In wastewater treatment, which process uses microorganisms to break down organic matter?

The correct answer focuses on aerobic digestion as a key process in wastewater treatment where microorganisms play a vital role. This process relies on the activity of bacteria and other microorganisms to consume organic matter, typically in the presence of oxygen. During aerobic digestion, these microorganisms metabolize the organic material, converting it into carbon dioxide, water, and biomass. This not only helps in reducing the total organic content of the wastewater but also aids in stabilizing the sludge generated during treatment.

Aerobic digestion is particularly effective in reducing pathogens and improving the overall quality of the water that will be released or reused. It is an essential step in many wastewater treatment facilities, particularly in those designed to produce high-quality effluent for discharge or reuse applications.

Other treatment methods like filtration, chlorination, and coagulation do not primarily rely on microbial action to break down organic matter. Filtration involves physically removing solids from liquids, chlorination is a disinfection process that involves adding chlorine to kill pathogens, and coagulation is a chemical process used to aggregate and remove suspended solids. Thus, the unique function of aerobic digestion in utilizing microorganisms makes it the correct choice in this context.