Q. No.High value of BOD (Biochemical Oxygen Demand) indicates that:-
| 1. | water is pure |
| 2. | water have heavy metal |
| 3. | water is less polluted |
| 4. | consumption of organic matter in the water is higher by the microbes |
Subtopic: Microbes in Sewage Treatment |
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Level 1: 80%+
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What gases are produced in anaerobic sludge digesters?
| 1. | Methane and CO2. |
| 2. | Methane, Hydrogen sulphide and CO2. |
| 3. | Methane, Hydrogen sulphide and CO. |
| 4. | Hydrogen sulphide and CO2. |
Subtopic: Microbes in Sewage Treatment |
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Level 1: 80%+
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Masses of bacteria associated with fungal filaments to form mesh like structures is called as
1. Flocs
2. Primary sludge
3. Sewage
4. Biofertiliser
Subtopic: Microbes in Sewage Treatment |
98%
Level 1: 80%+
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Biochemical Oxygen Demand (BOD) is a measure of:
| 1. | The amount of oxygen required by aerobic microorganisms to decompose organic matter in water. |
| 2. | The oxygen content available in the air. |
| 3. | The efficiency of oxygen production by photosynthesis in plants. |
| 4. | The amount of carbon dioxide absorbed by water bodies. |
Subtopic: Microbes in Sewage Treatment |
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Measuring Biochemical Oxygen Demand (BOD) is a method used for
| 1. | Measuring the activity of Saccharomyces cervisae in producing curd on a commercial scale |
| 2. | Working out the efficiency of R.B.Cs. about their capacity to carry oxygen |
| 3. | Estimating the amount of organic matter in sewage water |
| 4. | Working out the efficiency of oil driven automobile engines |
Subtopic: Microbes in Sewage Treatment |
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During sewage treatment a small part of the activated sludge is pumped back into the aeration tank to
| 1. | Serve as inoculum |
| 2. | Serve as nutrient medium |
| 3. | Produce biogas |
| 4. | Produce CO |
Subtopic: Microbes in Sewage Treatment |
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If sewage is directly discharged into water bodies without treatment:
| 1. | Eutrophication occurs: algal bloom, oxygen depletion, fish death |
| 2. | Water quality improves |
| 3. | Water becomes potable |
| 4. | Aquatic life flourishes |
Subtopic: Microbes in Sewage Treatment |
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The growth of Flocs is facilitated by
| 1. | Constant agitation mechanically |
| 2. | Air is pumped |
| 3. | Both A and B |
| 4. | Filaments of algae |
Subtopic: Microbes in Sewage Treatment |
94%
Level 1: 80%+
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After secondary treatment, why a portion of the activated sludge is recycled back into the aeration tank?
| 1. | To decompose heavy metals in the sewage. |
| 2. | To act as an inoculum, promoting the growth of aerobic microbes for further BOD reduction. |
| 3. | To ensure that harmful gases are removed from the sewage before discharge. |
| 4. | To increase the oxygen concentration in the effluent. |
Subtopic: Microbes in Sewage Treatment |
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Which stage of sewage water treatment is essentially a ‘biological’ treatment?
1. Primary
2. Secondary
3. Tertiary
4. Quaternary
1. Primary
2. Secondary
3. Tertiary
4. Quaternary
Subtopic: Microbes in Sewage Treatment |
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