Practice Test: Question Set - 04
1. Traps
- (A) Are water
seals which prevent the entry of foul gases
- (B) Are used to
trap the rats entering sewers
- (C) Dissolve the
foul gases
- (D) Create
symphonic action to increase the quick disposal of sewerage
2. The sewage treatment units in which anaerobic decomposition of organic matter is used, are called
- (A) Imhoff tanks
- (B) Trickling
filters
- (C) Sludge
sedimentation tanks
- (D) None of
these
3. Pick up the correct statement from the following:
- (A) In treated
sewage, 4 ppm of D.O. is essential
- (B) Only very
fresh sewage contains some dissolved oxygen
- (C) The
solubility of oxygen in sewage is 95% that is in distilled water
- (D) All the
above
4. If the diameter of a sewer is 150 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
5. The sewer which received discharge from two or more main sewers, is known as
- (A) A trunk
sewer
- (B) An outfall
sewer
- (C) A main sewer
- (D) An
intercepting sewer
6. The grit and silt of the grit chambers, may not be used for
- (A) Raising low
lying areas by dumping
- (B) Concreting
- (C) Both (a) and
(b)
- (D) Neither (a)
nor (b)
7. For treating the sewage of a large city, you will recommend
- (A) A
sedimentation tank and an activated sludge treatment plant
- (B) A plant
consisting of Imhoff tanks with low rate trickling filters
- (C) Sedimentation
tanks with high rate trickling filters
- (D) None of
these
8. Imhoff cone is used to measure
- (A) Total
organic solids
- (B) Total solids
- (C) Total in
organic solids
- (D) Settleable
solids
9. Pick up the correct statement from the following:
- (A) The ratio of
the quantity of the diluting water to that of the sewage, is known as dilution
factor
- (B) The
automatic purification of polluted water, is known self purification phenomenon
- (C) The
photosynthesis is carried out in the presence of sun light
- (D) All the
above
10. 1000 kg of sewage contains
- (A) 0.112 kg in
suspension
- (B) 0.112 kg in
solution
- (C) 0.225 kg in
solution
- (D) Both (a) and
(c) of above
11. 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
12. If the peak discharge of a storm water drain (S.W. Drain) is expected to exceed 150 cumecs, the free board to be provided, is
- (A) 100 cm
- (B) 90 cm
- (C) 80 cm
- (D) 50 cm
13. The reduced levels of the string at the consecutive sight rails A and B are 203.575 m, 203.475 m respectively. If the difference of their R.D.s is 10 m, the gradient of the sewer line is
- (A) 1 in 100
upward
- (B) 1 in 500
upward
- (C) 1 in 100
downward
- (D) 1 in 503
upward
14. R.M.O. expenses include
- (A) Running
expenses
- (B) Maintenance
expenses
- (C) Operation
expenses
- (D) All the
above
15. For the COD test of sewage, organic matter is oxidised by K2Cr207 in the presence of
- (A) H2SO4
- (B) HNO3
- (C) HCl
- (D) None of
these
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