An anoxic packed-bed biological and chemical system for removing nitrates/perchlorate from water includes a vessel having a distribution plate that partitions the vessel into a lower influent-receiving chamber and an upper biological and chemical denitrification chamber. A granular media is supported by the distribution plate to provide a packed bed that has sites for biological growth. A recycle system recycles partially treated water into the closed lower end of the vessel for upflow through the distribution plate.