Question
Biology Question on Microbes in human welfare
Secondary sewage treatment is mainly a
A
physical process
B
mechanical process
C
chemical process
D
biological process
Answer
biological process
Explanation
Solution
The treatment of sewage is a biological process because it involves the treatment of microorganisms.
- The microbes function to reduce the waste toxicity tested by measuring the BOD (biological oxygen demand) and COD (chemical oxygen demand) value of the water.
- The microbeshelp to treat the sludge that is produced by the wastewater.
- Therefore, it is called a biological process.
Option A:
A physical includes gradual change through transient states. The treatment of sewage water is not a physical process.
Option B:
No objects interact to generate mechanical energy in secondary sewage treatment.
Option C :
Treatment of sewage is not a chemical process as a change in chemical state or production of different chemicals is not involved.
Therefore Option D is correct - Secondary sewage treatment is mainly a biological process.