Oxidation ditch activated sludge system is similar with EA system in different sequences as shown below.
Oxidation Ditch Activated Sludge System (OD)
The difference between OD and EA system are the aerobic, anaerobic and sedimentation process was operated in sequences of process in oxidation pond. Besides, the process shall be designed with minimum velocity (0.3 m/s) within the oxidation pond and sufficient unidirectional air to keep activated sludge in suspension for decomposed process occur. The oxygen supply in pond are generated by mechanical aeration equipment such as surface aerator and paddle wheel.