An ion-exchange based demineralisation process employs ion exchange resins, i.e. insoluble solid substances capable of exchanging their ions with others having the same charge and contained in the solution where they are immersed.

As it is well known, the water, whether from wells, rivers, lakes or even collected rain water, contains, in addition to silica and carbon dioxide, a quantity of dissolved salts, more or less dissociated into ions, their removal being one of the basic applications in the treatment of water for industrial use.

The production of service waters (like boiler feedwater, process water for the pharmaceutical industry and a variety of industrial activities, ultrapure water for the electronic industry) requires a demineralising process, which may be single or combined with other processes. This explains why the demineralisation technology represents one of the basic activities of the Water Treatment Division.

Various types of ion exchange resins are available to Termokimik's Customers, ranging from the weakly acid carboxylic to the strongly acid sulphonic and the weakly/strongly basic anion resins along with a wide range of processes including dealkalinisation, softening, demineralisation, condensate polishing and sugar juice treatment. Particular attention has been dedicated over the years by the Division's specialists to the problem of restoring the resin's ability to exchange ions (i.e. the regeneration process) which fundamentally consists in having diluted acid and basic solutions (saline solutions in special processes) flow through the resin bed.

These activities have led to the development of the countercurrent regeneration technique and to the refinement of the most recent "packed bed" technology, where the resin layer is packed between two plates fitted with special strainers that allow the passage of water and of the regenerating solution. This enables to eliminate dead spots and channelling (leak paths), thus improving the regeneration efficiency on the one side and minimising regenerant consumption and effluent production on the other side.



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