Explain the different steps involved during primary treatment phase of sewage.

Physical removal of particles (large and small), by filtration and sedimentation, forming primary sludge/Sedimented solids, forming effluent (supernatant) for secondary treatment.

Detailed Answer : 

Primary treatment: The primary phase of sewage treatment involves physical removal of particles by filtration and sedimentation. Different steps involved during the primary treatment are as follows : 

Initially, floating debris of sewage water is removed by sequential filtration through many screens. 

Then, girl (soil + small pebbles) is removed by sedimentation in large settling tanks. The remaining solid particles, which have settled down, form the sludge while the supernatant forms the effluent. Effluent is then taken for secondary treatment.

Primary treatment or physical treatment

• It is the physical removal of large and small particles from sewage.

• First, the floating debris is removed by sequential filtration by passing through wire mesh screens.

• Then, the grit (soil and small pebbles) are removed by sedimentation in settling tanks. The sediment is called primary sludge and the supernatant is the effluent.

• The effluent is taken for secondary treatment.