Abstract: This invention provides new ways of distributing dilute and concentrate waters to the spaces between cation and anion ion exchange membranes in an electrodialysis system. An external attached manifold is used to distribute-and-retrieve concentrate water to-and-from each concentrate water space, which by the design of components can mitigate the power lost in the concentrate water distribution system. Furthermore, the dilute water is externally and simultaneously distributed to the dilute water spaces, that are between the adjacent anion and cation ion exchange membranes in the electrodialysis stack of components, and the thickness of the dilute water spaces can be kept to be as low as on-the-order-of one-tenth-inch while maintaining good dilute water flow rates. Finally, this invention provides a means of obtaining Zero Liquid Discharge ZLD desalination operation.

Abstract: Previous patent applications described, by way of examples, a Combined Electrodialysis and Reverse Osmosis (CERO) system capable of extracting 100% of the water in the saline feedwater as desalinated water and all its dissolved salt as solid salt. These examples only cover one special case of the reverse osmosis system operating with a 50% water-recovery factor of its input water. The present invention extends this principle, illustrated by narrow in scope examples, to accommodate any permissible RO water-recovery factor. In addition, whereas earlier descriptions of the CERO process required a cyclic sequence of serial operations, the invention further provides an implementation in which those cyclic operations are performed concurrently while achieving the same overall functional result.

Abstract: This electrodialysis unit is similar to conventional electrodialysis units, but uses modified spacer structures that alter water flow patterns and prevents water leaks. In this design, both dilute and concentrate waters flow horizontally, but in perpendicular directions within their respective dilute and concentrate water spacers, while the electric ion current flows vertically. This arrangement provides a simple means of distributing the dilute and concentrate water across the breadth of their respective spacers and facilitates achieving a targeted level of leakage electric current and the associated power loss within the water distribution systems. Moreover, the improved dilute and concentrate spacer structures effectively eliminate the risk of internal water leaks. When integrated with a precipitation tank, this system enables Zero Liquid Discharge ZLD operation when wastewater from reverse osmosis desalination is treated with this electrodialysis unit.

Abstract: This Gated Electrodialysis GED invention provides desalination of saline water while having only solid waste. The basic structure of an ordinary electrodialysis process is modified so that there is essentially no electrical power losses and no cross-water leakages in the concentrate, dilute, anolyte, and catholyte water distributions systems. Consequently, the concentrate water can be supersaturated while the dilute water can have any concentrations. Furthermore, the new process provides a means of operating such that the circulating concentrate supersaturated water can take tens of hours to flow through an enhanced clarifier. Consequently, there is time for solids to precipitate out of the concentrate supersaturated saline water and drift to the bottom of the enhanced clarifier and/or onto seed crystals before the concentrate water is reused. A representative design of this GED invention is given which is followed by the performance prediction for three examples.

Abstract: The concentrated and dilute saline water distribution systems of Electro Dialysis Reversal EDR or Capacitive Electro Dialysis Reversal CEDR are modified by feeding and retrieving the saline water to and from multiple spacers in an electrodialysis stack such that (1) the saline water enters and leaves the spacers in the plane of the thin spacers rather than traditionally perpendicular to them and (2) the saline waters are independently fed and retrieved to and from the spacers through long and small cross-sectional area tubes such that the electrical resistance to ion flow is very high relative to the electrical resistance to ion flow through the electrodialysis stack containing the cation and anion exchange membranes and dilute and concentrated saline water spacers.

Abstract: This Capacitive Electro Dialysis Reversal (CEDR) invention desalinates and concentrates saline water. The CEDR unit employs two identical parallel oppositely oriented modified Electro Dialysis Reversal EDR constructions that have shared dilute and concentrated saline water channels. The four electrodes of the two identical oppositely oriented parallel EDR like constructions are replaced with four supercapacitor electrodes. Each EDR like construction consists of a stack of ion exchange membranes and spacers plus the supercapacitor electrodes but one cation exchange membrane is trimmed from each of the two stacks of EDR like ion exchange membranes. During a cycle of operation, the supercapacitor electrodes discharge and then charge causing ions to be pulled out of the shared dilute saline water channels and placed in the shared concentrated saline water channels except at the ends where the ions flow in and out of the supercapacitor electrodes.

Abstract: This invention obtains fresh water and only solid waste from input saline water. This result is commonly known as desalination having zero liquid discharge (ZLD). The current common means of ZLD desalination is to use any common desalination process such as distillation, reverse osmosis, electrodialysis, etc. followed by brine recovery and crystallization which are both based on evaporation of water processes. This invention provides an alternative to the commonly used brine recovery and crystallization processes to produce only solid waste.