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. |
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. |
During which stage of the sewage treatment are the microbes used?
1. | Primary | 2. | Secondary |
3. | Tertiary | 4. | Quaternary |
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. |
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
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 |
Methanogenic bacteria are not found in:
1. rumen of cattle
2. gobar gas plant
3. bottom of water-logged paddy fields
4. activated sludge