Effectiveness of fluidized fibrous carrier in a membrane bioreactor for biofouling mitigation: A pilot-scale demonstration

This study developed a moving bed-membrane bioreactor (MBMBR), installing fluidized capsules filled with novel fibrous biocarriers, to suppress biofouling. The addition of the fluidized capsules may allow retaining prokaryotes and eukaryote communities, potentially contributing to biofouling deterrent in an MBR. A long-term operation (360 days) of a pilot-scale MBMBR system (500 m3/day), consisting of a Modified Ludzack-Ettinger (MLE) process where the latter aerobic tank installed a membrane module and fluidized capsules, was performed to treat municipal wastewater. The average removal efficiencies of total dissolved organic carbon (DOC) and total nitrogen (TN) were 77.8% and 73.0%, respectively. The introduction of the fluidized capsules slowed down an increase in transmembrane pressure in the latter stage of the MBMBR operation. The result indicates that the application of the fluidized capsules abates the occurrence of biofouling. On the contrary, the total membrane resistance was not improved by the application of the fibrous biocarrier, suggesting no clear link between trans membrane pressure (TMP) and membrane resistance. High-throughput amplicon sequencing based on the 16S and 18S rRNA gene revealed the substantial changes in prokaryotic and eukaryotic community compositions in the MBMBR unit. Besides, Bdelloidea, a class of rotifers, emerged in the later stage of the operation, likely contributing to the retardation of a TMP increase. Together, the application of fluidized capsules filled with fibrous biocarriers prevented membrane biofouling without compromising the DOC and TN removal performances.