Membrane fouling mitigation in Anoxic-Oxic membrane bioreactor with carbon nanotube/dopamine modification

In this study, hollow fiber membranes in Anoxic-Oxic Membrane Bioreactor (A/O-MBR) were modified using dopamine (DA) to crosslink carbon nanotubes (CNTs), referred as M-CNTs/PDA, and their fouling behavior was compared with original membranes (M-pristine). The experimental results indicated the total nitrogen removal rates kept exceeding 90 %. Transmembrane Pressure (TMP) data revealed that M-CNTs/PDA exhibits an extended operational lifespan than the M-pristine. Lower levels concentration of protein, polysaccharides and humic substances presented on the foulant layer of M-CNTs/PDA membranes. In filtration experiments, M-CNTs/PDA exhibited a smaller reduction in specific flux and higher fouling reversibility, with a flux recovery rate of 96.64 %. The confocal laser scanning microscopy (CLSM) images further indicated that the fouling layer on the M-CNTs/PDA is significantly thinner. Flow cytometry analyses indicated that M-CNTs/PDA has sterilizing effects that can effectively mitigate biological fouling to some extent. Overall, the M-CNTs/PDA membrane effectively mitigated both organic and biological fouling. This offers a promising strategy to enhance membrane performance and longevity in A/O-MBR systems, addressing a critical challenge in wastewater treatment by improving operational efficiency and reducing maintenance costs. • Successfully prepared carbon nanotube/dopamine (CNTs/PDA) hollow fiber membrane (M-CNTs/PDA) • CNTs/PDA modification exerts no effect on the nitrogen removal performance of AO-MBR. • CNTs/PDA modification exhibits excellent resistance to organic and biological fouling.