10-8 For the water quality in Problem 10-4, design an ion exchange system for th
ID: 519818 • Letter: 1
Question
10-8 For the water quality in Problem 10-4, design an ion exchange system for the removal of calcium (waters A and B), barium (waters C and D), or radium (water E), as selected by your instructor. The flowrate to be treated is 5.45 ML/d. The system should be sized so that the minimum time between regenerations is 72 h. The column diameter should be 3m and there should be at least 2 columns. Pilot testing indicates optimal regeneration efficiency corresponded to using a 10 percent NaCl solution (specific gravity 1.07) at a salt usage rate of 310 kg NaCl per m of resin at a flow rate of 10 m/h in a countercurrent mode. The slow rinse after regeneration should run for 2 bed volumes at the regeneration fl rate and the fast rinse for 3 bed volumes at the service flow rate. Summarize your design in a table that includes: (a) pl capacity, (b) water treated ant per cycle, (c) total resin volume, (d) service (volumetric) flow rate, (e) empty bed contact time (f) number, diameter, and depth of columns, (g) surface area loading rates (h) regeneration volume and time, (i) slow rinse volume and time, (j) fast rinse volume and time, (k) total waste volume produced per month, and (l) net water production rate, assuming treated water is used for regeneration and rinsing.Explanation / Answer
Ion exchange resins are polymers that are capable of exchanging particular ions within the polymer with ions in a solution that is passed through them. This ability is also seen in various natural systems such as soils and living cells. The synthetic resins are used primarily for purifying water, but also for various other applications including separating out some elements.In water purification the aim is usually eitherto soften the water or to remove the mineral content altogether. The water is softened by using a resin containing Na+ cations but which binds Ca2+ and Mg2+more strongly than Na+. As the water passes through the resin takes up Ca2+and Mg2+and releases Na+ making for a 'softer' water. If the water needs to have the mineral content entirely removed it is passed through a resin containing H+ (which replaces all the cations) and then through a second resin containing OH- (which replaces all the anions). The H+ and OH- then react together to give more water.The process has some disadvantages in that there are substances occuring in some water (such as organic matter or Fe3+ ions) which can foul the resin, but in general the advantages of the process (long life of resins, cheap maintainance etc.) outweigh the disadvantages. In addition, the process is very environmentally friendly because it deals only with substances already occuring in water.
Related Questions
Navigate
Integrity-first tutoring: explanations and feedback only — we do not complete graded work. Learn more.