Q. 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 DO. concentration was 5 mg/l. The BOD of raw sewerage is

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Q. The arrangement made for passing the sewer line below an obstruction below the hydraulic gradient lines called

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Q. The angle subtended by the surface of sewer water with partial flow, at sewer centre is 120°, the depth of sewerage is

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Q. Imhoff cone is used to determine

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Q. The sewage discharge in a detritus tank of a treatment plant is 576 litres/sec with flow velocity of 0.2 m/sec. If the ratio of width to depth is 2, the depth is

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Q. If the grit in grit chambers is 4.5 million litres per day, its cleaning is done

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Q. The gas evolved in sewers is

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Q. The maximum depth of sedimentation tanks, is kept

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Q. The reduced levels of the string at the consecutive sight rails A and B are 203.575 m, 203.475 m respectively. If the difference of their R.D.s is 10 m, the gradient of the sewer line is

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Q. The detention time (t) of a settling tank, may be defined as the time required for

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Q. In a residential colony, sewers of diameters 100 mm, 150 mm and 225 mm were laid with a gradient 1 in 120. Which portion of the sewage system does not choke in due course of time

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Q. If D is the diameter of upper circular portion, the overall depth of New Egg shaped sewer section, is

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Q. During putrifaction process of sewage the gas given off, is

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Q. A circular sewer section is preferred to because

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Q. Assertion (A) : The minimum self cleansing velocity in the sewer, at least once a day, must be generated. Reason (R) : If certain deposition takes place and is not removed, it obstructs free flow and causes further deposition leading to complete blocking of the sewer.

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Q. Discrete or granular particles change their

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Q. For a peak discharge of 0.0157 cumec, with a velocity of 0.9 m/sec, the diameter of the sewer main, is

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

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Q. In case of sewer lines

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Q. The sewerage system originates from

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