The oxidation of the organic substrate present in wastewaters generated in wine distilleries ("wine vinasses") is studied by both an ozonation process and by an aerobic activated sludge system. The ozonation process is conducted in a subsequent first discontinuous and a second continuous periods. Values are reported of the organic matter removal, measured as chemical oxygen demand (COD) (5-25.2%) and as total aromatic compounds content (16.8-51.4%). The influences of the inlet ozone partial pressure, the hydraulic retention time in the reactor and the presence of UV radiation and H2O2 in addition to ozone are established. Approximate kinetic studies are conducted for both periods which lead to the evaluation of the apparent rate constants for the substrate decomposition 216 l/(mol O-3 h) and 232 l/(g COD h), respectively. In the aerobic degradation by the activated sludge system, the evolution of the organic substrate and biomass are followed during both the discontinuous and continuous stages of the whole process, and COD removals from 31 to 85% are obtained for a hydraulic retention time between 24 and 72 h. For the first stage, a kinetic study is performed by using the Contois model, which applied to the experimental data provides the specific kinetic parameters: q(max) = 0.190 g COD/(g volatile suspended solids (VSS) h) and K-1 = 6.48 g COD/gVSS. For the continuous period, the kinetic study carried out provides the specific rate constant for the substrate decomposition, q = 0.027 g COD/(g VSS h). (C) 2003 Elsevier B.V. All rights reserved.