DOWEX Ion Exchange Resins WATER CONDITIONING MANUAL

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Dealkalization: Salt Splitting Process 5 DEALKALIZATION: SALT SPLITTING PROCESS 5.1 Ion Exchange Resin Specified DOWEX MARATHON A2 Type II strong base anion exchange resin in the chloride form is recommended. For best results, the dealkalizer should be preceded by a water softener using either DOWEX HCR-S or DOWEX MARATHON C strong acid cation resins. DOWEX MARATHON A2 Type II resin reduces the bicarbonate alkalinity of a water supply by exchanging bicarbonate, carbonate, sulfate, and nitrate anions for chloride anions. 5.2 Typical Reactions and Chemicals Used R + CI – + NaHCO3 R + HCO3 − + NaCl 2R + Cl − + Na2SO4 R + 2− 2SO4 + 2NaCI where R = DOWEX MARATHON A2 resin Sodium chloride, NaCl, is used to regenerate DOWEX MARATHON A2 resin. Some caustic soda, NaOH, may be added (usually 1 part NaOH to 9 parts NaCl) to improve capacity and reduce leakage of alkalinity and carbon dioxide by converting bicarbonate to carbonate (Table 6). Calcium carbonate (CaCO3) and magnesium hydroxide (Mg(OH)2) precipitated from NaCl by NaOH can cause hardness leakage from the dealkalizer. This regenerant should be filtered for best results. Table 6. Results of dealkalization by the salt splitting process. Dealkalized Water Dealkalized Water Constituent ppm as Typical Soft Water NaCl Regeneration NaCl/NaOH Regeneration Calcium CaCO3 Nil Nil Nil Magnesium CaCO3 Nil Nil Nil Sodium CaCO3 200 200 200 Total electrolyte CaCO3 200 200 200 Bicarbonate CaCO3 150 30 0 Carbonate CaCO3 0 0 20 Hydroxide CaCO3 0 0 0 Sulfate CaCO3 25 0 0 Chloride CaCO3 25 170 180 Nitrate CaCO3 0 0 0 M Alk CaCO3 150 30 20 P Alk CaCO3 0 0 10 Carbon dioxide CO2 10 20 0 pH – 7.5 5.5 8.3 Silica SiO2 10 10 10 5.3 Equipment Required The equipment includes a vessel to accommodate DOWEX MARATHON A2 resin, with piping, valves, chemical tanks, and accessories properly engineered for optimum operation. If a supply of soft water is unavailable, a water softener should be placed ahead of the dealkalizer. The regeneration system may be built to accommodate both the softener and the dealkalizer. Figure 14 is a general flow diagram for this system. DOWEX Ion Exchange Resins 30 Water Conditioning Manual
Dealkalization: Salt Splitting Process Raw Water DOWEX SAC Softening Resin (Optional) Waste 5.3.1 Equipment Sizing Figure 14. Dealkalization by the salt-splitting process. DOWEX MARATHON A2 Dealkalizer Resin Waste Regenerant Salt To Service 1. Determine the total anion content in the feed water as ppm CaCO3. Subtract from this value the chloride content of the feed as ppm CaCO3. The resulting number is the total exchangeable anion (TEA) content as ppm CaCO3, or divide by 17.1 to obtain grains/U.S. gallon (grpg). 2. Determine from Figure 15 the resin capacity for the TEA content as kgr/ft 3 at the feed water chloride level. Figure 15 shows the approximate capacity obtained at the recommended regeneration level as a function of the chloride content of the influent water. Figure 15. Effect of chloride on capacity of DOWEX MARATHON A2 resin in the chloride cycle. DOWEX Ion Exchange Resins 31 Water Conditioning Manual
Page 1 and 2: Dow Liquid Separations DOWEX Ion Ex
Page 3 and 4: TABLE OF CONTENTS 1 Introduction to
Page 5 and 6: TABLE OF TABLES Table 1. Terms comm
Page 7 and 8: Introduction to Ion Exchange 1 INTR
Page 9 and 10: Terms, Acronyms, And Abbreviations
Page 19 and 20: Sodium Cycle Ion Exchange Process (
Page 27 and 28: Brackish Water Softening Using H2SO
Page 29: Brackish Water Softening Resin oper
Page 33 and 34: Dealkalization: Weak Acid Cation Re
Page 35 and 36: Dealkalization: Weak Acid Cation Re
Page 37 and 38: Demineralization (Deionization) Pro
Page 39 and 40: Demineralization (Deionization) Pro
Page 41 and 42: The UPCORE Counter-Current Regenera
Page 47 and 48: Ion Exchange Resin Operational Info
Page 57 and 58: Ion Exchange Cleaning Procedures 10
Page 59 and 60: Ion Exchange Cleaning Procedures Re
Page 61 and 62: Ion Exchange Cleaning Procedures 10
Page 63 and 64: Ion Exchange Cleaning Procedures Ta
Page 65 and 66: Designing an Ion Exchange system fr
Page 67 and 68: Designing an Ion Exchange system As
Page 69 and 70: Designing an Ion Exchange system 11
Page 71 and 72: Useful Graphs, Tables, and Other In
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Useful Graphs, Tables, and Other In
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Index 14 INDEX A Abbreviations · 9
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Dow Liquid Separations Offices. For
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DOWEX Ion Exchange Resins WATER CONDITIONING MANUAL

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