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PSC Civil Engg: Environmental Quiz 5

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Question 1

The different actions that take place in anaerobic decomposition process are
(i) Alkaline fermentation
(ii) Acid fermentation
(iii) Acid regression
(iv) Methane formation
What is the correct sequence of these actions (from earlier to later)?

Question 2

How many kg of bleaching power is needed per day to chlorinate 4 MLD f water so that, after 40 minutes of contact, there remains residual chlorine of 0.25 mg/l. The input water has a chlorine demand of 1.25 mg/l, and that the bleaching powder has only 25% available chlorine.

Question 3

Consider the following statements regarding contact stabilization process:
1) Primary settling tank is not required in some cases.
2) BOD removal occurs in two stages.
3) Aeration volume requirements are approximately 50% of those of a conventional — or tapered — aeration plant.
4) Returned sludge is aerated for 30 min to 90 min in sludge aeration tank.
Which of the above statements are correct?

Question 4

Consider the following characteristics of E.Coli bacteria:
1) Gram negative
2) Spore-forming
3) Facultative anaerobic
4) Bacillus
Which of the above are correct?

Question 5

100 m3 of sludge holds a moisture content of 95%. If its moisture content changes to 90%, the volume of this sludge will then be
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