Question 1

In which unit operation, gases are released or absorbed in the water?
A)gas transfer
B)ion transfer
C)solute stabilization
D)solids transfer

Accepted Answer

Gas transfer is the unit operation specifically designed for the release or absorption of gases in water, such as oxygenation or carbon dioxide removal.

Question 2

How many types of aerators are commonly used in the treatment of water?
A)2
B)3
C)4
D)5

Accepted Answer

Four main types of aerators are commonly used in water treatment: cascade aerators, spray aerators, packed tower aerators, and diffused air aerators.

Question 3

Which of the following process is used to remove the colloidal particles from water?
A)chemical precipitation
B)chemical coagulation
C)ion exchange
D)adsorption

Accepted Answer

Chemical coagulation is the process used to remove colloidal particles from water by adding coagulants to destabilize the colloidal particles, allowing them to aggregate and settle out of the water.

Question 4

Flocculation of iron from water by the addition of lime is an example of which of the following process?
A)chemical precipitation
B)chemical coagulation
C)ion exchange
D)adsorption

Accepted Answer

Flocculation of iron from water by the addition of lime is an example of chemical precipitation. In chemical precipitation, a chemical is added to a solution to cause the formation of a solid precipitate. In this case, lime (calcium hydroxide) is added to the water to cause the formation of iron hydroxide, which precipitates out of solution.

Question 5

In which unit operation objectionable solutes are converted into unobjectionable forms without removal?
A)gas transfer
B)ion transfer
C)solute stabilization
D)solids transfer

Accepted Answer

Solute stabilization is the process where objectionable solutes are converted into unobjectionable forms without actually removing them from the solution. This process is used to neutralize or stabilize harmful or unwanted components in a solution, making them harmless or less harmful without physically removing them.

Question 6

In which form of solute stabilization, hydrogen sulfide in water is oxidized into sulfate?
A)chlorination
B)liming
C)re-carbonation
D)super-chlorination

Accepted Answer

The answer of In which form of solute stabilization, hydrogen...

Question 7

Which form of solute stabilization occurs when water passes through limestone?
A)chlorination
B)liming
C)re-carbonation
D)super-chlorination

Accepted Answer

Liming occurs when water passes through limestone, which can lead to the stabilization of the solute by increasing the pH and reducing acidity through the addition of calcium carbonate (CaCO3) from the limestone.

Question 8

In which process, excess lime is converted into bicarbonate?
A)chlorination
B)liming
C)re-carbonation
D)super-chlorination

Accepted Answer

Re-carbonation is the process where excess lime is converted into bicarbonate by adding carbon dioxide. This is often done in water treatment processes to adjust the pH and stabilize the water after lime has been added for softening.

Question 9

By which process, odour producing substances is oxidized?
A)chlorination
B)liming
C)re-carbonation
D)super-chlorination

Accepted Answer

Super-chlorination is a process where a high dose of chlorine is used to oxidize and eliminate odour-producing substances in water.

Question 10

Solids are removed from the water by which of the following unit operation?
A)inter facial contact
B)solid stabilization
C)ion transfer
D)solids transfer

Accepted Answer

Solids are removed from the water primarily through a unit operation known as solids transfer, which involves physical processes like sedimentation, filtration, or centrifugation to separate solids from liquids.

Question 11

Dealkalization results in removal of all the ions from the water.

Accepted Answer

Dealkalization specifically targets the removal of bicarbonate, carbonate, and hydroxide ions to reduce water alkalinity, not all ions.

Question 12

Organic contaminants are removed from the water by the process of________    
A)water softening
B)demineralization
C)absorption
D)adsorption

Accepted Answer

Adsorption is the process where organic contaminants are removed from water by adhering to a solid surface, typically activated carbon or other materials designed to attract and hold onto these contaminants.

Question 13

____________ is an operation designed to force agitation in the fluid and induce coagulation.
A)sedimentation
B)flocculation
C)disinfection
D)aeration

Accepted Answer

Flocculation is the process that involves the action of mixing water to promote the aggregation or coagulation of particles, typically to improve the efficiency of sedimentation or filtration.

Question 14

What is the normal value of the detention period adopted in a flocculator for design purpose?
A)30min
B)60min
C)90min
D)100min

Accepted Answer

The normal detention period for a flocculator is typically around 30 minutes to allow sufficient time for particles to aggregate into larger flocs.

Question 15

The design value of the velocity of flow in a flocculator is________      
A)0.2-0.8m/s
B)0.3-0.5m/s
C)0.6-0.8m/s
D)0.1-0.5m/s

Accepted Answer

The design value of the velocity of flow in a flocculator is 0.2-0.8m/s. This is because the velocity of flow must be high enough to keep the flocs in suspension, but not so high that the flocs are broken up.

Question 16

What is the detention period of a clarifier used in the treatment of water?
A)1hour
B)2hours
C)3hours
D)4hours

Accepted Answer

The answer of What is the detention period of a...

Question 17

The pulsator clarifier is a type of
A)horizontal flow sludge tank
B)vertical flow sludge tank
C)circular sludge tank
D)plain sedimentation tank

Accepted Answer

The pulsator clarifier is a type of vertical flow sludge tank, where water flows vertically through the tank, allowing for efficient sedimentation and sludge removal.

Question 18

Which device solved the problem of unstable hydraulic conditions and operation of sludge removal equipment?
A)centrifugal pump
B)pulsator clarifier
C)tube settler
D)flocculator

Accepted Answer

The answer of Which device solved the problem of unstable...

Question 19

In which device, the primary mixing is followed by a secondary reaction zone resulting in formation of sludge blanket?
A)centrifugal pump
B)flocculator
C)tube settler
D)solid contact clarifier

Accepted Answer

Solid contact clarifiers incorporate a primary mixing zone where coagulants can be added, followed by a secondary reaction zone where flocculation occurs and a sludge blanket is formed. This process aids in the removal of suspended solids from water.

Question 20

In which type of tube settler, tubes are slightly inclined in the direction of normal flow?
A)solid contact clarifier
B)steeply inclined tube settler
C)vertical tube settler
D)horizontal tube settler

Accepted Answer

The answer of In which type of tube settler, tubes...

Quiz 5: Water Treatment Processes and Unit Operations

In which unit operation, gases are released or absorbed in the water?

How many types of aerators are commonly used in the treatment of water?

Which of the following process is used to remove the colloidal particles from water?

Flocculation of iron from water by the addition of lime is an example of which of the following process?

In which unit operation objectionable solutes are converted into unobjectionable forms without removal?

In which form of solute stabilization, hydrogen sulfide in water is oxidized into sulfate?

Which form of solute stabilization occurs when water passes through limestone?

In which process, excess lime is converted into bicarbonate?

By which process, odour producing substances is oxidized?

Solids are removed from the water by which of the following unit operation?

Dealkalization results in removal of all the ions from the water.

Organic contaminants are removed from the water by the process of________

____________ is an operation designed to force agitation in the fluid and induce coagulation.

What is the normal value of the detention period adopted in a flocculator for design purpose?

The design value of the velocity of flow in a flocculator is________

What is the detention period of a clarifier used in the treatment of water?

The pulsator clarifier is a type of

Which device solved the problem of unstable hydraulic conditions and operation of sludge removal equipment?

In which device, the primary mixing is followed by a secondary reaction zone resulting in formation of sludge blanket?

In which type of tube settler, tubes are slightly inclined in the direction of normal flow?