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Lime Softening & Stabilization for Water Treatment Systems

Learn about water hardness and lime conversions for effective treatment. Explore lime kilns, handling, and precipitation techniques to soften water and prevent corrosion. Understand the stability relationship in water stabilization methods.

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Lime Softening & Stabilization for Water Treatment Systems

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  1. LIME SOFTENING & STABILIZATION

  2. Murder Parties Ralph Rottingrape Marilyn Merlot George W. Taliban

  3. Pen Ta Gon Advisor to the Emperor Queen Illicibeth; Gridlock, the Merchant of Tennis

  4. Description of water Hardness expressed as mg/L of CaCO3 Soft less than 50 Moderately soft 50–75 Slightly hard 75–150 Hard 150–300 Very hard greater than 300 Classifying Water Hardness

  5. What is “lime”? • Limestone, mainly calcium carbonate, CaCO3 • Quicklime, calcium oxide, CaO • Slaked lime, calcium hydroxide, Ca(OH)2

  6. Limestone mining, preparation and use

  7. Limestone Mining, cont’d

  8. Limestone Mining, cont’d

  9. Limestone Handling and Shipping

  10. Lime Conversions • Limestone can be converted to quick lime: CaCO3 CaO + CO2 (1800F) • Quick lime is slaked with water: CaO + H2O  Ca(OH)2 • Slaked lime slowly reacts with CO2 in air: …Ca(OH)2 + CO2  CaCO3 + H2O • Dissolved lime (hardness) can precipitate: Ca(HCO3)2  CaCO3 + H2O + CO2

  11. Lime Kilns

  12. Calcination of Limestone CaCO3  CaO + CO2

  13. Hydration: slaking with water Water reacts with the quicklime to form hydrated lime: CaO + H2O  Ca(OH)2

  14. The removal of divalent metal ions Precipitation/settling or IX resins

  15. Typical lime softening process… Ca(OH)2 Lime    Lime sludge …presented as a complete drinking water treatment process

  16. LIME SLAKING …and DOSING

  17. Precipitation occurs in a settling tank

  18. LAGOON DEWATERING

  19. Why are we concerned about corrosion?

  20. Stability Relationship • The basic Relationship in Stabilization Has been simplified by Powell, Bacon and Lill to pHs = p(Ca2+) + p(Alk) + C

  21. Powell, Bacon and Lill Diagram Langelier index mg/L

  22. Modified Caldwell Lawrence Diagram

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