Superior membrane fouling control in membrane bioreactors using reciprocation with limited aeration

Abstract

Membrane fouling control is crucial for the wide application of membrane bioreactors (MBR), highlighting the necessity for innovative strategies to reduce energy input and improve fouling control capability. In this study, three different membrane-fouling strategies, i.e., aeration, reciprocation, and reciprocation coupled with limited aeration (RecLA), were adopted and compared in MBR systems with a long-term investigation. Compared to the conventional aeration strategy, which achieved nitrogen and phosphorus removal efficiencies of 87.5 % ± 4.9 % and 30.2 % ± 4.3 % respectively, the reciprocation strategy demonstrated significantly higher removal efficiencies of 94.5 % ± 3.7 % for nitrogen and 94.3 % ± 3.7 % for phosphorus. More importantly, the filtration time was significantly extended from 4 days for aeration to 21.5 days for reciprocation and 26.7 days for RecLA. RecLA was effective in reducing cake layer thickness, enhancing foulant hydrophilicity, and decreasing the abundance of filamentous bacteria in the foulant. Particle image velocimetry analysis revealed that RecLA enhances bubble penetration into the module interior, increases the shear rate near the membrane surface, and mitigates foulant accumulation, thereby effectively alleviating membrane fouling. Therefore, the RecLA strategy achieves efficient membrane fouling control by enhancing hydrodynamic conditions and altering foulant properties, offering an innovative solution for the broader application of MBR systems.

Keywords: Cake layer; Low dissolved oxygen; Microbial community; Nutrients removal; Particle image velocimetry.