Question

Which of the following describes the correct sequence for treatment of wastewater in a wastewater treatment plant?

• A. Chemical → biological → physical
• B. Biological → physical → chemical
• C. Physical → biological → chemical
• D. Biological → chemical → physical

Answer 1

The correct option is C Physical → biological → chemical

Wastewater treatment is the process of removing harmful contaminants from water. Physical, chemical and biological processes are used to treat wastewater.

• Wastewater treatment starts with screening and is followed by removal of sand and grit which are physical processes.
• It is then followed by biological processes where wastes in water are decomposed by bacteria.
• Finally, it is treated with chemicals like chlorine and ozone to disinfect the water before it is released into natural waterbodies.
• Hence, correct sequence for treatment of wastewater in a wastewater treatment plant is physical, biological and then chemical.