During which stage of the sewage treatment are the microbes used?
1. | Primary | 2. | Secondary |
3. | Tertiary | 4. | Quaternary |
Statement I: | Primary treatment removes material that will either float or readily settle out by gravity. |
Statement II: | Secondary treatment removes the soluble organic matter that escapes primary treatment. |
1. | Statement I is correct but Statement II is incorrect |
2. | Statement I is incorrect but Statement II is correct |
3. | Statement I is correct and Statement II is correct |
4. | Statement I is incorrect and Statement II is incorrect |
Rivers may be considered severely polluted when BOD values exceed:
1. | 1 mg/L | 2. | 2 mg/L |
3. | 4 mg/L | 4. | 8 mg/L |
The large holes in ‘Swiss Cheese’ are due to the production of a large amount of carbon dioxide by:
1. Propionibacterium shermanii
2. Methylophilus methylotrophus
3. Penicillium roqueforti
4. Penicillium camemberti
What is true regarding the activated sludge generated during the secondary treatment of sewage water?
I: | It is made up of aerobic bacteria that sediment down |
II: | A large part of the activated sludge is pumped back into the aeration tank to serve as the inoculum. |
III: | A minor part of the sludge is pumped into large tanks called anaerobic sludge digesters. |
1. | Only I | 2. | Only II and III |
3. | Only I and III | 4. | I, II and III |
Consider the two statements:
I: | Indirectly, BOD is a measure of the organic matter present in the water. |
II: | The greater the BOD of wastewater, the more its polluting potential. |
1. Both I and II are correct
2. Only I is correct
3. Only II is correct
4. Both I and II are incorrect