Activated Sludge – Continuous Flow (CAS)

In a continuous activated sludge system, wastewater is continuously treated by exposing it to microorganisms and oxygen in a controlled biological process. These microorganisms convert organic pollutants into carbon dioxide, water, ammonia, and — under extended aeration conditions — nitrate. A portion of the organic load is transformed into biomass, with excess sludge removed from the system to maintain optimal process conditions.

Unlike batch-operated systems, a continuous activated sludge installation is designed for steady-state operation, making it highly suitable for applications with constant or high hydraulic loads. The process is typically divided into multiple stages, with separate aeration and clarification tanks operating simultaneously.

Wastewater enters the aeration tank where intensive mixing and aeration ensure optimal contact between biomass and pollutants. The mixed liquor then flows to a secondary settling tank (clarifier), where the activated sludge is separated from the treated water. A portion of this settled sludge is recirculated (RAS) back to the aeration tank to maintain a stable biomass concentration, while excess sludge is discharged.

This continuous flow configuration ensures consistent treatment performance, even at high capacities, and allows for precise control of key process parameters such as sludge age, oxygen levels, and nutrient removal.

The system is equipped with advanced automation and control, enabling real-time monitoring and adjustment of aeration, sludge return, and sludge wasting. This guarantees stable operation, energy efficiency, and compliance with stringent discharge standards.