Wastewater Treatment and Recycling Nptel Week 5 Answers
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Wastewater Treatment and Recycling Nptel Week 5 Answers (July-Dec 2025)
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Question 1. Which of the given treatment stages is considered as the primary (not preliminary) treatment of wastewater:
a) Oil and greases are removed by skimming tanks
b) Suspended matters are removed by sedimentation tank
c) Floating materials are removed by screening
d) Grit and sand are removed by grit chambers
Question 2. Sedimentation tanks are an appropriate example of:
a) Unit operations
b) Unit processes
c) Membrane processes
d) Bio-chemical processes
Question 3. Which of the following treatment units is not used in typical wastewater treatment plants:
a) Fine Screens
b) Bar Racks
c) Grit Chamber
d) Aeration Tank
Question 4. The function of equalization tank is:
a) Control variation in flow-rate
b) Improve performance of downstream processes
c) Balance fluctuating concentrations in the influent
d) All of these
These are Wastewater Treatment and Recycling Nptel Week 5 Answers
Question 5. Identify the correct statements regarding settling basins:
Statement I: In settling basins, suspended particles in water or wastewater often agglomerate.
Statement II: For real settling basins, the assumptions of ideal discrete particle settling always hold true.
a) Statement I is correct, while statement II is incorrect
b) Statement II is correct, while statement I is incorrect
c) Both, statements I and II are correct
d) Both, statements I and II are incorrect
Question 6. Match the treatment stages given in the first column with the target contaminants to be removed given in the second column:
(i) Primary Treatment — A. Dissolved Organic Matters
(ii) Secondary Treatment — B. Nutrients, Microbes and TDS
(iii) Tertiary Treatment — C. Suspended Matters
a) (i)-B, (ii)-A, (iii)-C
b) (i)-B, (ii)-C, (iii)-A
c) (i)-C, (ii)-A, (iii)-B
d) (i)-A, (ii)-C, (iii)-B
Question 7. In the equation for estimating the terminal settling velocity, Vs=g(ρp−ρ)d218μV_s = \dfrac{g(\rho_p – \rho)d^2}{18\mu}Vs=18μg(ρp−ρ)d2, μ\muμ refers to:
a) Settling efficiency of particles
b) Specific gravity of particles
c) Dynamic viscosity of water
d) Kinematic viscosity of water
These are Wastewater Treatment and Recycling Nptel Week 5 Answers
Question 8. For an ideal settling basin, the settling velocity of the smallest dia particle is equal to:
a) Efficiency of the settling basin
b) Overflow rate of the settling basin
c) Flow through velocity of the settling basin
d) None of the above
Question 9. Head loss through screen is generally proportional to:
a) The approach velocity before the screen
b) The velocity through the screen
c) The difference between velocity through the screen and approach velocity
d) None of the above
These are Wastewater Treatment and Recycling Nptel Week 5 Answers
Question 10. The width of the grit chamber is (in m)
Question 11. The detention time of the grit chamber is (in seconds)
Question 12. The length of the grit chamber is (in m)
These are Wastewater Treatment and Recycling Nptel Week 5 Answers
Question 13. The surface overflow rate of the tank is (in m³/d/m²)
Question 14. The detention time in the tank is (in hours)
Question 15. The % removal efficiency of particles having settling velocity as 0.00025 m/s would be (in %)
These are Wastewater Treatment and Recycling Nptel Week 5 Answers