Renewable energy can be captured from the mixing of salt and fresh water in reverse electrodialysis. This paper investigates the energy efficiency of this process for feed waters that pass a reverse electrodialysis cell once and waters that pass multiple cells or electrode segments. So far, the maximum theoretical energy efficiency was considered to be 50% when the feed waters pass a single cel...

Within an electrodialysis unit, the solutions are separated by alternately arranged anion exchange membranes (permeable only for anions) and cation exchange membranes (permeable only for cations). The membranes are arranged parallel to one another to form an electrodialysis stack. When a potential is applied across the selectively permeable membrane stack, anions selectively move through the an...

The use of ion-exchange membranes to concentrate sea water and to produce fresh water from brine has been investigated for about one quarter-century and has now achieved the practical stage. The entire domestic supply of table salt in Japan is produced by electrodialysis. Many positive results on production of fresh water from brine have been attained in the U.S., the Mediterranean regions and ...

Ion-exchange membranes have been used in various industrial processes, e.g., in the electrodialytic concentration of seawater to produce edible salt, as a separator for electrolysis, in the desalination of saline water by electrodialysis, in the separation of ionic materials from non-ionic materials by electrodialysis, in the recovery of acid and alkali from waste acid and alkali solution by di...

Reverse electrodialysis allows for the capture of energy from salinity gradients between salt and fresh waters, but potential applications are currently limited to coastal areas and the need for a large number of membrane pairs. Using salt solutions that could be continuously regenerated with waste heat (≥40°C) and conventional technologies would allow much wider applications of salinity-gradie...

In acetic acid fermentation by Acetobacter aceti, the acetic acid produced inhibits the production of acetic acid by this microorganism. To alleviate this inhibitory effect, we developed an electrodialysis fermentation method such that acetic acid is continuously removed from the broth. The fermentation unit has a computerized system for the control of the pH and the concentration of ethanol in...

The separation membrane techniques in which an external electric field is applied as a driving force (such as electrodialysis, electro-electrodialysis, and membrane electrolysis) are shortly described and their application in environment protection is presented. Attention was focused on recovery of valuable chemicals from effluents and waste gases. Examples of new production methods that elimin...