Biological, photo-Fenton (PF) and photo-Fenton mediated by ferrioxalate complexes (PF/Ferrioxalate) processes were examined for the degradation of a synthetic cotton-textile dyeing wastewater. Aerobic biological treatment had a negligible effect on discolouration whereas total organic content decreased mainly due to the biodegradation of acetic acid initially present in the wastewater. PF process yielded a fast and pronounced dissolved organic carbon concentration decay, mostly associated to the abrupt precipitation of Fe(III)-organic complexes. The addition of oxalic acid limited iron precipitation, allowing mineralization of most organic contaminants. The influence of the different dyes and main dyeing auxiliary constituents of the synthetic textile wastewater on the PF and the PF/Ferrioxalate efficiency was systematically analysed. The suitability of combining PF/Ferrioxalate with conventional biological processes as a pre and/or post treatment was evaluated.This study highlights the potential of PF/Ferrioxalate reaction to mineralize the synthetic cotton-textile wastewater under appropriate experimental conditions, the best being: [Fe3+]=40mgL-1, iron/oxalate molar ratio=1:3, pH=4.0 and [H2O2]=50-100 (1.5-2.9)mgL-1 (mmolL-1). At these conditions, the PF/Ferrioxalate treatment was carried out under natural sunlight in a pilot plant equipped with compound parabolic collectors.Fil: Doumic, Lucila Inés. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Mar del Plata. Instituto de Investigaciones en Ciencia y Tecnología de Materiales. Universidad Nacional de Mar del Plata. Facultad de Ingeniería. Instituto de Investigaciones en Ciencia y Tecnología de Materiales; Argentina. Universidad de Porto; Portugal. Universidad de Buenos Aires. Facultad de Ciencias Exactas y Naturales. Departamento de Industrias; ArgentinaFil: Soares, Petrick A.. Universidad de Porto; PortugalFil: Ayude, María Alejandra. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Mar del Plata. Instituto de Investigaciones en Ciencia y Tecnología de Materiales. Universidad Nacional de Mar del Plata. Facultad de Ingeniería. Instituto de Investigaciones en Ciencia y Tecnología de Materiales; ArgentinaFil: Cassanello Fernandez, Miryam Celeste. Universidad de Buenos Aires. Facultad de Ciencias Exactas y Naturales. Departamento de Industrias; ArgentinaFil: Boaventura, Rui A.R.. Universidad de Porto; PortugalFil: Vilar, Vítor J.P.. Universidad de Porto; Portugal