A membrane, module, system and method for mabr
Patent Information
- Authority / Receiving Office
- WO · WO
- Patent Type
- Applications
- Current Assignee / Owner
- FLUENCE WATER PROD & INNOVATION LTD
- Filing Date
- 2026-01-29
- Publication Date
- 2026-08-06
Smart Images
Figure IL2026050093_06082026_PF_FP_ABST
Abstract
Description
[0001] A MEMBRANE, MODULE, SYSTEM AND METHOD FOR MABR
[0002] TECHNOLOGICAL FIELD
[0003] The presently disclosed subject matter relates to MABR membranes, modules, systems, and methods for wastewater treatment.
[0004] BACKGROUND ART
[0005] References considered to be relevant as background to the presently disclosed subject matter are listed below:
[0006] International Patent Application Publication No. WOOl / 66474 International Patent Application Publication No. W016 / 038606 Acknowledgement of the above references herein is not to be inferred as meaning that these are in any way relevant to the patentability of the presently disclosed subject matter.
[0007] BACKGROUND
[0008] Membrane aerated biofilm reactors have emerged as a wastewater treatment technology providing advantages such as lower energy consumption than conventional aeration.
[0009] WOOl / 66474 describes an apparatus to transfer gas to or from a liquid, the apparatus having a flexible and oxygen permeable but liquid water impermeable membrane, a flexible and gas permeable spacer, an inlet conduit, an outlet conduit and a non-rigid restraint system. When used for treating wastewater, an aerobic biofilm is cultured adjacent the planar elements, an anoxic biofilm is cultivated adjacent the aerobic biofilm and the wastewater is maintained in an anaerobic state. WOOl / 66474 also describes a reactor for treating wastewater that has an anaerobic section, a plurality ofgas transfer membrane modules, and an aerobic section. Biofilm is cultivated on the surface of the gas transfer membranes in fluid communication with the anaerobic section.
[0010] W016 / 038606 describes a water treatment module, a bioreactor and system comprising one or more of such modules. The water treatment module comprises, inter alia, at least one elongated gas enclosure comprising a gas inlet and two vertical walls, at least one vertical wall comprising a water-impermeable and gas-permeable membrane having a water-facing side and a gas- facing side, the two vertical walls separating between water external to the enclosure and gas within the enclosure, the gas enclosure being in a rolled or folded configuration to thereby define a convoluted horizontal path and one or more water- treatment spaces formed between opposite water facing sides of the enclosure; and in some cases, one or more first spacer elements configured to maintain a minimal distance between the vertical walls, and one or more second spacer elements disposed within the one or more water treatment spaces to maintain a second minimal distance between the opposite water-facing sides. The spacers can be in the form of abutments integrally formed as part of the vertical walls.
[0011] GENERAL DESCRIPTION
[0012] The presently disclosed subject matter relates to Membrane Aerated Biofilm Reactors (MABR) membranes, modules, systems, and methods for wastewater treatment, having improved energy efficiency as well as efficient maintenance of the membranes.
[0013] There is provided, according to a first aspect of the presently disclosed subject matter, an MABR membrane comprising: an envelope comprising two opposing side walls at least indirectly joined together along a perimeter to define therebetween an internal gas space, the side walls comprising a water-impermeable and gas-permeable material; at least one gas inlet configured to allow supply of gas into the internal gas space; at least one gas outlet configured to allow discharge of gas from the internal gas space; and a plurality of inter-wall connections between the two opposing side walls that define a gas-flow pathway within the internal gas space from the at least one gas inlet to the at least one gas outlet.
[0014] There is provided, according to a second aspect of the presently disclosed subject matter, an MABR module comprising: a module frame; and a plurality of MABR membranes arranged in parallel to each other, each membrane including: an envelope comprising two opposing side walls at least indirectly joined together along a perimeter to define therebetween an internal gas space, the side walls comprising a water-impermeable and gas-permeable membrane; at least one gas inlet configured to allow supply of gas into the internal gas space; at least one gas outlet configured to allow discharge of gas from the internal gas space; and a plurality of inter-wall connections between the two opposing side walls that define a gas-flow pathway within the internal gas space from the at least one gas inlet to the at least one gas outlet, said plurality of inter-wall connections being arranged in a plurality of straight or curved lines, each line comprising one or more inter-wall connections spaced from each other, and each line being spaced from a neighboring line; wherein the lines on each membrane of the plurality of membranes extend in a direction different from the lines on a neighboring membrane.
[0015] There is provided, according to a third aspect of the presently disclosed subject matter, an MABR system for water treatment, said MABR system comprising including at least one tank having one or more MABR modules positioned therein, each MABR module comprising: a plurality of MABR membranes arranged parallelly to each other, each membrane including: an envelope comprising two opposing side walls at least indirectly joined together along a perimeter to define therebetween an internal gas space, the side walls comprising a water-impermeable and gas-permeable membrane; at least one gas inlet configured to allow supply of gas into the internal gas space; at least one gas outlet configured to allow discharge of gas from the internal gas space; and a plurality of interwall connections between the two opposing side walls that define a gas-flow pathway within the internal gas space from the at least one gas inlet to the at least one gas outlet, said plurality of inter-wall connections being arranged in a plurality of straight or curvedlines, each line comprising one or more inter-wall connections spaced from each other, and each line being spaced from a neighboring line; wherein the lines on each membrane of the plurality of membranes extend in a direction different from the lines on a neighboring membrane.
[0016] There is provided, according to a fourth aspect of the presently disclosed subject matter, a method for water treatment, including: feeding water to be treated into an MABR tank via a tank water inlet; submerging one or more MABR membranes in the water to be treated in the MABR tank; supplying a gas into the one or more MABR membranes, via respective gas inlets; allowing the gas to be discharged into the water from the membranes via respective outlets; and controlling at least one parameter of the supply of the gas into the membranes; and allowing the treated water to flow out of the MABR tank via tank water outlet.
[0017] LIST OF EMBODIMENTS
[0018] The embodiments listed below are disclosed both individually and in any technically feasible combination. Unless expressly stated otherwise, any feature, element, or limitation described in connection with one embodiment may be combined with any feature, element, or limitation described in connection with any other embodiment, including across different embodiment groups (membrane, module, system, and method), provided that such combination is not clearly incompatible and is directly and unambiguously derivable from the application as filed.
[0019] In particular, features described in connection with the MABR membrane embodiments may be applied to the MABR module, system, and method embodiments, and vice versa, insofar as such application is technically meaningful.
[0020] References to embodiments being "dependent at least indirectly" are intended to indicate dependency on any one or more preceding embodiments, whether directly or via intermediate embodiments.
[0021] 1. An MABR membrane comprising:an envelope comprising two opposing side walls at least indirectly joined together along a perimeter to define therebetween an internal gas space, the side walls comprising a water-impermeable and gas-permeable material;
[0022] at least one gas inlet configured to allow supply of gas into the internal gas space;
[0023] at least one gas outlet configured to allow discharge of gas from the internal gas space; and
[0024] a plurality of inter-wall connections between the two opposing side walls that define a gas-flow pathway within the internal gas space from the at least one gas inlet to the at least one gas outlet.
[0025] 2. The MABR membrane of embodiment 1, wherein the inter-wall connections attach internal surfaces of the sidewalls to each other.
[0026] 3. The MABR membrane of embodiment 1 or 2, wherein the at least one gas inlet and the at least one gas outlet are located on opposite regions of the perimeter.
[0027] 4. The MABR membrane of any one of embodiments 1 to 3, comprising a plurality of the at least one gas outlet located on the perimeter of the membrane, on opposite region to the at least one gas inlet.
[0028] 5. The MABR membrane of any one of embodiments 1 to 4, wherein the inter-wall connections are in a form of dots or dashes.
[0029] 6. The MABR membrane of any one of embodiments 1 to 5, wherein the plurality of inter-wall connections are arranged in a pattern.
[0030] 7. The MABR membrane of any one of embodiments 1 to 6, wherein the plurality of inter-wall connections are arranged in one or more straight or curved lines.
[0031] 8. The MABR membrane of any one of embodiments 1 to 7, wherein the plurality of inter-wall connections are arranged in a plurality of straight or curved lines, each line comprising one or more inter-wall connections spaced from each other, and each line being spaced from a neighboring line.9. The MABR membrane of embodiment 8, wherein spaces between the inter-wall connections of one line are smaller than the space between adjacent lines.
[0032] 10. The MABR membrane of embodiment 8 or 9, wherein the spaces between the neighboring dots or dashes along a line of the plurality of lines increases in a direction along the gas-flow pathway from the at least one gas inlet to the at least one gas outlet.
[0033] 11. The MABR membrane of any one of embodiments 8 to 10, wherein the inter-wall connections are arranged in a plurality of lines extending across at least a portion of the side walls.
[0034] 12. The MABR membrane of embodiment 11, wherein one or more of the lines are diagonal lines extending across the side walls.
[0035] 13. The MABR membrane of any one of embodiments 1 to 12, wherein the inter-wall connections include at least one of gluing and welding the side walls to each other. 14. The MABR membrane of any one of embodiments 1 to 13, wherein the MABR membrane is formed as a spirally wound membrane having a plurality of wraps around a central axis.
[0036] 15. The MABR membrane of embodiment 14, when dependent at least indirectly on embodiment 8, wherein the lines on each wrap of the plurality of wraps extend in a direction different from the lines on a neighboring wrap.
[0037] 16. An MABR module comprising:
[0038] a module frame; and
[0039] a plurality of MABR membranes arranged in parallel to each other, each membrane including:
[0040] an envelope comprising two opposing side walls at least indirectly joined together along a perimeter to define therebetween an internal gas space, the side walls comprising a water-impermeable and gas-permeable membrane;at least one gas inlet configured to allow supply of gas into the internal gas space;
[0041] at least one gas outlet configured to allow discharge of gas from the internal gas space; and
[0042] a plurality of inter-wall connections between the two opposing side walls that define a gas-flow pathway within the internal gas space from the at least one gas inlet to the at least one gas outlet, said plurality of inter-wall connections being arranged in a plurality of straight or curved lines, each line comprising one or more inter-wall connections spaced from each other, and each line being spaced from a neighboring line;
[0043] wherein the lines on each membrane of the plurality of membranes extend in a direction different from the lines on a neighboring membrane.
[0044] 17. The MABR module of embodiment 16, wherein the lines on each pair of neighboring membranes are transverse each other.
[0045] 18. The MABR module of embodiment 16 or 17, wherein each pair of neighboring membranes defines free passage of water therebetween.
[0046] 19. The MABR module of embodiment 18, wherein the free passage of water between the membranes extend at least partially along the lines of the inter-wall connections. 20. The MABR module of any one of embodiments 16 to 19, wherein at least one of the plurality of MABR membranes is the MABR membrane according to any one of embodiments 1 to 15.
[0047] 21. The MABR module of any one of embodiments 16 to 20, wherein the plurality of membranes are fixed to the module frame by a fixing arrangement.
[0048] 22. The MABR module of any one of embodiments 16 to 21, wherein the at least one gas inlet is positioned at a top portion of the module, and the at least one gas outlet is positioned at a bottom portion of the module.23. An MABR system for water treatment, said MABR system comprising including at least one tank having one or more MABR modules positioned therein, each MABR module comprising:
[0049] a plurality of MABR membranes arranged pa ra I lei ly to each other, each membrane including:
[0050] an envelope comprising two opposing side walls at least indirectly joined together along a perimeter to define therebetween an internal gas space, the side walls comprising a water-impermeable and gas-permeable membrane;
[0051] at least one gas inlet configured to allow supply of gas into the internal gas space;
[0052] at least one gas outlet configured to allow discharge of gas from the internal gas space; and
[0053] a plurality of inter-wall connections between the two opposing side walls that define a gas-flow pathway within the internal gas space from the at least one gas inlet to the at least one gas outlet, said plurality of inter-wall connections being arranged in a plurality of straight or curved lines, each line comprising one or more inter-wall connections spaced from each other, and each line being spaced from a neighboring line;
[0054] wherein the lines on each membrane of the plurality of membranes extend in a direction different from the lines on a neighboring membrane.
[0055] 24. The MABR system of embodiment 23, wherein the tank comprises a tank water inlet for receiving therethrough water to be treated into the tank.
[0056] 25. The MABR system of embodiment 24, wherein the at least one gas outlet is directly or indirectly in fluid communication with the water in the tank.
[0057] 26. The MABR system of any one of embodiments 23 to 25, wherein the at least one gas outlet is in fluid communication with atmosphere above the water in the tank.27. The MABR system of any one of embodiments 23 to 26, wherein, at least when in use, the at least one gas inlet is on top and the at least one gas outlet is on bottom of the respective membrane.
[0058] 28. The MABR system of any one of embodiments 23 to 27, further comprising at least one gas flow source in fluid communication with the at least one gas inlet.
[0059] 29. The MABR system of any one of embodiments 23 to 28, further comprising a controller to control one or more operations of the MABR system.
[0060] 30. The MABR system of embodiment 29, when dependent on embodiment 28, wherein the controller is configured to control at least one parameter of gas flowthrough the membrane.
[0061] 31. The MABR system of embodiment 30 wherein the at least one parameter comprises one or more of flow rate and pressure of the gas.
[0062] 32. A method for water treatment, including:
[0063] feeding water to be treated into an MABR tank via a tank water inlet; submerging one or more MABR membranes in the water to be treated in the MABR tank;
[0064] supplying a gas into the one or more MABR membranes, via respective gas inlets;
[0065] allowing the gas to be discharged into the water from the membranes via respective outlets; and
[0066] controlling at least one parameter of the supply of the gas into the membranes; and
[0067] allowing the treated water to flow out of the MABR tank via tank water outlet.
[0068] 33. The method of embodiment 32, wherein said controlling at least one parameter of the supply of the gas comprises providing the supply of gas via the gas inletsintermittently, and correspondingly allowing the discharge of gas via the gas outlets intermittently.
[0069] 34. The method of embodiment 32 or 33, wherein said controlling at least one parameter of the supply of the gas comprises providing the supply of gas via the gas inlets periodically, and correspondingly allowing the discharge of gas via the gas outlets periodically.
[0070] 35. The method of any one of embodiments 32 to 34, wherein the at least one parameter one or more of pressure and flow rate of the gas being supplied to the membranes.
[0071] 36. The method of any one of embodiments 32 to 35, wherein said controlling at least one parameter of the supply of the gas comprises varying the at least one parameter of the supply of the gas intermittently.
[0072] 37. The method of embodiment 36, wherein said varying the at least one parameter comprises varying the flow rate of the gas being supplied to the membranes.
[0073] 38. The method of embodiment 37, wherein said varying the flow rate of the gas being supplied to the membranes comprises varying the flow rate between a first pattern and a second pattern.
[0074] 39. The method of embodiment 38, wherein the first pattern includes flow rate lower than flow rate of the second pattern.
[0075] 40. The method of embodiment 38 or 39, wherein the first pattern includes a duration of supply of gas which is longer than a duration of supply of gas in the second pattern.
[0076] 41. The method of embodiment 40, wherein the duration of supply of gas in the second pattern ranges between 10 seconds and 60 seconds.
[0077] 42. The method of any one of embodiments 32 to 41, further comprising intermittently supplying an additional gas to a diffuser arrangement located underneath the membranes.BRIEF DESCRIPTION OF THE DRAWINGS
[0078] In order to better understand the subject matter that is disclosed herein and to exemplify how it may be carried out in practice, embodiments will now be described, by way of non-limiting example only, with reference to the accompanying drawings, in which:
[0079] Fig. 1A illustrates a perspective view of an MABR membrane according to an example of the presently disclosed subject matter;
[0080] Fig. IB illustrates a perspective view of an MABR membrane according to another example of the presently disclosed subject matter;
[0081] Fig. 1C illustrates a perspective view of an MABR membrane according to yet another example of the presently disclosed subject matter;
[0082] Fig. ID illustrates a perspective view of an MABR membrane according to yet another example of the presently disclosed subject matter;
[0083] Fig. IE illustrates a perspective view of an MABR membrane formed as a spirally wound membrane according to an example of the presently disclosed subject matter;
[0084] Fig. 2A illustrates a perspective view of an MABR membrane according to an example of the presently disclosed subject matter;
[0085] Fig. 2B illustrates a pair of membranes of the MABR module of Fig. 2A; and
[0086] Fig. 3 illustrates a perspective view of an MABR system according to an example of the presently disclosed subject matter.
[0087] DETAILED DESCRIPTION
[0088] The presently disclosure subject matter relates generally to Membrane Aerated Biofilm Reactors (MABR) for wastewater treatment, and particularly to MABR membranes, MABR modules, MABR systems, and MABR methods for wastewater treatment. The MABR membranes (also referred to herein as membranes) provided herein can be formed as envelopes or sleeves to have an internal gas space (also referredto herein as internal volume or internal space) for allowing air or any oxygen containing gas (collectively referred to herein as gas) to be passed therethrough. The membranes, for example assembled as modules, are submerged in the wastewater treatment tank, thereby constituting an MABR system. It is to be understood herein that the gas provided to the membranes can be any oxygen containing gas for the purpose of biological wastewater treatment, and specifically for simultaneous nitrification and denitrification.
[0089] The MABR membranes provided herein are structured to allow free flow of air through the internal gas space, and free flow of water along spaces between the external surfaces of the adjacent membranes. In particular, the membranes are so structured that when two membranes are arranged adjacent each other, and the gas is passed through the membrane, the water outside the membrane gets a free flow path between the membranes.
[0090] In general, the membrane can be formed as elongated flat sheet or can be spirally wound around a core, in each case having an enclosure shaped as an envelope or sleeve defined for example by two opposing side walls. The opposing side walls can be at least indirectly joined together, for example, at the perimeter of the side walls to define therebetween an internal gas space. It is to be understood herein that the side walls being at least indirectly joined is intended to include within its scope that the side walls can be either directly joined together or indirectly joined via an intermediate layer joining each of the side walls. The joining of the side walls or the intermediate layer to the side walls can be achieved by any suitable joining material and / or process including, for example, gluing by any suitable adhesives and / or welding by any suitable welding technique. In some examples, the sidewalls can include an oxygen permeable and water impermeable material, such as silicone or alternatively a dense non-woven fabric coated with a thin layer of an oxygen permeable material such as an alkyl-acrylate.
[0091] The gas can be supplied into the internal space by one or more gas inlets provided for example at a region of the perimeter of the membrane, which region, when the membrane is in use, generally constitutes a top portion of the membrane. The gas can be discharged via one or more gas outlets provided at a region of the perimeter of themembrane which region is opposite to the region at which the gas inlet(s) is provided. The region at which the gas outlet(s) is provided, when the membrane is in use, generally constitutes a bottom portion of the membrane.
[0092] The gas inlet(s) and / or the gas outlet(s) can be formed as openings establishing fluid communication between an interior and an exterior of the membrane. In some examples, the openings can be formed as perforations along the perimeter of the membrane or adjacent the perimeter. In some examples, the perforations can be created by a porous layer welded or glued between membrane side walls. The porous layer can be a nonwoven fabric with suitable properties relating to its melting temperature, thickness, void volume, or other similar properties. In some examples, the openings can comprise means to prevent water inlet into the membrane, for example as flaps that function as non-return valves, or any other suitable structure.
[0093] The opposing side walls are attached to each other by a plurality of inter-wall connections along the side walls of the membrane. For the purposes of the present description, the attachments at the inter-wall connections are to be considered as being not merely contacts, and physical connections that keep the side walls in attachment at the inter-wall connections when the gas is passed through the internal gas space. The inter-wall connections can be achieved by any suitable connection means including gluing (hot or cold) by any suitable adhesive(s) and / or welding by any suitable welding technique including thermal and / or ultrasonic welding.
[0094] The inter-wall connections divide the internal gas space to define a gas-flow pathway within the internal gas space from the gas inlet(s) to the gas outlet(s), and accordingly distribute the gas flow within the internal gas space into multiple gas flows through the gaps or spaces between the inter-wall connections. In some examples, the gas-flow pathway is constituted by a plurality of air volumes created by, and between, the inter-wall connections fluidly connected to each other for allowing the gas to flow freely through the internal gas space from the gas inlet(s) to the gas outlet(s).In some examples, the inter-wall connections can be continuous elongated connections extending along the side walls. In some examples, the inter-wall connections can be in the form of discrete connections formed in any suitable shapes or forms including dots, dashes, ovals, circles, triangles, or any other polygonal (regular or irregular) shape, and all such shapes are generally and collectively referred to herein as dots or dashes. The inter-wall connections can be arranged in any pattern (random or structured) that allows formation of the gas-flow path in the form of directional channels through which the gas can flow through the internal gas space. In some examples, the inter-wall connections can be arranged to form lines extending across the sidewalls. It is to be understood herein that, for the purposes of the present description, the inter-wall connections being arranged in lines does not necessarily means straight lines and is intended to include within its scope that the inter-wall connections can be arranged in curved lines, straight lines, zig-zag lines, or any other formation that can generally be referred to as a line. All such formations of lines including straight, curved, zig-zag, and equivalents thereof, are being collectively referred to herein as lines or straight or curved lines.
[0095] The lines can be substantially parallel to each other, or in other words extend in same direction across the side walls. It is to be understood herein that, for the purposes of the present description, the term "parallel" or "substantially parallel" in the context of lines and / or membranes being parallel to each other is intended to include within its scope absolutely parallel, i.e., zero degree angle, as well as generally parallel with a tolerance angle of up to 10 degrees, up to 20 degrees between the lines and / or membranes. Accordingly, in some examples, the lines, and / or adjacent membranes can be arranged as being diverging away from or converging towards each other.
[0096] The gas-flow pathway, i.e., the region between the inter-wall connections gets inflated when the gas passes through the internal gas space, while the side walls remain attached to each other. Accordingly, the external surfaces of the side walls form into undulating, and in some examples tortuous as well, surfaces defining crests at the regions of the external surfaces corresponding to the gas-flow pathway and troughs at the regionsof the external surfaces corresponding to the inter-wall connections. The troughs define channels for free flow of water along the external surface of the membrane. It is to be understood herein that the inter-wall connections can be in proximity to, and even touching, the perimeter of the membrane such that the troughs or channels begin from the edge of the membrane.
[0097] Reference is now made to Figs. 1A and IB illustrating MABR membranes 100, according to two respective examples of the presently disclosed subject matter. It is to be understood herein that the membranes 100 of the examples of Figs. 1A and IB can include some or all features of the membranes described generally herein above, and the description thereof can apply analogously to corresponding features of the membranes 100 of Figs. 1A and IB. The membrane 100 includes side walls 102 and 104, each having a respective external surface 102A and 104A, and a respective internal surface (not shown) defining an internal gas space (internal volume of the membrane 100, not visible). The side walls 102 and 104 have respective perimeters 102P and 104P joined together to constitute a perimeter 100P of the membrane 100, and to define the internal gas space.
[0098] A gas inlet 106 is provided at a region of the perimeter 100P that, when the membrane 100 is assembled in a module and / or is in use, constitutes a top portion 100T of the membrane 100, and a gas outlet 108 (one gas outlet in the example of Fig. 1A and a plurality of gas outlets 108 in the example of Fig. IB) is provided at a region of the perimeter 100P that is opposite to the region at which the gas inlet 106 is provided and, when the membrane 100 is in use, constitutes a bottom portion 100B of the membrane 100. It is to be understood herein that the membranes 100 of examples of Figs. 1A and IB are similar with the only difference being the number of gas outlets. Accordingly, all of the description provided herein with respect to Figs. 1A and / or Fig. IB can apply to examples of any or both of the Figs. 1A and IB.
[0099] The side walls 102 and 104 are attached to each other at plurality of inter-wall connections 110, which in the illustrated example are formed as dashes 110 and arranged in lines 112 extending diagonally across the side walls 102 and 104. The inter-wall connections 110 define therebetween a gas flow pathway generally depicted by arrowsFP in Fig. IB in the interior gas space of the membrane. It is to be understood herein that only two arrows FP have been shown for the purposes of conciseness and clarity, and the gas flow pathway can be constituted by all such paths existing through the spaces between the inter-wall connections.
[0100] In the illustrated example, the inter-wall connections 110 in each line 112 are spaced or distant from each other by inter-connection distance ICD. Each line 112 is spaced or distant from a neighboring line 112 by an inter-line distance ILD. The interconnection distance ICD is shorter or smaller than the inter-line distance 112. It is to be understood herein that the inter-connection distance ICD can vary, i.e., can be shorter or longer in some lines than in other lines while still maintaining the condition of being shorter than the inter-line distances. It is to be further understood herein that the interline distance ILD can vary, i.e., can be shorter or longer between some pairs of adjacent lines than in other pairs of adjacent lines, while still maintaining the condition of being longer than the inter-connection distances.
[0101] In some examples, the inter-line distances are same between all pairs of the adjacent lines. In some examples, the inter-line distances can increase or decrease along a direction extending from the gas inlet to the gas outlet.
[0102] Reference is now made to Figs. 1C and ID illustrating MABR membranes 100, according to two examples of the presently disclosed subject matter. It is to be understood herein that the membranes 100 of the examples of Figs. 1C and ID can include some or all features of the membranes described generally herein above and / or of the membranes 100 of the examples of Figs. 1A and IB, and the description thereof can apply analogously to corresponding features of the membranes 100 of Figs. 1C and ID. It is also to be understood herein that the membranes 100 of the examples of Figs. 1C and ID are similartothe membrane 100 of the example of Fig. 1A with the only difference being the variation in the inter-connection distances ICD along the gas-flow pathway.
[0103] In particular, in the example of Fig. 1C, the inter-connection distances ICD between the neighboring inter-wall connections 110 along the lines 112 increases in a directionalong the gas-flow pathway from the gas inlet 106 to the gas outlet 108. The neighboring inter-wall connections 110 in a first line 112-1 are spaced or distant by inter-connection distances ICD-1, and the neighboring inter-wall connections 110 in a second line 112-1 are spaced or distant by inter-connection distances ICD-2. In the illustrated example, the inter-connection distance ICD-2 is greater or longer than the inter-connection distance ICD-1. The second line 112-2 is downstream the gas-flow pathway as compared to the first line 112-1. In other words, the first line 112-1 is closer to the gas inlet 106 than the second line 112-2 is. In yet other words, the inter-connection distances ICD between the neighboring inter-wall connections 110 along the lines 112 increases in a direction extending from the gas inlet 106 to the gas outlet 108. In yet other words, the interconnection distances ICD between the neighboring inter-wall connections 110 along the lines 112 increases from top portion of the membrane 100 to the bottom portion of the membrane 100. The inter-connection distances between the inter-wall connections in a line at the top portion of the membrane are smaller than the inter-connection distances between the inter-wall connections in a line at the bottom portion of the membrane.
[0104] Further, in the example of Fig. ID, the inter-connection distances ICD between the neighboring inter-wall connections 110 along a single line 112 increase in a direction along the gas-flow pathway from the gas inlet 106 to the gas outlet 108. A first pair of neighboring inter-wall connections 110-1 in a line 112 are spaced or distant by interconnection distances ICD-1, and a second pair of neighboring inter-wall connections 110-2 in the same line 112 are spaced or distant by inter-connection distances ICD-2. In the illustrated example, the inter-connection distance ICD-2 is greater or longer than the inter-connection distance ICD-1. The second pair of inter-wall connections 110-2 is downstream the gas-flow pathway as compared to the first pair of the inter-wall connections 110-1. In other words, the first pair of the inter-wall connections 110-1 is closer to the gas inlet 106 than the second pair of the inter-wall connections 110-1 is. In yet other words, the inter-connection distances ICD between the neighboring inter-wall connections 110 along a (same) line 112 increases in a direction extending from the gas inlet 106 to the gas outlet 108. In yet other words, the inter-connection distances ICDbetween the neighboring inter-wall connections 110 along a line 112 increases from top portion of the membrane 100 to the bottom portion of the membrane 100.
[0105] It is to be understood herein that the features of the examples of Figs. 1C and ID can be combined. In particular, in some examples, the inter-connection distances between the neighboring inter-wall connections along a single line can increase in a direction along the gas-flow pathway, as well as the inter-connection distances between the neighboring inter-wall connections in different lines can increase in a direction along the gas-flow pathway.
[0106] The variation in the inter-connection distances provides higher attachment strength at portions where the pressure difference between the interior and exterior of the membrane is higher than other portions of the membrane. For instance, the hydrostatic pressure of the water outside the membrane is higher at the bottom (near the gas outlets) than at the top (near the gas inlet) of the membrane, thereby reducing pressure difference (between interior and exterior of the membrane) gradually along the gas flow path. The inter-wall connections being closer near the top (than near the bottom) of the membrane provide higher attachment strength at the top portion of the membrane than at the bottom of the membrane, to be able to deal with the pressure differences. It is to be noted herein that the pressure of the gas inside the membrane can be higher than the hydrostatic pressure outside the membrane at the bottom of the membrane (portions corresponding to the gas outlets) to allow the gas to escape from the gas outlets into the water.
[0107] The portions of the side walls of the membrane corresponding to the gas-flow pathway, i.e., the portions between the inter-wall connections, inflate when the gas passes through the internal gas space, while the portions of the side walls at the interwall connections remain attached to each other. Accordingly, the external surfaces 102A and 104A of the membrane 100 transforms into an undulating surface.
[0108] It is to be understood herein that in all of the examples described herein, the marked up lines ML shown in some of the drawings are merely exemplary to indicate thelines of the inter-wall connections according to some examples, and are not necessarily formed on the membrane.
[0109] Reference is now made to Fig. IE illustrating an MABR membrane 100, according to another example of the presently disclosed subject matter. It is to be understood herein that the membrane 100 of the example of Fig. IE can include some or all features of the membranes described generally herein above and / or of the membranes 100 of the examples of Figs. 1A to ID, and the description thereof can apply analogously to corresponding features of the membrane 100 of Fig. IE. In the example illustrated in example IE, the membrane 100 is formed as a spirally wound membrane 100 wound about a central core CC having a central axis CA. The spirally wound membrane 100 has a plurality of wraps 100-1, 100-2, and so on, around the central axis CA of the central core CC. Each wrap has the line 112 of the inter-wall connections 110, extending in a direction different from that of the adjacent wrap. In particular, the wrap 100-1 has line 112 of the inter-wall connections 110 extending a first direction and the wrap 100-2 has line 112 of the inter-wall connections 110 extending a second direction different than, and in the illustrated example transverse to, the first direction. It is to be noted herein that the lines 112 of the inter-wall connections 110 in adjacent wraps being in different directions is to be understood from the view point of the surfaces of the wraps facing other. In particular, the lines 112 of the first wrap 100-1 as seen on the surface of the first wrap 100-1 facing the second wrap 100-2 are in different direction as compared to the lines 112 of the second wrap 100-2 as seen on the surface of the second wrap 100-2 facing the first wrap 100-1. In Fig. IE, the surface of the first wrap 100-1 facing the second wrap 100-2 is not visible, and the surface of the second wrap 100-2 facing the first wrap 100-1 is visible.
[0110] In general, the MABR membranes provided herein can be arranged, for example in a module frame, in parallel to each other, for example to constitute an MABR module, according to an aspect of the presently disclosed subject matter. In some examples, in which the membranes are formed as flat sheet membranes, the membranes can be arranged or stacked parallel to each other. In some examples, in which the membranes are formed as spirally wound membranes, the wraps of the spirally wound membrane areparallel to each other. In any case, the membranes, or wraps, can be arranged with the lines of the inter-wall connections of each membrane, or wrap, extends in a direction different from the lines of the inter-wall connections of a neighboring membrane, or wrap. In some examples, the lines on each pair of neighboring membranes, or wraps, extend in directions transverse each other. It is to be understood herein that the lines of adjacent membranes being in different directions is intended to mean that these lines would intersect each other (the lines of first membrane would intersect the lines of second membrane) if they were in the same plane. In other words, the lines of first membrane would intersect the lines of second (adjacent) membrane in a projection of the membranes and the lines thereof on plane parallel to the membranes.
[0111] The above-described directional arrangement can be achieved by positioning the membranes, for example identical membranes, with alternating surfaces facing the neighboring membranes. In other words, all the membranes can be identical, and can be positioned in alternating directions. In other words, a first membrane is placed in a first orientation, and a second adjacent or neighboring membrane is placed in a second orientation which is 180 degrees rotated about the vertical central axis (vertical axis passing through a center of the membrane). Each pair of membranes can have two membranes having orientations rotated by 180 degrees about the vertical central axis with respect to each other. In order to further understand the above-described arrangement, if for example the external surface 102A were to be considered as front surface and the external surface 104A were to be considered as rear surface for each membrane, then for every pair of membranes, the surface 102A of one membrane faces the surface 104A of the neighboring membrane.
[0112] Accordingly, the membranes, or wraps of a membrane, while being identical can be arranged to have the lines of inter-wall connections on each membrane, or wrap, extending in a direction different from the lines of inter-wall connections on a neighboring membrane, or wrap. The above-described arrangement of the membranes, or wraps, provide free passage of water between each pair of two adjacent membranes, or wraps, even when the membranes are at least partially inflated when the gas passes through themembranes. In particular, when the gas is passed through the membranes at pressure higher than the hydrostatic pressure of water outside of the membranes, the membranes inflate (at least partially) at the portions corresponding to the gas-flow pathways, i.e., between the inter-wall connections. The portions at the inter-wall connections do not inflate and define free passage for water on the outside of the membranes along the lines of the inter-wall connections lines, in the form of channels.
[0113] In other words, when the gas is passed through the membranes, the portions of the side walls of the membranes corresponding to the gas-flow pathways, i.e., the portions between the inter-wall connections, inflate while the portions of the side walls at the inter-wall connections remain attached to each other (and do not inflate). Accordingly, the external surfaces of the membranes transform into undulating surfaces having crests at the portions that get inflated and troughs at the portions of the inter-wall connections (that do not get inflated). The crests of neighboring membranes, or wraps, come close to each other as compared to troughs, or even contact each other in some examples, while the troughs constitute free passage of water between the membranes, for example in the form of channels. It is to be understood herein that the inter-wall connections can be in proximity to, and even touching, the perimeter of the membranes such that the troughs or channels begin from the edges of the membranes. Accordingly, the edges of the adjacent membranes are spaced apart from each other to allow water to enter the spaces between the membranes and can pass therethrough.
[0114] Reference is now made to Fig. 2A illustrating an MABR module 500 according to an example of the presently disclosed subject matter. It is to be understood herein that the module 500 can include a plurality of membranes, any or all of which can include some or all of the features of the MABR membranes described herein. In the illustrated example, the module 500 includes a plurality of membranes 100 which are similar to the membranes 100 described herein above with reference to Figs. 1A to 1C. The membranes 100 are arranged in parallel to each other in a module frame 502, and are fixed to the frame 502 by a fixing arrangement 504 which in the illustrated example includes rods 504 passing through each membrane 100. It is to be understood herein that any fixingarrangement including cords, wires, straps, or equivalent means suitable for fixing each membrane through a fixing point on the membranes to a corresponding fixed point on the module frame can be used.
[0115] The gas inlets 106 of the membranes are positioned at top portions of the module 500 or module frame 502, and the gas outlets 108 are positioned at the bottom portion of the module 500 or module frame 502. This orientation of the module 500 and of the membranes 100 is the one in which the membranes and the module are used in an MABR tank for water treatment.
[0116] In the example illustrated in Fig. 2A, the gas inlets 106 of the membranes 100 are offset from the vertical center of the membrane. The gas inlets 106 of the neighboring membranes are positioned on laterally opposite sides of the membranes, which depicts that the membranes 100 while being identical to each other are placed in alternating directions as described above. The alternating placement of the membranes 100 cause the lines 112 of the inter-wall connections 110 of neighboring membranes being positioned in different directions, as shown more clearly in Fig. 2B, that would intersect each other if arranged in a plane parallel to the membranes.
[0117] Fig. 2B shows a pair of neighboring membranes 100 of the MABR module of Fig. 2A placed in alternating directions, with their respective lines 112 of inter-wall connections 110 extending in alternating directions. The alternating directions of the inter-wall connections 110 provide for a free passage for water between the membranes even when the gas is passed through the membranes at a pressure higher than a hydrostatic pressure of water outside of the membranes, as described above.
[0118] It is to be understood herein that although the features of providing free passage of water between the membranes have been described herein with reference to flat-sheet type membranes, however, the same description can apply to neighboring wraps of a spirally wound membrane. In other words, the alternating directions of the inter-wall connections of neighboring wraps of a spirally wound membrane provide for a freepassage for water between the wraps in the same manner as described above with respect to flat-sheet type membranes.
[0119] In some examples, spacers such as geotechnical sheets or nettings or distributed spacer elements can be provided between adjacent wraps of the spirally wound membrane or between adjacent flat-sheet membranes. The spacers ensure a distance between adjacent wraps, or adjacent membranes, that ensure a free volume for water to be treated therebetween.
[0120] It is to be understood herein that the supply of gas can be provided from a gas source, for example a blower, directly via dedicated conduits to the inlets of the membranes, or as an alternative the module can include a header having an inlet for gas supply such as from a blower, and outlets connected to the gas inlet of the membranes in the module, and the gas cab supplied to the membraned via the header.
[0121] In general, one or more modules provided herein, each including one or more membranes provided herein, can be positioned in an MABR tank (also referred to herein as tank), thereby constituting an MABR system. The wastewater (or water) to be treated can be fed into the tank volume of the MABR tank, for example via a tank water inlet, and the modules and membranes are submerged in the water within the tank volume. The treated water can flow out of the tank via a tank water outlet. In some examples, the wastewater can include activated sludge from a solid liquid separator such as a clarifier or a membrane filtration unit.
[0122] The membranes are arranged in the tank with the gas inlets facing upwards, i.e., the gas inlet being at the top of the membrane and the gas outlets at the bottom of the membranes. The gas outlets are in fluid communication with the water in the tank. In some examples, the gas outlets can be in direct fluid communication with the water. In some examples, the gas outlets can be in fluid communication with the water indirectly, for example via a diffuser arrangement positioned at the bottom of the modules or the membranes. In some examples, the gas outlets can be in fluid communication with the atmosphere above the level of water in the tank, for example via one or more dedicatedconduits extending from the gas outlets to the atmosphere. The gas discharge to the atmosphere through at least one conduit can be equipped with means to maintain a desired air pressure in the membrane to at least partially inflate the membrane in the water, such means can be a manually or automatically or mechanically throttled valve.
[0123] The gas can be fed into the membranes via respective gas inlets, and can be discharged into the water via the gas outlets. The MABR system can include a controller, for example in the form of a programmable controller (PLC), to control one or more operations of the MABR system. The controller can be configured to control one or more parameters, for example including pressure and / or flow rate, of the flow of gas through the membranes, as described in detail herein further below with reference to methods of water treatment.
[0124] In some examples, the MABR tank can have one partition dividing the tank volume to more than one process stages, and the MABR membranes can be installed in the first process stage. In some examples, the MABR system can include two tanks in series, and the MABR membranes can be installed in the first tank. In some examples, the tank can have at least two partitions dividing the tank volume into at least three process stages, whereas the first process stage can be anaerobic and the MABR membranes can be installed in the second process stage. In some examples, the MABR system can include more than two tanks in series, whereas the first tank can be anaerobic and the MABR membranes can be installed in the second tank.
[0125] Reference is now made to Fig. 3 illustrating an MABR system 1000 according to an example of the presently disclosed subject matter. It is to be understood herein that the MABR system 1000 can include one or more modules each including a plurality of membranes, any or all of which can include some or all of the features of the MABR membranes described herein. In the illustrated example, the system 1000 includes four modules 500 each including a plurality of membranes 100 which are similar to the membranes 100 described herein above with reference to Figs. 1A to 1C.The MABR system 1000 includes an MABR tank 1002 having a tank volume 1004, a tank water inlet 1006, and a tank water outlet 1008. The water to be treated is fed into the volume 1004 via the tank water inlet 1006 and the treated water can flow out of the tank water outlet 1008. During the treatment of the water in the tank 1002, the water occupies at least a part of the tank volume 1004 and the membranes 100 are submerged at least partially into the water. The tank is partitioned by two partitions 1010 and 1012 into three process stages, i.e., a first stage 1002-1, a second stage 1002-2, and a third stage 1002-3. The membraned 100 are arranged in the second process stage 1002-2.
[0126] The presently disclosed subject matter provides, according to some aspects thereof, a method of treatment of wastewater for example in the MABR system described herein. One example of the method of wastewater treatment is described herein below with reference to the MABR system 1000 illustrated in Fig. 3. The water to be treated is fed into the MABR tank 1002 via the tank water inlet 1006. The membranes 100 are submerged in the water, and the gas (a wastewater treatment gas, such as air or another oxygen containing gas) is supplied into the membranes 100 via the gas inlets 106 and is discharged into the water via the gas outlets 108. The treated water flows out of or is discharged from the MABR tank 1002 via the tank water outlet 1008. The method includes controlling one or more parameters of the gas being supplied into the membranes. The parameter can include pressure and / or flow rate the gas being supplied into the membranes.
[0127] In some examples, the gas is supplied to the membranes at a pressure essentially equal to or slightly higher than the hydrostatic pressure of the water in the tank. It is to be understood herein that, for the purposes of the present description, the term "essentially" when used in the context of a value is intended to include within its scope the same value as well as with a tolerance of up to 10 percent or 20 percent.
[0128] In some examples, the controlling of the at least one parameter of the supply of the gas can comprise providing the supply of gas via the gas inlets intermittently, and in some examples periodically. In some examples, the controlling of the at least one parameter of the supply of the gas can comprise varying the at least one parameter, for example theflow rate, of the supply of the gas intermittently, and in some examples periodically. In some examples, the flow rate of the gas being supplied to the membranes can be varied between a first pattern and a second pattern. The first pattern can include flow rate lower than flow rate in the second pattern. The first pattern can include a duration of supply of gas which is longer than a duration of supply of gas in the second pattern. In other words, the gas flow rate can be varied between long periods or durations of low flow rate and short periods or durations of high flow rate. In some examples, the long periods or durations can range between 2 to 60 minutes or between 5 to 30 minutes, and / or the short periods and durations can range between 2 to 120 seconds or between 5 to 60 seconds. The flow rates can depend on the floor area under the modules or membranes, and the high flow rate, for mixing and maintaining the membranes, can be in the range of 20-80 m3 / h or in the range of 30-60 m3 / h per m2of floor area under the modules. The low flow rate can be minimal flow rate required for the gas to escape the membrane from the gas outlets, i.e., minimal flow rate equal to or higher than the hydrostatic pressure of the water at the bottom portion of the membranes. In some examples, the low flow rate can be dependent on the size of the membranes and / or contaminant load.
[0129] The supply of the gas to the membranes at variable flow rate, and / or pressure, results in correspondingly different intensities of gas discharge to the water at the bottom part of the membranes. It is to be understood herein that discharging of gas from the membranes into the water at a high flow rate can be functional to maintain the membranes, or wraps of a spirally wound membrane, and the spacing between them free of accumulation and excessive growth of biofilm. For instance, as described herein, increasing the gas flow rate can be associated with increasing the gas pressure, and vice versa, which in turn inflates or deflates the membrane, thus changing the spacing between adjacent membranes to maintain the membranes by releasing accumulated solids between them. Also, the high flow rate can be associated with higher energy consumption and higher concentration of oxygen in the system, both of which can be undesirable. In order to optimize or control the benefits in the face of the disadvantages,alternating gas supply rate, at correspondingly alternating pressures, can be applied to the membranes.
[0130] In general, supply of the gas to the membranes can be provided at higher pressure than the hydrostatic pressure of the bottom part of the membrane, and the gas can be discharged into the water for mixing of the contents of the tank, and the pressure and / or flow rate of the gas can be decreased according to oxygen uptake measurement, to maintain an optimized oxygen concentration.
[0131] In particular, the gas flow rate can be maintained at a low flow rate most of the time in order to maintain anoxic conditions in the water, while also taking in consideration providing a sufficient driving force for the gas transfer through the membrane, which requires a certain average oxygen concentration in the gas. Accordingly, the flow rate of the gas provided to the membranes can be controlled to minimize excess energy consumption for providing of gas on one hand, and to provide sufficient oxygen for supporting the maximal biological activity on the other hand.
[0132] The gas flow through the membranes can be increased for a limited time in order to release excess biomass accumulated between adjacent membranes, or adjacent wraps of a spirally wound membrane, as well as in order to release adjacent membranes, or adjacent wraps of a spirally wound membrane, from each other. In some examples, the duration of providing a higher flow rate can be between 10 seconds and 60 seconds, and in some examples between 15 seconds and 45 seconds. The number of times per hour that a higher flow rate is provided to the membranes can depend on process conditions such as local organic loading rate and / or hydraulic residence time, and in some examples can be between 2-12 times per hour, or 3-5 times per hour.
[0133] It is to be understood herein that the supply of gas to the membranes can be controlled, for example by a controller, by any suitable means including controlling flow rate and / or pressure by variable speed drive (VSD) and / or variable frequency drive (VFD) on a blower or gas source providing the gas, and / or by an arrangement of controlled valves configured to control gas flow between different membranes in the system.In some examples, a diffuser arrangement can be located underneath the membranes, and the gas outlets of the membranes can be in fluid communication with the diffuser arrangement. An additional gas can be provided, for example intermittently, to the diffuser arrangement providing mixing of the water in the tank and scouring off of excess biofilm or any other accumulation of solids between adjacent membranes or adjacent wraps of a spirally wound membrane. The additional gas can be provided from the same source that provides gas into the membranes, or can be provided by a separate dedicated gas source for the diffuser arrangement.
[0134] In some examples, the MABR system can include a subsystem for cleaning the internal gas space of the membranes, for example, by providing chemical cleaning solutions into each membrane through its gas inlet.
Claims
CLAIMS1. An MABR membrane comprising:an envelope comprising two opposing side walls at least indirectly joined together along a perimeter to define therebetween an internal gas space, the side walls comprising a water-impermeable and gas-permeable material;at least one gas inlet configured to allow supply of gas into the internal gas space;at least one gas outlet configured to allow discharge of gas from the internal gas space; anda plurality of inter-wall connections between the two opposing side walls that define a gas-flow pathway within the internal gas space from the at least one gas inlet to the at least one gas outlet.
2. The MABR membrane of claim 1, wherein the inter-wall connections attach internal surfaces of the sidewalls to each other.
3. The MABR membrane of claim 1 or 2, wherein the at least one gas inlet and the at least one gas outlet are located on opposite regions of the perimeter.
4. The MABR membrane of any one of claims 1 to 3, comprising a plurality of the at least one gas outlet located on the perimeter of the membrane, on opposite region to the at least one gas inlet.
5. The MABR membrane of any one of claims 1 to 4, wherein the inter-wall connections are in a form of dots or dashes.
6. The MABR membrane of any one of claims 1 to 5, wherein the plurality of interwall connections are arranged in a pattern.
7. The MABR membrane of any one of claims 1 to 6, wherein the plurality of interwall connections are arranged in one or more straight or curved lines.
8. The MABR membrane of any one of claims 1 to 7, wherein the plurality of interwall connections are arranged in a plurality of straight or curved lines, each linecomprising one or more inter-wall connections spaced from each other, and each line being spaced from a neighboring line.
9. The MABR membrane of claim 8, wherein spaces between the inter-wall connections of one line are smaller than the space between adjacent lines.
10. The MABR membrane of claim 8 or 9, wherein the spaces between the neighboring dots or dashes along a line of the plurality of lines increases in a direction along the gas-flow pathway from the at least one gas inlet to the at least one gas outlet.
11. The MABR membrane of any one of claims 8 to 10, wherein the inter-wall connections are arranged in a plurality of lines extending across at least a portion of the side walls.
12. The MABR membrane of claim 11, wherein one or more of the lines are diagonal lines extending across the side walls.
13. The MABR membrane of any one of claims 1 to 12, wherein the inter-wall connections include at least one of gluing and welding the side walls to each other.
14. The MABR membrane of any one of claims 1 to 13, wherein the MABR membrane is formed as a spirally wound membrane having a plurality of wraps around a central axis.
15. The MABR membrane of claim 14, when dependent at least indirectly on claim 8, wherein the lines on each wrap of the plurality of wraps extend in a direction different from the lines on a neighboring wrap.
16. An MABR module comprising:a module frame; anda plurality of MABR membranes arranged in parallel to each other, each membrane including:an envelope comprising two opposing side walls at least indirectly joined together along a perimeter to define therebetween an internal gas space, the side walls comprising a water-impermeable and gas-permeable membrane;- Sl ¬at least one gas inlet configured to allow supply of gas into the internal gas space;at least one gas outlet configured to allow discharge of gas from the internal gas space; anda plurality of inter-wall connections between the two opposing side walls that define a gas-flow pathway within the internal gas space from the at least one gas inlet to the at least one gas outlet, said plurality of inter-wall connections being arranged in a plurality of straight or curved lines, each line comprising one or more inter-wall connections spaced from each other, and each line being spaced from a neighboring line;wherein the lines on each membrane of the plurality of membranes extend in a direction different from the lines on a neighboring membrane.
17. The MABR module of claim 16, wherein the lines on each pair of neighboring membranes are transverse each other.
18. The MABR module of claim 16 or 17, wherein each pair of neighboring membranes defines free passage of water therebetween.
19. The MABR module of claim 18, wherein the free passage of water between the membranes extend at least partially along the lines of the inter-wall connections.
20. The MABR module of any one of claims 16 to 19, wherein at least one of the plurality of MABR membranes is the MABR membrane according to any one of claims 1 to 15.
21. The MABR module of any one of claims 16 to 20, wherein the plurality of membranes are fixed to the module frame by a fixing arrangement.
22. The MABR module of any one of claims 16 to 21, wherein the at least one gas inlet is positioned at a top portion of the module, and the at least one gas outlet is positioned at a bottom portion of the module.
23. An MABR system for water treatment, said MABR system comprising including at least one tank having one or more MABR modules positioned therein, each MABR module comprising:a plurality of MABR membranes arranged pa ra I lei ly to each other, each membrane including:an envelope comprising two opposing side walls at least indirectly joined together along a perimeter to define therebetween an internal gas space, the side walls comprising a water-impermeable and gas-permeable membrane;at least one gas inlet configured to allow supply of gas into the internal gas space;at least one gas outlet configured to allow discharge of gas from the internal gas space; anda plurality of inter-wall connections between the two opposing side walls that define a gas-flow pathway within the internal gas space from the at least one gas inlet to the at least one gas outlet, said plurality of inter-wall connections being arranged in a plurality of straight or curved lines, each line comprising one or more inter-wall connections spaced from each other, and each line being spaced from a neighboring line;wherein the lines on each membrane of the plurality of membranes extend in a direction different from the lines on a neighboring membrane.
24. The MABR system of claim 23, wherein the tank comprises a tank water inlet for receiving therethrough water to be treated into the tank.
25. The MABR system of claim 24, wherein the at least one gas outlet is directly or indirectly in fluid communication with the water in the tank.
26. The MABR system of any one of claims 23 to 25, wherein the at least one gas outlet is in fluid communication with atmosphere above the water in the tank.
27. The MABR system of any one of claims 23 to 26, wherein, at least when in use, the at least one gas inlet is on top and the at least one gas outlet is on bottom of the respective membrane.
28. The MABR system of any one of claims 23 to 27, further comprising at least one gas flow source in fluid communication with the at least one gas inlet.
29. The MABR system of any one of claims 23 to 28, further comprising a controller to control one or more operations of the MABR system.
30. The MABR system of claim 29, when dependent on claim 28, wherein the controller is configured to control at least one parameter of gas flow through the membrane.
31. The MABR system of claim 30 wherein the at least one parameter comprises one or more of flow rate and pressure of the gas.
32. A method for water treatment, including:feeding water to be treated into an MABR tank via a tank water inlet; submerging one or more MABR membranes in the water to be treated in the MABR tank;supplying a gas into the one or more MABR membranes, via respective gas inlets;allowing the gas to be discharged into the water from the membranes via respective outlets; andcontrolling at least one parameter of the supply of the gas into the membranes; andallowing the treated water to flow out of the MABR tank via tank water outlet.- S ¬SS. The method of claim 32, wherein said controlling at least one parameter of the supply of the gas comprises providing the supply of gas via the gas inlets intermittently, and correspondingly allowing the discharge of gas via the gas outlets intermittently.
34. The method of claim 32 or 33, wherein said controlling at least one parameter of the supply of the gas comprises providing the supply of gas via the gas inlets periodically, and correspondingly allowing the discharge of gas via the gas outlets periodically.
35. The method of any one of claims 32 to 34, wherein the at least one parameter one or more of pressure and flow rate of the gas being supplied to the membranes.
36. The method of any one of claims 32 to 35, wherein said controlling at least one parameter of the supply of the gas comprises varying the at least one parameter of the supply of the gas intermittently.
37. The method of claim 36, wherein said varying the at least one parameter comprises varying the flow rate of the gas being supplied to the membranes.
38. The method of claim 37, wherein said varying the flow rate of the gas being supplied to the membranes comprises varying the flow rate between a first pattern and a second pattern.
39. The method of claim 38, wherein the first pattern includes flow rate lower than flow rate of the second pattern.
40. The method of claim 38 or 39, wherein the first pattern includes a duration of supply of gas which is longer than a duration of supply of gas in the second pattern.
41. The method of claim 40, wherein the duration of supply of gas in the second pattern ranges between 10 seconds and 60 seconds.
42. The method of any one of claims 32 to 41, further comprising intermittently supplying an additional gas to a diffuser arrangement located underneath the membranes.