Moving-bed biological treatment (MBBT) of municipal wastewater: denitrification

Denitrification in a full-scale installation and a pilot plant for moving-b ed biological treatment (MBBT) was subject to detailed investigation. Two d ifferent types of carriers were used in conventional activated sludge react ors: foam cubes and plastic tubes (Kaldnes((R))). Both investigated carrier s showed the same behavior with regard to denitrification capacity, tempera ture dependency and maximum COD and nitrate turnover, In contrast to the pl astic tubes (Kaldnes((R))), the sponge cubes stored remarkable amounts of s ubstrate. The maximum denitrification rate with acetate as a substrate was 420 9(N)m(-3)d(-1) at 10 degreesC and 730 g(N)m(-3)d(-1) at 20 degreesC. An average denitrification rate of 240 g(N)m(-3)d(-1) (10 degreesC) was achie ved with wastewater. A maximum of 37% of the COD in the influent was denitr ified with a volumetric loading rate in the anoxic zone of 2.2 kg(COD)m(-3) d(-1).