Abstract: A batch wastewater treatment process using a novel sequencing batch air-lift reactor (SBALR) and upflow sludge blanket is described. The static Fill step of the sequencing batch process has an upflow feed of wastewater through an upflow sludge blanket element. This step is followed by Aerated React, Settle, and Draw steps, all of which steps are confined to the single reactor. Reactor performance is excellent with a mean COD removal rate of 99.6%, mean final effluent suspended solids of 4.9 mg/l, and sludge volume index of 67.2 ml/g. Gas hold-up and mass transfer coefficient over a range of suspended solids values are representative of conventional and high-rate activated sludge treatment processes, as well aerobic digesters. The SBALR reactor meets the oxygen demand needed for both the activated sludge and aerobic digestion process.