What type of activated sludge process utilizes only one basin for its entire treatment process?

The Sequencing Batch Reactor (SBR) is designed to treat wastewater in a single basin by combining various phases of the treatment process into one unit. In an SBR, influent is added to the basin, and conditions are manipulated through cycles that typically include filling, reacting, settling, and decanting. This allows for aeration and sedimentation to occur in the same vessel, which can be more efficient than systems requiring separate basins.

This method offers several operational advantages, including flexibility in handling varying flow and load conditions as well as the potential for reducing space and construction costs since only one reactor is necessary for multiple stages of treatment. The capability to do the entire treatment process sequentially in one basin distinguishes the SBR from other processes that may need multiple basins or continuous flow systems, where water is treated in a constant manner.

The other options, while involved in active treatment processes, do not employ a single basin for the entirety of their operations. For instance, a batch reactor may involve separate operations for different phases, and continuous flow reactors typically require continuous inflow and outflow in a linear setup, while oxidation ditches often consist of a longer, elongated basin that necessitates continuous movement of wastewater through one or more stages of