Wastewater Management Basic Civil Engineering Questions - Set 06 - ObjectiveBooks

# 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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