Question

what is the main goal of secondary treatment in sewage treatment plants? to remove large objects and debris to remove organic waste using microorganisms to add nutrients to the water to increase water flow rate

Explanation:

In sewage treatment plants, primary treatment removes large objects and debris. Secondary treatment uses microorganisms to break down and remove organic waste from the water. Adding nutrients and increasing water - flow rate are not the main goals of secondary treatment.

Answer:

to remove organic waste using microorganisms