Final answer:
The F:M ratio is a primary process control parameter for wastewater treatment plants.
Step-by-step explanation:
The F:M ratio, also known as food-to-microorganism ratio, is used as a primary process control parameter for wastewater treatment plants in Biology. It refers to the ratio of the amount of food, or organic material, entering a treatment system to the amount of microorganisms present in that system. The F:M ratio impacts the efficiency of biological processes, such as activated sludge, in breaking down organic matter and removing pollutants from wastewater.