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
A. 100 mg/l
B. 200 mg/l
C. 300 mg/l
D. 400 mg/l
Select an option to see the answer and solution.
1000 kg of sewage contains
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
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Water content of sewage is about
A. 90 %
B. 95 %
C. 99 %
D. 99.9 %
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A circular sewer section is preferred to because
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
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The ratio of minimum hourly flow to the average flow of sewage is
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In a fully mechanised composting plant, involves
A. Mechanized receipt
B. Mechanized segregation
C. Mechanized pulverising of refuse
D. All of these
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For drainage pipes in buildings the test applied before putting them to use, is
A. Water test
B. Smoke test
C. Straightness test
D. All the above
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During purification process of sewage the gas given off, is
A. Carbon dioxide
B. Hydrogen
C. Ammonia
D. All the above
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Antisyphonage pipe is fitted
A. At the end of septic tanks
B. On manholes
C. With a W.'trap
D. At the beginning of sewer line
Select an option to see the answer and solution.
The detention time of a circular tank of diameter d and water depth H, for receiving the sewage Q per hour, is
A. Q d 2 ( 0.011 d + 0.785 H )
B. Q d ( 0.022 d + 0.085 H )
C. Q d ( 0.785 d + 0.011 H )
D. Q d ( 0.285 d + 0.011 H )
Select an option to see the answer and solution.
The water carried sewerage system removes
A. Domestic sewage
B. Industrial sewage
C. Storm sewage
D. All the above
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For the survival of fish in a river stream, the minimum dissolved oxygen is prescribed
A. 3 ppm
B. 4 ppm
C. 5 ppm
D. 10 ppm
Select an option to see the answer and solution.
Rate of flow of sewage is generally assumed
A. More than the rate of water supply
B. Equal to the rate of water supply
C. Less than the rate of water supply
D. At 150 litres per capita
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House connections to the laterals is generally made by
A. R.C.C.
B. P.C.C.
C. Cast iron
D. Glazed stonewares
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The self-cleansing velocity of water flowing through pipe lines, is
A. 2 metres/sec
B. 1 metre/sec
C. 0.5 metre/sec
D. 0.25 metre/sec
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Which of the following pumps in used to pump sewage solids with liquid sewage without clogging the pump is?
A. Centrifugal pump
B. Pneumatic ejector
C. Reciprocating pump
D. None of these
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The width of a rectangular sewer is twice its depth while discharging 1.5 m/sec. The width of the sewer is
A. 0.68 m
B. 0.88 m
C. 1.36 m
D. 1.76 m
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For a grit chamber, if the recommended velocity of flow is 0.2 m/sec and detention period is 2 minutes, the length of the tank, is
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If is the diameter of upper circular portion, the overall depth of a standard egg shaped section, is
A. 1.15 D
B. 1.25 D
C. 1.5 D
D. 1.75 D
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For a peak discharge of 0.0157 cumec, with a velocity of 0.9 m/sec, the diameter of the sewer main, is
A. 10 cm
B. 12 cm
C. 15 cm
D. 18 cm
Select an option to see the answer and solution.
