Question

Write the differences between primary and secondary treatment of wastewater? [4 marks]

Answer 1

Primary treatment	Secondary treatment
It is a physical method of treatment.	It is a biological method of treatment.
It involves the separation of organic solid which settles down at the bottom of the tank.	It involves the removal of dissolved organic matter by the action of microbes.
The settled solid in this process is called primary sludge.	The settled solid in this process is called activated sludge.
It is relatively simple and less time consuming process.	It is very expensive and complicated process.

[4 marks]
*one mark for each point of difference*