Solapur-University-M.Sc. – Environmental Science (Semester-II)-2019-On water And Wastewater Engineering
| Sr.No | Questions with multiple options |
| 1. | The pH value of fresh sewage is usually ______
(a) Equal to 7 (b) More than 7 (c) Less than 7 (d) Equal to zero |
| 2. | The maximum depth of sedimentation tanks, is kept ___
(a) 3 m (b) 3.5 m (c) 4 m (d) 4.5 m |
| 3. | If the depletion of oxygen is found to be 5 ppm after incubating a 2.5% solution of sewage sample for 5 days at 21 °C, B.O.D. of the sewage is _____
(a) 50 ppm (b) 100 ppm (c) 150 ppm (d) 200 ppm |
| 4. | For a continuous flow type of sedimentation tanks ____
(a) Width of the tank is normally kept about 6 m (b) Length of the tank is normally kept 4 to 5 times the width (c) Maximum horizontal flow velocity is limited to 0.3 m/minute (d) All the above |
| 5. | No treatment of the sewage is given if dilution factor is ____
(a) Less than 150 (b) Between 200 to 300 (c) Between 150 to 200 (d) More than 500 |
| 6. | 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 |
| 7. | Skimming tanks are ____
(a) Used to remove the grease and oil (b) Those from which sludge is skimmed out (c) Tanks provided with self-cleaning screens (d) Improved version of grit chambers |
| 8. | The detention period for plain sedimentation water tanks, is usually ___
(a) 4 to 8 hours (b) 16 to 24 hours (c) 8 to 16 hours (d) 24 to 36 hours |
| 9. | In a trickling filter ____
(a) Filtration process is used (b) Biological action is used (c) Neither (a) nor (b) (d) Both (a) and (b) |
| 10. | The temperature affects the _____
(a) Biological activity of bacteria in sewage (b) Solubility of gases in sewage (c) Viscosity of sewage (d) All the above |
| 11. | The grit chambers of sewage treatment plants are generally cleaned after
(a) 2 days (b) 7 days (c) 12 days (d) 14 days |
| 12. | In the activate 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 |
| Data Collected By – K. Jeyanthi | |
| Published on – 10th Nov 2021 | |
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