The aim of this study was to evaluate the effects of plastic media carriers presence in the activated sludge process through the operation under different solids retention times, for the removal of carbonaceous organic matter and ammonia nitrogen, of two aerobic systems. One of them, called LAC, was constituted by activated sludge reactors with suspended biomass only and compared with another, LAI, with integrated fixed-film activated sludge reactors. The growth of attached and suspended biomass and environmental conditions in the reactors have been monitored. Respirometric analyzes were used to determine kinetic coefficients related to nitrification. It was possible to apply approximately twice the load supported by an activated sludge system, nitrification was extended until low solids retention times related to the aerobic and suspended biomass, and denitrification has occurred efficiently. The specific growth rate of nitrifying bacteria in attached biomass has resulted similar to that observed in suspended biomass
activated sludge; nitrogen removal; MBBR; IFAS
