21
Dilution method of disposing of sewage, is not preferred to
A)
When sewage is fresh
B)
When diluting water has high dissolved oxygen content
C)
When diluting water is used for water supply near the point of sewage disposed
D)
When the diluting water is having flow currents
Answer & Solution
Answer: Option
C
22
In case of Imhoff tanks,
A)
The shape is rectangular
B)
Detention period is 2 hours
C)
The velocity of flow is restricted to 0.30 m/minute
D)
All the above
Answer & Solution
Answer: Option
D
23
If a 2% solution of sewage sample is incubated for 5 days at 20°C and the dissolved oxygen depletion was found to be 8 mg/l. The BOD of the sewage is
A)
100 mg/l
B)
200 mg/l
C)
300 mg/l
D)
400 mg/l
Answer & Solution
Answer: Option
D
24
If 2% solution of a sewage sample is incubated for 5 days at 20°C and depletion of oxygen was found to be 5 ppm, B.O.D. of the sewage is
A)
200 ppm
B)
225 ppm
C)
250 ppm
D)
None of these
Answer & Solution
Answer: Option
C
25
If the depletion of oxygen is found to be 2.5 mg/litre after incubating 2.5 ml of sewage diluted to 250 ml for 5 days at 20°C, B.O.D. of the sewage is
A)
50 mg/l
B)
100 mg/l
C)
150 mg/l
D)
250 mg/l
Answer & Solution
Answer: Option
D
26
If the depletion of oxygen is found to be 5 ppm after incubating a 2.5% solution of sewage sample for 5 days at 21°C, B.O.D. of the sewage is
A)
50 ppm
B)
100 ppm
C)
150 ppm
D)
200 ppm
Answer & Solution
Answer: Option
D
27
If the discharge of a sewer running half is 628 1.p.s., i = 0.001, and n = 0.010, the diameter of the sewer, is
A)
1.39 m
B)
1.49 m
C)
1.59 m
D)
1.69 m
Answer & Solution
Answer: Option
D
28
Acid regression stage of sludge digestion at a temperature 21°C extends over a period of
A)
15 days
B)
30 days
C)
60 days
D)
90 days
Answer & Solution
Answer: Option
D
29
For non-scouring velocity 5 m/sec, the type of sewers generally preferred to, is
A)
Cast iron sewers
B)
Cement concrete sewers
C)
Glazed bricks sewers
D)
Stone ware sewers
Answer & Solution
Answer: Option
C
30
A manhole is generally provided at each
A)
Bend
B)
Junction
C)
Change of gradient
D)
All the above
Answer & Solution
Answer: Option
D
