The aim of this research was to determine the performance of a submerged biological aerated filter, composed of a double-layer bed. This bed is made up of a top layer of ceramic material and a bottom layer of plastic material (both from previously used waste material). Effluent concentrations are presented related to the volumetric and hydraulic loads applied. The results were very satisfactory. If effluent concentrations of under 20 mg TBOD5/L and 25 mg SS/L are to be achieved, 4.87 kg TBOD5/m3/d and 3.0 kg SS/m3/d could be applied, respectively. For that maximum TBOD5 volumetric load that can be applied, a very reasonable consumption value of 1.0 kg O2/kg TBOD5, eliminated was obtained. The counter-current flow system outperformed the co-current flow system with respect to TBOD5 and SS removal. The tests were performed at a pilot plant with full scale height. The influent used was primary effluent of a conventional treatment plant. A multivariant analysis (ANOVA) was applied to the results.