The objective of this study was to evaluate the transition to biological filtration, determine optimal filter shutdown duration (at pilot-scale), and subsequently identify appropriate operating parameters for full-scale trials. Results of this study will be used to characterize the impact of biofilter shutdown on biomass characteristics and identify an operating strategy that will improve treated water quality while reducing overall treatment costs. This research provides insight regarding the operation of biologically active filters as well as operating information for future increases in demand. Research Partner: Eugene Water & Electric Board. Published in 2022.