Water desalination electrodialysis

AlMadani, H.M.N. 2003. Water desalination by solar powered electrodialysis process. Renew. Energ. 

Pilat, B. 2001. Practice of water desalination by electrodialysis. Desalination 139, 385-392. 

The two water desalination applications described above represent the majority of the market for electrodialysis separation systems. A small application exists in softening water, and recently a market has grown in the food industry to desalt whey and to remove tannic acid from wine and citric acid from fruit juice. A number of other applications exist in wastewater treatment, particularly regeneration of waste acids used in metal pickling operations and removal of heavy metals from electroplating rinse waters [11]. These applications rely on the ability of electrodialysis membranes to separate electrolytes from nonelectrolytes and to separate multivalent from univalent ions. 

M. Hamada, Brackish Water Desalination by Electrodialysis, Desalination Water... 

Electromembrane processes such as electrolysis and electrodialysis have experienced a steady growth since they made their first appearance in industrial-scale applications about 50 years ago [1-3], Currently desalination of brackish water and chlorine-alkaline electrolysis are still the dominant applications of these processes. But a number of new applications in the chemical and biochemical industry, in the production of high-quality industrial process water and in the treatment of industrial effluents, have been identified more recently [4]. The development of processes such as continuous electrodeionization and the use of bipolar membranes have further extended the range of application of electromembrane processes far beyond their traditional use in water desalination and chlorine-alkaline production. 

The electrod ialysis stack A key element in electrodialysis is the so-called stack, which is a device to hold an array of membranes between the electrodes that the streams being processed are kept separated. A typical electrodialysis stack used in water desalination contains 100-300 cell pairs stacked between the electrodes. The electrode containing cells at both ends of a stack are often rinsed with a separate solution which does not contain Cl- ions to avoid chlorine formation. 

Strathmann, H. (2004) Assessment of electrodialysis water desalination process costs. Proceedings of the International... 

Electrodialysis Electrical potential Selective ion transport Charged species (ions) Symmetrical ionic Water desalination, fractionation... 

Z. Amor, B. Bariou, N. Mameri, M. Taky, S. Nicolas, A. Elmidaoui, Fluoride removal from brackish water by electrodialysis, Desalination 133 (2001) 215-223. 

FIGURE 5.4 Principles of operation of two types of membrane water desalination units reverse osmosis and electrodialysis. (From Pryde [22], and reprinted courtesy of Cummings Publishing Co.)... 

Z. Amor, S. Malki, M. Taky, B. Bariou, N. Mameri and A. Elmidaoui, Optimization of fluoride removal from brackish water by electrodialysis, Desalination, 1998, 120, 263 D. Cohen and H.M. Conrad, 65,000 GPD fluoride removal membrane system in Lakeland, California, Desalination, 1998, 117, 19 P. Brandhuber and G. Amy, Alternative methods for membrane filtration for drinking water, Desalination, 1998, 117, 1. 

The desalination of brackish water by electrodialysis and the electrolytic production of chlorine and caustic soda are the two most popular processes using ion-exchange membranes. There are, however, many other processes such as diffusion dialysis, Donnan dialysis, electrodialytic water dissociation, etc. which are rapidly gaining commercial and technical relevance. Furthermore ion-exchange membranes are vital elements in many energy storage and conversion systems such as batteries and fuel cells. 

Several other potential applications of electrodialysis in wastewater treatment systems which have been studied on a laboratory scale are reported in the literature. In most of these applications the average plant capacity, however, is considerably lower than that in brackish water desalination or table salt production. 

Kneifel, K., G. Liihrs, H. Wagner. 1985. Nitrate removal by electrodialysis for brewing water. Desalination 55 203-209. 

The dialyzer used for desalination of water by electrodialysis (Figure 5.55) is an electric cell divided into a series of sub-cells that are separated by alternate polyanion and polycation membranes. While the ions move under the influence of the applied electric potential, the complimentary permselectivities of the ion-exchange membranes insure that salt is removed from alternate sub-cells and concentrated in the others. Desalination dialyzers used in practice have up to 100 such sub-cells. 

Allison RP (1991) Surface and waste-water desalination by electrodialysis reversal, Proceedings, American Water Works Association Conference, Orlando, FL. 

Ortiz JM, Exposito E, Gallud F, Garcfa-Garcfa V, Montiel V and Aldaz A (2006), Photovoltaic electrodialysis system for brackish water desalination modeling of global process , / Membrane Sd, 274,138-149. 

Desalination. Electrodialysis desalination plants for municipal water are operating successfully, particularly to obtain drinking water on small islands. In 1974, a desalination plant began operation in Noshima, which is a small island located in the Inland Sea in Japan. The plant produces 120 metric tons per day of drinking water from sea water. This is the first desalination plant to produce drinking water directly from sea water. Many other electrodialysis desalination plants are now in operation for both municipal water and industrial water. 

Fig. 15.7 Schematic representation of the desalination of water by electrodialysis. A refers to the anion-exchange membrane, and C refers to the cation-exchange membrane. The applied voltage attracts the ions from the low-flow water stream into the high-flow wastewater...

Adhikary, S., Tipnis, U., Harkare, W. Govindan, K. (1989) Defluoridation during desalination of brackish water by electrodialysis. Desalination, 71,301 312. 

Amor, Z., Bariou, B., Mameri, N., Taky, M., Nicolas, S. Elmidaoui, A. (2001) Fluoride removal from brackish water by electrodialysis. Desalination, 133,215 223. 

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