Simultaneous biological removal of nitrogen and phosphorus in a novel internal-loop A/O/IAT-IAT process

A novel wastewater biological treatment process, internal-loop Anaerobic/Oxic/double Intermitted Aerobic Tank (A/O/IAT-IAT), was investigated for simultaneous removal of nitrogen and phosphorus. Satisfactory nitrogen and phosphorus removal performance was achieved in both lab scale reactor and pilot plant. Over 90% removal efficiencies were accomplished in the experiments with average effluent concentration of NH₄⁺-N and PO₄^3--P being 2.5 mg/L and 0.1 mg/L receptively.