Denitrification of wastewater in a fixed film reactor

Denitrification of high nitrate containing synthetic wastewater was tested in a bench-scale upflow fixed bed filter. Molasses was used as carbon source. Maximum denitrification rates were achieved at COD/NO3-N ratios about 5-6 independent of hydraulic loading rate and influent NO3-N concentrations. Nitrate and COD surface removal rates increased with increasing surface and hydraulic loading. Results suggested that the quantity of COD used for nitrate removal is independent of the loading rate up to a certain limit. Nitrate removal efficiencies varied in the range of 71-99% depending on the operating conditions. Denitrification followed half-order kinetics. Calculated half order reaction rate constants were in the range of 0.013-0.034 g(1/2) m(-1/2)hr(-1).