Full Scale Experiences with Nutrient Removal at Two Wastewater Treatment Plants in The Netherlands

Two full scale projects are described in this paper; these are the Bergambacht wastewater plant (carrousel) and the Terneuzen wastewater plant (Schreiber system). Both plants use a system of intermittent aeration to combine nitrification and denitrification processes. At the Bergambacht plant biological phosphorus removal is carried out by the introduction of the side stream process. At the Terneuzen plant it is carried out by introducing anaerobic periods in the aeration tanks. The objective is to meet the new total nitrogen and phosphorus effluent standards in The Netherlands of resp. 10-15 and 1-2 mg/l. At the Terneuzen wastewater plant the standards could not be reached for total-nitrogen, mainly due to the low BOD to Kj-N ratio of 2:8 in the feed to the aeration tanks. Adjustments are suggested to improve the denitrification rate. At the Bergambacht wastewater plant effluent concentrations of 6 - 7 mg/l total N and 0.3 mg/l total P were achieved.