PERFORMANCE OF A 2-STAGE PLASTIC MEDIA TRICKLING FILTER IN GREECE

This paper presents the final results of a two years research programm e, which has been funded by the Commission of European Union (STEP pro gramme). The main objective was the study of sewage treatment for a wi de range of ambient temperatures, in order to produce effluents of ade quate quality to meet EU standards. Hydraulic and quality models of th e processes involved, with various types of filter media, have been pr oduced both for full scale and pilot size plants. The group from Arist otle University of Thessaloniki (A.U.T.), undertook the study of the r eduction of the organic and nitrogen loading, under the influence of t he very high sewage temperatures experienced during the prolonged summ er period. Hydraulic Loading Rate (HLR) was constant (0.40 m/h) while the Organic Loading Rate (OLR) varied between 0.35 - 0.60 kg BOD/m(3). d. Nitrogen loading rate was high with a mean period value of 150g N/m (3).d. Our pilot has shown a treatment stability at organic loading re duction. Nitrification was never stopped completely, even at the lowes t winter temperatures. Nitrogen level was within the EU standards for sensitive areas at the critical summer months, Phosphorus reduction wa s low only as result of sedimentation, therefore further treatment is required.