Nitrate Reduction in Acidogenic Reactor: Influence of Wastewater COD/N-NO3 Ratio on Denitrification and Acidogenic Activity

The denitrification and acidogenic potentials of a laboratory scale continuous stirred anaerobic reactor have been investigated. The reactor was fed with synthetic wastewater containing nitrate and glucose as carbon source. Under fixed conditions of chemical oxygen demand (COD) and hydraulic retention time (HRT), and under varied input nitrate concentration, volatile fatty acid (VFA) production without denitrification occurred at COD/N-NO3 ratios > 220; denitrification and VFA production at 88.5 ≤ COD/N-NO3 ratios ≤ 220 and denitrification and smallest VFA rates at COD/N-NO3 ratios < 44.3. At COD/N-NO3 ratios > 130, nitrate assimilation appeared to be the main nitrate reduction pathway. Lowest concentrations of VFA in outlet are obtained at COD/N-NO3 ratios < 20.