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Civil Engineering :: Waste Water Engineering

  1. The temperature affects the

  2. A.

     Biological activity of bacteria in sewage

    B.

     Solubility of gases in sewage

    C.

     Viscosity of sewage

    D.

     All the above

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  3. The drainage area of a town is 12 hectares. Its 40% area is hard pavement ( K = 0.85), the 40% area is unpaved streets (K = 0.20) and the remaining is wooded areas (K = 0.15). Assuming the time of concentration for the areas as 30 minutes and using the formula Ps = 900/(t + 60) the maximum run off is

  4. A.

     0.10 cumec

    B.

     0.12 cumec

    C.

     0.15 cumec

    D.

     0.20 cumec

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  5. The sewage treatment in septic tanks is due to

  6. A.

     Anaerobic decomposition

    B.

     Aerobic decomposition

    C.

     Parasitic decomposition

    D.

     None of these

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  7. Which one of the following statements regarding septic tanks is wrong?

  8. 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

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  9. If D.O. concentration falls down to zero in any natural drainage, it indicates the zone of

  10. A.

     Degradation

    B.

     Active decomposition

    C.

     Recovery

    D.

     Cleaner water

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  11. The asbestos cement sewers are

  12. A.

     Light in weight

    B.

     Not structurally strong to bear large compressive stress

    C.

     Susceptible to corrosion by sulphuric acid

    D.

     All the above

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  13. If D is the diameter of a circular sewer and D’ is the top horizontal diameter of an equivalent egg shaped section, the relationship which holds good, is

  14. A.

     D’ = 0.64 D

    B.

     D’ = 0.74 D

    C.

     D’ = 0.84 D

    D.

     D’ = 0.94 D

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  15. hydraulically equivalent, the relationship which holds good, is

  16. A.

     D8/3 = 4 b8/3

    B.

     D3/8 = 4 b3/8

    C.

     D2/3 = 4 b2/3

    D.

     D3/2 = 4 b3/2

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  17. For design of sewers, percentage of sewage discharge is assumed

  18. A.

     65 to 70%

    B.

     70 to 75%

    C.

     75 to 80%

    D.

     85%

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  19. Nitrogen cycle of sewage, is

  20. A.

     Liberation of ammonia-formation of nitrites-formation of nitrates-liberation of nitrogen

    B.

     Liberation of nitrogen-liberation of ammonia-formation of nitrites- formation of nitrates

    C.

     Liberation of nitrogen-formation of nitrates-formation of nitrites-liberation of ammonia

    D.

     Formation of nitrates-formation of nitrites-liberation of nitrates-liberation of nitrates

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