What shape is a complete-mix activated sludge basin typically?

In wastewater treatment, a complete-mix activated sludge basin is designed to provide uniform mixing of the wastewater and the activated sludge. This mixing is essential to ensure that microorganisms effectively break down organic matter. Among the typical shapes used for such basins, rectangular shapes are most common in practice.

Rectangular basins allow for efficient flow management and can accommodate varying volumes of influent. The shape helps maintain a consistent hydraulic retention time, which is crucial for the treatment process. This configuration also enables the basin to be tailored more easily to specific site conditions and treatment capacities, making it a practical choice in many wastewater plants.

Shapes like round or square might be used in some specific designs, but they are not as widely used for complete-mix systems due to potential issues with flow patterns and mixing efficiency. Triangular basins are generally not utilized for this purpose because they do not provide the same level of flow stability and mixing capabilities as rectangular basins.