Which process involves adding air to wastewater to promote the growth of aerobic microorganisms?

Aerobic digestion is the process that involves adding air to wastewater, thereby promoting the growth of aerobic microorganisms. These microorganisms thrive in the presence of oxygen and are essential for breaking down organic matter present in the wastewater. By aerating the wastewater, conditions are created that allow these beneficial microbes to effectively degrade pollutants, resulting in cleaner water.

In aerobic digestion, the introduction of air allows for the efficient breakdown of organic compounds, converting them into carbon dioxide, water, and microbial biomass. This process is crucial in wastewater treatment facilities, as it aids in removing harmful organic substances, making the effluent more suitable for discharge or further treatment.

The other processes listed do not involve the addition of air to support aerobic microorganisms. Anaerobic digestion, for example, occurs in the absence of oxygen and relies on different types of microorganisms that can decompose organic matter without it. Biological treatment can encompass both aerobic and anaerobic methods, while filtration primarily serves to physically separate solid particles from liquids rather than promoting microbial growth.