Denitrification characteristics of reject water in upflow biofiltration

Abstract Two types of bench-scale experiments using upflow biofilm reactors packed with granular floating polystyrene (GFP) or polyurethane foam cubes (PFC), were used to investigate the denitrification of reject water. A high denitrification rate was achieved in both upflow biofilm reactors since the highly concentrated volatile fatty acids in reject water served as effective hydrogen donors for denitrification. Of the two biofiltrations, the denitrification rate using GFP was 3.5 kg −1 N m −3 per day, and higher than that using PFC. The amount of total attached biomass and solid capture capacity were also greater in GFP than in PFC. Moreover, the backwashing of the GFP packed column was optimized with air and water agitation. Of the processes investigated in this study, upflow biofiltration using GFP was the most acceptable process for reject water treatment based on treatability and operation.