Question

Treatment of waste water is done by the ___________ naturally present in the sewage.

• A. autotrophic microbes
• B. heterotrophic microbes
• C. pathogenic microbes
• D. saporophytic microbes

Answer 1

The correct option is B heterotrophic microbes

Heterotrophs are a group of microorganisms (yeast, moulds & bacteria) that use organic carbon as food (as opposed to autotrophs like algae that use sunlight) and are found in every type of water.
The waste water of the sewage contains large amounts of organic matter and microbes. The treatment is done by the heterotrophic microbes naturally present in the sewage. This is carried out in two stages: primary and secondary treatments.