MCQOPTIONS
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MCQOPTIONS
This section includes 44 Mcqs, each offering curated multiple-choice questions to sharpen your Waste Water Engineering knowledge and support exam preparation. Choose a topic below to get started.
| 1. |
Consider the following statements regarding waste stabilization ponds:1. The pond has a symbiotic process of waste stabilization through algae on one hand and bacteria on the other2. The oxygen in the pond is provided by algae through photosynthesis3. The detention period is of the order of two to three days4. The bacteria which develop in the pond are aerobicWhich of the above statements are correct? |
| A. | 1 and 2 only |
| B. | 2 and 3 only |
| C. | 3 and 4 only |
| D. | 1 and 4 only |
| Answer» B. 2 and 3 only | |
| 2. |
A chamber made of concrete, fibre glass, PVC or plastic, through which domestic waste water, sewage flows for primary treatment is called |
| A. | drainage tank |
| B. | septic tank |
| C. | pit latrine tank |
| D. | water harvesting tank |
| Answer» C. pit latrine tank | |
| 3. |
In an oxidation pond, the sewage is made non-putrescible primarily by |
| A. | Algae bacteria symbiosis only |
| B. | Bacterial oxidation only |
| C. | Chemical oxidation only |
| D. | Algae photosynthesis and algae bacteria symbiosis |
| Answer» E. | |
| 4. |
For a colony of 10,000 persons having sewage flow rate of 200 L/capita/day, BOD of applied sewage of 300 mg/L and organic loading of 300 kg/day/hectare, the area of an oxidation pond required for treating the sewage of the colony is |
| A. | 0.2 hectare |
| B. | 1 hectare |
| C. | 2 hectare |
| D. | 6 hectare |
| Answer» D. 6 hectare | |
| 5. |
For detecting the nitrates in sewage, the matching colour may be developed by adding: |
| A. | Potassium permanganate |
| B. | Sulphuric acid and napthamine |
| C. | Phenol-di-sulphonic acid and potassium hydroxide |
| D. | None of these |
| Answer» D. None of these | |
| 6. |
Comminutors in wastewater treatment plant are adopted to: |
| A. | Remove colloidal matter |
| B. | Grind or chop large sized suspended solids |
| C. | Remove floating matter |
| D. | Remove sand and grit |
| Answer» C. Remove floating matter | |
| 7. |
In a sludge digestion tank, if the moisture content of sludge is reduced from 90% to 80% then the percentage decrease in the volume of sludge is |
| A. | 5% |
| B. | 10% |
| C. | 25% |
| D. | 50% |
| Answer» E. | |
| 8. |
If the efficiencies of BOD removal of first stage and second stage trickling filters are each 65%, then what is the overall BOD removal efficiency of these filters? |
| A. | 87.75% |
| B. | 77.25% |
| C. | 92.6% |
| D. | 65% |
| Answer» B. 77.25% | |
| 9. |
In the activated sludge process, sludge volume index is used to decide |
| A. | Quality of raw sewage |
| B. | Quality of final effluent |
| C. | Recirculation ratio of sludge |
| D. | Rate of aeration |
| Answer» D. Rate of aeration | |
| 10. |
Among the following, which is/are not pre-treatment units? |
| A. | Bar screen and grit chamber |
| B. | Flow equalisation and proportion tank |
| C. | Neutralization for pH adjustment tank |
| D. | Nutrient removal tank |
| Answer» E. | |
| 11. |
Aerobic attached growth process is classified under: |
| A. | Activated sludge process |
| B. | Chemical clarification |
| C. | Preliminary treatment |
| D. | Biological treatment |
| Answer» E. | |
| 12. |
As per Manual on Sewerage and Sewage Treatment, Central Public Health and Environmental Engineering Organization, Ministry of Urban Development, Government of India, when a sewer connects with another sewer having a difference of 600 mm in level between the water lines (peak flow levels) of main line and the invert of branch line, the connection may be provided using a |
| A. | Side entrance manhole |
| B. | Junction manhole |
| C. | Flushing manhole |
| D. | Drop manhole |
| Answer» E. | |
| 13. |
Consider the following statements in respect of aerated grit chamber:1. The grit accumulates at the bottom in advancing spiral-flow aeration tanks location ally preceded by grit chambers, led to the eventual development of aerate grit chambers.2. The excessive wear on grit handling equipment is a major factor for the popularity of aerated grit chambers.3. Aerated grit chambers are designed to provide detention period of 1 minute at maximum rate of flow.4. Diffusers are located at 0.45 m to 0.6 m above the bottom of the chamber.Which of the above statements are correct? |
| A. | 1, 2 and 3 only |
| B. | 3 and 4 only |
| C. | 1, 2 and 4 only |
| D. | 1, 2, 3 and 4 |
| Answer» D. 1, 2, 3 and 4 | |
| 14. |
A detritus tank is provided in the primary treatment of sewage to remove: |
| A. | suspended solids |
| B. | stones |
| C. | grit |
| D. | oil and greases |
| Answer» D. oil and greases | |
| 15. |
An appurtenance used to connect high-level branch sewer to low-level branch sewer is |
| A. | Manhole |
| B. | Drop manhole |
| C. | Inverted siphon |
| D. | Check basin |
| Answer» C. Inverted siphon | |
| 16. |
In designing Imhoff tanks, the usual retention period is |
| A. | 2 hours |
| B. | 8 hours |
| C. | 14 hours |
| D. | 20 hours |
| Answer» B. 8 hours | |
| 17. |
Consider the following statements regarding contact stabilization process:1. Primary settling tank is not required in some cases.2. BOD removal occurs in two stages.3. Aeration volume requirements are approximately 50% of those of a conventional – or tapered – aeration plant.4. Returned sludge is aerated for 30 min to 90 min in sludge aeration tank.Which of the above statements are correct? |
| A. | 1, 2, 3 and 4 |
| B. | 1 and 4 only |
| C. | 1, 2 and 3 only |
| D. | 2, 3 and 4 only |
| Answer» D. 2, 3 and 4 only | |
| 18. |
An activated sludge tank is 30 m in long 9 m wide and has liquid depth of 4 m. The influent sewage flow rate is 3.5 MLD. The primary effluent has BOD of 130 mg/l and suspended load of 15 mg/I. The MLSS concentration in the aeration tank is 1800 mg/I. The Corresponding F/M ratio is |
| A. | 0.19 |
| B. | 0.23 |
| C. | 0.32 |
| D. | 0.46 |
| Answer» C. 0.32 | |
| 19. |
A given sludge with 98% moisture is x times more bulky than with 95% moisture, then x is |
| A. | 3.5 |
| B. | 2.5 |
| C. | 3 |
| D. | 2 |
| Answer» C. 3 | |
| 20. |
Bangalore and Indore process of composting are which of the following? |
| A. | Both anaerobic processes |
| B. | Both aerobic processes |
| C. | Anaerobic process and aerobic process respectively |
| D. | Aerobic process and anaerobic process respectively |
| Answer» D. Aerobic process and anaerobic process respectively | |
| 21. |
Activated sludge process is an example of ______ growth process. |
| A. | anaerobic suspended |
| B. | aerobic suspended |
| C. | aerobic attached |
| D. | anaerobic attached |
| Answer» C. aerobic attached | |
| 22. |
Consider the following statements in respect of flow equalization in a wastewater treatment plant:1. Biological treatment is enhanced because shock loadings are eliminated or minimized.2. Flow equalization is an attractive option for upgrading the performance of overloaded treatment plants.3. Inhibiting substances can be diluted and pH can be stabilized.4. Thickening performance of primary sedimentation tanks following grit removal is improved.Which of the above statements are correct? |
| A. | 1, 2, 3 and 4 |
| B. | 1, 2 and 3 only |
| C. | 1, 2 and 4 only |
| D. | 3 and 4 only |
| Answer» B. 1, 2 and 3 only | |
| 23. |
Consider the following statements in respect of anaerobic sludge digester:1. It is less expensive compared to several other methods available.2. Processing of separable solids impacts the environment to a minimum.3. Quantity of separated solids requiring disposal is minimal4. Digested sludge is very readily dewatered able.Which of the above statements are correct? |
| A. | 1, 2, 3 and 4 |
| B. | 1, 2 and 3 only |
| C. | 3 and 4 only |
| D. | 1, 2 and 4 only |
| Answer» B. 1, 2 and 3 only | |
| 24. |
A floor trap commonly used to collect water from the floors, kitchen & bath- rooms is called |
| A. | Gully trap |
| B. | Nahni trap |
| C. | Intercepting trap |
| D. | S-trap |
| Answer» C. Intercepting trap | |
| 25. |
During sewage treatment, effluent from which one of the following treatment units has minimum wt/vol amount of suspended solids? |
| A. | Detritus channel |
| B. | Primary sedimentation tank |
| C. | Secondary sedimentation tank |
| D. | Activated sludge process aeration tank |
| Answer» E. | |
| 26. |
In which of the following wastewater treatment units is organic matter destroyed and stabilised by anaerobic bacteria? |
| A. | Trickling filter |
| B. | Oxidation pond |
| C. | Sedimentation tank |
| D. | Septic tank |
| Answer» E. | |
| 27. |
Biodegradable pollutants are |
| A. | Quickly degraded by natural means |
| B. | Cannot be degraded |
| C. | Can be degraded by burning only |
| D. | Disposed in flowing water only |
| Answer» B. Cannot be degraded | |
| 28. |
For the sludge digestion system to work effectively, the pH of the sludge should be between: |
| A. | 10 - 12 |
| B. | 8.5 - 10 |
| C. | 3.5 - 5.5 |
| D. | 6.5 - 7.4 |
| Answer» E. | |
| 29. |
Match the items in Group – I with those in Group – II and choose the right combination.Group - IP. Activated sludge processQ. Rising of sludgeR. Conventional nitrificationS. Biological nitrogen removalGroup - II1. Nitrifiers and denitrifiers2. Autotrophic bacteria3. Heterotrophic bacteria4. Denitrifiers |
| A. | P-3, Q-4, R-2, S-1 |
| B. | P-2, Q-3, R-4, S-1 |
| C. | P-3, Q-2, R-4, S-1 |
| D. | P-1, Q-4, R-2, S-3 |
| Answer» B. P-2, Q-3, R-4, S-1 | |
| 30. |
In a shallow waste stabilization pond, the sewage is treated by ______. |
| A. | aerobic bacteria only |
| B. | sedimentation |
| C. | dual action of both aerobic bacteria and algae |
| D. | algae only |
| Answer» D. algae only | |
| 31. |
Consider the following statements as regards a Septic Tank:1. The size required is large and uneconomical when serving more than roughly 100 persons.2. It can remove around 90% of BOD and 80% of suspended solids.3. As compared to the sludge holding of a plain sedimentation tank, a septic tank can hold about 90% less of sludge volume.4. Frequent removal of sludge is not required.Which of the above statements are correct? |
| A. | 1 and 2 |
| B. | 2 and 3 |
| C. | 3 and 4 |
| D. | 1 and 4 |
| Answer» D. 1 and 4 | |
| 32. |
100 m3 of sludge holds a moisture content of 95%. If its moisture content changes to 90%, the volume of this sludge will then be |
| A. | 40.5 m3 |
| B. | 50 m3 |
| C. | 75 m3 |
| D. | 95 m3 |
| Answer» C. 75 m3 | |
| 33. |
In very first stage of decomposition of the organic matter in sewage |
| A. | Nitrites are formed |
| B. | Nitrates are formed |
| C. | Carbon dioxide is formed |
| D. | Ammonia is formed |
| Answer» E. | |
| 34. |
In an aerobic attached-culture system, the biomass at the biofilm-medium surface interface experiences: |
| A. | Aerobic and endogenous metabolism |
| B. | Anaerobic and endogenous metabolism |
| C. | Anaerobic and exogenous metabolism |
| D. | Aerobic and exogenous metabolism |
| Answer» C. Anaerobic and exogenous metabolism | |
| 35. |
Municipal sewage has BOD5 of 200 mg/L. It is proposed to treat it and dispose of into a marine environment. For what minimum efficiency should the sewage treatment plant be designed? |
| A. | 85% |
| B. | 50% |
| C. | 100% |
| D. | 33.67% |
| Answer» C. 100% | |
| 36. |
BOD5 at 20°C should not be more than ______ for discharging the treated effluent into inland surface water. |
| A. | 30 mg/L |
| B. | 600 mg/L |
| C. | 100 mg/L |
| D. | 14 mg/L |
| Answer» B. 600 mg/L | |
| 37. |
What is the rate of backwash water? |
| A. | 0.3-1 m/min |
| B. | 1-1.5 m/min |
| C. | 0.03-0.3 m/min |
| D. | 15-3 m/min |
| Answer» B. 1-1.5 m/min | |
| 38. |
What is the specified minimum time for backwash of rapid filters? |
| A. | 2 minutes |
| B. | 5 minutes |
| C. | 10 minutes |
| D. | 3 minutes |
| Answer» C. 10 minutes | |
| 39. |
At what pressure is the air blown during cleaning? |
| A. | 5-10 KN/m<sup>2</sup> |
| B. | 10-15 KN/m<sup>2</sup> |
| C. | 15-30 KN/m<sup>2</sup> |
| D. | 20-35 KN/m<sup>2</sup> |
| Answer» E. | |
| 40. |
Air is blown in the reverse direction during cleaning of filter beds. |
| A. | True |
| B. | False |
| Answer» B. False | |
| 41. |
What is the maximum head loss at which the filter should be cleaned? |
| A. | 1.5 m |
| B. | 2 m |
| C. | 2.5 m |
| D. | 3 m |
| Answer» D. 3 m | |
| 42. |
How many hours does it take for filters to attain turbidity breakthrough? |
| A. | 12-16 hours |
| B. | 18-22 hours |
| C. | 23-36 hours |
| D. | 38-42 hours |
| Answer» D. 38-42 hours | |
| 43. |
Biological action takes place in a rapid filtration unit. |
| A. | Tue |
| B. | False |
| Answer» C. | |
| 44. |
Rapid filtration is used as the _______ clarifying step in municipal water treatment plants. |
| A. | First |
| B. | Second |
| C. | Intermediate |
| D. | Final |
| Answer» E. | |