Water Softening System Operation
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Questions and Answers

What is the main reason for water to be considered hard?

  • Excessive amount of chlorine
  • Large quantity of dissolved oxygen
  • High concentration of sodium ions
  • Presence of dissolved bicarbonates (correct)
  • Which type of hardness can be easily removed by heating?

  • Alkaline hardness
  • Permanent hardness
  • Sulphate and chloride hardness
  • Temporary hardness (correct)
  • What causes permanent hardness in water?

  • Dissolved bicarbonates
  • Sulphates and chlorides of calcium and magnesium (correct)
  • Excessive amount of fluoride
  • High concentration of potassium ions
  • Why is it important to remove or treat dissolved solids like calcium and magnesium before water enters a boiler system?

    <p>To prevent scale formation and lower heat transfer efficiency</p> Signup and view all the answers

    What concentration of calcium or magnesium ions classifies water as hard?

    <p>Over 120 ppm (120 mg/L)</p> Signup and view all the answers

    Which method is NOT effective for removing permanent hardness from water?

    <p>Boiling the water</p> Signup and view all the answers

    What are the main concerns for consumers regarding hard water?

    <p>Less likelihood to lather well and white residue on faucets and dishware</p> Signup and view all the answers

    What is the purpose of the lime-soda softening process?

    <p>To remove harmful ions from water</p> Signup and view all the answers

    In the lime-soda softening process, what reacts with the impurities causing carbonate hardness?

    <p>Lime and soda ash</p> Signup and view all the answers

    What is a characteristic of hot lime-soda softening process compared to the cold process?

    <p>It can remove silica while the cold process cannot</p> Signup and view all the answers

    What is the function of zeolite softeners in water treatment?

    <p>To remove hardness-causing calcium and magnesium ions using ion exchange</p> Signup and view all the answers

    What is a benefit of using ion-exchange zeolite softeners compared to lime-soda softeners?

    <p>They are easier to control and have safer chemicals for operators</p> Signup and view all the answers

    What type of ions replace scale-forming magnesium and calcium ions in an ion exchange softener?

    <p>Sodium ions</p> Signup and view all the answers

    What is a characteristic of zeolite softeners in terms of removing hardness from water?

    <p>They can bring the hardness down to zero</p> Signup and view all the answers

    What is the purpose of backwashing in a zeolite softener?

    <p>To expand the volume of the bed and remove entrained dirt</p> Signup and view all the answers

    What is the purpose of brining in a zeolite softener?

    <p>To remove calcium and magnesium from the zeolite material</p> Signup and view all the answers

    What happens during slow rinse in a zeolite softener?

    <p>Water flows downwards creating a slow moving plug of water</p> Signup and view all the answers

    Why should the backwash flow not be too fast in a zeolite softener?

    <p>To avoid carrying out zeolite resin with the backwash effluent</p> Signup and view all the answers

    What can cause a reduction in the capacity of a softener or incomplete softening?

    <p>Fouled exchange material</p> Signup and view all the answers

    What is a potential result of excessive flow during backwash in a zeolite softener?

    <p>Loss of zeolite material</p> Signup and view all the answers

    How can improper flow rates affect the operation of a zeolite softener?

    <p>Causing incomplete softening of the water</p> Signup and view all the answers

    What is the purpose of periodic replacement of the zeolite resin?

    <p>To regenerate the ion exchangers</p> Signup and view all the answers

    What is the effluent of the cation exchanger in the demineralizer?

    <p>An acidic solution</p> Signup and view all the answers

    What happens during the regeneration of the cation exchanger in the ion exchangers?

    <p>Calcium ions are released and replaced by sodium ions</p> Signup and view all the answers

    What is the main purpose of reverse osmosis (RO)?

    <p>To desalinate sea water</p> Signup and view all the answers

    How does reverse osmosis differ from regular osmosis?

    <p>Reverse osmosis applies pressure to separate impurities</p> Signup and view all the answers

    In a demineralizer, what happens in the anion exchanger?

    <p>Anions are exchanged for hydroxide ions</p> Signup and view all the answers

    What is the standard range for the conductivity reading of water after treatment by demineralizers?

    <p>Between 15-30 μS/cm</p> Signup and view all the answers

    How are ion exchangers in demineralizers regenerated when exhausted?

    <p>By using a diluted solution of sulfuric acid for both exchangers</p> Signup and view all the answers

    What total dissolved solids (TDS) value does sea water typically have?

    <p>38000</p> Signup and view all the answers

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