The feasibility of an up-flow partially aerated biological filter (U-PABF) for nitrogen and COD removal from domestic wastewater

An up-flow partially aerated biological filter (U-PABF) was developed to study the removal of nitrogen and chemical oxygen demand (COD) from synthetic domestic wastewater. The removal of NH4+-N was primarily attributed to adsorption in the zeolite U-PABF and to bioprocesses in the ceramic U-PABF. When the hydraulic retention time (HRT) was 5.2 h, the ceramic U-PABF achieved a good performance and the NH4+-N, total nitrogen (TN), and COD removal efficiency reached 99.08 ± 8.79%, 72.83 ± 0.68%, and 89.38 ± 1.04%, respectively. The analysis of NH4+-N, NO3−-N, NO2−-N, and TN at different depths revealed the simultaneous existence of nitrification-denitrification, and anaerobic ammonium oxidation (anammox) in ceramic U-PABF. Illumina pyrosequencing confirmed the existence of Planctomycetes, which are responsible for anammox. The results indicated that the nitrification-denitrification and anammox all contributed to the high removal of NH4+-N, TN, and COD in the U-PABF.