Antimicrobial and Antibiofouling Electrically Conducting Laser-Induced Graphene Spacers in Reverse Osmosis Membrane Modules

Biofouling is an ongoing challenge for water treatment membrane processes. Reducing biofilm growth on the membrane surface or on the polymeric feed spacer will reduce operation, maintenance, and module replacement costs. Laser-induced graphene (LIG) is a low cost, environmentally friendly, electrically conductive carbon material shown to have antibiofouling properties. Here it has been shown that an electrically conductive LIG-coated polypropylene (PP) feed spacer has both antimicrobial and antifouling effects under a low electrical current, and when implemented into a spiral wound membrane module reduced biofilm growth on both the membrane and the spacer components. The antibacterial property of the LIG spacer is tested using Pseudomonas aeruginosa and the brackish water Rheinheimera sp. as model organisms. Using a voltage of 12 V, P. aeruginosa is completely inactivated in 10 h, while a dynamic accumulation assay employing Rheinheimera sp. showed significant reduction (p < 0.05) in bacterial adhesion compared to an uncoated spacer. The spacer is incorporated into a spiral wound reverse osmosis (RO) membrane module, and reduced biofouling is observed on both the membrane and LIG spacers components using brackish water and 12 V. This study demonstrates the feasibility of electrically conductive feed spacer components in spiral wound RO membrane modules.