What Is secondary treatment of sewage?

Secondary sewage treatment includes further two types of process:

1. Aerobic treatment- this is a biological treatment that uses oxygen to dilute the matter and break down it, and removes nitrogen and phosphorus from the organic matter.

in this treatment technologies used are:

• Activated sludge process
• Sequential batch reactor
• Moving bed biofilm reactor
• Membrane bioreactor

1. Anaerobic treatment- this is a treatment where dissolved oxygen is not used instead micro-organisms are used to break down organic matter. But bacteria find oxygen from oxidized matter or the organic matter of sewage.