Waste Water Engineering Mcqs - Set 9

1)   If the diameter of a sewer is 100 mm, the gradient required for generating self cleansing velocity is__________________?

a. 1 in 60
b. 1 in 100
c. 1 in 120
d. None of these
Answer  Explanation 

ANSWER: 1 in 60

Explanation:
No explanation is available for this question!


2)   In 1000 kg of sewage, the total solids approximate___________________?

a. 0.5 to 1.0 kg
b. 1 kg to 2.0 kg
c. 5 kg to 7.5 kg
d. 7.5 kg to 10 kg
Answer  Explanation 

ANSWER: 0.5 to 1.0 kg

Explanation:
No explanation is available for this question!


3)   Before discharging the foul sewage into rivers, it is generally treated by_____________________?

a. Screening
b. Sedimentation
c. Oxidation
d. All the above
Answer  Explanation 

ANSWER: All the above

Explanation:
No explanation is available for this question!


4)   Aerobic activity is maximum_______________?

a. In freshly produced sewage
b. At sewer pipes
c. In sewer treatment plants
d. None of these
Answer  Explanation 

ANSWER: In freshly produced sewage

Explanation:
No explanation is available for this question!


5)   Sewer manholes are generally provided at________________?

a. The change of gradient
b. The change of direction
c. The junctions of sewers
d. All of these
Answer  Explanation 

ANSWER: All of these

Explanation:
No explanation is available for this question!


6)   hydraulically equivalent, the relationship which holds good, is _______________?

a. D8/3 = 4 b8/3
b. D3/8 = 4 b3/8
c. D2/3 = 4 b2/3
d. D3/2 = 4 b3/2
Answer  Explanation 

ANSWER: D8/3 = 4 b8/3

Explanation:
No explanation is available for this question!


7)   Sewer pipes need be checked for_________________?

a. Minimum flow
b. Maximum flow
c. Both A. and B.
d. None of these
Answer  Explanation 

ANSWER: Both A. and B.

Explanation:
No explanation is available for this question!


8)   In septic tanks, decomposition of organic bacteria, is done by_____________________?

a. Anaerobic bacteria
b. Aerobic bacteria
c. Both types of bacterias
d. None of these
Answer  Explanation 

ANSWER: Anaerobic bacteria

Explanation:
No explanation is available for this question!


9)   The sewerage system originates from__________________?

a. House sewers
b. Lateral sewers
c. Branch sewers
d. Main sewers
Answer  Explanation 

ANSWER: House sewers

Explanation:
No explanation is available for this question!


10)   During purification process of sewage the gas given off, is________________?

a. Carbon dioxide
b. Hydrogen
c. Ammonia
d. All the above
Answer  Explanation 

ANSWER: All the above

Explanation:
No explanation is available for this question!


11)   Drop manholes at the junctions of sewer lines, are provided if________________?

a. Invert level of a branch sewer is more than 60 cm that of the main sewer
b. Sewer line runs along a main road
c. Ordinary manhole cannot be built
d. Two sewer lines intersect
Answer  Explanation 

ANSWER: Invert level of a branch sewer is more than 60 cm that of the main sewer

Explanation:
No explanation is available for this question!


12)   The sewage discharge in a detritus tank of a treatment plant is 576 litres/sec with flow velocity of 0.2 m/sec. If the ratio of width to depth is 2, the depth is____________________?

a. 100 cm
b. 110 cm
c. 120 cm
d. 150 cm
Answer  Explanation 

ANSWER: 120 cm

Explanation:
No explanation is available for this question!


13)   Fresh sewage may become stale in_________________?

a. One hour
b. Two to three hours
c. Three to four hours
d. Six hours
Answer  Explanation 

ANSWER: Three to four hours

Explanation:
No explanation is available for this question!


14)   The standard B.O.D. of water is taken for_________________?

a. 1 day
b. 2 days
c. 3 days
d. 5 days
Answer  Explanation 

ANSWER: 5 days

Explanation:
No explanation is available for this question!


15)   The gradient of sewers depends upon_________________?

a. Velocity of flow
b. Diameter of the sewer
c. Discharge
d. All the above
Answer  Explanation 

ANSWER: All the above

Explanation:
No explanation is available for this question!


16)   Removal of oil and grease from sewage, is known____________________?

a. Screening
b. Skimming
c. Filtration
d. None of these
Answer  Explanation 

ANSWER: Skimming

Explanation:
No explanation is available for this question!


17)   The ratio of minimum hourly flow to the average flow of sewage is_________________?

a. 1/4
b. 1/3
c. 1/2
d. 3/4
Answer  Explanation 

ANSWER: 1/3

Explanation:
No explanation is available for this question!


18)   The coagulant widely used for sewage treatment, is_________________?

a. Alum
b. Ferric chloride
c. Ferric sulphate
d. Chlorinated copperas
Answer  Explanation 

ANSWER: Ferric chloride

Explanation:
No explanation is available for this question!


19)   For the survival of fish in a river stream, the minimum dissolved oxygen is prescribed________________?

a. 3 ppm
b. 4 ppm
c. 5 ppm
d. 10 ppm
Answer  Explanation 

ANSWER: 4 ppm

Explanation:
No explanation is available for this question!


20)   In SI units the power of sound is represented in __________________?

a. Kgs
b. Joules
c. Newtons
d. Watts
Answer  Explanation 

ANSWER: Watts

Explanation:
No explanation is available for this question!