Upgrading of existing trickling filter plants for denitrification

Abstract

New European Union Guidelines ask for nutrient removal. For trickling filters it was necessary to develop new design criteria for denitrification. The paper presents the results of half-scaled and full-scaled experiments with activated sludge systems, fixed bed reactors prepositioned and postpositioned. Further results out of literature are added. Possible design criteria are shown. It is emphasized that some trickling filters show simultanous nitrogen elimination of up to 80 %.