Higher Regeneration Efficiency

Regeneration is the least efficient step in the ion exchange process since particle diffusion is the rate-controlling step and, consequently, the selectivity relationships are unfavorable. An increase in regeneration efficiency will result in a more complete removal of ionic contaminants. At regenerant concentrations, the rate of exchange is inversely proportional to the square of the bead radius (or diffusion path length). Large beads will, therefore, regenerate more slowly than small beads. UPS resins, with a smaller average particle diameter, will regenerate more quickly resulting in a more efficient use of regenerant chemicals. This reduces regenerant and waste neutralization costs, while the more complete removal of ionic contaminants will lead to a higher operating capacity in the service cycle.

Greater Operating Capacity

During the service cycle, the equilibrium factors are highly favorable for the removal of ions from water. For dilute solutions, where film diffusion is the rate controlling step, the kinetics of this process is facilitated by the higher surface area per unit volume of the smaller beads found in UPS resins. This leads to an increase in usage of the entire resin capacity from the top to the bottom of the bed (i.e., greater capacity utilization). The net effect of a more efficient regeneration and a higher operating capacity is greater throughput.

Better Rinse Efficiency

The purpose of the rinse step is to flush excess regenerant (much of which is inside the bead matrix) from the ion exchange bed. Since the diffusion path lengths of UPS beads are smaller than conventional resins, excess regenerants diffuse more quickly from within the beads, thus decreasing the amount of time required to reach a specified endpoint such as conductivity. The net result of this is a faster rinse time (i.e., less down time) and less rinse water usage (i.e., lower wastewater disposal costs).

Reduced Leakage

An increase in the regeneration efficiency, capacity utilization and rinse efficiency will also result in less ionic leakage during the service cycle. This results in the production of purer water for a longer time since the leakage endpoint is extended beyond the previous breakpoint.

Less Resin Loss

Fines contained in conventional resins can float to the surface of the resin bed and escape through the top distributor during the backwash cycle. Since UPS resins do not contain these very small beads, the installed bed volume and, hence, the operating capacity of the system, is maintained for a longer period of time.

Lower Pressure Drop

Since the void fraction of a bed of UPS resin is greater than that of a bed of conventional resin having the same average particle diameter, the pressure drop will be less. Therefore, UPS resins with the same average particle size can be used to reduce the pressure drop and, consequently, the pumping costs, of a bed containing conventional resin. Conversely, UPS resin with a smaller average particle size can be used to maintain the same pressure drop while increasing the performance of the bed due to the benefits attributed to smaller size described above.

Similar Expansion Characteristics

UPS resins have backwash expansion characteristics similar to those for conventional resins. Consequently, they can be used to rebed existing systems that have been designed around other resins without any changes in the process conditions.

Increased Organic Fouling Resistance

Organic fouling of the anion resin reduces operating capacity, run times and regeneration efficiency, as well as increasing rinse water requirements. The homogeneity of the UPS anion resins provides excellent resistance to organic fouling. Should fouling occur, however, these resins have the durability to handle repeated brine cleanings without significant bead breakage.