→ Sewage treatment plant contains mainly two steps:
(1) Primary treatment:
→ Primary treatment steps basically involve physical process during which removal of particles- large and small is done from the sewage.
→ For this process, filtration and sedimentation is done repeatedly.
→ This treatment is less expensive and comparatively simple process.
(2) Secondary treatment (biological treatment): (
→ This is a biological process in which organic matter is decomposed by microbes.
→ Here, by using aerobic and anaerobic microbes, organic matter is decomposed. This process is complex and expensive.