TRIAL OPERATION OF A SELECTOR AT THE NORTHPEST WASTEWATER TREATMENT PLANT

The goal of the experiments was to establish a bioreactor configuration that enables an enhanced nitrogen removal at the Northpest Wastewater Treatment Plant. At first lab-scale experiments were performed to determine the effect and size of a selector installed in the first part of the existing aeration tank. On the basis of the model experiment an anoxic selector was established in one of the trains of the full-scale plant. During the field experiment three trains were operated simultaneously, train I with the new configuration and trains II and IV without having a selector. Installation of an anoxic selector in the first part of the flow-through activated sludge basin proved to be effective both in the model experiment and consequent field studies. The reconfiguration of the system resulted in low and stable SVI values and facilitated an enhanced nitrogen removal originating from a high rate nitrification and an effective denitrification. All of the different reference systems proved to be less stable and provided relatively poor performance in sludge settling characteristics and nitrogen removal. The reconfigured system maintained its favorable results also at a 30\% increased load