A two-stage electrodialysis system and a method for recovering waste CO.sub.2-lean amine solvent are provided. The system includes an amine solution pretreatment filtering system, a C-A homogeneous membrane electrodialysis device, a BP-A bipolar membrane electrodialysis system, and a CO.sub.2 recovery and capture system. The C-A homogeneous membrane electrodialysis system includes a material chamber, a C-A homogeneous membrane electrodialysis device, a concentrated HSSs waste solution chamber, an electrode solution chamber, and corresponding pipelines and peristaltic pumps. The BP-A bipolar membrane electrodialysis system includes a secondary feed chamber, a BP-A bipolar membrane electrodialysis device, an acid liquor chamber, an electrode solution chamber, and corresponding pipelines and peristaltic pumps. The waste CO.sub.2-lean amine solvent enters the material chamber after passing through the amine solution pretreatment filtering system. The concentrated HSSs waste solution chamber is connected to the secondary feed chamber by a buffer tank.

A method of chemical extraction from an aqueous solution includes receiving an aqueous solution including dissolved inorganic carbon. The method also includes increasing a pH of a first portion of the aqueous solution to form a basic solution. The basic solution is then combined with a second portion of the aqueous solution to precipitate calcium salts. The calcium salts are then collected.

A conductive nanoporous membrane system has a first ion exchange membrane formed from a nanoporous substrate that is coated with a metal or carbon or conductive polymers to form a conductive membrane, a second ion exchange membrane that is also formed from a nanoporous substrate coated with a metal to form a conductive membrane is positioned in spaced relation to the first conductive membrane and coupled to a voltage source; the negatively potential membrane acts as a cation exchange membrane in the presence of an electrolyte, and the positively connected electrode behave as anodic exchange membrane in the presence of an electrolyte due to the formation of electrical double layers at the interface between metal and liquid electrolyte.

A photodialysis device that can desalinate saline streams is described herein. The device can have a desalination rate that is significantly faster than current solar thermal desalination technology. Salt is removed from water by passing ionic current derived from sunlight through this water using dye-sensitized membranes. The device can serve as a distributed, low-cost technology that can efficiently and effectively desalinate low salinity sources of water, which is particularly useful for agriculture and drinking water applications.

A method of making building materials from an aqueous solution includes receiving the aqueous solution with dissolved ions and increasing a pH of the aqueous solution so the dissolved ions precipitate from the aqueous solution as salt. The method also includes collecting the salt precipitated from the aqueous solution and forming the building materials from the salt.

Provided are a system and a method of treating wastewater. The system includes a wastewater chamber, positive and negative electrode chambers, acid and basic solution chambers and a buffer chamber. The wastewater chamber receives wastewater containing a first ion. The positive and the negative electrode chambers are respectively on opposite sides of the wastewater chamber. The acid chamber is between the wastewater chamber and the positive electrode chamber. The basic chamber is between the wastewater chamber and the negative electrode chamber. The buffer chamber is between one of the acid and the basic chambers and the wastewater chamber, and receives the buffer solution containing the first ion. The interfaces between the wastewater chamber and the buffer chamber and between the one of the acid and the basic chambers and the buffer chamber are ion exchange membranes having the same electrical properties.

Wastewater containing scale components, organic substances, inorganic ions, and the like, such as human effluent, generated in a closed system space, such as a nuclear shelter, a hazardous shelter, a space station or a moon-Mars mission manned spacecraft, or a lunar base is efficiently treated by a simple structural apparatus, so that water is recovered. After a hardness component is removed from water to be treated, such as human effluent, by a softening device, and heat exchange is performed between softening treated water and electrolysis treated water by a heat exchanger, by a high-temperature and high-pressure electrolysis device, organic substances, urea, ammonia, and the like are removed by electrolysis performed under high-temperature and high-pressure conditions. After the electrolysis treated water is processed by a deaeration treatment using a deaeration membrane device, a desalting treatment is performed by acid/alkali manufacturing electrodialysis devices and provided in series at two stages.

A process for ion-exchanging an exchangeable-ion containing solid material involves several steps. There is a bipolar membrane electrodialysis step, which involves subjecting an aqueous ion-containing solution to a bipolar membrane electrodialysis to produce an acid liquid. The process also contains an ion-exchange step, during which the exchangeable-ion containing solid material is contacted with the acid liquid to conduct ion-exchange to produce a slurry containing the ion-exchanged solid material. It further include a solid-liquid separation step, during which the slurry containing the ion-exchanged solid material is subject to a solid-liquid separation to produce a solid phase and a liquid phase. The pH value of the liquid phase is adjusted to 4-6.5. The pH-adjusted liquid phase is further subject to a solid-liquid separation to produce a treatment liquid.

Methods and circuits for a device for interrupting concentration-related polarisation phenomenon and for self-cleaning of electromembrane processes by application of asymmetric inverse-polarity pulses with high intensity and variable frequency are described. The device, a bipolar switch, is based on the use of solid-state electronics to carry out polarity inversion in a range of frequencies, intensities and pulse widths to prevent or reduce formation of precipitates on the surfaces of the membranes. The inversion protocol, with a frequency that varies as a function of the appearance of dirt on the membranes, as measured by the decrease in voltage or electrical resistance of the membrane cell during electromembrane processes, is also provided. This device and configuration provides application of modulated and stable high-intensity pulses using a second power source. Electromembrane processes can be updated by replacing electrodes, suitable for polarity inversion, and adding a second power source and the bipolar switch described.

An apparatus and method for abating scale formation during the purification and demineralization of water in an electrochemical deionization apparatus. In the apparatus and method, scale forming ions in a raw water feed are precipitated at a controlled location remote from the deionization chambers of the deionization apparatus. Concentrate water produced during the deionization process to produce demineralized product water is acidified and circulated through the deionization apparatus to prevent scale formation and build-up in the deionization apparatus.