1) Hydraulic mean radius is_______________? a. Mean radius of sewer b. Difference in heads between two points in circular pipes c. Mean of radii in a pipe line of varying cross -sections d. Cross-sectional area/wetted perimeter
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2) The sewer which received discharge from two or more main sewers, is known as_______________? a. A trunk sewer b. An outfall sewer c. A main sewer d. An intercepting sewer
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3) For treating the sewage of a large city, you will recommend_________________? a. A sedimentation tank and an activated sludge treatment plant b. A plant consisting of Imhoff tanks with low rate trickling filters c. Sedimentation tanks with high rate trickling filters d. None of these
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4) 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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5) R.M.O. expenses include___________________? a. Running expenses b. Maintenance expenses c. Operation expenses d. All the above
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6) The sludge does not contain waste water from_________________? a. Bath rooms b. Wash basins c. Kitchen sinks d. Toilets
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7) Pick up the correct statement from the following? a. Hydrogen sulphide gas in excess, may cause corrosion of concrete sewers b. 4 ppm of Dissolved Oxygen (D.O.) is ensured before discharging the treated sewage in river c. Solubility of oxygen in sewage is 95% of that of distilled water d. All the above
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8) The rainfall at any place may be determined by__________________? a. Its intensity b. Its direction c. Its frequency d. All the above
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9) Pick up the correct statement from the following ? a. Rate of digestion of sludge is more at higher temperature b. Thermophilic organisms digest the sludge if the temperature ranges from 40° to 60°C c. Mesophilic organisms digest the sludge if the temperature is between 25° and 40°C d. All the above
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10) The sewer which resists sulphide corrosion, is____________________? a. Brick sewer b. Cast iron sewer c. R.C.C. sewer d. Lead sewer
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11) The formula which accepts the value of rugosity coefficient n = 0.012 to be used in Manning’s formula, is given by______________________? a. Bazin b. Crimp and Bruges c. William-Hazen d. Kutter
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12) Skimming tanks are__________________? a. Used to remove the grease and oil b. Those from which sludge is skimmed out c. Tanks provided with self- cleansing screens d. Improved version of grit chambers
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13) If the peak discharge of a storm water drain (S.W. Drain) is expected to exceed 150 cumecs, the free board to be provided, is_________________? a. 100 cm b. 90 cm c. 80 cm d. 50 cm
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14) The detention period for plain sedimentation water tanks, is usually____________________? a. 4 to 8 hours b. 8 to 16 hours c. 16 to 24 hours d. 24 to 36 hours
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15) Hume steel pipes are__________________? a. Steel pipes b. Steel shell coated from inside with cement mortar c. Steel shell coated from outside with cement mortar d. Both B. and C.
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16) If the length of overland flow from the critical point to the mouth of drain is 13.58 km and difference in level between the critical point and drain mouth is 10 m, the inlet time is___________________? a. 2 hours b. 4 hours c. 6 hours d. 8 hours
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17) In a trickling filter_________________? a. Filtration process is used b. Biological action is used c. Neither A. nor B. d. Both A. and B.
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18) The rate of accumulation of sludge in septic tanks is recommended as____________________? a. 30 litres/person/year b. 25 litres/person/year c. 30 litres/person/month d. 25 litres/person/month
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19) 15 cumecs, the depth d and width are related by For drains up to___________________? a. d = 0.2 B b. d = 0.5 B c. B = 0.2 d d. B = 0.5 d
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20) Self-cleansing velocity is__________________? a. Velocity at dry weather flow b. Velocity of water at flushing c. Velocity at which no accumulation remains in the drains d. Velocity of water in a pressure filter
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