About Lesson
Sewage and sludge
- In the modern sanitation system in big cities and town where underground flush system is provided with a good deal of human excreta and urine dissolved in water which is flushed out with water is called sewage.
- The semi-solid part of sewage water that has been sedimented as acted upon by bacteria is called sludge.
- The liquid portion of sewage (liquid of kitchen, bathroom, and urine) is known as sullage
