Water Softening Process

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What is the main cause of temporary hardness in water?

High temperature

Presence of dissolved bicarbonates Ca and Mg (correct)

Presence of dissolved sulphates and chlorides

Special methods like lime soda process

How can temporary hardness be easily removed?

By boiling the water (correct)

By increasing the concentration of calcium and magnesium ions

By using zeolite process

By using special methods like lime soda process

What is the main cause of permanent hardness in water?

Using zeolite process

Presence of dissolved bicarbonates Ca and Mg

Presence of dissolved sulphates and chlorides (correct)

High temperature

Why is hard water less likely to lather well?

Due to the presence of dissolved bicarbonates Ca and Mg Signup and view all the answers

What are the main concerns for consumers regarding hard water?

Reduced lathering ability and white residue on faucets Signup and view all the answers

Why do calcium and magnesium ions need to be removed or treated with a softener prior to entering a boiler system?

To prevent the formation of scale and improve heat transfer Signup and view all the answers

What is the purpose of lime-soda softeners?

To remove harmful ions from water Signup and view all the answers

What is the pH at which the reactions occur in the lime-soda softening process?

11 Signup and view all the answers

Why is the hot process of lime-soda softening more common than the cold process?

The hot process removes silica, while the cold process does not Signup and view all the answers

What is the main principle behind zeolite softeners?

Ion exchange Signup and view all the answers

What is a significant advantage of zeolite softeners compared to lime-soda softeners?

Zeolite softeners can bring the hardness down to zero Signup and view all the answers

What determines the capacity of a zeolite softener?

Quantity and type of exchange material, and mechanical condition of the softener Signup and view all the answers

What is the purpose of backwashing in the zeolite softener?

To remove fine particles and entrained dirt from the resin bed Signup and view all the answers

What occurs during the brining step of the zeolite softener regeneration?

Removal and replacement of calcium and magnesium with sodium Signup and view all the answers

What causes a reduction in the capacity of a zeolite softener?

Fouled exchange material Signup and view all the answers

What is the purpose of the slow rinse step during zeolite softener regeneration?

To create a slow moving plug of water to force remaining brine into areas it may not have penetrated earlier Signup and view all the answers

What can cause incomplete softening of water in a zeolite softener?

Improper brine injection during regeneration Signup and view all the answers

Why should contaminants in the supply water be removed before entering the zeolite softener?

To prevent reduced output and poor water distribution Signup and view all the answers

What is the purpose of the cation exchanger in the demineralizer unit?

To replace cations with hydrogen ions Signup and view all the answers

What is the effluent of the anion exchanger in the demineralizer unit?

Pure water Signup and view all the answers

Which method can effectively remove up to 99% of dissolved solids, organic matter, and colloidal matter?

RO - reverse osmosis Signup and view all the answers

What is the total dissolved solids content of sea water (approximately)?

38,000 mg/L Signup and view all the answers

How is regular osmosis different from reverse osmosis?

Regular osmosis separates two fluids, while reverse osmosis applies pressure to impure solution. Signup and view all the answers

How are exhausted ion exchangers regenerated?

By passing a diluted solution of sulfuric acid through the bed Signup and view all the answers

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

Less than 15 μS/cm Signup and view all the answers