Question:

When domestic sewage mixes with river water

Updated On: May 17, 2024
  • Small animals like rats will die after drinking river water
  • The increased microbial activity releases micronutrients such as iron
  • The increased microbial activity uses up dissolved oxygen
  • The river water is still suitable for drinking as impurities are only about 0$\cdot$1%
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The Correct Option is C

Solution and Explanation

When sewage mixes with water body, micro- organisms present in it biodegrade organic matter of sewage using oxygen. This results into a sharp decline in dissolved oxygen which may cause mortality of aquatic creatures. Gradually, however, dissolved oxygen increases in concentration with the completion of biodegradation of sewage matter.
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