Question

Physical removal of large and small particles from the sewage through filtration and sedimentation is called:

• A. primary treatment
• B. secondary treatment
• C. anaerobic sludge digestion
• D. hlorinaiton

Answer 1

The correct option is A

primary treatment

Primary treatment is the first treatment of sewage water where the small solid particles are removed by sedimentation and the large particles re removed by filteration process.The sewage in this step is split into solid and liquid components. This is achieved by sedimentation and by filtration. Sedimentation describes the passive process by which small solid particles are separated from the liquid water by gravitational forces. When the sewage is left standing, the solid content will eventually fall to the bottom, while the liquid portion will stay at the top. The separation of solids and liquids can be furthered by active filtration processes, in which sewage is passed through a porous material to remove large particles. The liquid post primary treatment is ready for secondary treatment with helpful bacteria that breakdown organic matter present in sewage.