Abstract
The authors evaluated the energy efficiency of a novel oxidation ditch (OD) system with dual dissolved oxygen (DO) control technology through clean water tests and continuous treatment of domestic wastewater in a full-scale OD. The system maintained a constant DO gradient in the loop channel by independently controlling the aeration intensity and the circulation flow rate. Clean water tests demonstrated that a standard aeration efficiency of 1.4 - 2.1 kgO2/kWh was obtained in the OD equipped with membrane diffusers, blowers and vertical flow boosters, and these values were relatively higher than the previously reported values. The calculated standard aeration efficiency varied depending on the airflow rate and rotational speed of the flow boosters. Continuous treatment revealed that the power consumption was reduced by 67% when compared with the existing OD system. Reducing endogenous respiration, improving the standard aeration efficiency, and applying dual DO control were estimated to contribute 15%, 28% and 23%, respectively, to the total reduction of power consumption. Overall, this novel OD system showed extraordinary nitrogen removal performance with very low energy consumption.
