Multiple choice

What is primary treatment?

Water pollution can be defined as an undesirable change in the physical, chemical and biological characteristics of water that will be harmful to humans, animals or plant life and productivity. It is customary to consider the treatment of polluted water in three phases- Primary treatment, Secondary treatment and Tertiary or advanced treatment.

  1. The process in which the waste water is passed over stones or racks of plastic surface.

  2. The process where waste water is passed through a series of wire-meshes of decreasing size.

  3. Process that is carried out by a biological system where microorganisms decompose organic matter.

  4. The process in which waste water is mechanically stirred in a tank in presence of increased oxygen with help of electronic pump.

  5. The process in which different chemical components like phosphate, nitrogen, ammonia, poly-electrolytes, etc. are removed in treatment plants.
Reveal answer Fill a bubble to check yourself
B Correct answer
Explanation

In primary treatment, different suspended and floating pollutants of water like plastic, paper, solid substances, etc. are passed through a system of screening and degrading, grease and scum removal, sedimentation, sludge thickening. The waste water passed through a series of wire-meshes of decreasing size where suspended and floating solid are maintained in a large water body in stagnant condition where sedimentation and precipitation occur.

Keep practicing — related questions