Oxidation Ditch

The oxidation ditch consists of a ring- or oval-shaped channel and is equipped with mechanical aeration devices (Figure 16). Screened wastewater enters the ditch and is aerated, or circulates about 0.25 to 0.35 m/s. Oxidation ditches classically operate within an extended aeration mode along with long detention and solids retention times. Secondary sedimentation tanks are used for most applications. BOD removal efficiency varies among 75-95%.

                      Figure 16: Oxidation Ditch Activated Sludge Process