Abstract:PHBV (poly-3-hydroxybutyrate-co-3-hydroxyvalerate) as a biodegradable polymer was used as carbon source and biofilm carrier to remove nitrate in water. A short start-up period was observed and nitrate-nitrogen (NO3--N) removal rates were greater than 93%. With a decrease of HRT from 1h to 0.5h, denitrification changed remarkably. The denitrification system was however found to be resistant to the shock load of influent NO3--N. The concentrations of effluent DOC (Dissolved Organic Carbon) were lower than 27.5mg/L, indicating that controlled carbonrelease was applicable to PHBV. Nitrate removal rates varied significantly with reactor height while the highest was obtained at the middle height layer (10~15cm).