| (i) In secondary treatment useful aerobic microbes grow rapidly and form floes of bacterial and fungal filaments in a mesh- like structure. |
| (ii) The growing microbes consume organic matter reducing the BOD after which the effluent is passed into settling tank. |
| (iii) In settling tank, the bacterial floes settle and the sediment is called activated sludge. |
| (iv) A small part of the sludge is used as an inoculum. The remaining part is passed into anaerobic sludge digesters. |
| (v) On anaerobic digestion of bacteria and fungi mixture of gases such as, carbon dioxide, nitrogen and carbon monoxide are produced. |
A) (i), (ii), (iii) and (iv)
B) (i), (iii), (iv) and (v)
C) (ii), (iii), (iv) and (v)
D) (i), (ii), (iii), (iv) and (v)
Correct Answer: A
Solution :
[a] All statements are correct except (v). Methane, hydrogen sulphide and C02 are the main gases produced in the digesters by the anaerobic digestion by heterotrophic bateria and fungi.
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