Ozone-biologically active filtration (ozone-BAF) is gaining momentum in potable reuse applications. However, few wastewater facilities currently utilize ozone-BAF, resulting in limited knowledge associated with this treatment technology. This project will develop a better understanding of the transformation from granular activated carbon (GAC) to biologically activated carbon (BAC) filtration, and evaluate media-seeding strategies to minimize acclimation period, optimize biofilter performance, and improve treated water quality. Data collected during this project will provide valuable insight and guidance to utilities on adopting biological filtration systems to address issues with filter performance and the impact on water quality during the transition period from GAC to BAC. Research partner: Gwinnett County.