Denitrification in a moving bed upflow sand filter.

The denitrification performance of a moving bed upflow sand filter with methanol added as a carbon source was evaluated. Hy draulic loading rates were varied between 3.4 and 11.0 m/d and influent N02 + N03-N concentrations of up to 22 g/m3 were tested. The turnover rate of the sand bed ranged between 0.4 and 3.8 bed volumes/d. It was found that complete denitrification (effluent N02 + NO3-N < 1.0 g/m3) was obtained at daily loadings of up to 2.7 kg/m3 total equivalent nitrate nitrogen (N03-N?,). The minimum methanol dosage required for com plete denitrification was in the range of 3.3 to 3.5 g CH3OH/g N03-Neq. Methanol leakage, as evidenced by an increase of BOD5 across the filter, was negligible at dosages of 3.5 g/g NOa-Ngq or less. Res J. Water Pollut. Control Fed., 62,239 (1990).