electrodialysis

Complete removal of ions from water is regarded as electrodialysis.

This fouling decreases the efficiency of the electrodialysis system.

Since the 1980's, these separation processes, along with electrodialysis, are employed in large plants and, today, a number of experienced companies serve the market.

In application, electrodialysis systems can be operated as continuous production or batch production processes.

Electrodialysis is usually applied to deionization of aqueous solutions.

Electrodialysis has inherent limitations, working best at removing low molecular weight ionic components from a feed stream.

Power could be obtained by either of two technologies that have been tested in the laboratory, reverse electrodialysis and pressure-retarded osmosis.

Some applications of electrodialysis include:

A second method being developed and studied is reversed electrodialysis or reverse dialysis, which is essentially the creation of a salt battery.

This is done by three methods: distillation/freezing; reverse osmosis using membranes and electrodialysis; ion exchange.

Reversed electrodialysis (RED)

Reversed electrodialysis (RED) is the salinity gradient energy retrieved from the difference in the salt concentration between seawater and river water.

In reversed electrodialysis a salt solution and fresh water are let through a stack of alternating cathode and anode exchange membranes.

Practical Potential of Reverse Electrodialysis, Environ.

This process differs from electrodialysis, where the salts are extracted from the feedwater by using a membrane with an electrical current to separate the ions.

Electrodialysis reversal (EDR)

The system was installed to minimize the brine from an Electrodialysis reversal (EDR) system.

The following treatment method(s) have proven to be effective for removing nitrate to below 10 mg/L or 10 ppm: ion exchange, reverse osmosis, electrodialysis.

The membranes, which are made of highly cross-linked ion exchange resins that allow passage of ions, but not of water, are used for electrodialysis.

In batch processes, the diluate and/or concentrate streams are re-circulated through the electrodialysis systems until the final product or concentrate quality is achieved.

Another important application for electrodialysis is the production of pure water and ultrapure water by electrodeionization (EDI).

The existing commercialized desalination methods are multi-stage flash evaporation, vapor-compression, multi effect evaporation, reverse osmosis and electrodialysis.

Electrodialysis (ED) is used to transport salt ions from one solution through ion-exchange membranes to another solution under the influence of an applied electric potential difference.

As with RO, electrodialysis systems require feed pretreatment to remove species that coat, precipitate onto, or otherwise "foul" the surface of the ion exchange membranes.