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.

A device for sewage treatment comprises a treatment tank, a power and electric control unit, a gas supply and tail gas recovery unit and a circular reaction treatment unit; the treatment tank is provided with a liquid inlet, a liquid outlet, a gas intake port and a tail gas exhaust port; the gas supply and tail gas recovery unit is communicated with the treatment tank through the gas intake port; the tail gas exhaust port is communicated with the gas supply and tail gas recovery unit; the circular reaction treatment unit comprises an external circulating device and a reaction treatment element arranged inside the treatment tank.

Iron electrocoagulation (Fe-EC) reactors for removing contaminants from water comprising an assembly of spiral-wound or folded iron-containing anode and cathode plates separated with perforated insulating spacers, or an oxidant to accelerate oxidation of Fe(II) ions released from the anode to obtain Fe(III) ions, and/or to oxidize the contaminant.

The present invention provides a strong polymer electrolyte membrane which can provide a water electrolyzer operable at low electrolysis voltage. The polymer electrolyte membrane of the present invention comprises a fluorinated polymer and a woven fabric, wherein the weight of the woven fabric is from 20 to 95 g/m.sup.2, and the warp and weft of the woven fabric independently have a denier of from 30 to 100.

A system comprises an electrodialysis apparatus, which includes first and second reservoirs, wherein a salt concentration in the first reservoir reduces below a threshold concentration and salt concentration in the second reservoir increases during an operation mode. A first electrode comprises a first solution of a first redox-active electrolyte material, and a second electrode comprises a second solution of a second redox-active electrolyte material. In a first reversible redox reaction between the first electrode and first electrolyte material at least one ion is accepted from the first reservoir, and in a second reversible redox reaction between the second electrode and second electrolyte material at least one ion is driven into the second reservoir. A first type of membrane is disposed between the first and second reservoirs, and a second type of membrane, different from the first type, is disposed between the respective electrodes and reservoirs.

Disclosed are electrochemical systems that include an electrodialyzer and a vapor-fed CO.sub.2 reduction (CO.sub.2R) cell to capture and convert CO.sub.2 from ocean water. The electrodialyzer includes a stack of bipolar membrane electrodialysis (BPMED) cells between end electrodes. The electrodialzyer incorporates monovalent cation exchange membranes (M-CEMs) that prevent the transfer of multivalent cations between adjacent cell compartments, allowing continuous recirculation of electrolytes and solutions, and thus providing a safer and more scaling-free electrodialysis system. In some embodiments, the electrodialyzer may be configured to replace the water-splitting reaction at end electrodes with one-electron, reversible redox couples in solution at the electrodes. As a result, in the entire electrodialyzer stack, there is no bond-making, bond-breaking reactions and there is no gas generation, which significantly simplifies the cell design and improves operational safety. The systems provide a unique technological pathway for CO.sub.2 capture and conversion from ocean water with only electrochemical processes.

A wastewater treatment method includes: a soft water treatment 1 of crystallizing calcium carbonate from wastewater to remove the calcium carbonate therefrom; and an electrolysis 2 of electrolyzing some of the wastewater from which the calcium carbonate has been removed to obtain an acidic aqueous solution and an alkaline aqueous solution, wherein at least some of the alkaline aqueous solution is circulated to be used in the soft water treatment 1.

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.

A method and apparatus for producing hydroxyl radicals in a fluid chamber in an electrochemical cell comprising at least one cathode, at least one anode and at least one source of photolyzing radiation. The method comprises causing an electrochemical cell to produce hydrogen peroxide in the fluid, and causing at least one photolyzing radiation source, such as UV-LED, to photolyze the hydrogen peroxide to produce hydroxyl radicals. The fluid treatment apparatus includes: a structure defining a fluid chamber; at least one cathode facing into the fluid chamber; at least one anode facing into the fluid chamber; and a photolyzing radiation source operable to emit photolyzing radiation into at least one electrochemical cell portion of the fluid chamber, which is suitable for producing hydrogen peroxide.

The present disclosure relates to methods and systems for algae cultivation including the integration of electrochemical carbonate production for enhancing algae growth. More particularly, the present disclosure relates to methods and systems for producing a sodium hydroxide from brine using an electrochemical cell, contacting the sodium hydroxide stream with a CO.sub.2 gas sweep and producing a carbonate stream, and cultivating an algae slurry in a cultivation vessel comprising at least a portion of the carbonate stream.