550+ Water-and-waste-water Questions - Set 26 [With Solutions]

Water-and-waste-water Questions Set 26:

Quiz Mode

Choose the correct sequence of the zones of pollution in a river stream.

1

2, 4, 1, 3

2

1, 2, 3, 4

3

2, 1, 4, 3

4

1, 2, 4, 3

Solution:

Fresh sludge has a moisture content of 99%, and after thickening, its moisture content is reduced to 96%. The reduction in volume of the sludge is:

1

30%

2

50%

3

75%

4

67%

Solution:

The BOD₅ of a wastewater sample was measured as 250 mg/L. If the deoxygenation constant is 0.23/day, the percentage of BOD_u that would remain unoxidized after 8 days is:

1

85%

2

90%

3

84%

4

95%

Solution:

In which of the following wastewater treatment processes does a 'symbiotic relationship between algae and micro-organisms' occur?

1

Activated sludge process

2

Trickling filter

3

Septic tank

4

Oxidation pond

Solution:

Which of the following correctly describes the cost of filter materials used in water treatment?

1

Sand > Anthracite > Garnet sand

2

Sand < Anthracite < Garnet sand

3

Sand = Anthracite > Garnet sand

4

Sand < Anthracite > Garnet sand

Solution:

Analysis of a water sample revealed that the sample contains the following species.
CO₃^2-, Na⁺, H⁺, PO₄^3-, Al³⁺, H₂CO₃, Cl^-, Ca²⁺, Mg²⁺, HCO₃^-, Fe²⁺, OH^-
Concentrations of which of the species will be required to compute alkalinity?

1

H⁺, H₂CO₃, HCO₃^-, OH^-

2

CO₃^2-, H⁺, HCO₃^-, OH^-

3

CO₃^2-, H⁺, H₂CO₃, HCO₃^-

4

CO₃^2-, H₂CO₃, HCO₃^-, OH^-

Solution:

A city with a population of 200,000 is supplied water at a rate of 220 liters per capita per day (lpcd). The water supply source is located 9 km away from the city. Find the diameter of the main conveying pipe required if the friction factor is 0.004. The elevation difference between the source and supply point is 12 m.

1

0.52 m

2

0.58 m

3

0.64 m

4

0.47 m

Solution:

Treated sewage is to be discharged in a natural stream having a dry weather flow of sewage = 10 MLD, BOD of raw sewage = 325 mg/l, minimum flow of the stream = 0.20 m³/s, permissible maximum BOD of the stream downstream = 8 mg/l, and BOD upstream = 5 mg/l. What is the percentage of purification required in the treatment plant?

1

99%

2

97.2%

3

96.4%

4

95.5%

Solution:

Match List-I (Type of water source) with List-2 (Treatment to be given) and select the correct answer using the codes given below the lists:

List-I

A. Surface water (river or canal)

B. Water from infiltration gallery

C. Lake/pond water

D. Tube well water

List-2

1. Aeration, coagulation, sedimentation and disinfection

2. Disinfection

3. Copper sulfate (CuSO₄) treatment, coagulation, sedimentation, filtration and disinfection

4. Coagulation, flocculation, sedimentation, filtration and disinfection

1

A-4, B-1, C-3, D-2

2

A-1, B-4, C-3, D-2

3

A-4, B-1, C-2, D-3

4

A-1, B-4, C-2, D-3

Solution:

Which of the following statements about the process of coagulation are correct?

1

1. Percentage removal is higher when turbidity is more

2. Addition of activated silica aids in the process of coagulation

3. pH of water is an important consideration for selecting a coagulant

2

1. Percentage removal is higher when turbidity is more

2. Addition of activated silica aids in the process of coagulation

3

2. Addition of activated silica aids in the process of coagulation

3. pH of water is an important consideration for selecting a coagulant

4

1. Percentage removal is higher when turbidity is more

3. pH of water is an important consideration for selecting a coagulant

Solution:

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