Mechanistic Insights into Mitigation of Combined Scaling-Biofouling for a Novel Thin-Film Composite Membrane Based on Incorporated Defensive-Offensive Strategy.

Combined scaling-biofouling is commonly encountered in practical wastewater treatment and desalination due to the coexistence of inorganic scalants and microorganisms, which is a major obstacle limiting the applications of membrane-based technologies. In this study, we developed a simple and effective modification method for the preparation of an anticombined scaling-biofouling thin-film composite (TFC) nanofiltration membrane via a synergetic strategy based on defensive (, sequestering carboxyl groups) and offensive (, immobilizing antimicrobial peptides (AMPs)) functions. According to the Extended Derjaguin-Landau-Verwey-Overbeek (XDLVO) analysis, the sequestration of carboxyl groups by AMPs diminishes the acid-base polarity interaction between the biofoulants and membranes, playing a critical role in dismantling the bridge of carboxyl-Ca-carboxyl and subsequently rendering both scaling ions and carboxyl groups unavailable to fouling. Meanwhile, the immobilization of AMPs on the membranes prevents microbial metabolism and growth by contact-killing mechanisms, endowing the membrane resistance to severe biofouling in the presence of scaling ions. Furthermore, the synergetic effects overcome the permeability-rejection-antifouling trade-off by enhanced water permeance without sacrificing salt rejection. This research provides a novel dimension for developing high-performance TFC membranes for the mitigation of combined scaling-biofouling in the practical application of wastewater treatment and desalination.