1) If a 2% solution of sewage sample is incubated for 5 days at 20°C and the dissolved oxygen depletion was found to be 8 mg/l. The BOD of the sewage is_________________? a. 100 mg/l b. 200 mg/l c. 300 mg/l d. 400 mg/l
|
||||
2) A well oxidized sewage contains nitrogen mainly as___________________? a. Nitrates b. Nitrites c. Free ammonia d. None of these
|
||||
3) In a sludge tank, the gas mainly produced, is_________________? a. Oxygen b. Nitrogen c. Hydrogen d. Carbon dioxide
|
||||
4) are available in size Stoneware sewers________________? a. 10 cm b. 15 cm c. 20 cm d. All the above
|
||||
5) In normal conditions, the period for sludge digestion, is_______________? a. 10 days b. 20 days c. 30 days d. 60 days
|
||||
6) In trickling filter, B.O.D. is reduced to___________________? a. 30 to 40% b. 40 to 60% c. 60 to 80% d. 80 to 90%
|
||||
7) The grit chambers of sewage treatment plants, are generally cleaned after__________________? a. 2 days b. 7 days c. 12 days d. 14 days
|
||||
8) Maximum permissible velocity 1.5 m/sec, is adopted in drains_______________________? a. With beds of rocks and gravels b. Lined with stones c. Both A. and B. d. Neither A. nor B.
|
||||
9) If the discharge of a sewer running half is 628 1.p.s., i = 0.001, and n = 0.010, the diameter of the sewer, is__________________? a. 1.39 m b. 1.49 m c. 1.59 m d. 1.69 m
|
||||
10) running partially full with central angle , For a circular sewer of diameter__________________? a. d/D = ½ (1 – – b. a/A c. r/R = [1 – d. All the above
|
||||
11) In the activated sludge process__________________? a. Aeration is continued till stability b. Aeration is done with an admixture of previously aerated sludge c. Sludge is activated by constant stirring d. Water is removed by centrifugal action
|
||||
12) The settling velocity of a spherical particle of diameter less than 0.1 mm as per Stock’s law, is__________________? a. Vs = 418 (Gs – Gw) d [(3T + 70)/100] b. Vs = 418 (Gs – Gw)d² [(3T + 70)/100] c. Vs = 218 (Gs – Gw)d² [(3T + 70)/100] d. Vs = 218 (Gs – Gw)d [(3T + 70)/100]
|
||||
13) Inter-distance between ventilation columns in a sewer line is kept__________________? a. 25 to 50 m b. 50 m to 100 m c. 100 m to 150 m d. 150 m to 300 m
|
||||
14) The intensity of rain is expressed in________________? a. cm/minute b. cm/hour c. cm/day d. None of these
|
||||
15) Which one of the following part of human body withstands minimum radiation ? a. Thyroid b. Kidneys c. Eyes d. Ovaries/testis
|
||||
16) The bottom of the sewage inlet chamber of septic tanks, is provided an outward slope_________________? a. 1 in 5 b. 1 in 10 c. 1 in 15 d. 1 in 20
|
||||
17) Primary treatment of sewage consists of removal of__________________? a. Large suspended organic solids b. Oil and grease c. Sand and girt d. Floating materials
|
||||
18) Cement concrete sewers are only suitable if non-scouring velocity is between_________________? a. 2.5 to 3.0 m/sec b. 3.0 to 4.0 m/sec c. 3.5 to 4.5 m/sec d. 4.5 to 5.5 m/sec
|
||||
19) The most widely used pump for lifting sewage is_________________? a. Centrifugal pump b. Reciprocating pump c. Pneumatic ejector d. Air pressure pump
|
||||
20) Pick up the correct statement from the following ? a. Maximum daily flow = 2 times the average daily flow b. Maximum daily flow = average daily flow c. Sewers are designed for minimum permissible velocity at minimum flow d. All the above
|