What is treatment of polluted water?

• Wastewater Treatment Plant:

The process of wastewater treatment includes the following steps:

1. Screening: This is the first step in which wastewater is passed through bar screens to remove large objects like rags, wood pieces, sticks, stones, etc.
2. Grit and sand removal tanks: Water is then allowed to go into a grit and sand removal tank. This allows the grit, sand, stones and heavy objects to settle at the bottom.
3. Sedimentation tanks: Water is now allowed to pass through large tanks called sedimentation tanks. These tanks are large enough so that organic solid matter like faeces sinks slowly to the bottom and materials like grease and oil float at the surface and skimmed off.
4. Aeration: The clarified water is passed into an aeration tank which contains aerobic bacteria. This bacteria rapidly grows and consume organic matter like human and animal wastes and convert it into carbon dioxide.