The evaluation of columnar denitrification was initiated on a small scale with the intention of applying gained information to additional denitrification studies in the 0.3 mgd (1,140 cu m/day) four-stage carbon tertiary sewage pilot plant. Since denitrification is, by itself, of significant importance, its use is not confined to carbon column operation and would be applicable to column design using media other than carbon to provide surface area. Many applications exist for denitrification that do not require the reduction of dissolved organic material to very low levels. For this reason, a parallel study using 2 in. (5.1 cm) columns was conducted to compare the nitrate removal efficiencies in both granular carbon and sand media. (Author)