Primary water treatment: A. uses aerobic microorganisms to decompose organic wastes. B. removes suspended particles. C. removes phosphorus and nitrogen. D. involves the anaerobic digestion of organic wastes. E. removes heavy metals and pesticides.

B. removes suspended particles.

Explanation:

The first step in water treatment involves the removal of of suspended particles through the process of coagulation, sedimentation and filtration.

Coagulation process involves the addition of positively charged chemicals to the water. The positively charged chemicals neutralizes the negatively charged particles suspended in the water to form larger particles known as flocs.

The particles are then allowed to settle down through the process of sedimentation after which they are then filtered off in a process known as filtration.