Q. No.Identify the incorrect statement regarding the primary treatment of sewage water in a sewage treatment plant:
| 1. | It basically involves the physical removal of particles – large and small. |
| 2. | Floating debris is removed by sequential filtration. |
| 3. | Grit [soli and small pebbles] are removed by sedimentation. |
| 4. | All solids that settle form the activated sludge. |
Subtopic: Microbes in Sewage Treatment |
79%
Level 2: 60%+
Hints
Which one of the following impurities is easiest to remove from wastewater?
| 1. | Bacteria | 2. | Colloids |
| 3. | Dissolved solids | 4. | Suspended solids |
Subtopic: Microbes in Sewage Treatment |
83%
Level 1: 80%+
Hints
The primary objective of the secondary treatment of sewage water is:
| 1. | the removal of coarse solids and other large materials often found in raw wastewater. |
| 2. | the removal of settleable organic and inorganic solids by sedimentation, and the removal of materials that will float by skimming. |
| 3. | production of biogas that can be used as an efficient fuel, especially in rural households. |
| 4. | the removal of biodegradable dissolved and colloidal organic matter using aerobic biological treatment processes. |
Subtopic: Microbes in Sewage Treatment |
70%
Level 2: 60%+
Hints
During which stage of the sewage treatment are the microbes used?
| 1. | Primary | 2. | Secondary |
| 3. | Tertiary | 4. | Quaternary |
Subtopic: Microbes in Sewage Treatment |
91%
Level 1: 80%+
Hints
Consider the given two statements:
| I: | BOD is an indirect measure of the organic matter present in the water. |
| II: | The BOD test measures the rate of uptake of oxygen by microorganisms in a sample of water. |
| 1. | Both I and II are correct and II explains I. |
| 2. | Both I and II are correct but II does not explain I. |
| 3. | Only II is correct. |
| 4. | Both I and II are incorrect. |
Subtopic: Microbes in Sewage Treatment |
73%
Level 2: 60%+
Hints
During the secondary or biological treatment of sewage water:
| I. | The BOD of the wastewater gets reduced significantly. |
| II. | The activated sludge contains aerobic micro-organisms that can clump together. |
| III. | The entire activated sludge is pumped into anaerobic sludge digesters. |
1. Only I is correct
2. Only I and II are correct
3. I, II and III are correct
4. I, II and III are incorrect
Subtopic: Microbes in Sewage Treatment |
55%
Level 3: 35%-60%
Hints
What would happen if oxygen availability to activated sludge flocs is reduced?
| 1. | It will slow down the rate of degradation of organic matter. |
| 2. | The center of flocs will become anoxic, which would cause the death of bacteria and eventually breakage of flocs. |
| 3. | Flocs would increase in size as anaerobic bacteria would grow around flocs. |
| 4. | Protozoa would grow in large numbers. |
Subtopic: Microbes in Sewage Treatment |
53%
Level 3: 35%-60%
Hints
In the anaerobic sludge digesters during sewage water treatment:
| 1. | The primary sludge is treated with aerobic microbes and activated sludge is created |
| 2. | The primary sludge is treated with anaerobic microbes and activated sludge is created |
| 3. | The activated sludge is digested by anaerobic microbes producing biogas during the process |
| 4. | The activated sludge is digested by aerobic microbes producing biogas during the process |
Subtopic: Microbes in Sewage Treatment |
77%
Level 2: 60%+
Hints
Methanogens:
1. Only I is correct
2. Only II is correct
3. Both I and II are correct
4. Both I and II are incorrect
| I: | are commonly found in the anaerobic sludge during sewage treatment. |
| II: | are also present in the rumen (a part of stomach) of cattle. |
2. Only II is correct
3. Both I and II are correct
4. Both I and II are incorrect
Subtopic: Microbes in Sewage Treatment |
91%
Level 1: 80%+
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All the following statements regarding the primary treatment of sewage water in a STP are true except:
| 1. | Initially, floating debris is removed by sequential filtration. |
| 2. | Then the grit (soil and small pebbles) are removed by sedimentation. |
| 3. | All solids that settle form the primary sludge, and the supernatant forms the effluent. |
| 4. | The effluent from the primary settling tank is discharged in rivers. |
Subtopic: Microbes in Sewage Treatment |
91%
Level 1: 80%+
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