Water treatment

Abstract

A water treatment system for recovering water from impaired water is provided. The water treatment system comprises a membrane distillation module, configured to receive the water to be treated, and a cooling module, configured to receive a cooling fluid, with the membrane distillation module and cooling module are in thermal communication such that in operation the water treatment system provides for the efficient recovery of treated water. In addition, a method for recovering water from impaired water using a water treatment system is also provided.

Description

Water treatmentTechnical Field

[0001] The present disclosure relates generally to a water treatment system for recovering water from impaired water. The present disclosure also relates to a method for recovering water from impaired water using a water treatment system.Background

[0002] Clean water is a basic necessity for humans, and demand for water grows with growth in both population and industry. With water being a finite resource, water treatment systems which can produce water of suitable quality for the end user from impaired water sources are essential for meeting the increased demand for water. The quality of the water required may be potable water suitable for drinking or water of satisfactory purity for other purposes, including medical, pharmacological, chemical, and other industrial applications.

[0003] Water treatment systems may be used to remove unwanted constituents from a water source and / or to recover high quality water from an in impaired water source.Various water treatment systems have been developed including: membrane distillation which uses a temperature difference across a membrane to evaporate feed water and the vapour produced from feed side of the membrane permeates through the porous membrane and condenses as pure water on the other side of the membrane; reverse osmosis which uses semi-permeable membranes and applied pressure (on the membrane feed side) to induce water permeation through the membrane while rejecting salts; and forward osmosis which uses a semi-permeable membrane to separate water from dissolved solutes by utilising an osmotic pressure gradient.

[0004] Systems such as the above can have a large footprint when combined as individual processes, be energy intensive and not adaptable to certain types of feedwater sources. Therefore, it would be advantageous to develop alternative system and / or methods which can produce high quality water from impaired water sources.Summary

[0005] The present disclosure relates generally to a water treatment system for recovering water from impaired water and a method for recovering water from impaired water using a water treatment system. The system described herein provides an efficient integrated systems with a smaller footprint compared to conventional water treatment systems. Through the adaptation of individual water treatment systems into an integrated system, benefits in terms of water recovery and efficiency relative to the individual systems operating separately are realised.

[0006] According to one aspect of the present disclosure, there is provided a system for recovering water, the system comprising: a membrane distillation module comprising: a membrane distillation membrane defining a membrane distillation feed side and a membrane distillation permeate side, wherein membrane distillation permeate vapour passing through the membrane distillation membrane undergoes condensation on the membrane distillation permeate side; a membrane distillation feed inlet for receiving a membrane distillation feed solution and a membrane distillation feed outlet for outputting concentrated membrane distillation feed solution, the membrane distillation feed inlet and the membrane distillation feed outlet defining a membrane distillation feed flow path; a membrane distillation permeate outlet for outputting condensed membrane distillation permeate comprising recovered water from the membrane distillation feed solution; a cooling module comprising; a cooling fluid inlet for receiving a cooling fluid and a cooling fluid outlet for outputting a heated cooling fluid, the cooling fluid inlet and the cooling fluid outlet defining a cooling fluid flow pathwherein the cooling module and the membrane distillation permeate side are separated by a thermally conductive wall such that the cooling fluid removes heat generated from the condensation of the membrane distillation permeate vapour on the membrane distillation permeate side.

[0007] According to a further aspect of the present disclosure, there is provided a system for recovering water, the system comprising: a forward osmosis module comprising: a forward osmosis membrane defining a forward osmosis feed side and a forward-osmosis draw side; a forward osmosis feed inlet for receiving a forward osmosis feed solution and a forward osmosis feed outlet for outputting concentrated feed solution, the forward osmosis feed inlet and the forward osmosis feed outlet defining a forward osmosis feed side flow path; a forward osmosis draw inlet for receiving a concentrated forward osmosis draw solution and a forward osmosis draw outlet for outputting diluted forward osmosis draw solution, the forward osmosis draw inlet and the forward osmosis draw outlet defining a forward osmosis draw flow path; a membrane distillation module comprising: a membrane distillation membrane defining a membrane distillation feed side and a membrane distillation permeate side, wherein membrane distillation permeate vapour passing through the membrane distillation membrane undergoes condensation on the membrane distillation permeate side; a membrane distillation feed inlet for receiving a membrane distillation feed solution and a membrane distillation feed outlet for outputting concentrated membrane distillation feed solution, the membrane distillation feed inlet and the membrane distillation feed outlet defining a membrane distillation feed flow path; a membrane distillation permeate outlet for outputting condensed membrane distillation permeate comprising recovered water from the membrane distillation feed solution wherein the forward osmosis draw side and the membrane distillation permeate side are separated by a thermally conductive wall such that the forwardosmosis draw solution flowing along the forward osmosis draw flow path is heated by heat generated from the condensation of the membrane distillation permeate vapour on the membrane distillation permeate side.

[0008] According to a further aspect of the present disclosure, there is provided a method for recovering water, the method comprising: feeding a feed solution to a forward osmosis feed side of a forward osmosis module; feeding a concentrated forward osmosis draw solution to a forward osmosis draw side of the forward osmosis module, such that water passes from a forward osmosis feed solution through a forward osmosis membrane to the forward osmosis draw solution to provide a diluted forward osmosis draw solution; feeding a membrane distillation feed solution to a membrane distillation feed side of a membrane distillation module, wherein membrane distillation permeate vapour passing through a membrane distillation membrane undergoes condensation in a membrane distillation permeate side of the membrane distillation module, and is recovered as a permeate solution; and heating the forward osmosis draw solution flowing through the forward osmosis draw side of the forward osmosis module with heat generated from the condensation of the membrane distillation permeate vapour on the membrane distillation permeate side.Brief Description of Drawings

[0009] Embodiments of the present disclosure will now be described, by way of example only, with reference to the accompanying drawings in which:Figure l is a commercial air gap membrane distillation system;Figure 2 is a block flow diagram of a system according to a first embodiment of the present disclosure;Figure 3 is a block flow diagram of the system according to a second embodiment of the present disclosure;Figure 4 is a block flow diagram including exemplary temperatures and flow rates of the system according to the second embodiment as shown in Figure 3;Figure 5 is a block flow diagram of the system according to a third embodiment of the present disclosure;Figure 6 is a block flow diagram of the system comprising a collection tank, whereby vacuum is applied using venturi vacuum generator;Figure 7 is a block flow diagram of the system comprising a collection tanke, whereby vacuum is created from condensing vapour in permeate side;Figure 8 is a perspective view of a first embodiment of a stacked flat plate configuration;Figure 9 is a perspective view of a second embodiment of a stacked flat plate configuration;Figure 10 is an exploded view of a stacked flat plate configuration as shown in Figure 9;Figure 11 is an exploded view of a third embodiment of a stacked flat plate configuration; andFigure 12 is an exploded view of a cooling module as shown in Figure 11Description of Embodiments

[0010] In the following description, reference is made to the accompanying drawings which form a part hereof, and which is shown, by way of illustration, severalembodiments. It is understood that other embodiments may be utilized and structural changes may be made without departing from the scope of the present disclosure.GENERAL TERMS

[0011] With regards to the definitions provided herein, unless stated otherwise, or implicit from context, the defined terms and phrases include the provided meanings. Unless explicitly stated otherwise, or apparent from context, the terms and phrases below do not exclude the meaning that the term or phrase has acquired by a person skilled in the relevant art. The definitions are provided to aid in describing particular embodiments, and are not intended to limit the claimed invention, because the scope of the invention is limited only by the claims. Furthermore, unless otherwise required by context, singular terms shall include pluralities and plural terms shall include the singular.

[0012] All publications discussed and / or referenced herein are incorporated herein in their entirety.

[0013] Any discussion of documents, acts, materials, devices, articles or the like which has been included in the present specification is solely for the purpose of providing a context for the present disclosure. It is not to be taken as an admission that any or all of these matters form part of the prior art base or were common general knowledge in the field relevant to the present disclosure as it existed before the priority date of each claim of this application.

[0014] Throughout this disclosure, unless specifically stated otherwise or the context requires otherwise, reference to a single step, composition of matter, group of steps or group of compositions of matter shall be taken to encompass one and a plurality (i.e., one or more) of those steps, compositions of matter, groups of steps or groups of compositions of matter. Thus, as used herein, the singular forms “a”, “an” and “the” include plural aspects unless the context clearly dictates otherwise. For example, reference to “a” includes a single as well as two or more; reference to “an” includes asingle as well as two or more; reference to “the” includes a single as well as two or more and so forth.

[0015] Each example of the present disclosure described herein is to be applied mutatis mutandis to each and every other example unless specifically stated otherwise. The present disclosure is not to be limited in scope by the specific examples described herein, which are intended for the purpose of exemplification only. Functionally- equivalent products, compositions and methods are clearly within the scope of the disclosure as described herein.

[0016] Those skilled in the art will appreciate that the disclosure herein is susceptible to variations and modifications other than those specifically described. It is to be understood that the disclosure includes all such variations and modifications. The disclosure also includes all of the examples, steps, features, methods, processes, and compositions, referred to or indicated in this specification, individually or collectively, and any and all combinations or any two or more of said steps or features.

[0017] The term “and / or”, e.g., “X and / or Y” shall be understood to mean either “X and Y” or “X or Y” and shall be taken to provide explicit support for both meanings or for either meaning.

[0018] As used herein, the term “about”, unless stated to the contrary, typically refers to a range of up to + / - 10% of the designated value, and includes smaller ranges therein, for example + / - 5% or + / - 1% of the designated value.

[0019] It is to be appreciated that certain features that are, for clarity, described herein in the context of separate embodiments, may also be provided in combination in a single embodiment. Conversely, various features that are, for brevity, described in the context of a single embodiment, may also be provided separately or in any subcombination.

[0020] Throughout the present specification, various aspects and components of the invention can be presented in a range format. The range format is included for convenience and should not be interpreted as an inflexible limitation on the scope of the invention. Accordingly, the description of a range should be considered to have specifically disclosed all the possible sub-ranges as well as individual numerical values within that range, unless specifically indicated. For example, description of a range such as from 1 to 5 should be considered to have specifically disclosed sub-ranges such as from 1 to 3, from 1 to 4, from 1 to 5, from 2 to 4, from 2 to 5, from 3 to 5 etc., as well as individual and partial numbers within the recited range, for example, 1, 2, 3, 4, 4.5, 4.75, and 5, unless where integers are required or implicit from context. This applies regardless of the breadth of the disclosed range. Where specific values are required, these will be indicated in the specification.

[0021] Throughout this specification the word "comprise", or variations such as "comprises" or "comprising", will be understood to imply the inclusion of a stated element, integer or step, or group of elements, integers or steps, but not the exclusion of any other element, integer or step, or group of elements, integers or steps.SYSTEM

[0022] In one aspect, the present disclosure relates to a system for recovering water from a feed solution. Embodiments of the system described herein allow for a highly integrated system to be configured whereby the product streams from one process unit may be, at least partially, utilised as inputs for other process units thereby reducing reliance on new input material. System integration also allows for improved control over the process conditions. The system described herein provides benefits in terms of system footprint, water recovery and / or efficiency relative to the conventional water treatment systems.

[0023] In an aspect of the present disclosure, there is provided a system for recovering water, the system comprising: a membrane distillation module comprising:a membrane distillation membrane defining a membrane distillation feed side and a membrane distillation permeate side, wherein membrane distillation permeate vapour passing through the membrane distillation membrane undergoes condensation on the membrane distillation permeate side; a membrane distillation feed inlet for receiving a membrane distillation feed solution and a membrane distillation feed outlet for outputting concentrated membrane distillation feed solution, the membrane distillation feed inlet and the membrane distillation feed outlet defining a membrane distillation feed flow path; a membrane distillation permeate outlet for outputting condensed membrane distillation permeate comprising recovered water from the membrane distillation feed solution; a cooling module comprising; a cooling fluid inlet for receiving a cooling fluid and a cooling fluid outlet for outputting a heated cooling fluid, the cooling fluid inlet and the cooling fluid outlet defining a cooling fluid flow path, wherein the cooling module and the membrane distillation permeate side are separated by a thermally conductive wall such that the cooling fluid removes heat generated from the condensation of the membrane distillation permeate vapour on the membrane distillation permeate side.

[0024] In some embodiments, the cooling module is a forward osmosis module comprising: a forward osmosis membrane defining a forward osmosis feed side and a forward-osmosis draw side; a forward osmosis feed inlet for receiving a forward osmosis feed solution and a forward osmosis feed outlet for outputting concentrated feed solution, the forward osmosis feed inlet and the forward osmosis feed outlet defining a forward osmosis feed side flow path; the cooling fluid inlet is a forward osmosis draw inlet for receiving a concentrated forward osmosis draw solution and the cooling fluid outlet is a forward osmosis draw outlet for outputting diluted forward osmosis draw solution, the forwardosmosis draw inlet and the forward osmosis draw outlet defining a forward osmosis draw flow path; wherein the forward osmosis draw side and the membrane distillation permeate side are separated by the thermally conductive wall such that the forward osmosis draw solution flowing along the forward osmosis draw flow path is heated by heat generated from the condensation of the membrane distillation permeate vapour on the membrane distillation permeate side

[0025] In a further aspect there is provided system for recovering water, the system comprising: a forward osmosis module comprising: a forward osmosis membrane defining a forward osmosis feed side and a forward-osmosis draw side; a forward osmosis feed inlet for receiving a forward osmosis feed solution and a forward osmosis feed outlet for outputting concentrated feed solution, the forward osmosis feed inlet and the forward osmosis feed outlet defining a forward osmosis feed side flow path; a forward osmosis draw inlet for receiving a concentrated forward osmosis draw solution and a forward osmosis draw outlet for outputting diluted forward osmosis draw solution, the forward osmosis draw inlet and the forward osmosis draw outlet defining a forward osmosis draw flow path; a membrane distillation module comprising: a membrane distillation membrane defining a membrane distillation feed side and a membrane distillation permeate side, wherein membrane distillation permeate vapour passing through the membrane distillation membrane undergoes condensation on the membrane distillation permeate side; a membrane distillation feed inlet for receiving a membrane distillation feed solution and a membrane distillation feed outlet for outputting concentrated membrane distillation feed solution, the membrane distillation feed inlet and the membrane distillation feed outlet defining a membrane distillation feed flow path; a membrane distillation permeate outlet for outputting condensed membrane distillation permeate comprising recovered water from the membrane distillation feed solution; wherein the forward osmosis draw side and the membrane distillation permeate side are separated by a thermally conductive wall such that the forward osmosis draw solution flowing along the forward osmosis draw flow path is heated by heat generated from the condensation of the membrane distillation permeate vapour on the membrane distillation permeate side.

[0026] In some embodiments, the system is configured such that a vacuum can be applied to the membrane distillation permeate side. In some embodiments, the system is configured such that a vacuum may be applied using venturi effect. In some embodiments, the system is configured such that a vacuum may be applied using the natural vacuum created by the condensing vapour. In some embodiments, the permeate water is recovered without use of a vacuum.Feed solution / feed wastewater

[0027] The system and process described herein is capable of recovering water from feed stocks comprising a wide range of salts and / or pollutants and / or chemicals. Throughout the speciation, the term feed wastewater may be used interchangeable with the term feed solution. However, the person skilled in the art will understand that any aqueous solution might be treated using the systems and methods described herein.Feed wastewater can be obtained from any suitable source including, but not limited to, impaired water, seawater, brackish water, groundwater, surface water, bore water, reverse osmosis concentrate, brine, chemical and natural solutions, industrial water and wastewaters including mine water and acid mine drainage.

[0028] Feed wastewater, or any other aqueous solutions that might be treated using the systems and methods described herein, may be introduced to the system at various locations depending on the embodiment of the system or method. Feed wastewater may be utilised as at least a portion of one or more of the: forward osmosis feed solution; forward osmosis draw side feed solution; membrane distillation feed solution; and reverse osmosis feed solution.

[0029] It will be understood that prior to be used as at least a portion of the one or more feed solutions, feed wastewater may be introduced to one or more process units described here, for example a heater or a cooler.Forward osmosis module

[0030] In some embodiments, the water treatment system described herein comprises a forward osmosis module. Forward osmosis utilises a semi-permeable membrane to separate water from dissolved solutes via an osmotic pressure gradient. The osmotic pressure gradient induces water to flow from a feed side through the membrane to a draw solution, thus separating the feed water from solutes contained therein. Advantageously, forward osmosis requires significantly less energy to be input than reverse osmosis. Further, as forward osmosis can operate at low hydraulic pressure, the module is less prone to fouling and there is lower likelihood of fouling materials being compacted on the membrane surface.Forward osmosis membrane

[0031] The forward osmosis module comprises a forward osmosis membrane. It will be appreciated that to be suitable the forward osmosis membrane is a semi-permeable membrane. In some embodiments, the forward osmosis membrane is hydrophilic. In some embodiments, the forward osmosis membrane is permeable to water and substantially impermeable to salt and / or contaminants in the feed wastewater. The forward osmosis membrane defines a forward osmosis feed side and a forward osmosis draw side.Forward osmosis feed side

[0032] In some embodiments, the forward osmosis feed side is the side of the forward osmosis module wherein the feed wastewater is introduced to the system. The forward osmosis feed side comprises a forward osmosis feed inlet for receiving the feed wastewater and a forward osmosis feed outlet for outputting concentrated feedwastewater. The forward osmosis feed inlet and the forward osmosis feed outlet define a forward osmosis feed side flow path. At least a portion of the forward osmosis feed side flow path abuts at least a portion of the forward osmosis membrane.Forward osmosis draw side

[0033] The forward osmosis draw side is the side of the forward osmosis module wherein the concentrated forward osmosis draw solution with higher osmotic pressure than the feed wastewater flows. The forward osmosis draw side comprises a forward osmosis draw inlet for receiving the concentrated forward osmosis draw solution and a forward osmosis draw outlet for outputting diluted forward osmosis draw solution. The forward osmosis draw inlet and the forward osmosis draw outlet define a forward osmosis draw side flow path. At least a portion of the forward osmosis draw side flow path abuts at least a portion of the forward osmosis membrane.

[0034] In some of the embodiments described in the present aspect, at least a portion of the forward osmosis feed side flow path and at least a portion of the forward osmosis draw side flow path abut the forward osmosis membrane such that there is fluidic communication between the forward osmosis feed side and forward osmosis draw side of the forward osmosis module.

[0035] In some embodiments, the forward osmosis draw side comprises a forward osmosis draw side surface opposing the forward osmosis membrane. In some embodiments, at least a portion of the forward osmosis draw side flow path is defined by the forward osmosis membrane and the forward osmosis draw side surface.Membrane distillation module

[0036] The water treatment system described herein comprises a membrane distillation module. Membrane distillation is a process of separating water from an aqueous liquid phase by utilising differences in partial pressure of water across on the two sides of the membrane. Often the partial vapour pressure difference of water iscaused by a temperature difference on the two sides of the membrane. The membrane presents a barrier to the passage of liquid water but allows for transport of water vapour across the membrane.

[0037] In some embodiments, the membrane distillation module is an air gap membrane distillation module. In air gap membrane distillation water vapour is transported across the membrane distillation membrane and at least a part of said vapour is condensed on a surface that is separated from the membrane distillation membrane via an air gap.

[0038] In some embodiments, the air gap of the air gap membrane distillation module has a width (in mm) of between about 0.5 to about 10, of between 1 to about 5, of between about 1 to about 3, of between about 1 to about 2, of between about 0.5 to about 2.Membrane distillation membrane

[0039] The membrane distillation module comprises a membrane distillation membrane. It will be appreciated that to be suitable the membrane distillation membrane is a porous membrane that presents a barrier for the liquid phase but allows for a vapour phase to be transported across the membrane. In some embodiment, the membrane distillation membrane is porous. In some embodiment, the membrane distillation membrane is hydrophobic. In some embodiments, the membrane distillation membrane is impermeable to liquid water. In some embodiments, the membrane distillation membrane is permeable to water vapour. In some embodiments, the membrane distillation membrane is impermeable to liquid water and is permeable to water vapour. The membrane distillation membrane defines a membrane distillation feed side and a membrane distillation permeate side.Membrane distillation feed side

[0040] The membrane distillation feed side is the side of the membrane distillation module wherein the membrane distillation feed solution is introduced to the system. The membrane distillation feed side comprises a membrane distillation feed inlet for receiving the membrane distillation feed solution and a membrane distillation feed outlet for outputting concentrated membrane distillation feed solution. The membrane distillation feed inlet and the membrane distillation feed outlet define a membrane distillation feed flow path. At least a portion of the membrane distillation feed flow path abuts at least a portion of the membrane distillation membrane.Membrane distillation permeate side

[0041] The membrane distillation permeate side is the side of the membrane distillation module wherein, in use, the membrane distillation permeate vapour passing through the membrane distillation membrane undergoes condensation. The membrane distillation permeate side comprises a membrane distillation permeate outlet for outputting membrane distillation permeate solution.

[0042] In some embodiments, the membrane distillation permeate outlet is connected to a permeate extraction port. In some embodiments, a permeate extraction port is connected to at least one membrane distillation permeate outlet such that the permeate extraction port is configured to collect water from one or more permeate outlets. Thus, a permeate extraction port may be configured to combine water from one or more permeate outlets into one larger outlet for outputting membrane distillation permeate solution.

[0043] In some embodiments, the membrane distillation permeate side comprises a membrane distillation permeate side surface opposing the membrane distillation membrane. In some embodiments, the membrane distillation permeate side surface is separated from the membrane distillation membrane by an air gap. In some embodiments, the membrane distillation permeate side surface is thermally conductive.Thermal communication between cooling and membrane distillation modules

[0044] In some embodiments, in use, the cooling fluid flowing along the cooling flow path is heated by heat released from the condensation of the vapour which crosses the membrane distillation membrane on the membrane distillation permeate side surface of the thermally conductive wall.Thermal communication between forward osmosis and membrane distillation modules

[0045] In some embodiments, the forward osmosis draw side surface and the membrane distillation permeate side surface define a wall. In some embodiments, the wall is thermally conductive, such that there is thermal communication between the forward osmosis module and the membrane distillation module. In some embodiments, in use, the forward osmosis draw solution flowing along the forward osmosis draw flow path is heated by heat released from the condensation of the vapour which crosses the membrane distillation membrane on the membrane distillation permeate side surface.Construction of the cooling and membrane distillation modules

[0046] The cooling module and the membrane distillation module may be arranged in any suitable configuration. In some embodiments the system has a stacked, spiral wound, cylindrical or tubular configuration. In some embodiments, the cooling module and the membrane distillation module are an integrated stack such that the membrane distillation membrane, the thermally conductive wall, and the cooling module define a laminar arrangement.

[0047] In some embodiments, the system comprises two or more cooling modules and / or two or more membrane distillation modules, wherein the cooling module(s) and the membrane distillation module(s) are an integrated stack such that each membrane distillation membrane and cooling module are separated by a thermally conductive wall. In some embodiments, the system comprises two or more cooling modules and / or two or more membrane distillation modules, wherein the cooling module(s) and themembrane distillation module(s) are an integrated stack such that each membrane distillation membrane and cooling module are separated by a thermally conductive wall and form parallel planes thereby defining a laminar arrangement.Construction of forward osmosis and membrane distillation modules

[0048] The forward osmosis membrane module and the membrane distillation module may be arranged in any suitable configuration. In some embodiments the system has a stacked, spiral wound, cylindrical or tubular configuration. In some embodiments, the forward osmosis module and the membrane distillation module are an integrated stack such that the forward osmosis membrane, the membrane distillation membrane and the thermally conductive wall form parallel planes thereby defining a laminar arrangement.

[0049] In some embodiments, the system comprises two or more forward osmosis modules and / or two or more membrane distillation modules, wherein the forward osmosis module(s) and the membrane distillation module(s) are an integrated stack such that each forward osmosis membrane, membrane distillation membrane and thermally conductive wall form parallel planes thereby defining a laminar arrangement.Thermally conductive wall

[0050] In some embodiments, the thermally conductive wall is integral with the cooling module. In some embodiments, the cooling module comprises two thermally conductive walls integrally connected with the cooling module and located on opposing sides of the cooling fluid flow path.

[0051] In some embodiments, the thermally conductive wall is integral with the membrane distillation module.

[0052] In some embodiments, the thermally conductive wall comprises one or more surfaces structures configured to enhance heat transfer to the cooling fluid and / or heat removal from the membrane distillation permeate. In some embodiments, the one orsurfaces structures comprise one or more surface features which increase the surface area of one or both surfaces of the thermally conductive wall. In some embodiments, the one or more surfaces features may be any suitable raised portions providing a textured surface with increased surface area.System assembly

[0053] In some embodiments, the cooling module, thermally conductive wall, and membrane distillation module are configured for sealing engagement with each other.

[0054] In some embodiments, the one or surfaces structures of the thermally conductive wall are configured for sealing engagement with one or more complementary receiving elements of the membrane distillation module.Plate and frame modules

[0055] In some embodiments, the cooling module and membrane distillation module are configured as flat sheet plate and frame type modules. In some embodiments, the cooling module and the membrane distillation module are configured to be stacked and mounted in a filter press type setup.

[0056] In some embodiments, the forward osmosis module and membrane distillation module are configured as flat sheet plate and frame type modules. In some embodiments, the forward osmosis module and the membrane distillation module are configured to be stacked and mounted in a filter press type setup.

[0057] In some embodiments, the forward osmosis draw and membrane distillation air gap permeate side are configured as flat sheet plate and frame type modules. In some embodiments, the modules are configured to be stacked and mounted in a filter press type setup.Reverse osmosis module

[0058] The system as described herein may further comprise may further comprise a reverse osmosis module. In some embodiments, the forward osmosis / membrane distillation system described herein is retrofitted to an existing reverse osmosis module.

[0059] The reverse osmosis module comprises a reverse osmosis membrane defining a reverse osmosis feed side and a reverse osmosis permeate side; a reverse osmosis feed inlet for receiving a reverse osmosis feed solution and a reverse osmosis feed outlet for outputting concentrated reverse osmosis feed solution, the reverse osmosis feed inlet and the reverse osmosis feed outlet defining a reverse osmosis feed side flow path; a reverse osmosis permeate outlet for outputting reverse osmosis permeate comprising recovered water from the reverse osmosis feed solution.

[0060] The reverse osmosis feed solution can be obtained from any suitable source including, but not limited to, impaired water, seawater, brackish water, groundwater, surface water, bore water, reverse osmosis concentrate, brine, chemical and natural solutions, industrial water and wastewaters including mine water and acid mine drainage.

[0061] In some embodiments, the reverse osmosis feed inlet is in fluid communication with the forward osmosis draw outlet such that the reverse osmosis feed solution comprises at least a portion of the diluted forward osmosis draw solution.

[0062] In some embodiments, the reverse osmosis feed outlet is in fluid communication with the membrane distillation feed inlet such that the membrane distillation feed solution comprises at least a portion of the concentrated reverse osmosis feed solution.

[0063] The reverse osmosis module comprises a reverse osmosis membrane defining a reverse osmosis feed side and a reverse osmosis permeate side; a reverse osmosis feed inlet for receiving a reverse osmosis feed solution and a reverse osmosis feed outlet for outputting concentrated reverse osmosis feed solution, the reverse osmosis feed inlet and the reverse osmosis feed outlet defining a reverse osmosis feed side flowpath; a reverse osmosis permeate outlet for outputting reverse osmosis permeate comprising recovered water from the reverse osmosis feed solution; wherein the reverse osmosis feed inlet is in fluid communication with the forward osmosis draw outlet such that the reverse osmosis feed solution comprises at least a portion of the diluted forward osmosis draw solution.Reverse osmosis membrane

[0064] The reverse osmosis module comprises a reverse osmosis membrane. It will be appreciated that to be suitable the reverse osmosis membrane is a semi-permeable membrane. In some embodiment, the reverse osmosis membrane is hydrophilic. In some embodiments, the reverse osmosis membrane is permeable to water and substantially impermeable to salts and / or contaminants in an aqueous solution. The reverse osmosis membrane defines a reverse osmosis feed side and a reverse osmosis permeate side.Reverse osmosis feed side

[0065] The reverse osmosis feed side is the side of the reverse osmosis module wherein the reverse osmosis feed solution is fed. The reverse osmosis feed side comprises a reverse osmosis feed inlet for reverse osmosis feed solution and a reverse osmosis feed outlet for outputting concentrated reverse osmosis feed solution. The reverse osmosis feed inlet and the reverse osmosis feed outlet define a reverse osmosis feed side flow path. At least a portion of the reverse osmosis feed side flow path abuts at least a portion of the reverse osmosis membrane.Reverse osmosis permeate side

[0066] The reverse osmosis permeate side is the side of the reverse osmosis module wherein the water separated from solutes is recovered. The reverse osmosis permeateside comprises a reverse osmosis permeate outlet for outputting recovered water from the reverse osmosis feed solution.Permeate collection recovery port

[0067] In some embodiments, the system further comprises a membrane permeate recovery port. In some embodiments, the membrane permeate recovery port comprises a membrane permeate recovery port inlet in fluid communication with the membrane distillation permeate outlet and a membrane permeate recovery port outlet. In some embodiments, the permeate recovery port may be configured to be in fluid communication with one or more membrane distillation permeate outlets.Vacuum module

[0068] The system as described herein may further comprise a means for applying a vacuum to the membrane distillation permeate side of the membrane distillation module. Advantageously, the inclusion of a means of applying a vacuum to the membrane distillation permeate side of the membrane distillation module can improve removal of condensed membrane distillation permeate from the membrane distillation permeate outlet.

[0069] In some embodiments, the means for applying a vacuum to the membrane distillation permeate side of the membrane distillation module may be through the permeate recovery port.

[0070] In some embodiments, the means for applying a vacuum comprises one or more venturi vacuum generators and the one or more venturi vacuum generators comprise a fluid flow path for flow of a fluid to generate the vacuum.

[0071] In some embodiments, the means for applying a vacuum comprises one or more venturi vacuum generators in communication with the membrane distillation permeate side and defining a flow path for the condensed membrane distillationpermeate. In some embodiments, the means for applying a vacuum comprises one or more venturi vacuum generators in communication with the membrane distillation permeate collection vessel, membrane distillation permeate recovery port, membrane distillation permeate side and defining a flow path for the condensed membrane distillation permeate. The inclusion of one or more venturi vacuum generator(s) in the system allows for the redistribution of energy in the system and to improve the overall energy efficiency of the system.

[0072] In some embodiments, the means for applying a vacuum inherently from condensing vapor in the membrane distillation permeate side and the membrane distillation permeate collection tank, the membrane distillation permeate recovery port, and the membrane distillation permeate side defining a flow path for the condensed membrane distillation permeate, wherein the membrane distillation permeate is fed to the membrane distillation permeate collection tank below the surface of membrane distillation permeate collected therein. The membrane distillation permeate collection tank is preferably positioned at a lower height than the membrane distillation permeate recovery port and membrane distillation permeate outlet.

[0073] In some embodiments, the system as described herein may further comprise a venturi vacuum generator in fluid communication with the feed wastewater thereby to generate a vacuum applied to the membrane distillation air-gap permeate side of the membrane distillation module. In some embodiments, the system as described herein may further comprise a venturi vacuum generator in fluid communication with the diluted forward osmosis draw solution thereby to generate a vacuum applied to the membrane distillation permeate side of the membrane distillation module.Crystalliser

[0074] In some embodiments, the system further comprising a crystalliser comprising: a crystalliser feed inlet for receiving the concentrated membrane distillation feed solution;a concentrated crystalliser outlet for outputting a concentrated crystalliser solution; and optionally, a depleted crystalliser outlet for outputting a depleted crystalliser solution.Cooling fluid cooler

[0075] In some embodiments, the system further comprises a cooling fluid cooler comprising: a cooling fluid cooler inlet in fluid communication with the cooling fluid outlet for receiving the heated cooling fluid; a cooling fluid cooler outlet in fluid communication with the cooling fluid inlet for outputting a concentrated crystalliser solution.Colling fluid pump

[0076] In some embodiments, the system further comprises a cooling fluid pump in fluid communication with the cooling fluid inlet for introducing the cooling fluid to the cooling module.

[0077] In some embodiments, the system further comprises a cooling fluid pump in fluid communication with the cooling module and the cooling fluid cooler for recirculating the cooling fluid throughout the system.Heat exchanges / heaters

[0078] The system as described herein may further comprise a one or more heat exchangers. The inclusion of one or more heat exchanges in the system allows for the redistribution of energy in the system and to improve the overall energy efficiency of the system.

[0079] In some embodiments, the system described herein further comprises at least one heat exchanger for maintaining a temperature of the membrane distillation feed solution greater than a temperature of the forward osmosis draw solution.

[0080] In some embodiments, the system described herein further comprises a heat exchanger for heating the membrane distillation feed solution; and / or a heat exchanger for cooling the concentrated forward osmosis draw solution; and / or a heat exchanger for cooling the concentrated membrane distillation feed solution. In some embodiments, the system described herein further comprises a heat exchanger for heating the membrane distillation feed solution. In some embodiments, the system described herein further comprises a heat exchanger for cooling the concentrated forward osmosis draw solution. In some embodiments, the system described herein further comprises a heat exchanger for cooling the concentrated membrane distillation feed solution. In some embodiments, the system described herein further comprises a heat exchanger for heating the membrane distillation feed solution and a heat exchanger for cooling the concentrated forward osmosis draw solution. In some embodiments, the system described herein further comprises a heat exchanger for cooling the concentrated forward osmosis draw solution and a heat exchanger for cooling the concentrated membrane distillation feed solution. In some embodiments, the system described herein further comprises a heat exchanger for heating the membrane distillation feed solution and a heat exchanger for cooling the concentrated membrane distillation feed solution. In some embodiments, the system described herein further comprises a heat exchanger for heating the membrane distillation feed solution, a heat exchanger for cooling the concentrated forward osmosis draw solution, and a heat exchanger for cooling the concentrated membrane distillation feed solution.

[0081] In some embodiments the heating and / or cooling is effected by a renewable energy source. In some embodiments, heating the membrane distillation feed solution is effected by a renewable energy source. In some embodiments, cooling the concentrated forward osmosis draw solution is effected by a renewable energy source. In some embodiments, cooling the concentrated membrane distillation feed solution is effected by a renewable energy source.Energy recovery

[0082] The system as described herein may further comprise an energy recovery device. In some embodiments, the energy recovery device is configured to be in communication with the reverse osmosis feed side flow path.Collection tanks

[0083] The system may further comprise one or more collection tanks. Collection tanks may be used to store water recovered from the system.

[0084] In some embodiments, the system further comprises a membrane distillation permeate collection tank comprising a permeate inlet in fluid communication with the membrane distillation permeate outlet. The membrane distillation permeate collection tank is preferably positioned at a lower height than the membrane distillation permeate outlet. In some embodiments, the system further comprises a membrane distillation permeate collection tank comprising a permeate collection tank inlet in fluid communication with the membrane distillation permeate recovery port and membrane distillation permeate outlet. The membrane distillation permeate collection tank is preferably positioned at a lower height than the membrane distillation permeate recovery port and membrane distillation permeate outlet. In some embodiments, the membrane distillation permeate may be fed to the membrane distillation permeate collection tank above the surface of membrane distillation permeate collected therein.

[0085] In some embodiments, the membrane distillation permeate collection tank is open to atmosphere, wherein the membrane distillation permeate is fed to the membrane distillation permeate collection tank below the surface of membrane distillation permeate collected therein.

[0086] In other embodiment, the membrane distillation permeate collection tank is an air-tight closed tank. In such embodiments, the membrane distillation permeate may befed to the membrane distillation permeate collection tank above the surface of membrane distillation permeate collected therein.

[0087] In some embodiments, the system further comprises a reverse osmosis collection tank in fluid communication with the reverse osmosis permeate outlet. In some embodiments, the reverse osmosis permeate collection tank is open to atmosphere.METHOD

[0088] In another aspect of the present disclosure there is provided a method for recovering water from a feed solution. The method utilises the system described herein.

[0089] In another aspect of the present disclosure, there is provided a method for recovering water from a membrane distillation feed solution, the method comprising: feeding a membrane distillation feed solution to a membrane distillation feed side of a membrane distillation module, wherein membrane distillation permeate vapour passing through a membrane distillation membrane undergoes condensation in a membrane distillation permeate side of the membrane distillation module, and is recovered as a permeate solution comprising recovered water from the membrane distillation feed solution; feeding a cooling fluid to a cooling fluid inlet of a cooling module, such that the cooling fluid passes though the cooling module to a cooling fluid outlet of the cooling module; and heating the cooling fluid flowing through the cooling module with heat generated from the condensation of the membrane distillation permeate vapour on the membrane distillation permeate side.

[0090] In some embodiments, the cooling module is a forward osmosis module and the method further comprises: feeding a forward osmosis feed solution to a forward osmosis feed side of a forward osmosis module;feeding a concentrated forward osmosis draw solution to a forward osmosis draw side of the forward osmosis module, such that water passes from the forward osmosis feed solution through a forward osmosis membrane to the forward osmosis draw solution to provide a diluted forward osmosis draw solution; and wherein the forward osmosis draw solution is the cooling fluid.

[0091] In another aspect of the present disclosure, there is provided a method for recovering water comprising: feeding a feed solution to a forward osmosis feed side of a forward osmosis module; feeding a concentrated forward osmosis draw solution to a forward osmosis draw side of the forward osmosis module, such that water passes from the lower osmotic pressure feed solution through a forward osmosis membrane to the higher osmotic pressure forward osmosis draw solution to provide a diluted forward osmosis draw solution; feeding a membrane distillation feed solution to a membrane distillation feed side of a membrane distillation module, wherein membrane distillation permeate vapour passing through a membrane distillation membrane undergoes condensation in a membrane distillation permeate side of the membrane distillation module; and heating the forward osmosis draw solution flowing through the forward osmosis draw side of the forward osmosis module with heat generated from the condensation of the membrane distillation permeate vapour.

[0092] In some embodiments, the method comprises, wherein the combined system design of the cooling module or the forward osmosis module and the membrane distillation membrane module, wherein a thermally conductive wall separates the membrane distillation permeate side and the forward osmosis draw side, herein the permeate outlet is in communication with a permeate recovery port and membrane distillation collection tank with the means of applying vacuum.

[0093] In some embodiments, the method comprises the membrane distillation, or forward osmosis and the membrane distillation modules have one or multiple stacked flat plate modules and are mounted in a filter press type setup.

[0094] In some embodiments, the method further comprises:feeding reverse osmosis feed solution to a reverse osmosis feed side of a reverse osmosis module such that water passes through a reverse osmosis membrane to provide a reverse osmosis permeate comprising recovered water from the reverse osmosis feed solution and a concentrated reverse osmosis feed solution; and wherein the membrane distillation feed solution comprises at least a portion of the concentrated reverse osmosis feed solution.

[0095] In some embodiments, the method further feeding the concentrated membrane distillation feed solution to a crystalliser to form and concentrated crystalliser composition; and optionally, a depleted crystalliser solution. In some embodiments, the depleted crystalliser solution is combined with the permeate solution.Heating and cooling

[0096] In some embodiments, the method further comprises heating the membrane distillation feed solution; cooling the concentrated forward osmosis draw solution; and / or cooling the concentrated membrane distillation feed solution.

[0097] In some embodiments, the method described herein further comprises heating the membrane distillation feed solution; and / or cooling the concentrated forward osmosis draw solution; and / or cooling the concentrated membrane distillation feed solution. In some embodiments, the method described herein further comprises heating the membrane distillation feed solution. In some embodiments, the method described herein further comprises cooling the concentrated forward osmosis draw solution. In some embodiments, the method described herein further comprises cooling the concentrated membrane distillation feed solution. In some embodiments, the method described herein further comprises heating the membrane distillation feed solution and cooling the concentrated forward osmosis draw solution. In some embodiments, the method described herein further comprises cooling the concentrated forward osmosis draw solution and cooling the concentrated membrane distillation feed solution. In some embodiments, the method described herein further comprises heating the membrane distillation feed solution and cooling the concentrated membrane distillationfeed solution. In some embodiments, the method described herein further comprises heating the membrane distillation feed solution, cooling the concentrated forward osmosis draw solution, and cooling the concentrated membrane distillation feed solution.

[0098] In some embodiments, the method further comprises recirculating the cooling fluid. In some embodiments, the method described herein further comprises cooling the heated cooling fluid for re-use as the cooling fluid.

[0099] In some embodiments the heating and / or cooling is effected by a renewable energy source. In some embodiments, heating the membrane distillation feed solution is effected by a renewable energy source. In some embodiments, cooling the concentrated forward osmosis draw solution is effected by a renewable energy source. In some embodiments, cooling the concentrated membrane distillation feed solution is effected by a renewable energy source.Description of figures

[0100] The system and method described herein are highly tailorable, and a variety of flow path configurations can be implemented to achieve a desired efficiency and / or effectiveness for a given system. Depending on the nature of the feed wastewater and / or the solution available to act as the concentrated forward osmosis draw solution, the configuration of the flow paths can be modified to achieve optimal results. The system integration allows for efficient energy transfer between streams and or process units reducing the need for additional energy to be input in the system.

[0101] Figure 1 shows a commercial air gap membrane distillation system in which comprises a membrane distillation membrane (1310) defining a membrane distillation feed side (1320) and an air gap (1330). Membrane distillation feed solution (AGMDFIN, AGMDFOUT) flows through the membrane distillation feed side (1320), whereby water vapour (permeate) passes through the membrane (1310) into the air gap (1330) where it condenses to form the condensed permeate (AGMDPOUT). The air gapis cooled by a cooling solution (AGMDCIN, AGMDCOUT) flowing through a cooling section (1380).

[0102] Referring initially to Figure 2, in some embodiments, feed wastewater (FOFSIN) is input to the forward osmosis feed side (220). A concentrated forward osmosis draw solution (FODSIN) is input to the forward osmosis draw side (230). The concentrated forward osmosis draw solution (FODSIN) comprises a higher concentration of solutes than the feed wastewater (FOFSIN) such that an osmotic pressure gradient exists between the feed and draw sides of the forward osmosis module (200) which induces water on the forward osmosis feed side (220) to cross the forward osmosis membrane (210). This water dilutes the concentrated forward osmosis draw solution (FODSIN) such that a diluted forward osmosis draw solution (FODSOUT) is output from the forward osmosis draw side (230). The water depleted stream on the forward osmosis feed side is output from the forward osmosis feed side (220) as concentrated feed wastewater (FOFSOUT). The concentrated feed osmosis draw solution (FODSIN) may be any suitable solution including, but not limited to, seawater, brine solution, or salt solution. The membrane distillation feed solution (MDFIN) may comprise, but is not limited to, at least a portion of the diluted forward osmosis draw solution (FODSOUT). Prior to being fed to the membrane distillation module (300) the membrane distillation feed solution (MDFIN) may be heated to above ambient temperature and more than the temperature of inlet concentrated forward osmosis draw solution (FODSIN). This creates a difference in water vapour pressure on the membrane distillation feed side (320) relative to the membrane distillation permeate side (330) such that water vapour from the membrane distillation feed side (320) crosses the membrane distillation membrane (310) to the membrane distillation permeate side (330).

[0103] In some embodiments, the system (100) may be configured such that the membrane distillation feed outlet is in fluidic communication with the forward osmosis draw inlet such that the concentrated forward osmosis draw solution (FODSIN) comprises at least a portion of the concentrated membrane distillation feed solution (MDFOUT). Advantageously, this configuration can increase the concentration ofsolutes in the concentrated forward osmosis draw solution (FODSIN), in particular where there is a source of concentrated forward osmosis draw solution (FODSIN) that has sufficient solute concentration to provide an adequate osmotic pressure gradient between the feed and draw side of the forward osmosis module (200). Prior to being fed to the forward osmosis draw inlet the at least a portion of the concentrated membrane distillation feed solution (MDFOUT) may be cooled.

[0104] In the embodiment depicted in Figures 3 and 4, the reverse osmosis feed solution (ROFSIN) comprises at least a portion of the diluted forward osmosis draw solution (FODSOUT). The water recovered from the reverse osmosis permeate side (630) is high quality water, such as to potable level, and can be obtained from the impaired water, such as mine wastewaters. The system (100) is configured such that the reverse osmosis feed outlet is in fluid communication with the forward osmosis draw inlet such that the concentrated forward osmosis draw solution (FODSIN) comprises at least a portion of the concentrated reverse osmosis feed solution (ROFSOUT). In addition, the system (100) is configured such that the membrane distillation feed outlet is in fluidic communication with the forward osmosis draw inlet such that the concentrated forward osmosis draw solution (FODSIN) comprises at least a portion of the concentrated membrane distillation feed solution (MDFOUT). Advantageously, this configuration can increase the concentration of solutes in the concentrated forward osmosis draw solution, in particular where there is a source of concentrated forward osmosis draw solution (FODSIN) that has sufficient solute concentration to provide an adequate osmotic pressure gradient between the feed and draw side of the forward osmosis module (200).

[0105] Prior to being fed to the forward osmosis draw inlet the at least a portion of the concentrated reverse osmosis feed solution (ROFSOUT) may be cooled. Prior to being fed to the forward osmosis draw inlet the at least a portion of the concentrated membrane distillation feed solution (MDFOUT) may be cooled. Prior to being fed to the forward osmosis draw inlet the at least a portion of the concentrated membrane distillation feed solution (MDFOUT) and the concentrated reverse osmosis feed solution (ROFSOUT) may be mixed to form a single fluid stream. Prior to being fed to theforward osmosis draw inlet the single fluid stream may be cooled. The membrane distillation feed solution (MDFIN) comprises at least a portion of the diluted forward osmosis draw solution (FODSOUT). Prior to being fed to the membrane distillation module (300) the membrane distillation feed solution (MDFIN) is heated to above ambient temperature. The heating above ambient temperature creates a difference in water vapour pressure on the membrane distillation feed side (320) relative to the membrane distillation permeate side (330) such that water vapour from the membrane distillation feed side (320) crosses the membrane distillation membrane (310) to the membrane distillation permeate side (330).

[0106] Advantageously, the forward osmosis draw solution (FODSIN) flowing along the forward osmosis draw flow path is heated by heat released from the condensation of the vapour which crosses the membrane distillation membrane (310) on the membrane distillation permeate side (330) surface. This thereby raises the temperature of the diluted forward osmosis draw solution (FODSOUT) meaning less energy is required to be input to heat the portion of the diluted forward osmosis draw solution (FODSOUT) which is used as the membrane distillation feed solution (MDFIN) to the desired temperature to create a satisfactory vapour pressure difference in the membrane distillation module (300). Further, the removal of heat from the membrane distillation permeate side (330) of the membrane distillation module (300) by the forward osmosis draw solution (FODSOUT) can assist in maintaining the temperature difference between the membrane distillation feed side (320) and membrane distillation permeate side (330) thereby ensuring that a satisfactory vapour pressure difference exists between the two sides of the membrane distillation module (300) to induce water vapour diffusion across the membrane distillation membrane (310).

[0107] In the embodiments in Figures 2-5, and as shown in more detail in Figure 6, the system (100) is configured such that a venturi vacuum generator (500) is in fluid communication with a fluid thereby to generate a vacuum applied to the membrane distillation air-gap permeate side (330) of the membrane distillation module (300). In some embodiments, the fluid generating the vacuum may be the feed waste water (FOFSIN) or the diluted forward osmosis draw solution (FODSOUT). The presence of theventuri vacuum generator (500) may enhance the water recovery through the membrane (330) and removes the requirement of additional separate vacuum pumps.

[0108] The system (100) may further be configured such that the condensing vapour in the membrane distillation air-gap permeate side (330) generate a vacuum to the membrane distillation air-gap permeate side (330) of the membrane distillation module (300).

[0109] In some embodiments, as depicted in Figures 2-5, feed wastewater (FOFSIN) is input to the forward osmosis feed side (220). A concentrated feed osmosis draw solution (FODSIN) is input to the forward osmosis draw side (230). The concentrated forward osmosis draw solution (FODSIN) comprises a higher concentration of solutes than the feed wastewater (FOFSIN) such that an osmotic pressure gradient exists between the feed and draw sides of the forward osmosis module (200) which induces water on the forward osmosis feed side (220) to cross the forward osmosis membrane (210). This water crossing the forward osmosis membrane (210) dilutes the concentrated forward osmosis draw solution (FODSIN) such that a diluted forward osmosis draw solution (FOFSOUT) is output from the forward osmosis draw side (220). The water depleted stream on the forward osmosis feed side (220) is output from the forward osmosis feed side (220) as concentrated feed wastewater (FOFSOUT). The concentrated feed osmosis draw solution (FODSIN) may be any suitable solution including, but not limited to, seawater, brine solution, or salt solution.

[0110] In the embodiment depicted in Figure 5, the reverse osmosis feed solution (ROFSIN) comprises the diluted forward osmosis draw solution (FODSOUT). The water recovered from the reverse osmosis permeate side (630) is high quality water, such as to potable level, and can be obtained from the impaired water, such as the mine wastewater. The system (100) is configured such that the reverse osmosis feed outlet is in fluidic communication with the membrane distillation feed inlet such that the membrane distillation feed solution (MDFIN) comprises at least a portion of the concentrated reverse osmosis feed solution (ROFSOUT). Prior to being fed to the membrane distillation module (300) the membrane distillation feed solution (MDFIN) isheated to above ambient temperature. The heating above ambient temperature creates a difference in water vapour pressure on the membrane distillation feed side (320) relative to the membrane distillation permeate side (330) such that water vapour from the membrane distillation feed side (320) crosses the membrane distillation membrane (310) to the membrane distillation permeate side 9330). In addition, the system (100) is configured such that the membrane distillation feed outlet is in fluidic communication with the forward osmosis draw inlet such that the concentrated forward osmosis draw solution (FODSIN) comprises at least a portion of the concentrated membrane distillation feed solution (MDFOUT). Advantageously, this configuration can increase the concentration of solutes in the concentrated forward osmosis draw solution (FOFSOUT), in particular where there is a source of concentrated forward osmosis draw solution (F OF SIN) that has sufficient solute concentration to provide an adequate osmotic pressure gradient between the feed and draw side of the forward osmosis.

[0111] In some embodiments, prior to being fed to the forward osmosis draw inlet the at least a portion of the concentrated membrane distillation feed solution (MDFOUT) may be cooled. Advantageously, the forward osmosis draw solution (FODSIN) flowing along the forward osmosis draw flow path is heated by heat released from the condensation of the vapour which crosses the membrane distillation membrane (310) on the membrane distillation permeate side (330) surface. This thereby raises the temperature of the diluted forward osmosis draw solution (FODSOUT) meaning less energy is required to be input to heat the portion of the diluted forward osmosis draw solution (FODSOUT) which is used as the membrane distillation feed solution (MDFIN) to the desired temperature to create a satisfactory vapour pressure difference in the membrane distillation module (300). Further, the removal of heat from the membrane distillation permeate side (330) of the membrane distillation module (300) by the forward osmosis draw solution (FODSIN) can assist in maintaining the temperature difference between the membrane distillation feed side (320) and membrane distillation permeate side (330) thereby ensuring that a satisfactory vapour pressure difference exists between the two sides of the membrane distillation module (300) to induce water vapour diffusion across the membrane distillation membrane (310).

[0112] In some embodiments, the system (100) may be configured such that a first venturi vacuum generator (500) is in fluid communication with the feed wastewater (FOFSIN) or is in fluid communication with the diluted forward osmosis draw solution (FODSOUT) thereby to generate a vacuum applied to the membrane distillation air-gap permeate side (330) of the membrane distillation module (300). In another embodiment, the system (100) is configured such that a venturi vacuum generator (500) is in fluid communication with any fluid thereby to generate a vacuum applied to the membrane distillation air-gap permeate side (330) of the membrane distillation module (300). The presence of the venturi vacuum generators (500) may enhance the water recovery through the membrane (310) and removes the requirement of additional separate vacuum pump.

[0113] In some embodiments, , the system (100) is configured such that the condensing vapour in the membrane distillation air-gap permeate side generate a vacuum to the membrane distillation air-gap permeate side (330) of the membrane distillation module (300).

[0114] In the embodiment, as depicted in Figure 7, the means of applying vacuum comprising a venturing vacuum generator (500) thereby to generate a vacuum to the membrane distillation air-gap permeate side (330) of the membrane distillation module (300). In the embodiment shown in Figure 7, the membrane distillation permeate collection tank (800) is an air-tight closed tank, wherein the membrane distillation permeate (MDPOUT) is fed to the membrane distillation permeate collection tank (800) above the surface of membrane distillation permeate collected therein.

[0115] In another embodiment as depicted in Figure 7, the means of applying vacuum (800) from condensing vapour in the membrane distillation air-gap permeate side to generate a vacuum to the membrane distillation air-gap permeate side (330) of the membrane distillation module. In this embodiment, the membrane distillation permeate collection tank (800) is open to atmosphere, wherein the membrane distillation permeate (MDPOUT) is fed to the membrane distillation permeate collection tank (800) below the surface of membrane distillation permeate (MDPOUT) collected therein. Themembrane distillation permeate collection tank (800) is at a lower height than the membrane distillation air-gap permeate side (330) of the membrane distillation module. The overflow from the permeate collection tank is the recovered permeate water and can be collected continuously.

[0116] In some embodiments, as depicted in Figures 8-10, the system (100) is in the form of a series of stacked flat plates configured to define the forward osmosis and membrane distillation modules. The stacked flat plates include a forward osmosis feed cell (201), a membrane distillation feed cell (301) and a connecting cell (401).

[0117] The forward osmosis feed cell (201) comprises a forward osmosis feed side, the membrane distillation feed cell (301) comprises a membrane distillation feed side, and the connecting cell (401) comprises a forward osmosis draw side and a membrane distillation permeate side, with the thermally conductive wall integrally formed between the forward osmosis draw side and the membrane distillation permeate side.

[0118] The forward osmosis membrane (210) is configured to be received between the forward osmosis feed side of the forward osmosis feed cell (201) and the forward osmosis draw cell of the connecting cell (401). The membrane distillation membrane (310) is configured to be received between the membrane distillation permeate side of the connecting cell (401) and the membrane distillation feed side of the membrane distillation feed cell (301).

[0119] In use, the forward osmosis cell (201), the connecting cell (401), and the membrane distillation cell (301) are sealed together with the respective membranes (210, 310) in place such that the forward osmosis cell (201), the forward osmosis membrane (210) and the connecting cell (401) define the forward osmosis module (200) and the connecting cell (401), the membrane distillation membrane (310) and the membrane distillation cell (301) define the membrane distillation module (300). The system may further comprises one or more end plates (120) and one or more support legs (110). In some embodiments, the system may comprise one or more spacers (130) for positioning between the cells (201, 401, 301).

[0120] In some embodiments, as shown for example in Figure 8, the system may comprise one such set of planar cells (201, 401, 301). In other embodiments, such as shown in Figure 9, the system may comprise multiple sets of the planar cells (201, 301, 401).

[0121] In some embodiments, the planar cells (201, 401, 301) may be configured to be received in a conventional plate and frame filter assembly. In this way, the plates can be easily assembled and pressed together.

[0122] In some embodiments, as shown for example in Figures 8 to 10, the system may comprise one or more membrane distillation permeate recovery ports (340). In some embodiments, the membrane distillation permeate recovery port (340) is configured to attach to the connecting cell (401) to allow for the efficient permeate recovery while maintaining a small air gap width of between connecting cell (401) and membrane distillation membrane (310).

[0123] Referring to Figures 11 and 12, an alternate embodiment of a system (1000) combining cooling and membrane distillation modules is shown. The system (1000) comprises a membrane distillation feed cell (1301) and cooling cells (1201).

[0124] The cooling cells (1201) comprise cooling fluid flow paths (1240) for flow of the cooling fluid within the cell (1201). The cell further comprises a pair of walls (1400) enclosing the fluid flow paths. In the system of Figures 11 and 12, the walls (1400) act as the thermally conductive wall as described herein.

[0125] To assist in heat transfer between the membrane distillation feed cell (1301) and the cooling cell (1201) the walls (1400) are provided with a number of surface structures (1410). In the embodiment of Figures 11 and 12, 8 such surface structures (1410) are provided and defined by a boundary. Each of the surface structures (1410) is provided with surface features (1420), shown here with four parallel angled elements across the surface structure (1410). However, it will be appreciated that other such structures and features may be utilised.

[0126] The membrane distillation feed cell (1301) comprises a number of receiving elements (1350) of complementary shape, size and positioning to the boundaries of the surface structures (1410), so as to receive the surface structures (1420) in sealing engagement with the membrane distillation membrane (1310) and the cooling cell (1201).Stream temperaturesMembrane distillation feed solution (MDFIN)

[0127] The temperature of the membrane distillation feed solution (MDFIN) may be provided such that that the vapour developing at the membrane distillation feed side (320) of the membrane distillation membrane (310) follows the pressure drop, permeating through the pores and condenses on the cooler side membrane distillation permeate side (33) of the membrane distillation membrane (310). In one embodiment, the membrane distillation feed solution (MDFIN) may be feed to the membrane distillation module (300) at a temperature of between about 30°C to about 80°C, about 40 °C and 70 °C, about 50 °C and 60 °C. In one example, the membrane distillation feed solution (MDFIN) may be feed to the membrane distillation module (300) at a temperature of about 55 °C.

[0128] In one embodiment, the membrane distillation feed solution (MDFIN) is heated to a temperature prior to feeding to the membrane distillation feed side (320) of the membrane distillation module (300) of between about 30°C to about 80°C, about 40 °C and 70 °C, about 50 °C and 60 °C. In one example, the membrane distillation feed solution (MDFIN) is heated to a temperature prior to feeding to the membrane distillation feed side (320) of the membrane distillation module (300) at a temperature of about 55 °C.Concentrated forward osmosis draw solution (FODSIN)

[0129] The temperature of the concentrated forward osmosis draw solution (FODSIN) may be provided such that that there is a sufficient temperature difference between the forward osmosis draw side (230) and the membrane distillation permeate side (330) to ensure satisfactory removal of heat from the membrane distillation permeate side (330) by the forward osmosis draw solution (FODSIN). In one embodiment, the concentrated forward osmosis draw solution (FODSIN) may be feed to the forward osmosis module (200) at a temperature of between about 5°C to about 35°C, about 10 °C to about 30 °C, about 15 °C to about 25 °C. In one example, the concentrated forward osmosis draw solution (FODSIN) may be feed to the forward osmosis module (200) at a temperature of about 15 °C. In one example, the concentrated forward osmosis draw solution (FODSIN) may be feed to the forward osmosis module (200) at a temperature of about 20 °C.Diluted forward osmosis draw solution (FODSOUT)

[0130] The temperature of the diluted forward osmosis draw solution (FODSOUT) may be controlled such that the feed to either the membrane distillation module (300) and / or the reverse osmosis module (600) does not require heating. In one embodiment, the diluted forward osmosis draw solution (FODSOUT) has a temperature of between about 15°C to about 55°C, about 20°C to about 50 °C, about 30 °C to about 40 °C. In one example, the diluted forward osmosis draw solution (FODSOUT) may be outlet from the forward osmosis module (200) at a temperature of about 30 °C. In one example, the diluted forward osmosis draw solution (FODSOUT) may be outlet from the forward osmosis module (200) at a temperature of about 35 °C.Concentrated membrane distillation feed solution (MDFQUT)

[0131] At least a portion of the concentrated membrane distillation feed solution (MDFOUT) may be cooled before being included as at least a portion of the concentrated forward osmosis draw solution (FODSIN). In one embodiment, the at least a portion of the concentrated membrane distillation feed solution (MDFOUT) may be cooled to a temperature of between about 5°C to about 35°C, about 10 °C and 30 °C, about 15 °Cand 25 °C. In one example, at least a portion of the concentrated membrane distillation feed solution (MDFOUT) may be cooled to a temperature of about 15 °C. In one example, at least a portion of the concentrated membrane distillation feed solution (MDFOUT) may be cooled to a temperature of about 20 °C.Cooling fluid

[0132] The temperature of the cooling fluid input to the cooling module may be provided such that that there is a sufficient temperature difference between the cooling module and the membrane distillation permeate side to ensure satisfactory removal of heat from the membrane distillation permeate side by the cooling fluid. In one embodiment, the the cooling fluid may be feed to the cooling module at a temperature of between about 5°C to about 35°C, about 10 °C to about 30 °C, about 15 °C to about 25 °C. In one example, the cooling fluid may be feed to the cooling module at a temperature of about 15 °C. In one example, the cooling fluid may be feed to the cooling module at a temperature of about 20 °C.

[0133] In one embodiment, the cooling fluid outlet from the cooling module has a temperature of between about 10°C to 55°C, 15°C to about 55°C, about 20°C to about 50 °C, about 30 °C to about 40 °C. In one example, the cooling fluid outlet from the cooling module is at a temperature of about 30 °C. In one example, the cooling fluid outlet from the cooling module is at a temperature of about 35 °C.Concentrated reverse osmosis feed solution (ROFSOUT)

[0134] At least a portion of the concentrated reverse osmosis feed solution (ROFSOUT) may be cooled before being included as at least a portion of the concentrated reverse forward osmosis draw solution (ROFSOUT). In one embodiment, the at least a portion of the concentrated reverse osmosis feed solution (ROFSOUT) may be cooled to a temperature of between about 5°C to about 35°C, about 10 °C and 30 °C, about 15 °C and 25 °C. In one example, at least a portion of the concentrated reverse osmosis feed solution (ROFSOUT) may be cooled to a temperature of about 15 °C. Inone example, at least a portion of the concentrated reverse osmosis feed solution (ROFSour)may be cooled to a temperature of about 20 °C.Temperature difference between membrane distillation feed side (320) and membrane distillation permeate side (330)

[0135] The temperature difference through the membrane (310) of the membrane distillation module (300) ensures that the vapour developing at the membrane surface follows the pressure drop, permeating through the pores and condensing on the cooler side. In some embodiments, the difference between the two sides of the membrane distillation module (300) is between about 40°C and 70 °C, 5 °C and 35 °C, about 5 °C and 20 °C.Flow ratesFeed wastewater (F OF SIN)

[0136] In some embodiments, the volumetric flow rate of the feed wastewater (FOFSIN) in litres per minute (L / min) is greater than about 0.1, 0.5, 1, 2, 3, 4, 5, 10, 15, 20, 25 50, 75, 100, 150, 200, 250, 500, 750, 1000, 2000, 3000, 4000, or 5000. In some embodiments, the volumetric flow rate of the feed wastewater (FOFSiN)in litres per minute (L / min) is less than about 10000, 5000, 4000, 3000, 2000, 1000, 750, 500, 250, 200, 150, 100, 75, 50, 100. The volumetric flow rate of the feed wastewater (FOFSIN) may be in a range provided by any two or more of the upper and / or lower amounts, for example between about 0.1 and 10000, between about 1 and 5000, or between about 5 and 25. These volumetric flow rates may relate to the feed to a single or multiple forward osmosis modules. It will be appreciated by the person skilled in the art that multiple forward osmosis modules may be combined such that volumetric flow rate of feed wastewater (FOFSIN) to the system is greater than the volumetric flow rate of feed wastewater (FOFSIN) to a single forward osmosis module.Concentrated feed wastewater (FOFSOUT)

[0137] In some embodiments, the volumetric flow rate of the concentrated feed wastewater (FOFSOUT) is defined in terms of equivalents ((L / min) / (L / min)), relative to the volumetric flow rate of feed wastewater (FOFSIN), that is the ratio the volumetric flow rate of the concentrated feed wastewater (FOFSOUT) relative to the volumetric flow rate of feed wastewater (FOFSIN), is less than about 1, 0.9, 0.8, 0.7, 0.6, 0.05 or 0.1. In some embodiments, the volumetric flow rate of the concentrated feed wastewater (FOFSOUT) is defined in terms of equivalents ((L / min) / (L / min)), relative to the volumetric flow rate of feed wastewater (FOFSIN), is greater than about 0.01, 0.1, 0.2, 0.3, 0.4, or 0.5. The volumetric flow rate of the concentrated feed wastewater (FOFSour)defined in terms of equivalents ((L / min) / (L / min)), relative to the volumetric flow rate of feed wastewater (FOFSIN) may be in a range provided by any two or more of the upper and / or lower amounts, for example between about 0.01 and 1, between about 0.1 and 0.9, between about 0.2 and 0.9, or between about 0.3 and 0.7.Concentrated forward osmosis draw solution (FODSIN)

[0138] In some embodiments, the volumetric flow rate of the concentrated forward osmosis draw solution (FODSIN) defined in terms of equivalents ((L / min) / (L / min)), relative to the volumetric flow rate of feed wastewater (FOFSIN), that is the ratio the volumetric flow rate of the concentrated forward osmosis draw solution (FODSIN) relative to the volumetric flow rate of feed wastewater (FOFSIN), is less than about 5, 4, 3, 2, 1.5, 1.2, 1, 0.9, 0.8, 0.7, 0.6, or 0.5. In some embodiments, the volumetric flow rate of the concentrated forward osmosis draw solution (FODSIN) defined in terms of equivalents ((L / min) / (L / min)), relative to the volumetric flow rate of feed wastewater (FOFSIN), is greater than about 0.1, 0.2, 0.3, 0.4, 0.5, 0.6, 0.7, 0.8, 0.9, 1, 1.2, 1.5 or 2. The volumetric flow rate of the concentrated forward osmosis draw solution (FODSIN) defined in terms of equivalents ((L / min) / (L / min)), relative to the volumetric flow rate of feed wastewater (FOFSIN) may be in a range provided by any two or more of the upper and / or lower amounts, for example between about 0.1 and 5, between about 0.2 and 3, between about 0.5 and 1, or between about 1 and 2.Diluted forward osmosis draw solution (FODSOUT)

[0139] In some embodiments, the volumetric flow rate of the diluted forward osmosis draw solution (FODSOUT) defined in terms of equivalents ((L / min) / (L / min)), relative to the volumetric flow rate of feed wastewater (FOFSIN), that is the ratio the volumetric flow rate of the diluted forward osmosis draw solution (FODSOUT) relative to the volumetric flow rate of feed wastewater (FOFSIN), is less than about 5, 4, 3, 2, 1.5, 1, 0.9, 0.8, 0.7, 0.6, or 0.5. In some embodiments, the volumetric flow rate of the diluted forward osmosis draw solution (FODSOUT) defined in terms of equivalents ((L / min) / (L / min)), relative to the volumetric flow rate of feed wastewater (FOFSIN), is greater than about 0.1, 0.2, 0.3, 0.4, 0.5, 0.6, 0.7, 0.8, 0.9 or 1. The volumetric flow rate of the diluted forward osmosis draw solution (FODSOUT) defined in terms of equivalents ((L / min) / (L / min)), relative to the volumetric flow rate of feed wastewater (FOFSIN) may be in a range provided by any two or more of the upper and / or lower amounts, for example between about 0.1 and 5, between about 0.2 and 3, between about 2 and 3, or between 1 and 4.Membrane distillation feed solution (MDFIN)

[0140] In some embodiments, the volumetric flow rate of the membrane distillation feed solution (MDFIN) defined in terms of equivalents ((L / min) / (L / min)), relative to the volumetric flow rate of feed wastewater (FOFSIN), that is the ratio the volumetric flow rate of the membrane distillation feed solution (MDFIN) relative to the volumetric flow rate of feed wastewater (FOFSIN), is less than about 5, 4, 3, 2, 1.5, 1, 0.9, 0.8, 0.7, 0.6, or 0.5. In some embodiments, the volumetric flow rate of the membrane distillation feed solution (MDFIN) defined in terms of equivalents ((L / min) / (L / min)), relative to the volumetric flow rate of feed wastewater (FOFSIN), is greater than about 0.1, 0.2, 0.3, 0.4, 0.5, 0.6, 0.7, 0.8, 0.9 or 1. The volumetric flow rate of the membrane distillation feed solution (MDFIN) defined in terms of equivalents ((L / min) / (L / min)), relative to the volumetric flow rate of feed wastewater (FOFSIN) may be in a range provided by any two or more of the upper and / or lower amounts, for example between about 0.1 and 5, between about 0.2 and 3, or between about 0.2 and 1, or between 1 and 4.Concentrated membrane distillation feed solution (MDFOUT)

[0141] In some embodiments, the volumetric flow rate of the concentrated membrane distillation feed solution (MDFOUT) defined in terms of equivalents ((L / min) / (L / min)), relative to the volumetric flow rate of feed wastewater (FOFSIN), that is the ratio the volumetric flow rate of the concentrated membrane distillation feed solution (MDFOUT) relative to the volumetric flow rate of feed wastewater (FOFSIN), is less than about 5, 4, 3, 2, 1.5, 1, 0.9, 0.8, 0.7, 0.6, or 0.5. In some embodiments, the volumetric flow rate of the concentrated membrane distillation feed solution (MDFOUT) defined in terms of equivalents ((L / min) / (L / min)), relative to the volumetric flow rate of feed wastewater (FOFSIN), is greater than about 0.1, 0.2, 0.3, 0.4, 0.5, 0.6, 0.7, 0.8, 0.9 or 1. The volumetric flow rate of the concentrated membrane distillation feed solution (MDFOUT) defined in terms of equivalents ((L / min) / (L / min)), relative to the volumetric flow rate of feed wastewater (FOFSIN) may be in a range provided by any two or more of the upper and / or lower amounts, for example between about 0.1 and 5, between about 0.2 and 3, or between about 0.2 and 0.8.Membrane distillation permeate solution (MDPQUT)

[0142] In some embodiments, the volumetric flow rate of the membrane distillation permeate solution (MDPOUT) defined in terms of equivalents ((L / min) / (L / min)), relative to the volumetric flow rate of feed wastewater (FOFSIN), that is the ratio the volumetric flow rate of the membrane distillation permeate solution (MDPOUT) relative to the volumetric flow rate of feed wastewater (FOFSIN), is less than about 1, 0.9, 0.8, 0.7, 0.6, 0.5, 0.4, 0.3, 0.2, or 0.1. In some embodiments, the volumetric flow rate of the membrane distillation permeate solution (MDPOUT) defined in terms of equivalents ((L / min) / (L / min)), relative to the volumetric flow rate of feed wastewater (FOFSIN), is greater than about 0.01,0.02, 0.03, 0.04, 0.05, 0.1, 0.2, 0.3, 0.4, 0.5, 0.6, 0.7, 0.8, 0.9 or 1. The volumetric flow rate of the membrane distillation permeate solution (MDPOUT) defined in terms of equivalents ((L / min) / (L / min)), relative to the volumetric flow rate of feed wastewater (FOFSIN) may be in a range provided by any two or more of theupper and / or lower amounts, for example between about 0.01 and 1, between about 0.02 and 0.8, or between about 0.05 and 0.5.Reverse osmosis feed solution (ROFSIN)

[0143] In some embodiments, the volumetric flow rate of the reverse osmosis feed solution (ROFSIN) defined in terms of equivalents ((L / min) / (L / min)), relative to the volumetric flow rate of feed wastewater (FOFSIN), that is the ratio the volumetric flow rate of the reverse osmosis feed solution (ROFSIN) relative to the volumetric flow rate of feed wastewater (FOFSIN), is less than about 5, 4, 3, 2, 1.5, 1, .9, 0.8, 0.7, 0.6, or 0.5. In some embodiments, the volumetric flow rate of the reverse osmosis feed solution (ROFSIN) defined in terms of equivalents ((L / min) / (L / min)), relative to the volumetric flow rate of feed wastewater (FOFSIN), is greater than about 0.1, 0.2, 0.3, 0.4, 0.5, 0.6, 0.7, 0.8, 0.9 or 1. The volumetric flow rate of the reverse osmosis feed solution (ROFSIN) defined in terms of equivalents ((L / min) / (L / min)), relative to the volumetric flow rate of feed wastewater (FOFSIN) may be in a range provided by any two or more of the upper and / or lower amounts, for example between about 0.1 and 5, between about 0.5 and 3, or between about 0.5 and 1.5.Concentrated reverse osmosis feed solution (ROFSOUT)

[0144] In some embodiments, the volumetric flow rate of the concentrated reverse osmosis feed solution (ROFSOUT) defined in terms of equivalents ((L / min) / (L / min)), relative to the volumetric flow rate of feed wastewater (FOFSIN), that is the ratio the volumetric flow rate of the concentrated reverse osmosis feed solution (ROFSOUT) relative to the volumetric flow rate of feed wastewater (FOFSIN), is less than about 5, 4, 3, 2, 1.5, 1, .9, 0.8, 0.7, 0.6, or 0.5. In some embodiments, the volumetric flow rate of the concentrated reverse osmosis feed solution (ROFSOUT) defined in terms of equivalents ((L / min) / (L / min)), relative to the volumetric flow rate of feed wastewater (FOFSIN), is greater than about 0.1, 0.2, 0.3, 0.4, 0.5, 0.6, 0.7, 0.8, 0.9 or 1. The volumetric flow rate of the concentrated reverse osmosis feed solution (ROFSOUT) defined in terms of equivalents ((L / min) / (L / min)), relative to the volumetric flow rateof feed wastewater (F OF SIN) may be in a range provided by any two or more of the upper and / or lower amounts, for example between about 0.1 and 5, between about 0.2 and 3, or between about 0.2 and 0.8.Reverse osmosis permeate solution (ROPOUT)

[0145] In some embodiments, the volumetric flow rate of the reverse osmosis permeate solution (ROPOUT) defined in terms of equivalents ((L / min) / (L / min)), relative to the volumetric flow rate of feed wastewater (FOFSIN), that is the ratio the volumetric flow rate of the reverse osmosis permeate solution (ROPOUT) relative to the volumetric flow rate of feed wastewater, is less than about 3, 2, 1, 0.9, 0.8, 0.7, 0.6, 0.5, 0.4, 0.3, 0.2, or 0.1. In some embodiments, the volumetric flow rate of the reverse osmosis permeate solution (ROPOUT) defined in terms of equivalents ((L / min) / (L / min)), relative to the volumetric flow rate of feed wastewater, is greater than about 0.1, 0.2, 0.3, 0.4, 0.5, 0.6, 0.7, 0.8, 0.9 or 1. The volumetric flow rate of the reverse osmosis permeate solution (ROPOUT) defined in terms of equivalents ((L / min) / (L / min)), relative to the volumetric flow rate of feed wastewater (FOFSIN) may be in a range provided by any two or more of the upper and / or lower amounts, for example between about 0.1 and 3, between about 0.2 and 2, or between about 0.2 and 0.8.It will be appreciated by persons skilled in the art that numerous variations and / or modifications may be made to the above-described embodiments, without departing from the broad general scope of the present disclosure. The present embodiments are, therefore, to be considered in all respects as illustrative and not restrictive.REFERENCES100 - system110 - support legs120 - end plates130 - spacers200 - forward osmosis module201 - forward osmosis feed cell210 - forward osmosis membrane220 - forward osmosis feed side230 - forward osmosis draw side300 - membrane distillation module301 - membrane distillation feed cell310 - membrane distillation membrane320 - membrane distillation feed side330 - membrane distillation permeate side340 - membrane distillation permeate recovery port400 - thermally conductive wall401 - connecting cell500 - vacuum means600 - reverse osmosis module610 - reverse osmosis membrane620 - reverse osmosis feed side630 - reverse osmosis permeate side700 - heat exchangers800 - collection tank1000 - system1120 - end plates1201 - cooling cell1240 - cooling fluid flow1301 - membrane distillation feed cell1310 - membrane distillation membrane1350 - receiving elements1400 - thermally conductive wall1410 - surface structures1420 - surface featuresFOFSIN - Forward osmosis feed solutionFOFSOUT - concentrated forward osmosis feed solutionFODSIN - concentrated forward osmosis draw solutionFODSOUT - diluted forward osmosis draw solutionMDPOUT - condensed membrane distillation permeateMDFIN - membrane distillation feed solutionMDFOUT - concentrated membrane distillation feed solutionROFSIN - Reverse osmosis feed solutionROFSOUT - concentrated reverse osmosis feed solutionROPOUT - reverse osmosis permeateAGMDCIN - feed membrane distillation cooling solutionAGMDCOUT - membrane distillation cooling solutionAGMDFIN - membrane distillation feedAGMDFOUT - concentrated membrane distillation feedAGMDPOUT - permeate

Claims

CLAIMS:

1. A system for recovering water, the system comprising: a membrane distillation module comprising: a membrane distillation membrane defining a membrane distillation feed side and a membrane distillation permeate side, wherein membrane distillation permeate vapour passing through the membrane distillation membrane undergoes condensation on the membrane distillation permeate side; a membrane distillation feed inlet for receiving a membrane distillation feed solution and a membrane distillation feed outlet for outputting concentrated membrane distillation feed solution, the membrane distillation feed inlet and the membrane distillation feed outlet defining a membrane distillation feed flow path; a membrane distillation permeate outlet for outputting condensed membrane distillation permeate comprising recovered water from the membrane distillation feed solution; a cooling module comprising; a cooling fluid inlet for receiving a cooling fluid and a cooling fluid outlet for outputting a heated cooling fluid, the cooling fluid inlet and the cooling fluid outlet defining a cooling fluid flow path wherein the cooling module and the membrane distillation permeate side are separated by a thermally conductive wall such that the cooling fluid removes heat generated from the condensation of the membrane distillation permeate vapour on the membrane distillation permeate side.

2. A system according to claim 1, wherein the cooling module is a forward osmosis module comprising: a forward osmosis membrane defining a forward osmosis feed side and a forward-osmosis draw side; a forward osmosis feed inlet for receiving a forward osmosis feed solution and a forward osmosis feed outlet for outputting concentrated feed solution, the forward osmosis feed inlet and the forward osmosis feed outlet defining a forward osmosis feed side flow path;the cooling fluid inlet is a forward osmosis draw inlet for receiving a concentrated forward osmosis draw solution and the cooling fluid outlet is a forward osmosis draw outlet for outputting diluted forward osmosis draw solution, the forward osmosis draw inlet and the forward osmosis draw outlet defining a forward osmosis draw flow path; wherein the forward osmosis draw side and the membrane distillation permeate side are separated by the thermally conductive wall such that the forward osmosis draw solution flowing along the forward osmosis draw flow path is heated by heat generated from the condensation of the membrane distillation permeate vapour on the membrane distillation permeate side.

3. A system according to claim 1 or claim 2, having a stacked flat plates, spiral wound, cylindrical or tubular configuration.

4. A system according to any one of claims 1 to 3, wherein the cooling module and the membrane distillation module are an integrated stack such that the cooling fluid flow path, the membrane distillation membrane and the thermally conductive wall form parallel planes thereby defining a laminar arrangement.

5. A system according to any one of the preceding claims, wherein the modules are configured horizontally or vertically during operation.

6. A system according to any one of the preceding claims, comprising two or more cooling modules and / or two or more membrane distillation modules, wherein the cooling module(s) and the membrane distillation module(s) are an integrated stack such that each cooling fluid flow path, membrane distillation membrane and thermally conductive wall form parallel planes thereby defining a laminar arrangement.

7. A system according to any one of the preceding claims when dependent on claim 2, wherein the forward osmosis draw outlet is in fluid communication with the membrane distillation feed inlet such that the membrane distillation feed solution comprises at least a portion of the diluted forward osmosis draw solution.

8. A system according to any one of the preceding claims when dependent on claim 2, wherein the membrane distillation feed outlet is in fluid communication with the forward osmosis draw inlet such that the concentrated forward osmosis draw solution comprises at least a portion of the concentrated membrane distillation feed solution.

9. A system according to any one of the preceding claims, further comprising a reverse osmosis module comprising: a reverse osmosis membrane defining a reverse osmosis feed side and a reverse osmosis permeate side; a reverse osmosis feed inlet for receiving a reverse osmosis feed solution and a reverse osmosis feed outlet for outputting concentrated reverse osmosis feed solution, the reverse osmosis feed inlet and the reverse osmosis feed outlet defining a reverse osmosis feed side flow path; a reverse osmosis permeate outlet for outputting reverse osmosis permeate comprising recovered water from the reverse osmosis feed solution; wherein: the reverse osmosis feed outlet is in fluid communication with the membrane distillation feed inlet such that the membrane distillation feed solution comprises at least a portion of the concentrated reverse osmosis feed solution; and / or the reverse osmosis feed inlet is in fluid communication with the forward osmosis draw outlet such that the reverse osmosis feed solution comprises at least a portion of the diluted forward osmosis draw solution.

10. A system according to claim 9, wherein the reverse osmosis feed outlet is in fluid communication with the forward osmosis draw inlet such that the concentrated forward osmosis draw solution comprises at least a portion of the concentrated reverse osmosis feed solution.

11. A system according to claim 9 or claim 10, wherein the reverse osmosis feed outlet is in fluid communication with the membrane distillation feed inlet such that themembrane distillation feed solution comprises at least a portion of the concentrated reverse osmosis feed solution.

12. A system according to any one of claims 9 to 11, further comprising an energy recovery device in communication with the reverse osmosis feed side flow path.

13. A system according to any one of the preceding claims, further comprising means for applying a vacuum to the membrane distillation permeate side of the membrane distillation module.

14. A system according to claim 13, wherein the means for applying a vacuum comprises one or more venturi vacuum generators in communication with the membrane distillation permeate side and defining a flow path for the condensed membrane distillation permeate.

15. A system according to claim 14, comprising: a venturi vacuum generator in fluid communication with the forward osmosis feed solution thereby to generate at least a portion of the vacuum applied to the membrane distillation permeate side of the membrane distillation module; and / or a venturi vacuum generator in fluid communication with the diluted forward osmosis draw solution thereby to generate at least a portion of the vacuum applied to the membrane distillation permeate side of the membrane distillation module.

16. A system according to any one of the preceding claims, further comprising a permeate recovery port to recover the permeate from the permeate outlet of the membrane distillation permeate side of the membrane distillation module.

17. A system according to claim 16, further comprising a membrane distillation permeate collection tank in fluid communication with the membrane distillation permeate outlet and the permeate recovery port.

18. A system according to claim 17, wherein the membrane distillation permeate collection tank is open to atmosphere, wherein the membrane distillation permeate is fed to the membrane distillation permeate collection tank below the surface of membrane distillation permeate collected therein.

19. A system according to claim 18, wherein the membrane distillation permeate collection tank is an air-tight closed tank, wherein, the membrane distillation permeate may be fed to the membrane distillation permeate collection tank above the surface of membrane distillation permeate collected therein.

20. A system according to any one of the preceding claims when dependent on claim 2, further comprising at least one heat exchanger for maintaining a temperature of the membrane distillation feed solution greater than a temperature of the forward osmosis draw solution.

21. A system according to claim 20, comprising: a heat exchanger for heating the membrane distillation feed solution; a heat exchanger for cooling the concentrated forward osmosis draw solution; a heat exchanger for cooling the concentrated membrane distillation feed solution; and / or a heat exchanger for cooling the concentrated reverse osmosis feed solution.

22. A system according to claim 21, wherein the heating and / or cooling is effected by a renewable energy source.

23. A system according to any one of the preceding claims, wherein the cooling module comprises a pair of spaced walls defining the cooling fluid flow path therebetween, wherein at least one of the cooling module walls forms the thermally conductive wall with the membrane distillation module.

24. A system according to claim 23, wherein the thermally conductive wall defined by the cooling module wall comprises one or more non-planar surface structures.

25. A system according to claim 24, wherein the one or more surface structures comprise one or more surface features.

26. A system according to claim 24 or claim 25, wherein the membrane distillation module comprises one or more complementary receiving elements for receiving the one or more surface structures in sealing engagement.

27. A system according to any one of the preceding claims, wherein the cooling module and membrane distillation module are configured as flat sheet plate and frame type modules.

28. A system according to claim 27, wherein the modules are configured to be stacked and mounted in a filter press type setup.

29. A system according to any one of the preceding claims, further comprising a crystalliser comprising: a crystalliser feed inlet for receiving the concentrated membrane distillation feed solution; a concentrated crystalliser outlet for outputting a concentrated crystalliser solution; and optionally, a depleted crystalliser outlet for outputting a depleted crystalliser solution.

30. A system for recovering water, the system comprising: a forward osmosis module comprising: a forward osmosis membrane defining a forward osmosis feed side and a forward-osmosis draw side;a forward osmosis feed inlet for receiving a forward osmosis feed solution and a forward osmosis feed outlet for outputting concentrated feed solution, the forward osmosis feed inlet and the forward osmosis feed outlet defining a forward osmosis feed side flow path; a forward osmosis draw inlet for receiving a concentrated forward osmosis draw solution and a forward osmosis draw outlet for outputting diluted forward osmosis draw solution, the forward osmosis draw inlet and the forward osmosis draw outlet defining a forward osmosis draw flow path; a membrane distillation module comprising: a membrane distillation membrane defining a membrane distillation feed side and a membrane distillation permeate side, wherein membrane distillation permeate vapour passing through the membrane distillation membrane undergoes condensation on the membrane distillation permeate side; a membrane distillation feed inlet for receiving a membrane distillation feed solution and a membrane distillation feed outlet for outputting concentrated membrane distillation feed solution, the membrane distillation feed inlet and the membrane distillation feed outlet defining a membrane distillation feed flow path; a membrane distillation permeate outlet for outputting condensed membrane distillation permeate comprising recovered water from the membrane distillation feed solution; wherein the forward osmosis draw side and the membrane distillation permeate side are separated by a thermally conductive wall such that the forward osmosis draw solution flowing along the forward osmosis draw flow path is heated by heat generated from the condensation of the membrane distillation permeate vapour on the membrane distillation permeate side.

31. A method for recovering water, the method comprising: feeding a membrane distillation feed solution to a membrane distillation feed side of a membrane distillation module, wherein membrane distillation permeate vapour passing through a membrane distillation membrane undergoes condensation in a membrane distillation permeate side of the membrane distillation module, and isrecovered as a permeate solution comprising recovered water from the membrane distillation feed solution; feeding a cooling fluid to a cooling fluid inlet of a cooling module, such that the cooling fluid passes though the cooling module to a cooling fluid outlet of the cooling module; and heating the cooling fluid flowing through the cooling module with heat generated from the condensation of the membrane distillation permeate vapour on the membrane distillation permeate side.

32. The method of claim 31, wherein the cooling module is a forward osmosis module and the method further comprises: feeding a forward osmosis feed solution to a forward osmosis feed side of a forward osmosis module; feeding a concentrated forward osmosis draw solution to a forward osmosis draw side of the forward osmosis module, such that water passes from the forward osmosis feed solution through a forward osmosis membrane to the forward osmosis draw solution to provide a diluted forward osmosis draw solution; and wherein the forward osmosis draw solution is the cooling fluid.

33. A method for recovering water, the method comprising: feeding a feed solution to a forward osmosis feed side of a forward osmosis module; feeding a concentrated forward osmosis draw solution to a forward osmosis draw side of the forward osmosis module, such that water passes from a forward osmosis feed solution through a forward osmosis membrane to the forward osmosis draw solution to provide a diluted forward osmosis draw solution; feeding a membrane distillation feed solution to a membrane distillation feed side of a membrane distillation module, wherein membrane distillation permeate vapour passing through a membrane distillation membrane undergoes condensation in a membrane distillation permeate side of the membrane distillation module, and is recovered as a permeate solution comprising recovered water from the membrane distillation feed solution; andheating the forward osmosis draw solution flowing through the forward osmosis draw side of the forward osmosis module with heat generated from the condensation of the membrane distillation permeate vapour on the membrane distillation permeate side.

34. A method according to claim 32 or claim 33, wherein the membrane distillation feed solution comprises at least a portion of the diluted forward osmosis draw solution.

35. A method according to any one of claims 32 to 34, further comprising: feeding at least a portion of the diluted forward osmosis draw solution to a reverse osmosis feed side of a reverse osmosis module such that water passes from the diluted forward osmosis draw solution through a reverse osmosis membrane to provide a reverse osmosis permeate comprising recovered water from the reverse osmosis feed solution and a concentrated reverse osmosis feed solution.

36. A method according to any one of claims 32 to 35, further comprising: feeding reverse osmosis feed solution to a reverse osmosis feed side of a reverse osmosis module such that water passes through a reverse osmosis membrane to provide a reverse osmosis permeate comprising recovered water from the reverse osmosis feed solution and a concentrated reverse osmosis feed solution; and wherein the membrane distillation feed solution comprises at least a portion of the concentrated reverse osmosis feed solution.

37. A method according to any one of claims 31 to 36, further comprising: heating the membrane distillation feed solution; cooling the concentrated forward osmosis draw solution; cooling the concentrated membrane distillation feed solution; and / or cooling the concentrated reverse osmosis feed solution.

38. A method according to claim 37, wherein the heating and / or cooling is effected by a renewable energy source.

39. A method according to any one of claims 31 to 38, wherein the membrane distillation feed solution is heated to a temperature of from about 30°C to about 80°C prior to feeding to the membrane distillation feed side of the membrane distillation module.

40. A method according to claim 39, wherein the membrane distillation feed solution is heated to a temperature of about 55°C prior to feeding to the membrane distillation feed side of the membrane distillation module.