Disclosed herein are systems and methods for purifying aqueous solutions. For example, disclosed herein are flexible membrane distillation systems comprising one or more stages stacked on top of each other, wherein each stage comprises: a feedwater layer; a membrane distillation layer; a distillate layer; and a thermally conductive layer. The systems further comprise substantially impermeable top surface, bottom surface, and perimeter. Each feedwater layer is independently receives a portion of a contaminated aqueous solution (a feed solution). Each feedwater layer further receives heat from a heat source to distill at least a portion of the feed solution through the membrane distillation layer, thereby producing a distillate in the distillate layer. Distilling said portion of the feed solution through the membrane distillation layer purifies said portion of the feed solution to produce a purified aqueous solution, which is condensed in the distillate layer to form a condensate.

The invention relates to a modular flow system having a plurality of frame elements (101, 102) configured to be combined together to form a stack for forming afunctional member such as in particular a membrane distillation stage, a vapor generator, a condenser, a heat exchanger, a filter and/or a pervaporation stage, wherein the frame elements (101, 102) each include: an outer frame (39) and an inner frame (43), the inner frame (43) encasing a central inner region (40) and being surrounded by the outer frame (39), passage openings (13 to 16) and vapor and/or liquid channels (17, 18) arranged between the outer frame (39) and the inner frame (43), wherein at least one of the vapor and/or liquid channels (17, 18) comprises at least one internal strut member (48) extending between the inner frame (43) and the outer frame (39).

The present disclosure describes a desalination system, comprising a membrane distillation unit; a preheater having a liquid inlet and a liquid outlet, the outlet being in communication with the inlet; an evaporator in communication with the liquid outlet of the MD, and having a fluid inlet configured to provide heat to aqueous liquid in the evaporator, the evaporator having a vapor outlet; at least one adsorption-desorption unit, having a vapor inlet in communication with the vapor outlet of the evaporator, the AD including a fluid inlet configured to receive either a heating or a cooling fluid and a fluid outlet, the AD having a vapor outlet and further including a fluid inlet in communication with the fluid inlet of the AD, a fluid outlet in communication with the heating fluid inlet of the preheater; and a condenser in communication with the permeate vapor outlet of the MD or the AD or both and having a condensation outlet.

A method for assembling a scalable, multi-stage membrane distillation module includes providing plural thermal conduction layers, plural first gaskets, plural membranes for distilling water, and plural second gaskets, where a periphery of each layer and gasket has plural holes formed all around the periphery, stacking on top of each other a first thermal conduction layer, a first gasket, a first membrane, and a second gasket, to form a first stage, stacking on top of each other, and also on top of the first stage, a second thermal conduction layer, a third gasket, a second membrane, and a fourth gasket, to form a second stage, placing plural bolts through the plural holes formed all around the periphery of each layer and each gasket of the first and second stages, and tightening with nuts the plural bolts to form one evaporation layer and one condensation layer for each of the first and second stages.

Embodiments provide methods and structures for purification or volume reduction of a brine by an advanced vacuum distillation process (AVMD) to achieve higher flux by passage of vapors through an AVMD distillation unit. In one example, brine is circulated in a tank. The tank may include one or more membrane pouches that are submerged in the circulating brine or placed above the water level of the hot circulating brine. In other embodiments the membrane pouches are outside of the tank that includes the hot circulating brine but still in communication with it. The circulating brine is heated, allowing creation of water vapor. Using a vacuum, the water vapor is drawn through the membrane, where it may be condensed and subjected to further beneficial use. This process can concentrate to levels to generate crystals or solids, which can be separated and utilized.

A membrane distillation (MD) system includes a membrane module and reduced graphene oxide-carbon nanotube immobilized membrane for organic solvent separation. The MD module could include a feed inlet and outlet, a sweep gas inlet, and a sweep gas outlet. Thermostats are positioned at the feed inlet and outlet to measure the change in temperature. Preferential sorption of the organic, specifically tetrahydrofuran (THF), on a hybrid reduced graphene oxide-carbon nanotube immobilized membrane contributes to enhanced solvent removal of the MD system.

Systems and methods using membrane distillation are provided for desalinating water, for example for the production of potable water, to address freshwater requirements. In an aspect the systems and methods do not require applying an external heat source, or the energy cost of the heating source, to heat the feed stream to the membrane. In an aspect, the sensible heat present in surface seawater is used for the heat energy for the warm stream fed to the membrane, and deep seawater is used as the cold/coolant feed to the membrane to provide the needed temperature gradient or differential across the membrane.

The invention relates to a multistage membrane distillation apparatus (5000), comprising a plurality of multistage membrane distillation modules (500, 600), the modules being configured to be flowed through in parallel by a liquid (F) to be concentrated. Each module comprises a plurality of serial condensation/evaporation stages (50, 60) configured to be flowed through in series by the liquid to be concentrated. Each condensation/evaporation stage comprises a plurality of parallel condensation/evaporation elements (101, 102) configured to be flowed through in parallel by the liquid to be concentrated. Each condensation/evaporation element comprises at least one condensation unit and at least one evaporation unit. The apparatus further comprises at least one of: a centralized heating stage configured to generate steam and to provide the steam to each of the modules in parallel, and a centralized condensation stage configured to receive steam from each of the modules in parallel and to condensate the steam.

The invention relates to a modular flow system having a plurality of frame elements (101, 102) configured to be combined together to form a stack for forming a functional member. This functional member may be in particular a membrane distillation stage, a vapor generator, a condenser, a heat exchanger, a filter and/or a pervaporation stage. The frame elements (101, 102) each include: ⋅ an outer frame (39) and an inner frame (43), the inner frame (43) encasing a central inner region (40) and being surrounded by the outer frame (39), and ⋅ passage openings (13 to 16) and vapor and/or liquid channels (17, 18) arranged between the outer frame (39) and the inner frame (43). At least one of the two vapor and/or liquid channels (17, 18) is connected to the central inner region (40) by at least one vapor and/or liquid channel opening (22) constituting a through hole in the inner frame. In the frame elements (101, 102), when combined together to form the modular flow system, the vapor and/or liquid channels (17, 18) are arranged above the inner region (40).

The invention relates to a modular flow system having a plurality of frame elements (101, 102) configured to be combined together to form a stack for forming afunctional member such as in particular a membrane distillation stage, a vapor generator, a condenser, a heat exchanger, a filter and/or a pervaporation stage, wherein the frame elements (101, 102) each include: an outer frame (39) and an inner frame (43), the inner frame (43) encasing a central inner region (40) and being surrounded by the outer frame (39), passage openings (13 to 16) and vapor and/or liquid channels (17, 18) arranged between the outer frame (39) and the inner frame (43), wherein at least one of the vapor and/or liquid channels (17, 18) comprises at least one internal strut member (48) extending between the inner frame (43) and the outer frame (39).