Efficient Nitrogen Removal using a Continuous-Flow Reactor with Double-Layer Alternating Aeration for Treating Municipal Wastewater

Achieving nitrogen removal in a single device has attracted great attention of researchers in recent years due to its small footprint and low energy consumption. In this study, a novel continuous-flow air-lifting reactor is designed to establish multi-functional zones, including an aerobic zone, an anoxic zone, and a settling zone. With an alternation aeration of double-layer aerators (DLAs), multiple dissolved oxygen (DO) environments are maintained and denitrification and carbon removal in the same reactor are achieved. Results demonstrate that frequent alternating aeration with a short duration (aeration of the upper-layer aerators for 30 min + aeration of the lower-layer aerators for 0.6 min) can achieve better mixing of microorganisms and pollutants, and lead to a good nitrogen removal efficiency of over 90%. This new reactor presents a good TN removal performance in treating real domestic wastewater with an effluent TN concentration lower than 10 mg/L without external carbon source addition.