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Civil Engineering :: Waste Water Engineering

  1. In septic tanks, decomposition of organic bacteria, is done by

  2. A.

     Anaerobic bacteria

    B.

     Aerobic bacteria

    C.

     Both types of bacterias

    D.

     None of these

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  3. Pick up the correct statement from the following:

  4. A.

     Rate of digestion of sludge is more at higher temperature

    B.

     Thermophilic organisms digest the sludge if the temperature ranges from 40° to 60°C

    C.

     Mesophilic organisms digest the sludge if the temperature is between 25° and 40°C

    D.

     All the above

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  5. Pick up the incorrect statement from the following:

  6. 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

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  7. The angle subtended by the surface of sewer water with partial flow, at sewer centre is 120°, the depth of sewerage is

  8. A.

     20 cm

    B.

     25 cm

    C.

     40 cm

    D.

     50 cm

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  9. depends upon The Chezy’s constant C in the formula V = C

  10. A.

     Size of the sewer

    B.

     Shape of the sewer

    C.

     Roughness of sewer surface

    D.

     All the above

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  11. If the over land flow from the critical point to the drain is 8 km and the difference in level is 12.4 m, the inlet time is

  12. A.

     2 hours

    B.

     3 hours

    C.

     4 hours

    D.

     5 hours

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  13. 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

  14. A.

     2 hours

    B.

     4 hours

    C.

     6 hours

    D.

     8 hours

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  15. 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

  16. A.

     1 in 100 upward

    B.

     1 in 500 upward

    C.

     1 in 100 downward

    D.

     1 in 503 upward

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  17. The sewer pipes

  18. A.

     Carry sewage as gravity conduits

    B.

     Are designed for generating self-cleansing velocities at different discharge

    C.

     Should resist the wear and tear caused due to abrasion

    D.

     All the above

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  19. The detention time (t) of a settling tank, may be defined as the time required for

  20. A.

     A particle to travel along its length

    B.

     A particle to travel from top surface to bottom sludge zone

    C.

     The flow of sewage to fill the tank

    D.

     None of these

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