DOWEX Ion Exchange Resins WATER CONDITIONING MANUAL

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Ion Exchange Cleaning Procedures Chlorine treatment: Sodium hypochlorite (NaOCl 5H2O or bleach cleaning is a very intense treatment for sterilizing and removing organic contaminants on cation exchange resins. Note that chlorine can be explosive under certain conditions. The recommended procedure for cation resins is as follows: 1. Regenerate the resin (hydrogen form). If the resin has iron or other metal contamination, pretreat with about two bed volumes of 10% HCl solution. 2. Ensure that the resin is completely exhausted by treating with brine solution (for strong acid cation resins) or caustic (for weak acid cation resins) because any residual H + on the resin can lead to the generation of free Cl2. Take care to allow for resin swelling. 3. Use a sodium hypochlorite solution of 0.10% concentration (1000 ppm). 4. Apply 143 g free Cl2/ft 3 (5 g/L) resin by passing two bed volumes of the NaOCI solution at ambient temperature down through the resin bed with a 30–45 minute contact time. Allow the resin to soak in the solution for 1–2 h. 5. Rinse out with one to two bed volumes of deionized water. 6. For the most effective treatment, apply more solution, repeating step 4. Perform a final rinse with three to four bed volumes of deionized water (until no Cl2 is detectable in effluent). The recommended procedure for anion resins is as follows: 1. Put resin into exhausted (Cl) form. If the resin has iron or other metal contamination, pretreat with about two bed volumes of 10% HCl solution. 2. Use a sodium hypochlorite solution of 0.05% concentration (500 ppm). 3. Apply 57 g free Cl2/ft 3 (2 g/L) resin by passing two bed volumes of the NaOCI solution at ambient temperature through the resin bed with a 30–45 minute contact time. Measure the effluent and stop if free Cl2 reaches a level of about 10% of the inlet concentration. 4. Rinse out with three to four bed volumes of deionized water (until no Cl2 is detectable in effluent). Reference Document: Tech Facts 177-01744 DOWEX Ion Exchange Resins 60 Water Conditioning Manual
Ion Exchange Cleaning Procedures 10.2 Ion Exchange Troubleshooting The three prime problem areas are system loss of throughput capacity, failure to produce specified water quality, and increased pressure drop. Table 20. System loss of throughput capacity. Symptom Possible Causes Remedies Loss of throughput capacity Faulty or inaccurate measurement system (flow meter, conductivity meter, etc.) Inappropriate rinse water quality Check measurement system. Repair or replace if necessary. Use softened water for cation resins, decationized water for anion resin, demineralized water for mixed-bed resin Long rinse down See “Resin degradation/fouling” below. Change in water composition/increase in influent TDS Early breakthrough due to decreased water quality Low flow rate due to pressure drop increase Obtain a current water analysis to confirm (the computer design program CADIX has this functionality), then increase regeneration level or evaluate potential for upgrading system to UPCORE See Table 21. Failure to produce specified water quality. See Table 22. Increased pressure drop. Resin loss Measure resin bed depth, in the same form that the resin was supplied. Add more resin as required. If a sudden high loss of resin occurs, check vessel and distribution system for leaks Inadequate regeneration Check for correct resin contact time, flow rates, and concentration Leaking/by-pass of Check and adjust all valves. regenerant valves Resin degradation/fouling Take sample and confirm with resin analysis, clean or replace resin as appropriate. See Section 9.4 and Section 10. DOWEX Ion Exchange Resins 61 Water Conditioning Manual
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Dow Liquid Separations DOWEX Ion Ex
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TABLE OF CONTENTS 1 Introduction to
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TABLE OF TABLES Table 1. Terms comm
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Introduction to Ion Exchange 1 INTR
Page 9 and 10: Terms, Acronyms, And Abbreviations
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Page 27 and 28: Brackish Water Softening Using H2SO
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Page 31 and 32: Dealkalization: Salt Splitting Proc
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Page 41 and 42: The UPCORE Counter-Current Regenera
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Page 65 and 66: Designing an Ion Exchange system fr
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Page 71 and 72: Useful Graphs, Tables, and Other In
Page 91 and 92: Index 14 INDEX A Abbreviations · 9
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