Wastewater Treatment MCQ with answer and solution

Concept

Removal of oil and grease

Step-by-step solution

1. Oil and grease are lighter than water and float. 2. A skimming tank (with air blowing) allows them to rise to the surface where they are skimmed off.

Explanation

Skimming tanks remove floating matter such as oil, grease and soap from sewage. Screening removes large floating and suspended solids, and sedimentation removes settleable solids.

Shortcut

Floating oil and grease → skimming tank.

Common mistake

Choosing sedimentation.