NPTEL Water and waste water treatment Week 12 Assignment Answers 2024

NPTEL Water and waste water treatment Week 12 Assignment Answers 2024

1. Select True or False.

“Saw Dust is used as a bulking agent in composting.”

  • True
  • False
Answer :- 

2. hich of the following is a common sludge conditioning agent?

  • Ferric Chloride
  • Sulfuric Acid
  • Sodium hydroxide
  • All the above
Answer :- 

3. Match the following residual characteristics with the type of residual:

  • 1 – A, 2 – C, 3 – B
  • 1 – C, 2 – B, 3 – A
  • 1 – B, 2 – C, 3 – A
  • 1 – B, 2 – A, 3 – C
Answer :- 

4. During Anaerobic digestion, if anaerobic conditions exist and sulphate is present, then it might act as electron acceptor and form hydrogen sulphide, which is toxic for methanogens.
Select True or False.

  • True
  • False
Answer :- 

5. With reference to sludge treatment, match the following:

  • A-1, B-3, C-2, D-4
  • A-4, B-2, C-3, D-1
  • A-4, B-3, C-2, D-1
  • A-1, B-3, C-2, D-4
Answer :- 

6. Consider the following data from a primary settling tank: 

Q = 0.05 m3/s 

Influent suspended solids = 280 mg/L 

Removal efficiency wrt suspended solids= 60% 

Sludge solids concentration = 5.0% 

Specific gravity of solids = 2.65 

Specific gravity of sludge, Ssl=1050kg/m3 

The volume of the sludge produced daily in m3/day is _____________.

Answer :- 

7. Consider an aeration tank of the activated sludge process (ASP)

Solid’s content (by weight) = 5%

Specific gravity of sludge solids = 2.6

Density of water = 1000 kg/m³

The sludge is put in a sludge thickener, from the aeration tank to reduce its volume.

The density (kg/m3) of the sludge removed from the aeration tank is ____________.(upto two decimal places)

Answer :- 

8. Select the class of micro-organisms that are most active in the anaerobic digestion of sludge.

  • Mesophiles and Halophiles
  • Psychrophiles and Thermophiles
  • Mesophiles and Thermophiles
  • Psychrophiles and Mesophiles
Answer :- 

9. Select the correct sequence of anaerobic digestion process.

  • The correct sequence of digestion is Hydrolysis –> Methanogenesis –> Acetogenesis –> Acidogenesis.
  • The correct sequence of digestion is Acidogenesis –> Methanogenesis –> Acetogenesis –> Hydrolysis.
  • The correct sequence of digestion is Hydrolysis –> Acidogenesis –> Acetogenesis –> Methanogenesis.
  • The correct sequence of digestion is Hydrolysis –> Acetogenesis –> Acidogenesis –> Methanogenesis.
Answer :- 

10. Which of the following statements correctly describe aerobic and anaerobic digestion processes?

  • In anaerobic digestion, if the supernatant is high in strength and is recirculated to ASP process, then it can interfere with Activated sludge process.
  • Operational costs tend to be higher for anaerobic processes compared to aerobic processes.
  • Aerobic digestion can be challenging to operate, and initial costs are typically higher.
  • The primary aim of digestion is to diminish pathogens and decrease Volatile Suspended Solids (VSS).
Answer :- 

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