Water Desalination by Two-stage Electro-dialysis
New Desalination Technology Based on Two-Stage Electrodialysis for Seawater
Tech Area / Field
- CHE-IND/Industrial Chemistry and Chemical Process Engineering/Chemistry
8 Project completed
Senior Project Manager
Komarkov D A
VNIPIET (Novosibirsk Branch), Russia, Novosibirsk reg., Novosibirsk
- Institute of Inorganic Chemistry, Russia, Novosibirsk reg., Akademgorodok\nNovosibirsk Chemical Concentrates Plant, Russia, Novosibirsk reg., Novosibirsk
- SENTECH Instruments CmbH, Germany, Berlin\nEquipamento Criogenico e de Laboratorio, LDA, Portugal, Leca da Palmeira\nFiBAC, Denmark, Copenhagen\nAguas do Sotavento Algarvio, Portugal, Faro\nAQUA-TEK CmbH, Germany, Berlin\nUltramet Inc., USA, CA, Pacoima\nTohoku University/Computer Center, Japan, Sendai
Project summaryPURPOSE of the PROJECT:
Upon successful execution of the project, the new technique of cost-effective desalination of sea type waters will be developed.
Oceans account for about 97% of the total amount of water on the Earth. Because of this, the preparation of drinking water from sea-type waters is one of the most promising ways to provide a potable water source. The problem of preparing desalinated water from more concentrated natural salt-containing waters and seawater is very urgent.
Reverse osmosis is one of the most widespread methods to desalinate sea water. However, installations involving this method are very expensive and this fact limits their use. Desalinzation installations based on electrodialysis are much cheaper but, until now, it has been generally accepted that the installations of this type can be used efficiently only when desalinating water with salt content up to 8 kg/cu.m.
The authors of the Project propose to broaden the range of efficient use of electrodialysis for desalinization of water with a salt content of up to 40 kg/cu.m.
In order to solve the problem of desalinization of mineralized natural water, we use a novel approach involving two stage electrodialysis: in the first stage of the process, the maximum possible salt transfer for the selected surface membranes is provided without achieving deep desalinization of the initial water. In the second stage, the required desalting of the dializate obtained in the first stage is achieved. This order of process performance will increase the competitive merits of the electrodialysis method of desalination of natural mineralized water and broaden the limits of its efficient application. For these purposes electrodialysis desalinization devices will be created that will be different from all currently existing paradigms of dialysis devices used to produce freshwater.
The realization of this project is possible only by using electrodes with coating from precious metals. A new economically efficient technology of deposition of protected coatings from platinum metals by MO CVD (Metal Organic Chemical Vapor Deposition) will be designed within the framework of the project.
The project includes experimental construction developments with simultaneous tests at the proving ground. Recommendations for the development of industrial units will be worked out.
The fulfillment of this project will allow for:
1. Development of an efficient electrodialysis set-up, operable in automatic regime. The set-up is intended for production of drinking-quality water from sea and salty waters. This will broaden the existing limits for applications of electrodialysis in desalinization of naturally occurring mineralized waters.
2. Establishment of the production of titanium electrodes with composite coatings from platinum metals for a multi-purpose electrodialysis set-up. These electrodes will be distinguished for their high corrosive resistance.
3. The creation of a novel step in the development of electrodiaysis desalinization technique which will allow desalinization of various water samples with a salt content of up to 40 kg/cu.m.
4. The use of new materials of electrodes and reversing electrical supplies which will provide for a lower risk of deposition of indissoluable salts on membranes as well as increasing the operation time of membranes in concentrating-desalting devices.
The realization of this project will provide the basis for industrial production of a new generation of electrodialysis installations to begin.
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