Kinetic interpretation of nitrogen removal in pilot scale experiments

Pilot plant experiments have been performed over a period of four years in order to establish an experimental basis for the upgrading of the treatment plants of The City of Copenhagen to nutrient removal. The choice of design is the alternating mode of operating biological nitrogen removal with biological and chemical phosphorus removal. Nitrification and denitrification rates have been measured in batch tests on activated sludge extracted from the pilot plants and by measuring transient concentrations during the alternating mode of operation in the aerobic and anoxic tanks. The data were normalized to standard conditions by correcting them according to the kinetic theory. The average normalized nitrification rate was measured to be between 54 and 60 mg NH+4-N/(g VSSnit•h) by different test methods at 7°C. The denitrification rate was measured to vary between 0.85 and 0.95 mg NO−3-N/(g VSS•h) at 7°C, depending on the carbon source availability.