In a conventional water purifier, when a purification pack fed with RO permeate and a conductivity of 35 µS/cm at 1.5 to 2 L/min has reached the stage when output water quality drops below 18.2 Mohm-cm, it is necessary to change the cartridge in order to maintain water quality. At this point, only about 40-45% of its total ion exchange capacity has been used up.

The capacity advantage of the Cascada BIO- and AN-water Systems are illustrated in Figure 1. With a conventional water purifier, the pack would have to be changed after 880 liters when the product water resistivity had dropped to 17.5 Mohm-cm.

In the Cascada BIO- and AN-water Systems, the first purification pack is used until its output quality has decreased to 1 Mohm-cm, using about 80% of the total cartridge capacity (1590 liters) in the Figure 1 example shown. Output quality from the system is maintained at 18.2 Mohm-cm by the second purification pack.

Over 80% greater utilization of resin capacity is achieved by this means. The relative gain depends on the quality of the feed water and the flow rate. The lower the feed quality and the faster the flow, the smaller the proportion of primary purification pack capacity that is used before the output quality drops below 18.2 Mohm-cm and the greater the cartridge capacity advantage is with the Cascada BIO- and AN-water Systems. The Cascada BIO- and AN-water Systems enable a high output flow rate of 2.0 L/min to be achieved with high resin utilization.

When the quality of the output from the first purification pack has fallen to 1 Mohm-cm, the first pack is still removing over 95% of the ions from the feed (with a conductivity of 20 µS/cm or greater). The second pack is only removing the remaining few percentage of ions. The overall effect is that less than 5% of the polishing pack’s capacity is used in gaining 80% extra from the primary purification pack.

Figure 1
Product Resistivity Profile of Cascada BIO- and AN-water Systems Pack Feed : NaCI, 37 µS/cm, 1.8 L/min

This is demonstrated in Figure 2 which shows the water quality in Mohm-cm against usage in thousands of liters for both a Cascada BIO- and AN-water Systems pack. This new cartridge was fitted in the primary pack position, which was first used in the polishing position. If the capacity of the polishing cartridge had been significantly used, the user would expect to find the capacity curve shown to be significantly to the left of that of the new cartridge. In practice they are virtually identical, confirming that use of the cartridge in the polishing position has a negligible effect on its capacity and that the extra capacity achieved from the primary purification pack is fully realized.

Figure 2
Sodium Chloride Capacity of Cascada BIO- and AN-water Systems Pack Feed : NaCI, 37 µS/cm, 1.8 L/min