Sludge Treatment and Disposal MCQ – Environmental Engineering

31. Recirculation in activated sludge process is done to

  1. Dilute the incoming sewage
  2. Dampen the effect of the flow variation
  3. Operate the plant continuously
  4. Supply seed materials to the aeration tank
Answer. d

32. Sludge drying beds are used to separate water from

  1. raw sludge
  2. primary raw sludge
  3. activated excess sludge
  4. digested sludge
Answer. d

33. Sludge digestion produces gas with maximum content of

  1. methane
  2. carbon dioxide
  3. hydrogen sulphide
  4. nitrogen
Answer. a

34. Activated sludge process is a biological process

  1. Aerobic + anaerobic bacteria
  2. Aerobic bacteria + Protozoa + algae
  3. Anaerobic bacteria + fungi
  4. Facultative bacteria + algae
Answer. b

35. In activated sludge plants, Rising sludge occurs due to

  1. Industrial waste
  2. Low Ph
  3. De-nitrification in the settling tank
  4. Sudden discharge of septic solids
Answer. c

36. Activated sludge process is an example of _____________ growth process.

  1. anaerobic suspended
  2. aerobic suspended
  3. aerobic attached
  4. anaerobic attached
  5. facultative attached
Answer. b

37. Which of the following coagulants is singularly effective in producing sludge for the activated sludge process?

  1. Ferric sulphate
  2. Ferric chloride
  3. Alum
  4. Chlorinated copperas
Answer. d