Methods of treating a waste stream containing perfluoroalkyl substances (PFAS) are disclosed. The methods include directing the waste stream to a dilution compartment of an electrochemical separation device, directing a treatment stream to a concentration compartment of the electrochemical separation device, and applying a voltage across the electrodes to produce a dilute stream substantially free of the PFAS and a concentrate stream. At least one of the waste stream and the treatment stream comprises a water miscible organic solvent. Methods of concentrating PFAS from a wastewater are also disclosed. PFAS concentration systems are also disclosed. The systems include a column comprising an ion exchange resin and an electrochemical separation device having a dilution compartment fluidly connected to an outlet of the column. Methods of facilitating treatment of a waste stream containing PFAS are also disclosed.

A switching system of an EDR water purifier has a first inlet end, a second inlet end, a first three-way solenoid valve, a second three-way solenoid valve, a third three-way solenoid valve, a fourth three-way solenoid valve, an EDR membrane stack, a first outlet end, and a second outlet end. The EDR membrane stack has a first inlet port, a second inlet port, a first outlet port, a second outlet port, a first electrode, and a second electrode. Each three-way solenoid valve has an inlet opening, a first outlet opening, and a second outlet opening. Each outlet opening of each three-way solenoid valve can be turned open or closed for switching two water routes passing the EDR membrane stack. Therefore, speed of forming limescale decreases, lifespan of the EDR membrane stack is prolonged, and water-purifying efficiency is improved.

A switching system has two inlet ends, two outlet ends, and an EDR membrane stack. Each inlet end and each outlet end are connected to both a primary branch and a secondary branch. Solenoid valves are mounted on each primary branch and each secondary branch to switch between opening and closing. The EDR membrane stack has two inlets, two outlets, and two electrodes. One inlet is connected to the primary branch of the two inlet ends while the other is connected to the secondary branch of the two inlet ends. One outlet is connected to the primary branch of the two outlet ends while the other is connected to the secondary branch of the two outlet ends. The polarity of the two electrodes is interchangeable to realize the reverse polarity of the electrodes. The two water flows that pass through the EDR membrane stack are interchangeable.

A switching system for an EDR water purifier has a first raw-water inlet end, a second raw-water inlet end, two four-way solenoid valves, an EDR membrane stack, a freshwater outlet end, and a wastewater outlet end. Each four-way solenoid valve has a first inlet end, a second inlet end, a first outlet end, and a second outlet end. The first inlet end of each four-way solenoid valve can communicate with one of the first outlet end and the second outlet end of the same four-way solenoid valve, and the second inlet end of the same four-way solenoid valve can communicate with the other one of the first outlet end and the second outlet end, to execute water-route switching. By switching two water routes passing through the EDR membrane stack, forming of limescale is alleviated, lifespan of the EDR membrane stack is extended, and water-purifying efficiency is improved.

The disclosure relates to systems, devices, and methods for flow control in a reverse osmosis filtration system, such as within a medical device. The systems, devices, and methods can respond to changes in permeate flow rate and solute concentration by adjusting feed water and concentrate water rates. Multiple feedback loops adjust parameters to meet water flow rate and purity requirements.

Disclosed are wastewater treatment systems and methods for semiconductor fabrication process. The method comprises performing first concentration on wastewater discharged from a semiconductor process chamber, and performing second concentration on concentrated wastewater or at least a portion of the wastewater concentrated by the first concentration. The step of performing the first concentration includes performing in a first electrodialysis apparatus an ion exchange between the wastewater and first treatment water. The step of performing the second concentration includes allowing the concentrated wastewater to circulate in a second electrodialysis apparatus, allowing second treatment water to circulate in the second electrodialysis apparatus, providing a power to an anode and a cathode of the second electrodialysis apparatus to perform an ion exchange between the second treatment water and the concentrated wastewater, and joining a portion of the concentrated wastewater to the second treatment water.

The present disclosure is directed to an electrodialytic stack with a concentrate stream that moves through a concentrate flow path bounded by a central ion exchange membrane and a first outer ion exchange membrane. A dilute stream moves through a dilute flow path bounded by the central ion exchange membrane and a second outer ion exchange membrane. A redox shuttle loop is separated from the concentrate and dilute streams by the first and second outer ion exchange membranes, respectively. The outer ion exchange membranes are a different type than the central ion exchange membrane. Electrodes are operable to apply a voltage across the stack. At least one collection of ion exchange materials is located in at least one of the flow paths. The ion exchange materials migrate ions between the central ion exchange membrane and at least one of the outer ion exchange membranes.

A water-softening system includes a filter device including filter units that are provided in at least some of a plurality of supply channels arranged in parallel to supply raw water to a consumption site and that remove at least part of ionic matter contained in supplied raw water by electro-deionization and discharge soft water containing less ionic matter than the raw water, a plurality of supply valves provided in the plurality of supply channels to open or close the supply channels, and a processor connected to the filter device and the plurality of supply valves. The processor determines whether water is supplied to the consumption site and controls at least one of the plurality of supply valves to remain open to maintain a state in which water is allowed to be supplied to the consumption site, when it is determined that no water is supplied to the consumption site.

A first stream of an aqueous solution flows through an upstream desalination or nanofiltration system. A second stream of the aqueous solution is mixed with the diluate output from the upstream desalination system or with the diluate or concentrate output from the upstream nanofiltration system with a flow ratio of the second stream of the aqueous solution to the feed stream of <0.47 or >0.63. A liquid composition flows into the concentrate channels of an electrically driven separation apparatus, while the feed stream flows into at least the diluate channels at a ratio of 0.3 to 0.81 to the flow of the liquid composition. An applied voltage selectively draws monovalent ions from the feed stream in the diluate channels through the monovalent-selective ion exchange membranes into the concentrate channels to produce a treated diluate having a sodium chloride ratio (SCR)<0.7.

In this disclosure, a process of recycling acid, base and the salt reagents required in the Li recovery process is introduced. A membrane electrolysis cell which incorporates an oxygen depolarized cathode is implemented to generate the required chemicals onsite. The system can utilize a portion of the salar brine or other lithium-containing brine or solid waste to generate hydrochloric or sulfuric acid, sodium hydroxide and carbonate salts. Simultaneous generation of acid and base allows for taking advantage of both chemicals during the conventional Li recovery from brines and mineral rocks. The desalinated water can also be used for the washing steps on the recovery process or returned into the evaporation ponds. The method also can be used for the direct conversion of lithium salts to the high value LiOH product. The method does not produce any solid effluent which makes it easy-to-adopt for use in existing industrial Li recovery plants.