Nitrification of high strength ammonium wastewater in an aerated submergedfixed bed

The submerged fixed bed offers several advantages for the nitrification pro cess because of its high stability, its compactness, the high applicable vo lumetric loadings and the very good distribution of the wastewater on the w hole biofilm in the reactor. The objectives of this study were to evaluate the performances of this process and the optimal C:N (organic carbon:ammoni um-nitrogen) ratio for the treatment of high strength ammonium wastewaters (0.2 to 5 kg NH4(+)N.m(-3)), The experiments had been performed with a labo ratory-scale aerated submerged fixed bed, fed by a synthetic substrate (loa ding rates (Bv) = 0.1 to 2.6 lag NH4+-N.m(-3).d(-1)). It was found that the best ammonium reduction (72%) is obtained for a C:N ratio of 1.7 (inlet co ncentration = 4 kg NH4+-N.m(-3), B-v = 1.9 kg NH4+-N.m(-3).d(-1)), The COD (Chemical Oxygen Demand) reduction was very good whatever the applied volum etric loading. The nitrification process was stopped when ammonium-N concen tration exceeded 5 5 kg.m(-3) (Bv = 2.6 kg NH4+-N.m(-3).d(-1)).