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Civil Engineering :: Waste Water Engineering

  1. 3.0 ml of raw sewage is diluted to 300 ml. The D.O. concentration of the diluted sample at the beginning of the test was 8 mg/l. After 5 day-incubation at 20°C, the D.O. concentration was 5 mg/l. The BOD of raw sewerage is

  2. A.

     100 mg/l

    B.

     200 mg/l

    C.

     300 mg/l

    D.

     400 mg/l


  3. 1000 kg of sewage contains

  4. 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


  5. Water content of sewage is about

  6. A.

     90 %

    B.

     95 %

    C.

     99 %

    D.

     99.9 %


  7. A circular sewer section is preferred to because

  8. A.

     It is cheaper in construction

    B.

     It provides maximum area for a given perimeter

    C.

     It provides maximum hydraulic mean depth

    D.

     All the above


  9. The ratio of minimum hourly flow to the average flow of sewage is

  10. A.

     1/4

    B.

     1/3

    C.

     1/2

    D.

     3/4


  11. In a fully mechanised composting plant, involves

  12. A.

     Mechanized receipt

    B.

     Mechanized segregation

    C.

     Mechanized pulverising of refuse

    D.

     All of these


  13. For drainage pipes in buildings the test applied before putting them to use, is

  14. A.

     Water test

    B.

     Smoke test

    C.

     Straightness test

    D.

     All the above


  15. During purification process of sewage the gas given off, is

  16. A.

     Carbon dioxide

    B.

     Hydrogen

    C.

     Ammonia

    D.

     All the above


  17. Antisyphonage pipe is fitted

  18. A.

     At the end of septic tanks

    B.

     On manholes

    C.

     With a W.'trap

    D.

     At the beginning of sewer line


  19. The detention time of a circular tank of diameter d and water depth H, for receiving the sewage Q per hour, is

  20. A.

     d² (0.011d + 0.785H)/Q

    B.

     d (0.022d + 0.085H)/Q

    C.

     d (0.785d + 0.011H)/Q

    D.

     d (0.285d + 0.011H)/Q