Activated sludge systems are a type of wastewater treatment process that uses microorganisms to break down organic matter. In this system, wastewater is aerated in a tank, allowing bacteria and other microorganisms to thrive. These organisms consume the organic pollutants, converting them into biomass and carbon dioxide. After aeration, the mixture is transferred to a settling tank, where the activated sludge settles to the bottom. The settled sludge can be recycled back into the aeration tank to maintain the microbial population, while the treated water is discharged or further processed. This method is efficient and widely used in municipal and industrial wastewater treatment facilities.