Influence of primary sedimentation on pre-denitrification system performances

The effects of suppressing primary sedimentation on nitrogen removal effici ency of a predenitrification system have been evaluated for a large municip al wastewater treatment plant. Simulations have been carried out using the STOAT model. For both the process schemes with and without primary sediment ation, nitrification efficiencies are calculated for increasing influent lo ads of COD, total N and suspended solids. The sensitivity analysis shows th at for the usual carbon to nitrogen ratios in the raw influent both the pro cess schemes allow the requested removal efficiencies, whereas for signific antly high C/N ratios the scheme with primary sedimentation is preferable.