Certification Action Line – Questions – June 2013

June 1, 2013

Questions about countercurrent regeneration and cation and anion exchange resins

Answers to these questions appear online at www.watertechonline.com/certification-action-line.

Certification Action Line features questions and answers typical of those appearing in Water Quality Association (WQA) certification examinations. Some answers may not satisfy everyone or every condition.

1. The principle reason to employ countercurrent regeneration in ion exchange softening is to:

          a) expand the bed

          b) provide even distribution of brine in low salting regenerations

          c) reclassify the resin bed

          d) reduce hardness leakage in the service run

2. With countercurrent regeneration of a water softener, the displacement rinse should be done using (a or b) water.

          a) hard

          b) softened

3. The final or fast rinse in countercurrent regeneration systems can be done in downflow using (a or b) water.

          a) hard

          b) softened

4. Greater utilization of resin bed capacity is generally observed in (a or b).

          a) countercurrent regeneration softener systems

          b) cocurrent regeneration softener systems

5. A key principle to proper operation of countercurrent regeneration systems is:

          a) to achieve fast kinetics with fine mesh resin

          b) air mixing after regeneration to break up the layer of poorly regenerated resin

          c) to be able to regenerate the resin in a compacted state

          d) all of the above       

6. Eighteen megohm-cm water is most often achieved with:

          a) double distillation systems

          b) mixed bed deionization

          c) single pass reverse osmosis

          d) all of the above

7. Cation and anion exchange resins each have approximately the same density or weight per cubic foot.

          a) True

          b) False

8. The cation and anion exchange resins in a mixed bed system must be re-separated prior to each regeneration cycle.

          a) True

          b) False

9. A moisture content above 50 percent generally signals replacement time for eight percent cross-linked softening resins.

          a) True

          b) False

10. Anion exchange resins are usually more durable against oxidation attack, high temperature and foulants than are cation exchange resins.

          a) True

          b) False

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