Question

Floating impurities such as oils and grease in the primary tank are

removed by it.​

Answer 1

Answer:

skimming is the correct answer

Explanation:

The floating matters such as oils, grease etc. are removed from the sewage by skimming tanks and this process of removing is called skimming.

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Answer 2

Answer:

screening

Explanation:

The process of removing the large matters from sewage by passing it through screens is called screening. The floating matters such as oils, grease etc.