Question

Match and find the correct option.

	I		II		III
(a)	BOD	(i)	Supernatant as effluent	(p)	Useful aerobic microbes
(b)	Flocs	(ii)	Measure of organic matter	(q)	All settled solids
(c)	Primary sludge	(iii)	Masses of bacteria associated with fungi	(r)	Methane hydrogen sulphide carbon dioxide
(d)	Biogas	(iv)	Anaerobic sludge digester	(s)	Polluting water has more BOD

• A. a-ii-s, b-iii-p, c-i-q, d-iv-r
• B. a-ii-p, b-i-r, c-iv-q, d-iii-s
• C. a-i-s, b-iii-q, c-iv-p, d-ii-r
• D. a-iv-r, b-ii-s, c-iii-p, d-i-q

Answer 1

The correct option is A a-ii-s, b-iii-p, c-i-q, d-iv-r

(a)BOD - (ii)Measure of organic matter-(s)Polluting water has more BOD-Biochemical Oxygen Demand is the amount of dissolved oxygen needed by aerobic microbes to break down organic material present in a given water sample at certain temperature over a specific time period. Polluting water has more organic matter thus required more oxygen for the breakdown. Hence polluting water has more BOD.

(b)Flocs-(iii)Masses of bacteria associated with fungi -(p)Useful aerobic microbes-Flocs are the masses of bacteria associated with fungi. Flocs are helpful in increasing the decomposition rate and are put in the aeration tank while the secondary sewage treatment process is in effect

(c)Primary sludge-(i)Supernatant as effluent-(q)All settled solids-Primary sludge includes settleable solids removed during primary treatment in primary clarifiers.

(d)Biogas-(iv)Anaerobic sludge digester-(r)Methane, hydrogen sulfide, carbon dioxide-Biogas is the mixture of gases(Methane, hydrogen sulfide, carbon dioxide)- produced by the breakdown of organic matter in the absence of oxygen(I.e from anaerobic sludge digesters).