Practice Test: Question Set - 06
1. The detention period for plain sedimentation water tanks, is usually
- (A) 4 to 8 hours
- (B) 8 to 16
hours
- (C) 16 to 24
hours
- (D) 24 to 36
hours
2. The factor responsible for purification of sewage in river is
- (A) Hydrology
- (B) Dissolved
oxygen in water
- (C) Temperature
- (D) All the
above
3. Hume steel pipes are
- (A) Steel pipes
- (B) Steel shell
coated from inside with cement mortar
- (C) Steel shell
coated from outside with cement mortar
- (D) Both (B) and
(C)
4. To maintain aerobic biological activity, the moisture content of the compost mass should be about
- (A) 45 %
- (B) 50 %
- (C) 55 %
- (D) 60 %
5. Pick up the correct statement from the following:
- (A) The larger
the sewer in size, more will be velocity
- (B) The smaller
the sewer in size, less will be velocity
- (C) The larger
the sewer in size, no deposition will take place
- (D) The larger
the sewer in size, deposition will take place
6. The pH value of sewage is determined with the help of
- (A) Imhoff Cone
- (B) Turbid meter
- (C) Potentiometer
- (D) None of
these
7. If the length of overland flow from the critical point to the mouth of drain is 13.58 km and difference in level between the critical point and drain mouth is 10 m, the inlet time is
- (A) 2 hours
- (B) 4 hours
- (C) 6 hours
- (D) 8 hours
8. The normal value of over flow rates for plain primary sedimentation tanks, ranges between
- (A) 25,000 to
35,000 liters/sqm/day
- (B) 40,000 to
50,000 liters/sqm/day
- (C) 50,000 to
60,000 liters/sqm/day
- (D) 80,000 to
100,000 liters/sqm/day
9. Pick up the incorrect statement from the following:
- (A) Septic
tanks are horizontal continuous flow type of sedimentation tanks
- (B) Septic tanks
are generally provided a detention period of 12 to 36 hours
- (C) Septic tanks
are completely covered and high vent shafts are provided for the escape of foul
gases
- (D) None of
these
10. Which one of the following statements regarding septic tanks is wrong?
- (A) A gap of 7.5
cm between the bottom of the covering slab and the top level of scum is
provided
- (B) The outlet
invert level is kept 5 to 7.5 cm below the inlet invert level
- (C) The minimum
width of septic level is 90 cm
- (D) The depth of
tank is kept equal to its width
11. In areas where rainy season is limited to a few months, the type of sewerage system recommended is
- (A) Combined
system
- (B) Partially
separate system
- (C) Separate
system
- (D) None of
these
12. In a trickling filter
- (A) Filtration
process is used
- (B) Biological
action is used
- (C) Neither (a)
nor (b)
- (D) Both (a) and
(b)
13. The rate of accumulation of sludge in septic tanks is recommended as
- (A) 30
liters/person/year
- (B) 25
liters/person/year
- (C) 30
liters/person/month
- (D) 25
liters/person/month
14. Dried sewage after treatment is used as
- (A) Fertilizer
- (B) Building
material
- (C) Chemical for
lowering B.O.D.
- (D) Base
material for paints
15. For drains up to 15 cumecs, the depth ‘d’ and width ‘B’ are related by
- (A) d =
0.2 B
- (B) d =
0.5 B
- (C) B =
0.2 d
- (D) B = 0.5 d
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