Energy saving in the operation of submerged MBRs by the insertion of baffles and the introduction of granular materials

A membrane bioreactor (MBR) is not a mainstream wastewater treatment technology, mainly because the energy consumption in an MBR operation is high. This study investigated the mitigation of membrane fouling and the reduction in aeration through the introduction of granules into a pilot-scale baffled membrane bioreactor (BMBR) used to treat municipal wastewater. With granular materials, the BMBR could be stably operated, even when the filterability of the mixed liquor suspensions was considerably low due to low temperatures. The aeration rate could be reduced by more than 50% with the help of granules. However, it was found that the introduction of granules damaged parts of the membrane surface. The damage might be avoided by adjusting the contact intensity of the granules and the membrane surface.