This set of Waste Water Engineering Multiple Choice Questions & Answers (MCQs) focuses on “Self Purification of Natural Streams”.
1. Which one of the following is the basic indicator of river health?
a) BOD
b) COD
c) DO
d) ThOD
View Answer
Explanation: The amount of dissolved Oxygen (DO) in water is one of the most commonly used indicators of a river health. Below 4 or 5 mg/l, the life forms that survive are reduced.
2. What is the minimum amount of DO required for the life survival of aquatic animals?
a) 10 mg/l
b) 5 mg/l
c) 2 mg/l
d) 1 mg/l
View Answer
Explanation: As DO drops below 4 or 5 mg/L the forms of life that can survive begin to be reduced. A minimum of about 2.0 mg/L of dissolved oxygen is required to maintain higher life forms.
3. Oxygen demanding wastes improves DO.
a) True
b) False
View Answer
Explanation: Oxygen demanding wastes remove DO. Plants add DO during the day but remove it at night. Respiration of organisms removes oxygen. Temperature is reduced in summer which inturn reduces flow.
4. In the concept of self purification of natural streams, complete the following phrase. Solution to pollution is _________
a) Control
b) Dilution
c) Reuse
d) Recycle
View Answer
Explanation: Waste water disposal practices are based on the premise that “the solution to pollution is dilution”. In this method relatively small quantities of waste are discharged into large bodies of water.
5. _________ is accomplished by the replenishment of oxygen lost to bacterial degradation of organic waste.
a) Gas transfer
b) Dilution
c) Filtration
d) Re-suspension
View Answer
Explanation: The transfer of gases into and out of water is an important part of the natural purification process. Gas transfer is accomplished by the replenishment of oxygen lost to bacterial degradation of organic waste.
6. On which of the following does the self purification process does not depend?
a) Volume
b) Flow rate
c) Temperature
d) Aquatic species
View Answer
Explanation: The speed and completeness of the self purification process depend upon many factors like volume, flow rate, the turbulence of flow, variation in sunlight, etc. Aquatic species are affected by polluted streams.
7. Flowing water bodies recover rapidly.
a) True
b) False
View Answer
Explanation: Flowing water bodies like streams, canals and rivers can recover rapidly from degradable, oxygen demanding wastes and excess heat through a combination of dilution and bacterial decay.
8. In a flowing stream, the breakdown of degradable wastes by bacteria ________ dissolved oxygen.
a) Increases
b) Depletes
c) Maintains
d) Improves
View Answer
Explanation: In a flowing stream, the breakdown of degradable wastes by bacteria depletes dissolved oxygen. This eliminates the populations with high oxygen requirements until the stream is cleansed of wastes.
9. What is the objective of water quality management?
a) Control the discharge of pollutants
b) Pollutants are discharged into flowing streams
c) Selective pollutants are released
d) Only highly toxic pollutants are released
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Explanation: To control the discharge of pollutants so that the water quality is not degraded to an unacceptable extent below the natural background level is the objective of water quality management.
10. The impact of pollution depends upon nature of the pollutants and the ___________
a) Toxic contaminants
b) Season
c) Contaminants
d) Characteristics of river
View Answer
Explanation: The impact of pollution depends upon nature of the pollutants and the characteristics of the river like discharge and speed of flowing water, depth of the river, type of bottom, surrounding vegetation, etc.
Sanfoundry Global Education & Learning Series – Waste Water Engineering.
To practice all areas of Waste Water Engineering, here is complete set of 1000+ Multiple Choice Questions and Answers.
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