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Features of electrosorption technology for water purification

   The ELECON and CASCADE® lines of water systems is  convenient, reliable, and safe way to maintain high water purity standards. The service life of CASCADE units is rated for many years’ use. An important advantage of our electrosorption technology is that it does not pollute the surrounding environment, neither while operating, nor during maintenance regeneration of the granular filter bed. Other technologies that address these water problems are typically plagued by the need for replaceable working elements or are connected to possible ecological problems in that they often use concentrated salt or toxic chemical solutions.  In stark contrast to these other water purification devices, CASCADE water systems do not require replacement of any cassette or membrane filter elements for restoration of output water purity. For complete recovery of CASCADE purifying ability, short-term washing of the device is carried out either manually or automatically depending on device model number.

       After the first laboratory researches the electrosorption technology has at once attracted experts’ attention as rather perspective one, because it allows to combine the advantages, of majority known water purification methods and except its lacks.

        In particular, in contrast to sandy filters and sorption devices, the electrosorption apparatus perfectly delete bacteria, viruses and other microorganisms, as well as any extrinsic micro-particles and macro-particles from water. In contrast to membrane or fiber filter systems, electrosorption apparatuses have high efficiency, which does not decrease during their exploitation. The electrofiltration has unique universality, because such filtration in an electrpsorbent layer (electrofiltration) is carried out not on the basis of the size distinction of the suspended components, but due to the distinction of physical-chemical properties of these components and water, which is always present. As a result, a complex of procedures for preparing water may be carried out with a single electrosorption device. The complete purification of water from all kinds of microorganisms, organic and mineral particles, insoluble in water oils, superficially-active substances, different soluble ionized components and not ionized components (except alkaline metals, which always should present in drinking water) is provided. Moreover, electrosorption devices do not require preliminary separation of emulsified oils and can work without preliminary thin filtration of mechanical admixtures.

       In the contrast to filter and sorption devices for water purification, which are available on the market today, electrosorption devices do not require periodic replacement of any elements while in service. Service life of all elements is designed for many years’ use. Due to an opportunity of simple and regular preventive measures electrosorption devices can constantly be supported in an efficient condition. While during the exploitation of devices of another types, for the users and even for the attendants, it is often very difficult to determine when they have already depleted their resources (by the way, rather insignificant in the conditions of real loading).

       Presence of electrodes, their active electrochemical functionality, as well as their high coagulation activity, provide water purification by electrosorption devices even from ionized components by electrooxidation, electroreduction or electrolysis.

       In the most general features the electrosorption technology looks as follows.

       At a stage of purification, water intended for purification passes through the working chamber. This working chamber contains electrodes inside it and filtering packing (granular packing); the size of packing particles depends on a task. On supplying of an electrical voltage of constant signs on electrodes, the sorption ability of a material used as filtering packing and sorption of many components, contained in water increases simultaneously.

       At periodically arising necessity of the electrofilter dispersion packing regeneration, the electrical voltage is disconnected, and the sorption ability of the packing decreases up to an initial level, providing complete regeneration of the electrofilter. The washing of the packing is carried out in a dynamic method with a level-by-level withdrawal of dispersion packing in a zone of intensive washing and then returning it to a zone of a filtration, or in a static method by a straight flow or, that is better, by a reverse flow of a regenerating liquid.

       Quartz, agate, corundum or zeolite granules and other minerals may be used as dispersion packing. Ceramic granules, strong polarizable granules of the “Segnetel”® (it is our new material) are better. Polymeric materials, with inclusions of ferroceramic powders, sand and dispersion packing, obtained on the base of cellulose and chitosan or ion-exchange resins may be used as dispersion packing too.

       The presence of surface heterogeneity both of chemical character, and of geometrical character is necessary for realization of a liquid purification. This mechanism of a liquid purification is based on a hitting of micro-particles, or ion-molecular units, contained in it, which are passing through dispersion packing, in zones with various values of charges and flow speeds.

       Under the influence of an external electrical field a polarization of micro-particles and molecules, contained in the liquid, occurs. That strengthens their coagulation due to dipole-dipole and quadrupole interactions. And also, under the influence of an external electrical field an electrosorption of micro-particles and their units takes place on dispersion packing. The irregularity of the flow with formation of stagnant zones in the packing, from which the escape of sorbing particles is complicated, provides necessary efficiency of purification process.

       The mentioned above minimal intensity of an electrical field provides rather effective purification of water environments from micro-heterogeneous impurity and water purification from pollution by biomaterials, at pumping  raw water environment. The intensity of an electrical field should increase at higher speeds of liquid feeding or increased requirements to a purification degree.       Dispersion materials, listed above, can be used individually, in a mixture among themselves and in a combination with other, traditional materials for a filtration on granular packing.

       The using of dispersed particles of the greater size reduces the efficiency of processing due to reduction of their surface area and volume of stagnant zones. The using of granules of the smaller size reduces to undesirable increase of hydrodynamical resistance and also to reduction of stagnant zone volume (electrosorption capacity).

       Typical electrosorption apparatus consists of the block of the power supplies and electrocolumn, inside which the electrodes are built in. As well, in side the column a polarized material of one or several kinds, with various sizes of particles is placed. The electrocolumn can be executed with various number of working chambers. In the working chamber of an electrocolumn in a zone of an electrical field the additional layers of dispersion materials can be placed. These additional layers are used for decision of specific tasks of purification from those or other specific components, or they simply may have different grain sizes.

       The regeneration of the sorption packing is usually carried out after switching off the power supplies or after changing polarity and feeding a flow of a washing liquid. The- washing liquid, for the purposes of more complete packing regeneration, can be electrochemicaly activated, to contain detergents or other purifier agents, can be prepared on water or on the base of organic solvents.