Self-purification of a river after receiving sewage depends on all EXCEPT:
Choose the correct answer
Dilution by river water
Sedimentation of suspended solids
The colour of the river water
Biological oxidation by microorganisms and reaeration
Correct Answer
C. The colour of the river water
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River self-purification mechanisms: dilution (mixing of river and effluent), sedimentation, biological oxidation (aerobic bacteria decompose BOD), and reaeration (oxygen from atmosphere dissolves). River colour does not directly determine self-purification capacity.
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