25 Questions
What is the main cause of temporary hardness in water?
Presence of dissolved bicarbonates Ca and Mg
How can temporary hardness be easily removed?
By boiling the water
What is the main cause of permanent hardness in water?
Presence of dissolved sulphates and chlorides
Why is hard water less likely to lather well?
Due to the presence of dissolved bicarbonates Ca and Mg
What are the main concerns for consumers regarding hard water?
Reduced lathering ability and white residue on faucets
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
What is the purpose of lime-soda softeners?
To remove harmful ions from water
What is the pH at which the reactions occur in the lime-soda softening process?
11
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
What is the main principle behind zeolite softeners?
Ion exchange
What is a significant advantage of zeolite softeners compared to lime-soda softeners?
Zeolite softeners can bring the hardness down to zero
What determines the capacity of a zeolite softener?
Quantity and type of exchange material, and mechanical condition of the softener
What is the purpose of backwashing in the zeolite softener?
To remove fine particles and entrained dirt from the resin bed
What occurs during the brining step of the zeolite softener regeneration?
Removal and replacement of calcium and magnesium with sodium
What causes a reduction in the capacity of a zeolite softener?
Fouled exchange material
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
What can cause incomplete softening of water in a zeolite softener?
Improper brine injection during regeneration
Why should contaminants in the supply water be removed before entering the zeolite softener?
To prevent reduced output and poor water distribution
What is the purpose of the cation exchanger in the demineralizer unit?
To replace cations with hydrogen ions
What is the effluent of the anion exchanger in the demineralizer unit?
Pure water
Which method can effectively remove up to 99% of dissolved solids, organic matter, and colloidal matter?
RO - reverse osmosis
What is the total dissolved solids content of sea water (approximately)?
38,000 mg/L
How is regular osmosis different from reverse osmosis?
Regular osmosis separates two fluids, while reverse osmosis applies pressure to impure solution.
How are exhausted ion exchangers regenerated?
By passing a diluted solution of sulfuric acid through the bed
What is the conductivity reading of water after treatment by demineralizers?
Less than 15 μS/cm
Test your knowledge of the water softening process with this quiz. Learn about the distribution of water through the bed and the flow of softened water to different components.
Make Your Own Quizzes and Flashcards
Convert your notes into interactive study material.
Get started for free
