Patent ID: 12186708

DETAILED DESCRIPTION

Membrane distillation (MD) is a combined thermal and membrane-based separation process, which allows vapor to permeate across a membrane while preventing liquid from crossing the membrane. The MD separation process is commonly applied in water desalination by separating water vapor from a brine stream using a micro- or nano-porous membrane, depending on the pore size desired. The feed liquid fed to the feed side of the MD is usually heated to encourage evaporation, while the temperature of the coolant stream received by the coolant side of the MD is usually kept lower than that of the feed stream temperature to encourage condensation. The driving force for water vapor permeation across the membrane is the vapor pressure difference. The vapor pressure difference is often induced by the temperature gradient across the membrane. Membrane distillation can be performed at a low feed temperature, for example, less than 100° C. The low operating temperatures allow membrane distillation to be operated using renewable energy and low-grade energy sources, such as solar energy, wind energy, geothermal energy, and waste heat.

Four types of membrane distillation configurations including sweeping gas membrane distillation (SGMD), vacuum membrane distillation (VIVID), direct contact membrane distillation (DCMD) and air gap membrane distillation (AGMD). These MD configurations operate on the same principle, for example, vapor generation, vapor permeation across membrane, and vapor. The differences among these configurations lie in the design of the condensation chambers, while the feed chambers of the modules typically remain the same for all configurations. While direct contact membrane distillation system yields high permeate flux, it also has high conductive heat loss and high temperature polarization effects. Further, permeate contamination is possible in DCMD. AGMD is characterized by low conductive heat loss and low temperature polarization effect. However, AGMD yields low permeate flux from resistance to mass transfer in the air in the distillate chamber. Permeate gap membrane distillation (PGMD) has a higher permeate flux than AGMD. PGMD is sometimes referred to as liquid gap membrane distillation (LGMD) or water gap membrane distillation (WGMD). In PGMD, the stagnant air in the distillate chamber of an AGMD is replaced with a liquid, such as distilled water or deionized water. In PGMD, vapor from the feed stream permeates across the membrane pores and condenses at the interface between the permeate side of the membrane and the water in the distillate zone.

A multi-stage sweeping gas membrane distillation (MS-SGMD) system and a process for using the MS-SGMD are provided herein. The MS-SGMD has multiple modules, for example, two or more, in which membrane fouling is controlled, and water flux is improved, by passing, or bubbling a carrier gas through a feed chamber in each module. The feed chamber in each module is fed a stream of material to be treated. Each module also includes a sweeping gas chamber separated from the feed chamber by a vapor permeable membrane that is liquid impermeable. As vapor from the material to be treated passes through the membrane from the feed chamber to the sweeping chamber in each module, a stream of sweeping gas carries the vapor out of the sweeping chamber. The sweeping gas and the carrier gas are fed to an external condenser, outside of the modules, to condense the vapor and produce purified liquid. The process also produces a concentrated feed solution, which may be diluted by the addition of fresh feed.

The flow of the carrier gas through the feed chamber of the MS-SGMD increases the mass transfer coefficient in the feed chamber of the module by increasing the turbulent dissipation rate in the feed liquid, improving the rate of vapor permeation. Further, the carrier gas introduces turbulence in the feed chamber, which assists in loosening deposits from the membrane, lowering the scaling or fouling of the membrane and sweeping gas chamber in each module. Thus, the carrier gas may extend the operating life of the membranes and modules, reducing costs for operating the modules.

As the carrier gas passes through the feed chamber, it is at least partially saturated with water vapor from bubbling through the feed liquid. The vapor in the carrier gas can be directly fed to the external condenser or, in some embodiments, is mixed with the sweeping gas in the sweeping gas chambers before it is condensed in the external condenser, thereby enhancing the productivity of the MS-SGMD module.

FIG.1Ais a simplified process flow diagram of a MS-SGMD system100including a number of modules102, in which each of the modules102is fluidly connected in parallel to a feed line104, a carrier gas line106, and a sweeping gas line108. Each of the modules102are also connected in parallel to a feed return line110, and a sweeping gas outlet line112, and a carrier gas outlet line114. An external condenser116is used to condense a fluid from the vapor flow in the sweeping gas outlet line112and the carrier gas outlet line114. The fluid, such as purified water, is removed from the MS-SGMD system100through a distillate outlet118. In the embodiment shown inFIG.1A, the modules102are contained in a housing120. In other embodiments, the modules102may be stand-alone units in individual housings. In some embodiments, a base set of modules102are enclosed in the housing120, and additional modules102in individual housings are added to increase the capacity of the MS-SGMD system100.

The feed line104provides a liquid feed to each of the modules102from a liquid feed tank122, for example, by a pump124. In some embodiments, the liquid feed is heated, for example, by a heating element in the liquid feed tank122or by a heat exchanger on the feed line104, to provide a hot liquid feed in the feed line104. In other embodiments, a heating element is inserted inside the feed chamber126of each module102. A combination of both heating methods can be used. The temperature of the liquid feed is generally less than about 100° C., or less than about 75° C., or less than about 60° C., or between about 40° C. and about 60° C., or about 50° C. The temperature used may be selected based on the configuration of the modules, as described herein. Modules in which the feed is fluidically coupled in series may use a higher temperature in earlier modules in the series to reduce the need for heating later modules in the series. In some embodiments, the feed liquid in the feed chamber126is statically processed by filling and closing valves on the inlet points from the feed line104and outlet points from the feed chamber126to the feed return line110. Alternatively, the feed liquid can be dynamically added to the feed chamber126from the feed line104under the flow of gravity by mounting of the liquid feed tank122higher than the modules102, then partially opening the inlet points from the feed line104and outlet points from the feed chamber126to the feed return line110. As mentioned herein, in some embodiments, the feed liquid is pumped through the feed chamber126using a pump124. In some embodiments, the pump124is variable and a control system is used to reach a desired flowrate, for example, sufficient to keep the feed chamber126liquid full.

The feed liquid provided from the liquid feed tank122can be an aqueous solution, for example, seawater, industrial wastewater, brackish water, produced water, fruit juice, blood, milk, dye, hazardous waste water, brine solution, non-condensable gas, non-potable water, or any liquid including a dissolved salt, for example, a mixture of salts, a salt and organic contaminant mixture, a salt and inorganic contaminant mixture, or a combination of these.

The sweeping gas outlet line112is fluidically coupled to a sweeping gas chamber128in each of the modules102. The sweeping gas in the sweeping gas line108is provided by a vacuum pump130, or other device on the condenser116, such as a compressor, and other devices, which the gas flow. The condenser116will create some vacuum by condensing the distillate outlet118from the vapor in the sweeping gas outlet line112and the humidified gas in the carrier gas outlet line114, assisting in the flow of the sweeping gas from the outlet of the sweeping gas chamber128of each module102. The condenser116vents noncondensable gases through a vent line132, such as the carrier gas from the carrier gas outlet line114and the sweeping gas from the sweeping gas outlet line112. The carrier gas may be nitrogen, air, helium, argon, carbon dioxide, and the like. In some embodiments, different carrier gases may be used in different modules102. For example, compressed air may be used in upstream modules102, while dried compressed air is used in modules102that are downstream to increase the removal of water.

The carrier gas can be supplied to the carrier gas line106from a device such as a blower134, compressor, gas tank, gas line, or the like. After exiting through the vent line132, the carrier gas may be recycled in the process, for example, by being passed through a dryer and returned to the blower134. The carrier gas may be injected to the feed chamber126at ambient conditions or may be heated prior to injection to feed chamber126. In various embodiments, the injection into the feed chamber126is from a single point injector or a multiple point injector, such as a sparger or orifice fluidically coupled to the carrier gas line106.

The heat source for the MS-SGMD system100can be from renewable energy sources, low-grade energy sources, electrical energy, waste heat from other thermal processes, or their combinations. As described herein, the heat can be applied to the liquid in the liquid feed tank122, a heater in the feed chamber126, or both.

The feed chamber126is separated from the sweeping gas chamber128by a membrane136. In various embodiments, the membrane136in each of the modules102is a reinforced hollow tube, a non-reinforced hollow tube, a spiral wound tube, a flat sheet, or a non-flat sheet. The membrane136includes multiple pores that are sized to allow water vapor originating from the hot liquid to pass from the feed chamber126through the membrane136to the sweeping gas chamber128. The membrane136prevents liquid flow between the feed chamber126and the sweeping gas chamber128.

In various embodiments, the membrane136is a composite membrane, a nano-composite membrane, a hydrophobic membrane, an omniphobic membrane, a hydrophilic and hydrophobic composite dual layer membrane, a modified ceramic membrane, a porous ceramic membrane, a surface modified membrane, a polymer electrolyte membrane, a porous graphene membrane, or a polymeric membrane. In some implementations, the membrane136includes a support layer and an active layer. The membrane136can be made, for example, from a porous material, such as a ceramic. In some implementations, a contact angle of a droplet of the liquid on the membrane136is greater than 90 degrees (°). In some embodiments, a different material is used for the membrane136in different modules102. For example, the membrane136used in modules102that are upstream may have smaller effective pore sizes as more vapor may be released from more dilute liquid, while downstream modules102may have larger effective pore sizes as the more concentrated liquid may release less vapor.

As described herein, the sweeping gas chamber128is fluidically coupled to the sweeping gas outlet line112, which pulls the water vapor from the sweeping gas chamber128to the condenser116. As the water vapor from the sweeping gas outlet line112and the water vapor in the gas from the carrier gas outlet line114are condensed to form the water released from the distillate outlet118, additional liquid is added to the liquid feed tank122through a make-up line138. As the liquid feed is concentrated in the process, it may reach a point at which it is too concentrated for efficient separation. Accordingly, a portion of the liquid feed may be removed from a drain line140, for example, fluidically coupled to the feed return line110, to allow dilution of the liquid feed with fresh liquid added through the make-up line138.

In some embodiments, the condenser116includes thin metallic tubes or thin polymeric tubes. The condenser116can be made, for example, from a metallic material, a composite material, or carbon fibers, among others. As described herein, the condensed water from the condenser116is removed through the distillate outlet118. The water from the distillate outlet118has a water purity level that is greater than a water purity level of the liquid feed from the liquid feed tank122.

The modules102, including the chambers126and128and the membrane136, of the MS-SGMD system100may be of any shape, such as rectangular, triangular, square, circular, cylindrical, hexagonal, or spherical. The housing120can be made, for example, from metallic material, polymeric material, composite material, carbon fiber, carbon nanotube, or sapphire. In some implementations, the housing120is made of steel, brass, copper, high-density polyethylene (HDPE), acrylic, or polyvinyl chloride (PVC).

In some implementations, the housing120includes a frame, support, gasket, or a combination of these, which can provide structural support, form the chambers126and128of the modules102, and hold the membrane136between the chambers126and128. The supporting structure can be made of a material that is non-corrosive and chemically inert in relation to the liquid feed. In various embodiments, the housing120is made, for example, from a metallic material, a polymeric material, a composite material, or carbon fibers, among others.

As described herein, the MS-SGMD system100removes water as vapor from the liquid feed using two different techniques. Water vapor is entrained in the carrier gas after it is bubbled through the liquid feed in the feed chamber126. Further, water vapor is transported across the membrane pores from the feed chamber126to the sweeping gas chamber128, and carried out from the sweeping gas chamber128through the sweeping gas outlet line112. The driving force for mass/vapor transfer across the pores of the membranes is the partial pressure difference across the membrane136, and thus, sweeping the vapor from the sweeping gas chamber128increases the partial pressure difference and increases the mass/vapor transfer.

The MS-SGMD system100is not limited to the configuration shown inFIG.1A. In other configurations, the modules102are connected in series to one or more of the lines used for fluid flow through the modules102, such as the feed line104and feed return line110, the carrier gas line106and the carrier gas outlet114, the sweeping gas line108and the sweeping gas outlet line112. These configurations are discussed with respect toFIGS.1B-1L.

FIG.1Bis a simplified process flow diagram of a MS-SGMD system142, wherein the modules102are connected in parallel to the feed line104, the feed return line110, the carrier gas line106, the sweeping gas line108, and sweeping gas outlet line112. In this embodiment, the carrier gas outlet line114from the feed chamber126of each module102is fluidically coupled to an inlet on the sweeping gas chamber128of that module102. Accordingly, the sweeping gas that is fed to the feed chamber126flows through the sweeping gas chamber128and is returned to the condenser116through the sweeping gas outlet line112.

FIG.1Cis a simplified process flow diagram of a MS-SGMD144, wherein the feed chamber126of each of the modules102is connected in parallel to the feed line104, the feed return line110, the carrier gas line106, and the carrier gas outlet line112, and in series with the sweeping gas line108. In this embodiment, the sweeping gas line108is fluidically coupled to a sweeping gas chamber128on a first module102, and then fluidically coupled from an outlet of the sweeping gas chamber128of the first module102to an inlet on the sweeping gas chamber128of a next module102. An outlet of the sweeping gas chamber128of the last module102in the series is fluidically coupled to the condenser116through the sweeping gas outlet line112.

FIG.1Dis a simplified process flow diagram of a MS-SGMD system146, wherein the feed chamber126of each of the modules102is connected in parallel to the feed line104, the feed return line110, and the carrier gas line106, and in series to the sweeping gas line108. In this embodiment, the sweeping gas line108is fluidically coupled to a sweeping gas chamber128on a first module102, and then fluidically coupled from an outlet of the sweeping gas chamber128of the first module102to an inlet on the sweeping gas chamber128of a next module102. An outlet of the sweeping gas chamber128of the last module102in the series is fluidically coupled to the condenser116through the sweeping gas outlet line112. Further, the carrier gas outlet line114from the feed chamber126of each module102is fluidically coupled to an inlet on the sweeping gas chamber128of that module102. Accordingly, the sweeping gas that is fed to the feed chamber126flows through the sweeping gas chamber128and is returned to the condenser116through the sweeping gas outlet line112.

FIG.1Eis a simplified process flow diagram of a MS-SGMD system148, wherein the modules102are fluidically coupled in parallel to the feed line104, the feed return line110, and the sweeping gas108, but are fluidically coupled in series to the carrier gas line106. In this embodiment, the carrier gas line106from the blower134is fluidically coupled to an inlet on the feed chamber126of the first module102downstream of the blower134. Each of the modules102downstream of that has a carrier gas line106fluidically coupled to an inlet of the feed chamber126of the module102that is fluidically coupled to an outlet of the feed chamber126of the preceding module102. The carrier gas outlet line114from the feed chamber126of the last of the modules102in the sequence is fluidically coupled to the condenser116.

FIG.1Fis a simplified process flow diagram of a MS-SGMD system150, wherein the modules102are fluidically coupled in parallel to the feed line104, and the feed return line110, but are fluidically coupled in series to the carrier gas line106and the sweeping gas line108. In this embodiment, the carrier gas line106from the blower134is fluidically coupled to an inlet on the feed chamber126of a first module102downstream of the blower134. Each of the modules102downstream of that has a carrier gas line106fluidically coupled to an inlet of the feed chamber126of the module102that is fluidically coupled to an outlet of the feed chamber126of the preceding module102. The carrier gas outlet line114from the feed chamber126of the last of the modules102in the sequence is fluidically coupled to the condenser116. Further, the sweeping gas line108is fluidically coupled to a sweeping gas chamber128on a first module102, and then fluidically fluidically coupled from an outlet of the sweeping gas chamber128of the first module102to an inlet on the sweeping gas chamber128of a next module102. An outlet of the sweeping gas chamber128of the last module102in the series is fluidically coupled to the condenser116through the sweeping gas outlet line112.

FIG.1Gis a simplified process flow diagram a MS-SGMD system152, wherein the modules102are fluidically coupled in parallel to the carrier gas line106, and the sweeping gas line108, but are fluidically coupled in series to the feed line104. In this embodiment, the feed line104from the feed pump124is fluidically coupled to an inlet on the feed chamber126of a first module102downstream of the feed pump124. The feed chamber126on each of the modules102downstream of that has a feed line104fluidically coupled to an inlet of the feed chamber126of the module102that is fluidically coupled to an outlet of the feed chamber126of the preceding module102. The feed return110from the feed chamber126of the last of the modules102in the sequence is fluidically coupled to the liquid feed tank122.

As the concentration of the liquid feed increases through the sequential arrangement of the modules102, the membrane136may be adjusted in downstream modules102to increase the amount of vapor transferred from the feed chamber126to the sweeping gas chamber128. The sequential arrangement of the liquid feed may lower the energy demands of the MS-SGMD system154, as the energy input to modules102that are upstream may lower the energy needed for modules102that are downstream.

FIG.1His a simplified process flow diagram of a MS-SGMD system154, wherein the modules102are fluidically coupled in parallel to the carrier gas line106, the sweeping gas line108, and the sweeping gas outlet line112, but are fluidically coupled in series to the feed line104, and the feed return line110. In this embodiment, the feed line104from the feed pump124is fluidically coupled to an inlet on the feed chamber126of a first module102downstream of the feed pump124. The feed chamber126on each of the modules102downstream of that has a feed line104fluidically coupled to an inlet of the feed chamber126of the module102that is fluidically coupled to an outlet of the feed chamber126of the preceding module102. The feed return110from the feed chamber126of the last of the modules102in the sequence is fluidically coupled to the liquid feed tank122. Further, the carrier gas outlet line114from the feed chamber126of each module102is fluidically coupled to an inlet on the sweeping gas chamber128of that module102. Accordingly, the sweeping gas that is fed to the feed chamber126flows through the sweeping gas chamber128and is returned to the condenser116through the sweeping gas outlet line112.

FIG.1Iis a simplified process flow diagram of a MS-SGMD system156, wherein the modules102are fluidically coupled in parallel to the carrier gas line106and the carrier gas outlet line114, but are fluidically coupled in series to the feed line104and the sweeping gas line108. In this embodiment, the feed line104from the feed pump124is fluidically coupled to an inlet on the feed chamber126of a first module102downstream of the feed pump124. The feed chamber126on each of the modules102downstream of that has a feed line104fluidically coupled to an inlet of the feed chamber126of the module102that is fluidically coupled to an outlet of the feed chamber126of the preceding module102. The feed return110from the feed chamber126of the last of the modules102in the sequence is fluidically coupled to the liquid feed tank122. Further, the sweeping gas line108is fluidically coupled to a sweeping gas chamber128on a first module102, and then fluidically coupled from an outlet of the sweeping gas chamber128of the first module102to an inlet on the sweeping gas chamber128of a next module102. An outlet of the sweeping gas chamber128of the last module102in the series is fluidically coupled to the condenser116through the sweeping gas outlet line112.

FIG.1Jis a simplified process flow diagram of a MS-SGMD system158, wherein the modules102are fluidically coupled in parallel to the carrier gas line106, but are fluidically coupled in series to the feed line104, the feed return line110, the sweeping gas line108, and the sweeping gas outlet line112. In this embodiment, the feed line104from the feed pump124is fluidically coupled to an inlet on the feed chamber126of a first module102downstream of the feed pump124. The feed chamber126on each of the modules102downstream of that has a feed line104fluidically coupled to an inlet of the feed chamber126of the module102that is fluidically coupled to an outlet of the feed chamber126of the preceding module102. The feed return110from the feed chamber126of the last of the modules102in the sequence is fluidically coupled to the liquid feed tank122. Further, the sweeping gas line108is fluidically coupled to a sweeping gas chamber128on a first module102, and then fluidically coupled from an outlet of the sweeping gas chamber128of the first module102to an inlet on the sweeping gas chamber128of a next module102. An outlet of the sweeping gas chamber128of the last module102in the series is fluidically coupled to the condenser116through the sweeping gas outlet line112. In addition, the carrier gas outlet line114from the feed chamber126of each module102is fluidically coupled to an inlet on the sweeping gas chamber128of that module102. Accordingly, the carrier gas that is fed to the feed chamber126flows through the sweeping gas chamber128and is returned to the condenser116through the sweeping gas outlet line112.

FIG.1Kis a simplified process flow diagram of a MS-SGMD system160, wherein the wherein the modules102are fluidically coupled in parallel to the sweeping gas line108and the sweeping gas return line112, but are fluidically coupled in series to the feed line104and the carrier gas line106. In this embodiment, the feed line104from the feed pump124is fluidically coupled to an inlet on the feed chamber126of a first module102downstream of the feed pump124. The feed chamber126on each of the modules102downstream of that has a feed line104fluidically coupled to an inlet of the feed chamber126of the module102that is fluidically coupled to an outlet of the feed chamber126of the preceding module102. The feed return110from the feed chamber126of the last of the modules102in the sequence is fluidically coupled to the liquid feed tank122. Further, the sweeping gas line108is fluidically coupled to a sweeping gas chamber128on a first module102, and then fluidically coupled from an outlet of the sweeping gas chamber128of the first module102to an inlet on the sweeping gas chamber128of a next module102. An outlet of the sweeping gas chamber128of the last module102in the series is fluidically coupled to the condenser116through the sweeping gas outlet line112.

FIG.1Lis a simplified process flow diagram of a MS-SGMD system160, wherein the modules102are fluidically coupled in series to the feed line104, the carrier gas line106, and the sweeping gas line108. In this embodiment, the feed line104from the feed pump124is fluidically coupled to an inlet on the feed chamber126of a first module102downstream of the feed pump124. The feed chamber126on each of the modules102downstream of that has a feed line104fluidically coupled to an inlet of the feed chamber126of the module102that is fluidically coupled to an outlet of the feed chamber126of the preceding module102. The feed return110from the feed chamber126of the last of the modules102in the sequence is fluidically coupled to the liquid feed tank122. Further, the sweeping gas line108is fluidically coupled to a sweeping gas chamber128on a first module102, and then fluidically coupled from an outlet of the sweeping gas chamber128of the first module102to an inlet on the sweeping gas chamber128of a next module102. An outlet of the sweeping gas chamber128of the last module102in the series is fluidically coupled to the condenser116through the sweeping gas outlet line112. In addition, the carrier gas line106from the blower134is fluidically coupled to an inlet on the feed chamber126of a first module102downstream of the blower134. Each of the modules102downstream of that has a carrier gas line106fluidically coupled to an inlet of the feed chamber126of the module102that is fluidically coupled to an outlet of the feed chamber126of the preceding module102. The carrier gas outlet line114from the feed chamber126of the last of the modules102in the sequence is fluidically coupled to the condenser116.

FIG.2is a process flow diagram of a method200for purifying a liquid feed using a MS-SGMD system. The method200begins at block202when a liquid is fed to a feed chamber in each of a plurality of modules. The liquid in the feed chamber is at a temperature of greater than about 50° C. The liquid can be heated before it is fed to the feed chamber or the liquid can be heated in the feed chamber. In some embodiments, the liquid is fed to a feed chamber of a first module of the plurality of modules, and the liquid exiting the feed chamber of the first module of the plurality of modules is then fed to a feed chamber of a second module of the plurality of modules.

At block204, a carrier gas is fed through the liquid in the feed chamber of each of the plurality of modules to form humidified carrier gas. In some embodiments, the carrier gas is fed to a feed chamber of a first module of the plurality of modules, and then the carrier gas exiting the feed chamber of the first module of the plurality of modules is fed to a feed chamber of a second module of the plurality of modules.

At block206, a sweeping gas is fed to a sweeping gas chamber in each of the plurality of modules through a sweeping gas line, wherein the sweeping gas chamber in each module is separated from the feed chamber in each module by a membrane, and wherein the membrane allows vapor to pass across the membrane while blocking liquid flow across the membrane. In some embodiments, the sweeping gas is fed to a sweeping gas chamber of a first module of the plurality of modules, and then the sweeping gas exiting the sweeping gas chamber of the first module is fed to a sweeping gas chamber of a second module of the plurality of modules.

At block208, a purified liquid is condensed from the carrier gas. At block210, the purified liquid is condensed from the sweeping gas.

The details of one or more implementations of the subject matter of this disclosure are set forth in the accompanying drawings and the description. Other features, aspects, and advantages of the subject matter will become apparent from the description, the drawings, and the claims.

The details of one or more implementations of the subject matter of this disclosure are set forth in the accompanying drawings and the description. Other features, aspects, and advantages of the subject matter will become apparent from the description, the drawings, and the claims.

Embodiments

An embodiment disclosed by example herein provides a multi-stage sweeping gas membrane distillation (MS-SGMD) system. The MS-SGMD includes a plurality of modules, wherein each module includes a feed chamber fluidically coupled to a feed line and a carrier gas line, wherein the feed line introduces a liquid feed into the feed chamber from a liquid feed tank, and wherein the carrier gas line introduces a carrier gas into the feed chamber. Each module includes a sweeping gas chamber fluidically coupled to a sweeping gas line and a sweeping gas return line, wherein a sweeping gas is passed through the sweeping gas chamber. Each module further includes a membrane separating the feed chamber from the sweeping gas chamber, wherein the membrane allows transportation of vapor from the feed chamber to the sweeping gas chamber while blocking liquid from moving from the feed chamber to the sweeping gas chamber.

In an aspect, the MS-SGMD system further includes a condenser fluidically coupled to the sweeping gas return line, wherein purified liquid is condensed from the sweeping gas.

In an aspect, the MS-SGMD system further includes a sweeping gas blower fluidically coupled to the condenser, wherein the sweeping gas blower feeds the sweeping gas through the sweeping gas chamber.

In an aspect, the MS-SGMD system further includes a carrier gas outlet line fluidically coupling a carrier gas outlet on the feed chamber to the condenser tank.

In an aspect, the MS-SGMD system further includes a carrier gas line fluidically coupled to an outlet on the feed chamber and fluidically coupled to an inlet on the sweeping gas chamber.

In an aspect, the plurality of modules are fluidically coupled in parallel to the feed line, the carrier gas line, and the sweeping gas feed line.

In an aspect, the plurality of modules are fluidically coupling in series to the feed line, wherein a liquid input to the feed chamber of a first module in the series is fluidically coupled to the feed line, a liquid outlet of the feed chamber of a last module in the series is fluidically coupled to a feed return line, and each intervening module between the first module and the last module is fluidically coupled by line from a liquid outlet on the feed chamber of the intervening module to a liquid inlet on the feed chamber of the next module.

In an aspect, the plurality of modules are fluidically coupled in series to the sweeping gas feed, wherein a sweeping gas feed line is fluidically coupled to an inlet of the sweeping gas chamber on a first module in the series, a sweeping gas return line is fluidically coupled to an outlet from the cold chamber of a last module in the series, and each intervening module between the first module and the last module is fluidically coupled by a line from an outlet of the sweeping gas chamber of the intervening module to an inlet of the sweeping gas chamber of the next module in the series.

In an aspect, the plurality of modules are fluidically coupled in series to the carrier gas, wherein a carrier gas inlet on the feed chamber of a first module in the series is fluidically coupled to the carrier gas line, a carrier gas outlet of the feed chamber of a last module in the series is fluidically coupled to a carrier gas outlet line, and each intervening module between the first module and the last module is fluidically coupled by line from the gas outlet of the feed chamber of the intervening module to a gas inlet of the feed chamber of the next module.

In an aspect, the MS-SGMD system further includes a heating element in a liquid feed tank, a heat exchanger on the feed line, or both.

In an aspect, the MS-SGMD system further includes a heating element disposed in a feed chamber of a module.

In an aspect, the liquid feed includes an aqueous solution.

In an aspect, the liquid feed includes a liquid including a dissolved salt, a mixture of salts, a salt and an organic contaminant mixture, or a salt and an inorganic contaminant mixture, or any combinations thereof.

In an aspect, the liquid feed includes seawater, industrial wastewater, brackish water, produced water, fruit juice, blood, milk, dye, hazardous-waste water, or a brine solution, or any combinations thereof.

In an aspect, the membrane includes a composite membrane, a nano-composite membrane, a hydrophobic membrane, an omniphobic membrane, a hydrophilic and hydrophobic composite dual layer membrane, a modified ceramic membrane, a porous ceramic membrane, a surface modified membrane, a polymer electrolyte membrane, a porous graphene membrane, or a polymeric membrane, or any combinations thereof.

In an aspect, the membrane includes a reinforced hollow tube, a non-reinforced hollow tube, a spiral wound2, a flat sheet, or a non-flat sheet, or any combinations thereof.

In an aspect, a contact angle of a droplet of the liquid feed on the membrane is greater than 90° (degrees).

In an aspect, the carrier gas includes air, nitrogen, helium, argon, or carbon dioxide, or any combinations thereof.

Another embodiment described by example herein provides a method for purifying a liquid using a multi-stage sweeping gas membrane distillation (MS-SGMD) system. The method includes feeding a liquid to a feed chamber in each of a plurality of modules, wherein the liquid in the feed chamber is at a temperature of greater than about 50° C. A carrier gas is fed through the liquid in the feed chamber of each of the plurality of modules to form humidified carrier gas. A sweeping gas is fed through a sweeping gas chamber in each of the plurality of modules, wherein the sweeping gas chamber in each module is separated from the feed chamber in each module by a membrane, and wherein the membrane allows vapor to pass across the membrane while blocking liquid flow across the membrane. A purified liquid is condensed from the sweeping gas. The purified liquid is condensed from the humidified carrier gas.

In an aspect, the method further includes heating the liquid before feeding the liquid to the feed chamber.

In an aspect, the method further includes heating the liquid in the feed chamber.

In an aspect, the method further includes feeding the liquid to a feed chamber of a first module of the plurality of modules, then feeding the liquid exiting the feed chamber of the first module of the plurality of modules to a second module of the plurality of modules.

In an aspect, the method further includes feeding the sweeping gas to the sweeping gas chamber of a first module of the plurality of modules, then feeding the sweeping gas from the first module to the sweeping gas chamber of a second module of the plurality of modules.

In an aspect, the method further includes feeding the carrier gas through a feed chamber of a first module of the plurality of modules, then feeding the carrier gas exiting the feed chamber of the first module of the plurality of modules to a feed chamber of a second module of the plurality of modules.

Other implementations are also within the scope of the following claims.