Integration of nitrification and denitrifying dephosphatation in airlift loop sequencing batch biofilm reactor

The paper described a laboratory scale experiment using an airlift loop sequencing batch biofilm reactor (SBBR) to enhance biological nitrogen and phosphorus removal by integrating nitrification and denitrifying dephosphatation. In the reactor, fibrous carriers were packed in aeration zone and reverse flow zone for the attached growth of nitrifiers and denitrifying polyphosphate accumulating organisms (DNPAOs), respectively. After periodically operating the reactor for 234 days with synthetic wastewater, optimal operation conditions were established to obtain stable and highest removal rates of COD, NH4+–N, and PO43−–P. Adequate cycle and phase duration, packing density were established and organic load were obtained for optimal operation. Under optimal conditions, the mean concentrations of influent were about 309.8 ± 8.7 mg COD/l, 116.0 ± 11.3 mg N/l and 10.5 ± 0.4 mg P/l and the removal efficiencies of them were about 95.3 ± 3.3%, 94.6 ± 4.1% and 73.1 ± 8.3%, respectively.