question_answer

DIRECTIONS: Read the passage given below and answer the questions that follow. Passage - 2 Treatment of waste water involves physical, chemical and biological processes, which remove physical, chemical and biological matter that contaminates the waste water. In WWTP, in one of the steps, the water is allowed to settle in large tank which is sloped towards the middle. In it impurities settle at the bottom. These settled impurities are called

A) Sewer                         

B) skimmer

C) sludge             

D) activated sludge