APPLICATION DIVERSITY NEEDS PROCESS DIVERSITY, PROCESS DIVERSITY ENABLES APPLICATION DIVERSITY
WHY THE LEWATIT® TEAM INVENTED THE COUNTERCURRENT TECHNOLOGY
In the beginning was the co-current technology: The feed solution and the regenerant passed through the resin bed in the same direction. Although the basic process of ion exchange worked, it had a number of disadvantages (and indeed still does where such units are in use). To be able to achieve adequate performance despite inefficient material exchange, very high quantities of regenerant have to be used - often more than twice the amount needed for the countercurrent technology. Because of compaction of the resin bed, for example, backwashing has to be performed before every regeneration. This requires large volumes of fresh water and also produces effluent. In addition, a high internal volume is needed for backwashing, which means that only half the entire unit is left for the ion exchange resin.
On top of this, because of the unfavorable concentration distribution, the use of regenerants is not very efficient, and there is an excessive consumption of acids and alkalis. This means long regeneration and rinse times. Summing up, one can say that co-current processes work in principle, but the principle is highly ineffective.
In Asia, eastern europe and in the USA the counter-current counter-pressure system is today widely established and is even used in power plants.