Nitrite accumulation under constant temperature in anoxic denitrification process: The effects of carbon sources and COD/NO3-N

► The most nitrite accumulation occurred with glucose through denitrification. ► Higher COD/NO3-N ratios resulted in greater accumulation of nitrite. ► Competition for electrons between nitrite and nitrate reductase led to different reduction rates. ► pH and ORP validly regulate addition of carbon source without nitrite accumulation.