[en] The photolysis (λ=254 nm) of aqueous EDTA, NTA and DBS in the presence of oxygen, ozone and TiO₂ individually and in mixtures of them as well as by ozonation only was investigated. Very high EDTA degradation yields were obtained by the synergistic action of UV light (λ=254 nm) in the presence of ozone and TiO₂. By adding of a 2.5 mg.ml^-1 TiO₂ suspension to an aqueous solution of 1x10^-3 mol.dm^-3 EDTA and passing through 1.9 mg.dm^-3.min^-3O₃ a G_iph (-EDTA) = 12.0 and at 29.3 mg.dm^-3.min^-1O₃ a G_iph = 25.2 was obtained. Comparative studies were performed with γ-irradiation under similar conditions. A somewhat higher yield of EDTA degradation, G_i(-EDTA) = 13.5 was observed upon γ-radiolysis of 1x10^-3 mol.dm^-3 EDTA in the presence of 1.9 mg.dm^-3.min^-1O₃ and 2.5 mg.ml^-1 TiO₂. In both cases the EDTA degradation depended on the absorbed radiation dose (UV-light or γ-rays), on the O₃-concentration, and on the amount of suspended TiO₂. By increasing the O₃ concentration also the degradation yield was strongly increased. Analysis of products resulting from photolysis and radiolytic of EDTA, NTA and DBS in the presence of oxygen, performed by the GC/MS-method are also reported. Pulse Radiolysis and chemical analysis of DBS in aqueous solution were performed and the results are presented. Economic considerations concerning the pollutant degradation by combined photochemical methods in comparison to ionizing radiation under similar conditions of EDTA, NTA and DBS have been made. (author)