Which term is the biological wastewater treatment process accelerated by aeration?

• A. Adsorption
• B. Absorption
• C. Aeration
• D. Activated sludge process

Answer: (D)

Aeration provides the oxygen microbes need to break down organic matter, speeding up biological wastewater treatment. The biological process that relies on this oxygen supply to keep the microbial population active and in suspension is the activated sludge process. In this method, air is bubbled through the wastewater in aeration tanks, creating aerobic conditions and encouraging fast oxidation of pollutants while forming flocs of microorganisms. This active biomass then settles in a subsequent clarifier, with part of the sludge returned to maintain the microbial population and excess removed as waste. Adsorption and absorption describe physical processes that transfer contaminants to surfaces or into liquids rather than relying on microbial digestion, so they don’t describe the biological treatment driven by aeration. Aeration itself is the means of delivering oxygen, while the activated sludge process is the biological treatment accelerated by that oxygen.