Question 1

Grit chamber is similar to which of the following?
A)Screening unit
B)Sedimentation tank
C)Coagulation tank
D)Sand bed

Accepted Answer

Grit chambers are designed to remove grit consisting of sand, gravel, cinders, or other heavy solid materials that have subsiding velocities or specific gravities substantially greater than those of the organic putrescible solids in wastewater. This process is similar to the operation of sedimentation tanks, where particles are removed by settling due to gravity.

Question 2

What is the specific gravity of settleable particles in the grit chamber?
A)2.98
B)2.56
C)2.65
D)2.89

Accepted Answer

The specific gravity of settleable particles typically found in a grit chamber is 2.65. This value is commonly used in the design and operation of grit chambers in wastewater treatment processes, as it represents the average specific gravity of inorganic particles like sand and gravel, which are targeted for removal in these systems.

Question 3

Stoke's law holds good for Reynolds's number ______
A)Less than 1
B)Equal to 1
C)Greater than 1
D)Nearer to 1

Accepted Answer

Stoke's law is applicable for very small Reynolds numbers, typically less than 1, indicating the flow regime where viscous forces dominate over inertial forces.

Question 4

What is the horizontal velocity considered for grit chamber?
A)0.25-0.4m/sec
B)0.6-0.9 m/sec
C)1-2 m/sec
D)3-4m/sec

Accepted Answer

The horizontal velocity considered for grit chambers is typically in the range of 0.25-0.4 m/sec. This velocity is slow enough to allow grit and other heavy particles to settle out of the wastewater without causing organic materials to settle.

Question 5

What is the detention time considered for aerated grit chamber?
A)5-6 mins
B)2-5 mins
C)1-2 mins
D)3-4 mins

Accepted Answer

The detention time considered for aerated grit chambers is typically 2-5 minutes. This range allows for the effective removal of grit and other settleable solids without removing organic material.

Question 6

Which of these is not a grit removal equipment installed in the aerated grit chamber?
A)Screw conveyers
B)Tubular conveyers
C)Jet pumps
D)Communitors

Accepted Answer

Communitors are not used for grit removal; they are used for grinding and shredding solids to protect downstream equipment from blockage, not for removing grit. Screw conveyers, tubular conveyers, and jet pumps are all used in various configurations for the removal of grit in wastewater treatment processes.

Question 7

What is the amount of air supplied for these grit chambers? A)1-2 m³/m.min B)0.2-0.5 m³/m.min C)0.5-0.8 m³/m.min D)0.8-1 m³/m.min

Accepted Answer

The correct amount of air supplied for grit chambers is typically in the range of 0.2-0.5 m^3/m.min to ensure proper grit removal without disturbing organic materials.

Question 8

At what depth are the air diffusers placed in the grit chamber?
A)0.6-0.9 m
B)1-2 m
C)0.1-0.4m
D)0.45-0.6 m

Accepted Answer

The answer of At what depth are the air diffusers...

Question 9

What is the amount of grit quantities captured by the aerated grit chamber? A)0.004-0.20 m3/103.m³ B)0.25 m3/103.m³ C)<0.004 m3/103.m³ D)0.5 m3/103.m³

Accepted Answer

The amount of grit quantities captured by the aerated grit chamber typically ranges from 0.004 to 0.20 cubic meters per 1000 cubic meters of influent.

Question 10

Usually while designing what is the range of the width of the aerated grit chamber assumed?
A)0.5-2 m
B)8-10 m
C)2.5-7.0m
D)12m

Accepted Answer

The typical range for the width of an aerated grit chamber is 2.5-7.0 meters, which allows for effective removal of grit while maintaining proper flow dynamics.

Question 11

Usually while designing what is the range of length of the aerated grit chamber assumed?
A)7.5-20
B)4-6 m
C)25 m
D)50 m

Accepted Answer

The typical length range for an aerated grit chamber is assumed to be between 7.5 to 20 meters. This range allows for effective grit removal while maintaining manageable chamber sizes for wastewater treatment facilities.

Question 12

Usually while designing what is the range of depth of the aerated grit chamber assumed?
A)0.5-2 m
B)8-10 m
C)2-5 m
D)12 m

Accepted Answer

The typical range of depth for an aerated grit chamber is between 2 to 5 meters, which allows for effective removal of grit while maintaining proper aeration.

Question 13

Aerated grit chambers are usually designed to remove particles in which range of size?
A)0.1mm diameter
B)0.35 mm diameter
C)0.21 mm diameter
D)0.41 mm diameter

Accepted Answer

The answer of Aerated grit chambers are usually designed to...

Question 14

Activated sludge process degrade organics and _________
A)Improve nutrients
B)Remove nutrients
C)Remove odour
D)Remove taste

Accepted Answer

The activated sludge process is primarily used for the removal of organic pollutants from wastewater, but it also has the capability to remove nutrients, such as nitrogen and phosphorus, through nitrification and denitrification processes, and phosphorus uptake by biomass.

Question 15

What is required to keep the activated sludge suspended?
A)Carbon-dioxide
B)Nitrogen
C)Oxygen
D)Ammonia

Accepted Answer

Oxygen is required to keep the activated sludge suspended in the aeration tank, as it promotes the growth and metabolism of aerobic microorganisms that consume organic matter.

Question 16

What does the bacterium use to grow?
A)Oxygen
B)Organic pollutants
C)Water
D)Carbon-dioxide

Accepted Answer

Bacteria can use organic pollutants as a source of nutrients and energy for growth.

Question 17

________ combines aeration basin and secondary clarifier into single unit.
A)Primary clarifier
B)Aerobic unit
C)Sequential batch reactor
D)Secondary clarifier

Accepted Answer

Sequential batch reactors (SBRs) are a type of wastewater treatment process that combines the functions of aeration and settling (clarification) within the same tank. This contrasts with traditional systems where the aeration basin and secondary clarifier are separate units.

Question 18

What does SBR stand for?
A)Secondary batch reactor
B)Sequential biological reactor
C)Secondary biological reactor
D)Sequential batch reactor

Accepted Answer

Sequential Batch Reactor (SBR) is a type of wastewater treatment process that operates in a batch mode rather than continuously.

Question 19

SBR operates as ________ process.
A)Batch
B)Continuous
C)Semi-continuous
D)Discontinuous

Accepted Answer

The answer of SBR operates as ________ process.
A)Batch
B)Continuous
C)Semi-continuous
D)Discontinuous...

Question 20

When the aeration system shuts off, the basin begins to perform as a ______
A)Primary clarifier
B)Secondary clarifier
C)Anaerobic unit
D)Aeration unit

Accepted Answer

When the aeration system shuts off, the basin begins to perform as a secondary clarifier because the lack of aeration allows solids to settle out, similar to the function of a secondary clarifier in wastewater treatment processes.

Quiz 7: Grit Chambers and Activated Sludge Processes

Grit chamber is similar to which of the following?

What is the specific gravity of settleable particles in the grit chamber?

Stoke's law holds good for Reynolds's number ______

What is the horizontal velocity considered for grit chamber?

What is the detention time considered for aerated grit chamber?

Which of these is not a grit removal equipment installed in the aerated grit chamber?

What is the amount of air supplied for these grit chambers?

At what depth are the air diffusers placed in the grit chamber?

What is the amount of grit quantities captured by the aerated grit chamber?

Usually while designing what is the range of the width of the aerated grit chamber assumed?

Usually while designing what is the range of length of the aerated grit chamber assumed?

Usually while designing what is the range of depth of the aerated grit chamber assumed?

Aerated grit chambers are usually designed to remove particles in which range of size?

Activated sludge process degrade organics and _________

What is required to keep the activated sludge suspended?

What does the bacterium use to grow?

________ combines aeration basin and secondary clarifier into single unit.

What does SBR stand for?

SBR operates as ________ process.

When the aeration system shuts off, the basin begins to perform as a ______