Waste Water Engineering

291. Water content of sewage is about

1. 90 %
2. 95 %
3. 99 %
4. 9.9 %

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292. When drainage to sewage ratio is 20, the peak dry weather flow is

1. 20% of the design discharge
2. Slightly less than 5% of the design discharge
3. Slightly more than 5% of the design discharge
4. None of these

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293. Which of the following pumps in used to pump sewage solids with liquid sewage without clogging the pump is?

1. Centrifugal pump
2. Pneumatic ejector
3. Reciprocating pump
4. None of these

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294. Which one of the following gases is most significant as air pollutant?

1. Carbondioxide
2. Oxygen
3. Nitrogen
4. Sulphur-dioxide

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295. Which one of the following part of human body withstands minimum radiation?

1. Thyroid
2. Kidneys
3. Eyes
4. Ovaries/testis

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296. Which one of the following resists hydrogen sulphide corrosion?

1. R.C.C.
2. Glazed stone wares
3. Asbestos cement
4. Glazed ware

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297. Which one of the following statements regarding septic tanks is wrong?

1. A gap of 7.5 cm between the bottom of the covering slab and the top level of scum is provided
2. The outlet invert level is kept 5 to 7.5 cm below the inlet invert level
3. The minimum width of septic level is 90 cm
4. The depth of tank is kept equal to its width

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298. Which one of the following tests is used for testing sewer pipes?

1. Water test
2. Ball test
3. Mirror test
4. All of these

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299. With self cleansing velocity in sewers

1. Silting occurs at bottom
2. Scouring occurs at bottom
3. Both silting and scouring occur at bottom
4. Neither silting nor scouring occurs at bottom

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300. You are asked to design sewer pipes of diameters 0.4 m to 0.9 m at maximum flow, you will assume the sewer flow running at

1. Full depth
2. Half full
3. Two third full
4. Three fourth full

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