Effect of media heights on the performance of biological aerated filter

The optimum media height of carbon oxidation and nitrification in a down-flow biological aerated filter was determined, and the distribution of the heterotrophic and nitrifying populations through studying the changes of organic carbon contents and ammonia concentration at different media height was got. The results showed that as a down flow BAF with granular media, the active layer of nitrifiers was deeper than heterotrophs in BAF. And the optimum media height for the removal of SS, COD(Cr) and NH4+ -N was 40 cm, 60 cm and 80 cm respectively. The removal efficiency of SS, COD(Cr), and NH4+ -N was 79.1%, 63.9% and 96.4% respectively under the influent COD(Cr), and NH4+ -N of 122.1 mgCOD(Cr)/L and 14.84 mgNH4+ -N/L, the influent flux of 15.8 L/h, air to liquid ratio of 3:1.