Nitrogen Removal from Water Resource Recovery Facility Secondary Effluent Using a Bioreactor

Solid-phase denitrification technology can potentially be used to remove nitrogen compounds, such as total nitrogen and nitrate nitrogen (NO3--N), from wastewater. In this study, the authors made use of an internal-circulation baffled biofilm reactor in which filamentous bamboo acted as a biocarrier for the removal of nitrogen (N) from water resource recovery facility (WRRF) secondary effluent. A laboratory-scale experiment was conducted to assess the efficacy and mechanisms of N removal from the WRRF secondary effluent operated in continuous-flow mode. Results indicated that total nitrogen and NO3--N removal rates reached 66.58 to 75.23% and 75.6 to 85.6%, respectively. Infrared spectrum analysis indicated biodegradation in the filamentous bamboo. A comparison of this method with the use of filamentous plastics as biocarriers indicated that higher NO3--N removal (as volumetric loading) and lower nitrite nitrogen accumulation rates were obtained when filamentous bamboo was used as a biocarrier. A NO3--N removal volumetric loading of 2.09 mg/L.h was reached when using bamboo as a single solid carbon source. These results confirm that filamentous bamboo can be used as an alternative to inert biocarriers in WRRF secondary effluent treatment systems.