too far apart.

The applicant has determined that it would be advantageous to provide a sheet-like membrane structure module for a bioreactor having improved operating efficiency. The present invention seeks in its preferred embodiments to at least partially alleviate the above problems.

Disclosure of Invention

According to one aspect of the present invention there is provided a crimpable sheet membrane structure for a bioreactor comprising: a sealing membrane layer and a support layer; the sealed film layer is defined by two adjacently positioned breathable, waterproof sheet-like films sealingly coupled to one another at or near their respective edges, the film layer including a top end and a bottom end with two outwardly facing sheet-like film surfaces positioned therebetween, wherein one or more internal air channels are defined between the top and bottom ends of the film layer; the support layer is operatively coupled to one of the two sheet membrane surfaces, the support layer comprising a plurality of elongate resilient ribs arranged in a lattice configuration relative to the sheet membrane surface between top and bottom ends of the support layer so as to define one or more fluid permeable channels therebetween, wherein the sheet membrane surface is configured to retain a biofilm in an aqueous solution in use.

Preferably, the sealing membrane layer includes a plurality of resilient support walls extending between adjacent membranes within the layer to maintain air flow channels within the one or more air channels.

Preferably, the plurality of resilient support walls define corrugations forming individual airflow channels within one or more air channels.

Preferably, the sheet-like membrane surface is pre-impregnated with a biofilm material.

Preferably, the sheet membrane surface is configured with a fibrous texture to increase the available surface area for biofilm growth. Preferably, the fibrous texture is formed by a thermal adhesive layer of non-woven polypropylene.

Preferably, the support layer is thermally or adhesively coupled to the sheet-like film surface of the sealing film layer.

Preferably, the plurality of elongate resilient ribs are arranged in a diagonal lattice configuration relative to the sheet membrane surface.

Preferably, the plurality of elongate resilient ribs are arranged in at least two successive layers. Alternatively, the resilient ribs are arranged in three consecutive layers.

Preferably, each of the elongated resilient ribs is configured to have a thickness of about 4 millimeters to about 10 millimeters.

Preferably, the support layer has a lateral width of about 6 mm when viewed from the top or bottom end of the support layer.

Preferably, the two adjacently positioned breathable, waterproof sheet-like membranes are sealingly coupled by ultrasonic or adhesive bonding.

Preferably, the sheet-like membrane is made of expanded Polytetrafluoroethylene (PTFE) or polypropylene material.

Preferably, the plurality of elongate resilient ribs is made of a polypropylene or polyethylene material.

According to another aspect of the present invention there is provided a bioreactor for treating wastewater, the bioreactor comprising a tank for containing wastewater and a roll of sheet like membrane structure as described.

Preferably, the sheet-like film structure is arranged as a roll in a can such that substantially each support layer of the film structure is at least partially in contact with any adjacent sealing film layer on each opposite side.

Preferably, the sheet-like film structure is arranged as a rolled column in the can, such that substantially each sealing film layer of the film structure is at least partially in contact with any adjacent supporting layer on each opposite side.

According to another aspect of the present invention, there is provided a method of treating wastewater in a bioreactor, comprising the steps of: (a) providing a bioreactor tank and providing a roll of said sheet-like membrane structure therein, wherein said sheet-like membrane structure is arranged in a roll column, each sheet layer of the roll being at least partially in contact with its adjacent sheet layer; (b) flowing wastewater into a bioreactor tank, wherein the wastewater flows through fluid permeable channels of a support layer of a sheet membrane structure; (c) an oxygen-containing gas is flowed into the bioreactor tank, wherein the gas flows through the internal air channel of the sealing membrane layer.

Drawings

The invention will now be described, by way of non-limiting example only, with reference to the accompanying drawings, in which:

FIG. 1 is a schematic cross-sectional view of a crimpable sheet film structure of indeterminate length in accordance with a preferred embodiment of the present invention;

FIG. 2 is a schematic cross-sectional view of a crimpable sheet film structure according to an alternative embodiment of the present invention;

fig. 3 is a schematic cross-sectional view of two adjacently disposed portions of the crimpable sheet membrane of fig. 1 in use.

Fig. 4 is a schematic cross-sectional view of two adjacently disposed portions of the crimpable sheet membrane of fig. 2 in use.

Fig. 5 is a schematic cross-sectional view of three adjacently disposed portions of the crimpable sheet membrane of fig. 1 in use.

Fig. 6 is a schematic cross-sectional view of three adjacently disposed portions of the crimpable sheet membrane of fig. 2 in use.

FIG. 7 is a schematic perspective view of a bioreactor tank and a roll of sheet membrane structures according to a preferred embodiment of the present invention;

FIG. 8 is a close-up schematic view of a roll of sheet-like membrane structures when installed within a bioreactor tank as shown in FIG. 7; and

fig. 9 is a photograph showing a cross section of a roll of sheet-like film structure according to a preferred embodiment of the present invention.

It should be understood that the schematic diagrams are provided for illustrative purposes only and are not drawn to scale.

Detailed Description

Preferred embodiments of the present invention relate to a sheet-like membrane structure, a bioreactor and a method of treating wastewater in a bioreactor. Referring to the cross-sectional view of the sheet-like film structure 10 as shown in fig. 1, the sheet-like film structure 10 includes a combination of a sealing film layer 20 and an adjacently positioned support layer 30. The sheet-like film structure 10 is referred to as a "structure" because it is constructed using two separate layers, and "rollable" because the film structure 10 is constructed to be sufficiently flexible to allow the film structure 10 to be rolled into a cylindrical shape, wherein portions of the film structure 10 are folded in layers over adjacent film structures 10. The double-layer construction of the membrane structure 10 advantageously provides separate channels for gas and liquid flow, as will be discussed in detail below. It should be understood that the rollable film structure 10 can be manufactured according to any suitable length and/or width, and their length is shown schematically as indeterminate.

The sealing film layer 20 includes two sheets of film 22, 24 aligned and sealingly coupled adjacent to each other at or near their respective edges. In particular, the sheet-like films 22, 24 are sealingly coupled by any suitable means, wherein the sheet-like surfaces of the films 22, 24 face each other, wherein non-limiting examples include thermal bonding, chemical bonding, and mechanical fastening, such that the cavity defined between the sealed sheet-like films 22, 24 is substantially sealed against any liquid intake. The sheet-like films 22, 24 are configured such that each film has properties of being air-permeable and liquid-impermeable (and in some configurations, waterproof). The sheet-like membranes 22, 24 can be constructed of suitable materials including expanded polytetrafluoroethylene or polypropylene materials.

In use, the film 20 is arranged upright, i.e. the transverse width of the film 20 is oriented vertically, and the length of the film 20 is rolled about a vertical axis to form a rolled column. In this configuration, the film layer 20 has a top end that is substantially at or near the top side of the roll column and a bottom end that is substantially at or near the bottom side of the roll column. Thus, it can be said that the film layer 20 includes a top end and a bottom end with the outwardly facing sheet film surfaces of the sheet films 22, 24 therebetween. The sealed chamber defined by the sheet-like membranes 22, 24 allows gas to move freely through the membranes 22, 24 and into the chamber, and out of the chamber through the membranes 22, 24, thereby forming an air passage for the flow of gas. It should be appreciated that gas is able to freely move between the top and bottom ends of the film layer 20 and between the cavity and its external environment through the gas permeable membranes 22, 24.

In one embodiment, the sealing membrane layer 20 is further provided with structural elements 26 to keep the sheet-like membranes 22, 24 spaced apart, thereby preventing the membranes 22, 24 from collapsing on themselves and causing the air flow passages within the air passages to close. Resilient support walls may be provided on the inside of the sealing membrane layer 20 to extend between adjacent sheet membranes 22, 24 within the cavity to maintain a consistent air flow path. In some configurations, the structural elements 26 are provided in the form of corrugations that define substantially discrete airflow channels 28 of the sealing membrane layer 20 during use. The structural element 26 can be made of any suitable resilient material including polypropylene or polyethylene materials.

In a preferred embodiment, the outwardly facing surfaces of the sheet-like membranes 22, 24 are provided with a fibrous texture to increase the available surface area for biofilm 25 growth. In one configuration, a thin layer of nonwoven polypropylene fibers is thermally bonded to one or both of the outwardly facing surfaces of the sheet-form films 22, 24. The rough, fibrous textured surface of the membranes 22, 24 provides a means for the biofilm 25 and organics to adhere to the membranes 22, 24 when adjacent fluid permeation channels, as will be described in detail below.

The support layer 30 is constructed as a lattice having openings 38 that form channels therethrough to facilitate the flow of fluid into and out of the lattice. The term "fluid" or "fluids" in the context of the present invention is used to denote liquid fluids, non-limiting examples of which include water, wastewater, chemical treatment solutions, and sludge. Referring to fig. 1, a support layer 30 is disposed adjacent to one of the two outwardly facing sheet membrane surfaces 27. In a preferred embodiment, the support layer 30 includes a plurality of elongated resilient ribs 36 arranged in a lattice configuration 32 relative to the sheet membrane surface 27. In one configuration, the elongated elastic ribs 36 and/or the lattice 32 are operatively coupled to the sheet membrane surface 27 using any suitable coupling method, such as thermal bonding, chemical bonding, and mechanical fastening. In a preferred embodiment, each of the elongated resilient ribs is configured to have a thickness of about 4 millimeters to about 10 millimeters, although other thickness dimensions may be suitable depending on the dimensional configuration of a given bioreactor device design. In one construction, the elongated resilient ribs 36 are made of a polypropylene or polyethylene material, although other suitable materials may be used.

The support layer 30 can be sized to match the size of the sheet films 22, 24 such that the combination of the sealing film layer 20 and the support layer 30 forms a unified sheet film structure that can be configured in a rolled form. Specifically, the lateral width of the support layer 30 substantially corresponds to the lateral width of the sealing film layer 20, and the longitudinal lengths of the support layer 30 and the sealing film layer 20 are substantially the same. Further, when coupled to the sealing membrane layer 20 and oriented with its longitudinal length arranged horizontally, the support layer 30 has top and bottom ends with a lattice 32 positioned therebetween. The top ends of the support layers 30 are positioned adjacent to the respective top ends of the sealing film layer 20, and the bottom ends of the support layers are positioned adjacent to the respective bottom ends of the sealing film layer 20. It can be said that the grooves and cavities formed by the openings through the lattice structures 32 define fluid permeable channels between the top and bottom ends of the support layer 30. It will be appreciated that fluid is able to move freely between the top and bottom ends of the support layers 20 and between the cavities and openings of the lattice 32 and its external environment.

In one embodiment, the support layer 30 includes a regular pattern of openings 38 and apertures formed by the lattice-like structure 32. The elongated resilient ribs 36 may form a lattice 32 having longitudinal side ribs 34 and bridging ribs 36. Referring to fig. 2, the support layer 30 includes adjacent layers of longitudinal side ribs 34 connected by transverse bridging ribs 36 extending therebetween. In one configuration, the bridging ribs 36 are rooted in corresponding grooves located along the side ribs 34. The elongated

resilient ribs

34, 36 of the support layer 30 can be joined together by any suitable means including thermal bonding, chemical bonding, and mechanical fastening.

The membrane surface 27 facing the support layer 30 is adapted to carry a biofilm 25 to facilitate biological oxidation and processing and treatment of wastewater and similar liquids. As previously described, biofilm 25 attached to and/or growing on the membrane surface 27 is provided with oxygen from the gas flow through the sealing membrane layer 20 via the membrane surface 27 and is simultaneously exposed to the fluid flow through the support layer 30. This arrangement promotes optimal biofilm growth on the membrane surface 27. It will be appreciated that the support layer 30 and its resilient ribs 36 serve as spacing members to prevent collapse of adjacent membrane layers attached to or on the membrane surface 27 of a biofilm 25 growing thereon and to accommodate sufficient fluid flow through the fluid permeable channels 38 between the top and bottom ends of the support layer 30, preferably without causing blockage or clogging of the fluid permeable channels 38. In a preferred embodiment, the support layer 30 has a lateral width of substantially about 6 millimeters when viewed from the top end. It should be understood that in other embodiments, the support layer 30 may be configured to have different dimensions depending on the particular factory design or requirements.

Reference is now made to fig. 3 and 4, which illustrate adjacent layers of the membrane structure 10, in accordance with preferred and alternative embodiments. As shown in fig. 3, a similar second film structure 10B underlies the first film structure 10A, wherein the support layer 30 of the first film structure 10A at least partially contacts or abuts the adjacently positioned sealing film layer 20 of the second film structure 10B. Effectively, the support layer 30 of the first membrane structure 10A provides a spacing structure between the sealing membrane layers 20 of the first membrane structure 10A and the sealing membrane layers 20 of the second membrane structure 10B to prevent adjacently disposed sealing membrane layers 20 from collapsing against each other and to provide sufficient fluid permeable channels therebetween. When deployed for use in a vertical curl, the

adjacent membrane structures

10A, 10B are preferably arranged in layers as described above.

The layered arrangement described above with reference to fig. 3 and 4 is similarly applied and illustrated in fig. 5 and 6, wherein three film structure layers are generally arranged adjacent to each other when the film structure 10 is in a rolled form with overlapping adjacent film structure layers. In this arrangement, the membrane structure layers at least partially join their adjacent similar membrane structure layers, and the membrane structures 10 in this form alternate between sealing membrane layer 20 and support layer 30, which also means that air channels and fluid-permeable channels are alternately provided on cross-sectional layers of a rolled or layered arrangement of membrane structures according to the invention. Similarly, fig. 9 shows photographs in alternating layers of the sheet film structure 10 when arranged in a rolled form. It will be appreciated that the membrane surface 27 facing the support layer 30 and thus exposed to the fluid permeable channels is ideal for locating the biofilm 25. In a preferred embodiment, each membrane surface 27 of the sealing membrane layer 20 adjacent to the support layer 30 is configured to hold a biofilm 25.

The biofilm 25 can be introduced into the membrane structure 10 by a variety of carriers, non-limiting examples of which include the natural proliferation of bio-oxidising substances from substances already present in the treatment fluid such as wastewater and sludge, or pre-impregnation of the membrane surface 27 with a suitable biofilm substance. Details of biofilm material are well known in the art and will not be described in further detail herein.

According to a preferred embodiment of the present invention, bioreactor 50 includes a bioreactor tank 52, as shown in fig. 7 and 8, within which is positioned a sheet-like membrane structure 10 in a vertically oriented rolled form. Fig. 8 provides a close-up view of the top end portion of the roll of film structure 10. In one embodiment, bioreactor tank 52 is provided with a cylindrical core 54 defining an opening 56 and attachment points for crimpable sheet membrane structure 10. In use, oxygen is provided in the tank 52 through the sealing membrane layer 20 of the sheet membrane structure 10 and wastewater flows through the fluid permeable channels defined by the support layer 30 of the sheet membrane structure 10. Advantageously, in this alternating arrangement of sealing film layer 20 and support layer 30, the surface area and therefore the density for the growth of the biofilm 25 is optimized, while reducing the occurrence of biological contamination. Thus, a bioreactor 50 embodying the membrane structure 10 of the present invention may provide improved biological treatment efficiency when treating wastewater.

In the description of the present embodiment and the drawings, the same reference numerals as already used in the first embodiment are used to denote and designate corresponding features.

While various embodiments of the present invention have been described above, it should be understood that they have been presented by way of example only, and not limitation. It will be apparent to persons skilled in the relevant art that various changes in form and detail can be made therein without departing from the spirit and scope of the invention. Thus, the present invention should not be limited by any of the above-described exemplary embodiments.

Throughout this specification and the claims which follow, unless the context requires otherwise, the word "comprise", and variations such as "comprises" and "comprising", will be understood to imply the inclusion of a stated integer or step or group of integers or steps but not the exclusion of any other integer or step or group of integers or steps.

Claims

1. A crimpable sheet membrane structure for use in a bioreactor comprising:

a sealed membrane layer defined by two adjacently positioned breathable, waterproof sheet-like membranes sealingly coupled to one another at or near their respective edges, the membrane layer including a top end and a bottom end with two outwardly facing sheet-like membrane surfaces therebetween, wherein one or more internal air channels are defined between the top and bottom ends of the membrane layer; and

a support layer operatively coupled to one of the two sheet membrane surfaces, the support layer comprising a plurality of elongated resilient ribs arranged in a lattice configuration relative to the sheet membrane surface between top and bottom ends of the support layer so as to define one or more fluid permeable channels therebetween,

wherein the sheet membrane surface is configured to retain a biofilm in an aqueous solution in use.

2. The membrane structure of claim 1, wherein the sealing membrane layer includes a plurality of resilient support walls extending between adjacent membranes inside the layer to maintain airflow channels within one or more air channels.

3. The membrane structure of claim 2, wherein the plurality of resilient support walls define corrugations that form individual air flow channels within the one or more air channels.

4. A membrane structure according to any one of the preceding claims, wherein the sheet-like membrane surface is pre-impregnated with a biofilm material.

5. The membrane structure according to any one of the preceding claims, wherein the sheet-like membrane surface is configured with a fibrous texture to increase the available surface area for biofilm growth.

6. The film structure of claim 5, wherein the fibrous texture is formed by a thermal adhesive layer of nonwoven polypropylene.

7. The film structure of any one of the preceding claims, wherein the support layer is thermally or adhesively coupled to the sheet-like film surface of the sealing film layer.

8. The membrane structure of any preceding claim, wherein the plurality of elongate elastic ribs are arranged in a diagonal lattice configuration relative to the sheet-like membrane surface.

9. The film structure of any one of the preceding claims, wherein the plurality of elongated resilient ribs are arranged in at least two consecutive layers.

10. The film structure of claim 9, wherein the plurality of elongated resilient ribs are arranged in three consecutive layers.

11. The film structure of any preceding claim, wherein each of the elongate resilient ribs is configured to have a thickness of about 4 mm to about 10 mm.

12. The membrane structure of any one of the preceding claims, wherein the support layer has a transverse width of about 6 millimeters when viewed from a top end or a bottom end of the support layer.

13. The membrane structure according to any one of the preceding claims, wherein said two adjacently positioned breathable, waterproof sheet-like membranes are sealingly coupled by ultrasonic or adhesive bonding.

14. A membrane structure according to any one of the preceding claims, wherein the sheet-like membrane is made of expanded Polytetrafluoroethylene (PTFE) or polypropylene material.

15. The film structure of any preceding claim, wherein the plurality of elongate resilient ribs are made of a polypropylene or polyethylene material.

16. A bioreactor for treating wastewater comprising a tank for containing wastewater and a roll of sheet-like membrane structures according to any one of claims 1 to 15.

17. The bioreactor of claim 16, wherein the sheet-like membrane structure is arranged as a rolled column in the tank such that substantially each support layer of the membrane structure is at least partially in contact with any adjacent sealing membrane layer on each opposing side.

18. A bioreactor according to claim 16 or 17, wherein the sheet-like membrane structure is arranged as a rolled column in the tank such that substantially each sealing membrane layer of the membrane structure is at least partially in contact with any adjacent support layer on each opposing side.

19. A method of treating wastewater in a bioreactor comprising the steps of:

(a) providing a bioreactor tank and providing therein a roll of a sheet-like membrane structure according to any one of claims 1 to 15, wherein the sheet-like membrane structure is arranged as a roll column, each sheet-like layer of the roll being at least partially in contact with its adjacent sheet-like layer;

(b) flowing wastewater into the bioreactor tank, wherein the wastewater flows through the fluid permeable channels of the support layer of the sheet membrane structure; and

(c) flowing an oxygen-containing gas into the bioreactor tank, wherein the gas flows through the internal air channel of the sealing membrane layer.