Effective nitrogen control is required to safeguard the quality of receiving waters in sensitive zones. There are a number of process alternatives, but the most widely used is the suspended growth system having anoxic and aerobic reactors for nitrification and denitrification. Design of such systems is quite complicated because of severe fluctuations in wastewater quantity and quality. Kinetic evaluation of the denitrification process reveals a number of useful relationships between significant parameters such as denitrification efficiency factor, COD/TKN ratio, V-D/V ratio. Design for nitrogen removal can be optimized by taking into account wastewater characterization and basic kinetic relationships. (C) 1996 IAWQ. Published by Elsevier Science id.