The authors have proposed a baffled membrane bioreactor (BMBR) that can eliminate the energy needed for the mixed liquor circulation. A combination of the BMBR concept and use of biomass carriers is promising, and a substantial reduction in energy consumption should be possible. In this study, a pilot-scale BMBR treating municipal wastewater was operated with sponge biomass carriers and its performance was investigated in terms of treated water quality and energy consumption (aeration intensity). Long-term operation of the BMBR revealed that aeration demand for the BMBR was substantially reduced with minimal membrane fouling and excellent nitrogen removal being achieved. The expected energy consumption (aeration intensity) in a full-scale BMBR operated with sponge carriers is very low, definitely lower than the values in “normal” MBRs. With the proposed modification of the MBR, processes using MBRs will no longer be considered to be energy-intensive processes.