Question

Arrange the given processes involved in a correct sequence that is followed in a waste water treatment plant.

• A. Screening
• B. Grit removal
• C. Sedimentation
• D. Disinfection

Answer 1

Wastewater treatment is the process of removing harmful contaminants from water. The steps involved in water treatment process are as follows-
$\bullet$ Wastewater treatment starts with screening where heavier wastes like plastic bags, wood pieces are removed.
$\bullet$ In second step of grit removal, particles like sand, grit and pebbles are removed.
$\bullet$ Next step is primary sedimentation, it includes settling of primary sludge and the removal of wastewater from the top of sedimentation tank.
$\bullet$ The wastewater is then treated with aerobic bacteria where waste is decomposed and forms activated sludge. This is followed by secondary sedimentation.
$\bullet$ Finally, it is treated with chemicals like chlorine or ozone to disinfect water before releasing water to natural waterbodies.