Energy efficiency and biofouling control in a pilot-scale membrane bioreactor using low-frequency reciprocating motion and the succession of biofilm communities resistant to mechanical shear

Abstract

We evaluated the energy consumption and permeability performance of a novel membrane bioreactor (MBR) that employs reciprocating motion to generate mechanically imposed shear on a hollow-fiber membrane. This pilot-scale reciprocation MBR was operated for eight months in a local wastewater treatment plant. The inertial forces generated by the reciprocating motion of membrane modules and the looseness of the fiber successfully mitigated membrane fouling without air scouring. The specific energy demand (SED) for the reciprocation MBR ranged from 0.003 to 0.015 kWh/m3 at 25 LMH, resulting in up to an 85% reduction of energy consumption as compared to conventional air scouring MBRs. The MLSS concentrations were correlated to the SED because of the drag forces acting on the mixed liquor in the reciprocation MBR. Also, the relative abundance of bacterial phylotypes in biofilm indicated that specific bacteria could become dominant in the succession of biofilm communities during the operational period.