The provision of technologies that can meet increasingly stringent wastewater discharge standards while reducing energy, operation, and maintenance costs is vital to government, local authorities, industry, and the public at large. The air suction flow biofilm reactor (ASF-BR) is a novel batch biofilm technology suitable for treating wastewaters from municipal, industrial, and agricultural sources. This paper presents an investigation into the performance of a laboratory-scale ASF-BR in treating municipal-strength wastewater over two operational periods-Phase 1 and Phase 2. Phase 1 concentrated on organic carbon removal and nitrification, whereas Phase 2 included an anoxic step to achieve denitrification. The operation of the unit was also investigated by monitoring organic carbon and nitrogen in the reactors during a number of treatment cycles. In Phases 1 and 2 (29 and 124 days of steady-state operation, respectively) of this laboratory study, using a municipal-strength synthetic wastewater, the average influent total chemical oxygen demand (CODt) was 288 and 313 mg/L, whereas the average influent filtered COD (CODf) was 127 and 148 mg/L, respectively. The average CODf removal rates were 92 and 79% during Phases 1 and 2, respectively. Average nitrogen removals during Phases 1 and 2 of greater than 95% ammonium nitrogen (NH4-N) were achieved. By reducing the number of pumping cycles during the aerobic step, the overall energy consumed was reduced by 37.5% during Phase 2 while achieving similar results. On the basis of these positive initial results, a pilot-scale reactor has been constructed at a local wastewater-treatment facility, and commissioning of the unit is currently underway. (C) 2013 American Society of Civil Engineers.