Three-dimensional crosslinked nanofiber membrane enhances biocompatibility and wastewater treatment performance in MABR

The membrane aerated biofilm reactor (MABR) technology holds broad prospects for reducing energy consumption and enhancing efficiency in wastewater treatment. However, the low biocompatibility of traditional membranes results in weak biofilm attachment, remaining a critical bottleneck for its practical implementation. Drawing inspiration from the three-dimensional fibrous cross-linked network of the human extracellular matrix (ECM), an electrospun membrane (EM) with a similar structure was fabricated via electrospinning. We evaluated the wastewater treatment performance and biofilm development across conventional microporous hydrophobic membrane (MHM), dense silicone membrane (DSM), and our fabricated EM. By integrating the physicochemical analysis of membrane materials with the biological assessment of biofilms, we unraveled the unique mechanism through which the EM accelerates biofilm formation and boosts MABR efficiency. The EM reduced the acclimatization period by 27.3% and 33.3% relative to traditional MHM and DSM. Under stable conditions, the EM reactor achieved removal efficiencies of 88.8% for COD and 98.2% for ammonia nitrogen, surpassing the MHM reactor's 86.7% and 94.9% and the DSM reactor's 84.0% and 92.0%, respectively. Moreover, the effluent showed a lower concentration of aromatic small molecules and fulvic acid-like organics. Analysis of the interactions between the three membrane materials and biofilms revealed that the EM possesses a higher thermodynamic binding affinity for proteins (PN) than for polysaccharides (PS). Furthermore, its unique three-dimensional interconnected fibrous architecture offers more attachment sites for EPS and microbes, promoting the formation of thicker and denser biofilms with higher PN/PS ratios. Besides, the principal nitrifiers, Nitrosomonas and Nitrospira, were more abundant on the EM at 6.6% and 5.4%, compared to lower levels on the MHM at 2.1% and 2.3%, and on the DSM at 3.3% and 1.7%. These findings may help address the challenge of poor biocompatibility in MABR membranes, contributing to the development of more efficient wastewater treatment technologies.