###### Abstract  
This study presents an analysis of the effectiveness of the removal of three dyes, Indigo Carmine, Tartrazine, and Allura Red AC, using advanced oxidation methods. The research showed low efficiency in removing these dyes using acoustic waves. Neither the addition of hydrogen peroxide to assist the process nor increasing the intensity of the acoustic waves improved the degradation of the analyzed dyes. However, when ozone was applied, a 91% removal efficiency of Indigo Carmine was achieved after 30 min, while the other two dyes were resistant to degradation by ozone. The introduction of an additional amount of oxidant in the form of hydrogen peroxide and waste catalyst (steel shavings) resulted in an increased efficiency of removing all dyes and a shortening of the degradation process time. Ultraviolet radiation in the presence of a TiO\({}_{2}\) catalyst was also effective only for Indigo Carmine. After 30 min, the removal efficiency of this dye reached 95%. It was also demonstrated that the catalyst dose affected the rate constant of the reaction. Kinetic studies revealed that the degradation of Indigo Carmine in an aqueous solution through advanced oxidation processes followed the first-order reaction kinetics. Energy demand calculations confirmed that the most effective Indigo Carmine removal process is the one using ozone with the addition of a catalyst and an oxidizer at pH = 3.  
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hand, Tartrazine is an artificial dye that imparts a yellow-orange color to products. Its acceptable daily intake (ADI) is set at 10 mg/kg of body weight. Tartrazine is commonly used in confectionery and beverages but may cause hyperactivity in children and allergic reactions, such as hives and asthma. Similarly, Allura Red AC is used to produce a red color in selected products. From a chemical perspective, it is an azo compound containing nitrogen atoms linked by a characteristic azo bond (-N=N-). Allura Red AC instead of Tartrazine can cause typical allergic reactions, such as hives, shortness of breath, and redness of the skin [1; 2; 3; 4]. The presence of dyes in aqueous solutions is considered problematic as a result of the formation of by-products that are toxic to aquatic life and carcinogenic to humans. Advanced oxidation processes (AOPs) offer a promising solution due to their ability to completely degrade pollutants in a short reaction time. AOPs are based on the in situ generation of highly potent oxidizing agents, such as hydroxyl radicals, which are exceptionally effective in removing persistent organic compounds from aqueous solutions. Commonly used AOP techniques include ultraviolet (UV) light, ultrasound, ozone, Fenton's reagent, or semiconductor surfaces. During ozonation, dyes lose their color as a result of the oxidative degradation of chromophores [5; 6; 7]. The popularity of ozone applications has significantly increased in recent years, mainly due to two factors: (i) a substantial reduction in ozone production costs over the past decade and (ii) the environmental benefits it offers compared to chlorine. Ozonation is an effective method for treating wastewater containing organic metals in complex form. Due to the instability of ozone, its generation must take place on-site. Ozonation has long been used as an oxidant and disinfectant in water treatment. As an oxidant, ozone is highly selective and primarily reacts with electron-rich functional groups, such as double bonds, amines, and activated aromatic rings. In real aqueous solutions, the reactions of ozone often lead to the formation of the -OH radical, which is why ozonation is often considered an AOP or AOP-like process. Ozone reacts with organic compounds either directly through an electrophilic attack or indirectly through chain radical reactions, depending on the pH of the process.