Page 356 - Water and wastewater engineering

ION EXCHANGE 8-25

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8-6 CHAPTER REVIEW
When you have completed studying this chapter, you should be able to do the following without the
aid of your textbooks or notes:
1. Explain the difference between a strong cation exchange resin and an weak cation exchange.
2. Given the separation factors for several cations, identify those that will be adsorbed in
preference with respect to the others.
3. Explain why high pressure drops through the resin bed are detrimental to ion exchange
performance and operating life.
4. Explain why multiple columns in series are preferred over a single column with the
same resin mass.
5. Sketch a three-column “merry-go-round” bed arrangement and explain how it works to
a client.
6. Select a softening ion exchange resin from breakthrough curves for several resins treat-
ing the same raw water source.
7. Define the following abbreviations: EBCT, SFR, SLR.
8. Explain why ion exchange may be of benefit in removing constituents of concern other
than calcium and magnesium.

With the use of this text, you should be able to do the following:
9. Given a table of screen sizes and a manufacturer’s specification, identify the largest and
smallest diameter resin particle that is being marketed.
10. Estimate the maximum volume of water per liter of resin that can be treated given the
total capacity of the resin and the concentration of the ions to be treated.
11. Calculate the fraction of the “split” for an ion exchange softening system.
12. Calculate EBCT, SFR, and SLR given appropriate data.
13. Design an ion exchange column including estimating the resin volume to treat a water
given the breakthrough data and the volume of water to be treated or the flow rate and
cycle time for regeneration.
14. Determine the number of columns and sequence of their use given the cycle time of a
single resin column.

8-7 PROBLEMS

8-1. Estimate the maximum volume of water per liter of resin that can be treated by a
strong acid exchange resin in the hydrogen form if the resin has total capacity of 2.0
eq/L, the magnesium concentration is 1.4 meq/L, and the sodium concentration is 2.6
meq/L. Assume no other cations are in the solution.