Waste Water Engineering Questions and Answers - Blowers Part-1

1. Aeration energy consumes _______ of all electrical usage.
a) 30%
b) 40%
c) 60%
d) 80%

Answer: c
Explanation: There are two important considerations for the wastewater treatment plant. They are proper aeration and blower selection. Aeration energy consumes 60% of all the electrical usage.

2. Which of the following is created by blowers?
a) Air flow
b) Water flow
c) Wastewater flow
d) Vacuum flow

Answer: a
Explanation: Blowers create air low. The blower system creates pressure through resistance to air flow. By combining the flow rate and back pressure, the actual operating air flow can be identified.

3. Proper air flow can help the bacteria remain suspended.
a) True
b) False

Answer: a
Explanation: The essential function of the aeration system is to fulfil the oxygen demands and maintain the treatment process at the lowest possible costs. Proper air flow can help the bacteria remain suspended.

4. What is the purpose of the blower?
a) Decrease air flow
b) Increase air flow
c) Create vacuum
d) Maintain air flow

Answer: b
Explanation: The purpose of the blower is to increase the air flow or create additional air flow, the purpose of blower controls is to provide the correct air flow at any time, which in time provides the enhanced aeration efficiency.

5. The presence of DO is necessary for wastewater.
a) True
b) False

Answer: a
Explanation: The presence of some amount of dissolved oxygen is necessary in wastewater otherwise the system becomes anaerobic and insufficient. DO help in satisfactory biological wastewater decomposition.

6. Air is used to ________ the filter bed.
a) Compact
b) Expand
c) Aerate
d) Fluidize

Answer: b
Explanation: Air is used to expand the filter bed, breaking up compacted material. When the clean water is pumped in for backwash, it suspends and loosens the material and the particles are lifted through and carried away.

7. Which technology’s principle is used in screw blowers?
a) Air expander
b) Air compressor
c) Ventilators
d) Vacuum creators

Answer: b
Explanation: The technology employed with the screw blowers is essentially a scaled version of the principles used in an air compressor. The rotors trap and then squeeze air between them. Air is progressively compressed during each rotation

8.Which blower among the following has the highest nominal efficiency?
a) Positive displacement
b) Single stage centrifugal
c) Multi stage centrifugal (inlet throttled)
d) Multi stage centrifugal (variable speed)

Answer: b
Explanation: The nominal efficiency for single stage centrifugal blower is 70-80%. The nominal efficiency for positive displacement blower is 45-65%. The nominal efficiency for multi stage centrifugal (inlet throttled) is 50-70%. The nominal efficiency for Multi stage centrifugal (variable speed) is 60-70%.

9. When is high pressure required, which type of blower is preferred?
a) Positive displacement blower
b) Centrifugal blower
c) Helical screw blower
d) Regenerative blower

Answer: a
Explanation: A blower is selected based on the system’s pressure requirements. When high pressure is required a positive displacement blower is preferred. Performance curve of the blower helps us to identify the suitable blower required for that application.

10. Which type of blower is preferred for fluid bed reactor?
a) Centrifugal blower
b) Positive displacement blower
c) Regenerative blower
d) Helical screw blower

Answer: a
Explanation: Centrifugal blowers are used for fluid bed reactors. These are used for dust controlling systems also. These are used for aeration systems in water or waste water treatment plant