1 / 27

Water Conditioning Process

Water Conditioning Process. Dr.Lek Wantha. Contents. Water usage in industries Water sources Water quality related to end-use Water treatment for industrial supply Water softening Ion exchange process Lime-soda process Demineralization Desalting or Desalinization Electrodialysis (ED)

luyu
Download Presentation

Water Conditioning Process

An Image/Link below is provided (as is) to download presentation Download Policy: Content on the Website is provided to you AS IS for your information and personal use and may not be sold / licensed / shared on other websites without getting consent from its author. Content is provided to you AS IS for your information and personal use only. Download presentation by click this link. While downloading, if for some reason you are not able to download a presentation, the publisher may have deleted the file from their server. During download, if you can't get a presentation, the file might be deleted by the publisher.

E N D

Presentation Transcript

  1. Water Conditioning Process Dr.LekWantha

  2. Contents • Water usage in industries • Water sources • Water quality related to end-use • Water treatment for industrial supply • Water softening • Ion exchange process • Lime-soda process • Demineralization • Desalting or Desalinization • Electrodialysis (ED) • Reverse osmosis (RO)

  3. Water Usage in Industries • Component in products • Energy carrying media (heat media), i.e. steam • Cooling media • Cleaning • Separating & Purification • Transportation of raw material & products • Mixing • Complete reaction

  4. Water Sources(exclude tap water) • Sea water • Salt >>>2.6% by mass NaCl, MgCl2, sulfate • Gases>>> N2, O2,CO2 • Surface water • Flowing in river, cannel • Contain of inorganic and organic compounds depend on climatic • Underground water • Artesian well • Water table well • Spring • Geysers(hot spring)

  5. Water Sources

  6. Water Quality Related to End-use • Inorganic salts • Ca2+ • Mg2+ • Na+ • K+ • Sulfate carbonate • Chloride ion • Organic compounds & dissolved gasses • CO2 • O2 • H2S • Organisms • Aquatic animals • Aquatic insects • Microorganisms

  7. Water Quality Related to End- use

  8. Water quality Requirement for Agriculture • Livestock • Low bacteria, <40/100 mL • Low toxic concentration • Irrigation • Low dissolved solids, <500 mg/L • Total bacteria, 100,000/100 mL • Low heavy metal • Fish, aquatic life, wide life requirements • Low toxic concentration • pH near neutral (6.5-8.5) • Low BOD (1-2 mg/L) • High DO • Cold: 6-7 mg/L (15 ºC) • Warm: 4-5 mg/L (20 ºC) • Low temperature, turbidity BOD= Biochemical oxygen demand OD = Dissolved oxygen

  9. Water quality Requirement for Industries • Cooling • Low hardness, 50 ppm of (Mg2+ + Ca2+) • Low corrosivity • Food processing, brewing & soft drinking • As public drinking water, but F- <1 ppm • Thermal power • Total Dissolved Solid (TDS) < 0.1 ppm • Public recreational requirements • Free of color, odor, taste and turbidity • Total bacteria, <1000/100 mL • Coliform bacteria <100/100 mL • Low nutrients

  10. Water quality Requirement for Industries • Public drinking water (treated) • No bacteria • Low nitrate, nitrite (< 10 ppm) • Very low pesticide (none or < 0.05 ppm) • Fluoride allowable to 2.4 ppm • Toxic substances (below criteria level) • TDS < 500 ppm

  11. Water Treatment for Industrial Supply

  12. Hydrated lime (Ca(OH)2)  Quicklime (CaO) Soda ash (Na2CO3)  Caustic soda (NaOH) • Ion exchange process • Reverse osmosis (RO) • Electrodialysis (ED)

  13. Water Softening • Reduce/remove hardness • Hardness • Dissolved salts: Calcium and magnesium • Problems Calcium bicarbonate → Calcium carbonate + Water + Carbon dioxide Ca(HCO3)2 → CaCO3 + H2O + CO2 • deposition of calcium carbonate scale in pipes and equipment • causes corrosion of iron or steel equipment • culprit in forming soap scum

  14. Softening Boiling Adding lime Adding sodium carbonate Exchange process Softening Adding sodium carbonate Exchange process

  15. Ca(HCO3)2 + heat  CaCO3 +CO2+H2O • Mg(HCO3)2 + heat  MgCO3 +CO2+H2O • Ca(HCO3)2 + Ca(OH)2  2CaCO3 +2H2O • MgCl2 + Ca(OH)2  Mg(OH)2  + CaCl2 • CaCl2+Na2CO3  CaCo3  + 2NaCl • MgSO4+Na2CO3+ Ca(OH)2  Mg(OH)2  +CaCo3  + Na2SO4 Sodium Cation Exchange Ion Exchange Process Hydrogen Cation Exchange Anion Exchanger

  16. Ion Exchange Process Zeolite softening

  17. Ion Exchange Process • Advantages  • Ion exchange can be used with fluctuating flow rates. • Makes effluent contamination impossible. • Resins are available in large varieties from suppliers and each resin is effective in removing specific contaminants. • Limitations  • Pretreatment is required for most surface waters. • Waste is highly concentrated and requires careful disposal. • Unacceptable high levels of contamination in effluent. • Units are sensitive to the other ions present.

  18. Sodium Cation Exchange

  19. Hydrogen Cation Exchange

  20. Anion Exchanger

  21. Lime-soda Process • Lime = CaO + Soda = soda ash (Na2CO3) • Carbonate hardness (temporary) • Ca(HCO3)2 + Ca(OH)2  2CaCO3 +2H2O • Mg(HCO3)2 + Ca(OH)2  MgCO3+CaCO3 +2H2O • MgCO3+ Ca(OH)2  Mg(OH)2 +CaCO3 • Non-carbonate hardness (Permanent) • MgCl2 + Ca(OH)2  Mg(OH)2  + CaCl2 • CaCl2+Na2CO3  CaCo3  + 2NaCl • CaSO4+Na2CO3  CaCo3  + Na2SO4 • MgSO4+Na2CO3+ Ca(OH)2  Mg(OH)2  +CaCo3  + Na2SO4

  22. Types of Lime Hydrated lime (Ca(OH)2)  quicklime (CaO) Soda ash (Na2CO3)  Caustic soda (NaOH)

  23. Demineralization Process • Removal of minerals and nitrate from the water • Ion exchange: • removal of hardness ions (magnesium and calcium) • water demineralization • 90% of barium, arsenic, cadmium, chromium, silver, radium, nitrites, selenium and nitrates can be effectively removed from water • Reverse osmosis • Electrodialysis • membrane processes, remove dissolved solids from water using membranes

  24. Desalting or Desalinization Process • Treatment of highly saline water: • sea water • 3,500 ppm of dissolved salt • Lowing saline contents • < 500 ppm • Two methods • Electrodialysis (ED) • Reverse Osmosis (RO)

  25. Electrodialysis (ED) 2H2O + 2e-2OH- +H2(g) 2Cl- 2e- +Cl2 (g)

  26. Osmosis vs. Reverse Osmosis (RO) Reverse Osmosis Osmosis Contaminants Contaminants Direction of water flow Direction of water flow

  27. Sources • http://water.me.vccs.edu/courses/ENV115/lesson9.htm

More Related