Desalination using low biofouling nanocomposite membranes: From batch-scale to continuous-scale membrane fabrication

This study shows the results of low-biofouling nanocomposite membranes, when using batch-scale fabrication and testing techniques, and when using continuous-scale fabrication and testing techniques. This holistic study begins with nanoparticle manufacturing and selection, then focuses on nanocomposite membrane synthesis and fabrication, and ends with testing and characterization. Nanocomposite membranes loaded with casein-coated silver nanoparticles (Casein-AgNPs) were cast using two approaches, doctor-blade extrusion (batch-scale) and slot-die casting (continuous-scale), to determine their biofouling control properties. In short-term dead-end filtration, cellulose acetate (CA) membranes showed a flux decline of approximately 26% as compared to 20% for nanocomposite (Casein-AgNPs CA) membranes, while the flux recovered after backwashing was higher for the nanocomposite membranes (93%) than for the CA membranes (84%). Cross-flow filtration experiments were conducted for 26 days. No flux decline was observed for nanocomposite membranes and SEM imaging indicated that bacterial cell damage might have occurred. Overall, filtration experiments and membrane testing following biofouling tests showed that laboratory-scale composite membranes operated for 24 h were effective in mitigating biofouling formation. Conversely, continuous-scale nanocomposite membranes operated for 26 days did not show clear improvement in biofouling control, however there was visible damage to cells accumulated on the membrane.