- 1(current)
Q. No.
| 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 |
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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
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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 |
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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
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| I: | Biochemical oxygen demand (BOD) is often used as an indicator of the degree of organic pollution of water. |
| II: | An increase in BOD is used as a gauge of the effectiveness of wastewater treatment plants. |
| 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: | vigorous growth of useful aerobic microbes into flocs is allowed |
| II: | aerobic microbes consume the major part of the organic matter in the effluent. |
| III: | the BOD of the water sample gets significantly increased |
| 1. | Only I and II are correct |
| 2. | Only I is correct |
| 3. | Only II and III are correct |
| 4. | I, II and III are correct |
| 1. | They can grow anaerobically on cellulosic material |
| 2. | They can produce large amounts of methane along with carbon dioxide and hydrogen |
| 3. | They can be found in anaerobic sludge during sewage treatment and in rumen of cattle |
| 4. | They are true bacteria and are chemoheterotrophs |
| 1. | The levels of both BOD and DO are high |
| 2. | The levels of both BOD and DO are low |
| 3. | The levels of BOD will be high and the levels of DO will be low |
| 4. | The levels of BOD will be low and the levels of DO will be high |
- 1(current)
Q. No.
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