With climate change, population growth and water scarcity, there is a growing demand to manage water resources in a sustainable approach. Recently, ozonation followed with biologically active filtration (BAF) drew interests due to their synergistic effects at reduced operating cost in terms of performance, media replacement, and ozone dosage. To investigate these operating parameters of the combined ozonation and BAF process for guiding future process design, a comprehensive pilot study was planned and started in January 2014, the process of which included an ozone contactor, and biological active filters at Hammarby Sjöstadsverk Wastewater Treatment Plant, Stockholm, Sweden. Anthracite and granular activated carbon (GAC) produced similar results in terms of COD and ammonia removal, achieving approximately 50% COD removal and reducing ammonia nitrogen to less than 0.2 mg/L. Ozone plays an important role in oxidizing micropollutants. GAC showed additional polishing effect for residual micropollutants while anthracite showed little removal.