Which of the following statements is correct with respect to wastew...

Which of the following statements is correct with respect to wastewater treatment?

A. Treatment of wastewater is carried out in three stages-Primary, Secondary and Biological Treatment

B. Primary treatment basically involves physical removal of particles-large and small-from the sewage through sedimentation then filtration

C. All solids that settle form the primary sludge, and the supernatant forms the effluent

D. The sludge from the primary settling tank is taken for secondary treatment