Water Softening with Potassium Chloride

WILLIAM WIST (deceased) spent eleven years at Central Canada Potash as a lab technician, senior chemist, and chief chemist. After joining Potash Corporation of Saskatchewan Inc. in 1980 as chief chemist, he set up and equipped a new research and development laboratory for them. From 1988 until his retirement in 2005, he was chief chemist and pilot plant supervisor. Bill spearheaded the research and development of the use of potassium chloride as a water softening regenerant, in addition to other projects involving potash product quality and analytical procedures. JAY H. LEHR holds a PhD in environmental science from the University of Arizona and an engineering degree from Princeton University. He is the author of twenty-eight books and over 600 journal and magazine articles. He has taught at the University of Arizona and The Ohio State University, directed a professional society of environmental scientists, and formed a variety of environmental teaching and consulting firms.ROD McEACHERN holds a PhD in chemistry from the University of Saskatchewan. He currently works as the Director of R&D with the Potash Corporation of Saskatchewan Inc. in Saskatoon, Canada. His research interests include the application of new technology to environmental stewardship through improved air pollution abatement equipment, improved waste management practices, and process improvements to potash operations.

• PREFACE xiACKNOWLEDGMENTS xiii1 WHAT IS POTASSIUM CHLORIDE? 1Saskatchewan Potash History 2Potash Mining 3Solution Mining 9Processing Potash Ore 13Storage, Transportation, and Distribution of Potash 27Potash Products 292 WHAT IS HARD WATER? 34Definition of Hard Water 34How Hard Water is Created 35Problems Associated With Hard Water 37How Hard Water is Measured 39Uniform Degrees of Hardness 40Types of Hardness 403 LOWERING WATER HARDNESS 43Ion Exchange 44Deionization or Demineralization 45Reverse Osmosis 47Distillation 49Precipitation 504 THE ION EXCHANGE PROCESS 54Synthesis and Structure of Ion Exchange Resins 55Types of Ion Exchange Resins 56Household Water Softening 57Typical Household Water Softeners 59Cocurrent and Countercurrent Regeneration 64Mathematical Treatment of Ion Exchange Equilibria 66Selectivity of Ion Exchange Reactions 755 BASIC CHEMISTRY OF ION EXCHANGE 78The Building Blocks of Matter 78Atomic and Molecular Weights 80Cations and Anions 83Chemical Reactions 846 OPERATION AND TYPES OF WATER SOFTENERS 86Historical Methods of Regeneration 86Operation of a Typical Water Softener 87Common Sequences of Cycles 93Types of Water Softeners 93Sizing a Water Softener 967 POTASSIUM CHLORIDE REGENERANT FOR WATER SOFTENING 99Alternate Regenerants 99Potassium Chloride Regenerant 101Initial Comparison of KCl and NaCl 102Challenges When Using KCl as a Regenerant 110Frequently Asked Questions 1128 COMPARISON OF KCl AND NaCl AS REGENERANT 115Definition of Terms 115Theoretical Capacities of KCl and NaCl Regenerants 118Calculation of Regeneration Efficiency 120Sizing a Softener for Salt Efficiency 121Implications for Salt Consumption 123Total Salt Released to the Environment 127Comparison of KCl and NaCl: Solubility 129Comparison of KCl and NaCl: Speed of Dissolution 130Comparison of KCl and NaCl: Capacity 132Comparison of KCl and NaCl: Used and Unused Regenerant 135Comparison of KCl and NaCl: Release of Chlorides to the Environment 138Comparison of KCl and NaCl: Taste 139Comparison of KCl and NaCl: Generation of Fines 144Comparison of KCl and NaCl: Sodium Content of Softened Water 145Comparison of KCl and NaCl: Potassium Content of Softened Water 154Comparison of KCl and NaCl: Total Dissolved Solids 1549 ENVIRONMENTAL CONSIDERATIONS 157Potassium versus Sodium: Impact on Soil 159Potassium versus Sodium: Impact on Septic Systems 162Potassium versus Sodium: Impact on Sewage Treatment Systems 164Potassium versus Sodium: Sewage Sludge 166Potassium versus Sodium: Algae Growth 166Potassium versus Sodium: Impact on Plants and Animals 169Potassium versus Sodium: Use of Recycled Graywater 170Recycling Regenerant Wastewater 171Use of Regenerant Wastewater Studies at University of California, Davis 172In Conclusion 17710 POTASSIUM AND HUMAN HEALTH 183Overview 183Introduction 184Cellular Physiology of Potassium 184Potassium Balance 186Defects in Potassium Elimination 188Medical Conditions Related to Potassium Excess 189Medical Conditions Related to Potassium Deficit 191Indirect Role of Potassium in Health 199Summary 20011 ONGOING RESEARCH 209Iron and Manganese Removal 209Grade of KCl Regenerant 213Cocurrent versus Countercurrent Regeneration 215Portable Exchange Tanks 217Research into Alternate Regenerants 220APPENDIX 1 STANDARD TEST PROTOCOL FOR COMPARISON OF KCl AND NaCl REGENERANTS 223Protocol Development 223Standard Test Protocol 226APPENDIX 2 LABORATORY DATA OBTAINED WITH THE STANDARD TEST PROTOCOL 233APPENDIX 3 ACCELERATED MUSH TEST 243Apparatus 243Method 244INDEX 245