Skimming tanks in wastewater treatment are primarily provided for what purpose?

Introduction / Context:
Grease and oil can foul downstream processes and cause scum accumulation. Skimming tanks (or grease traps) are used in preliminary treatment to remove floating matter.

Given Data / Assumptions:

• Municipal sewage with fats, oils, and grease (FOG).
• Tank equipped with baffles and skimming mechanisms.

Concept / Approach:
Skimming relies on gravity separation: lower-density oils/grease rise to the surface and are collected by scrapers or weirs, preventing carryover.

Step-by-Step Solution:
Step 1: Recognize FOG removal as the skimming tank function.Step 2: Distinguish from grit chambers (remove heavy inorganic grit) and screens (remove coarse debris).Step 3: Select the option describing grease/oil removal.

Verification / Alternative check:
Plant schematics show skimming tanks downstream of screening/grit removal or integrated with primary clarifiers as scum removal systems.

Why Other Options Are Wrong:

• Sludge removal is a function of sludge hoppers/valves, not skimming.
• Screens handle coarse solids, not oils.
• Grit chambers remove sand/gravel; skimmers handle floatables.

Common Pitfalls:
Confusing grit removal with skimming; neglecting grease control leads to scum blankets and odor issues.

Final Answer:
Removal of grease and oil from sewage