Abstract: As a new type of environmental treatment technology, supercritical water oxidation technology shows unique advantages in the field of hazardous waste disposal. The technology relies on the abnormal physical and chemical properties of supercritical water (reaction temperature more than 374 ℃, reaction pressure more than 22.1 MPa), whose physical properties such as density, viscosity, diffusion coefficient, hydrogen bonding and solubility are significantly altered compared to the normal aqueous phase, and exhibit dissolution characteristics similar to those of non-polar solvents. Research shows that this special medium not only has complete solubility for hydrocarbon organics, but also achieves efficient miscibility of gaseous oxidants, thus constructing a homogeneous reaction system, effectively eliminating the mass transfer limitations in the traditional multiphase reaction, and enabling rapid reaction between organic pollutants and oxidant molecules. Laundry wastewater generated in the special operating environment of the nuclear power industry is characterised by low radionuclide concentration and high surfactant content, which makes it the main component of liquid effluent from nuclear facilities. Although the radioactivity of laundry wastewater is at an exempt level, the persistent contamination characteristics of anionic surfactants in wastewater pose a potential threat to the ecology of water bodies. Sodium nitrate is a common contaminant in industrial wastewater. In this paper, ammonium dodecylbenzenesulfonate (ADBS) was selected as the research object, and by constructing a supercritical water oxidation reaction system and adopting sodium nitrate as the oxidising medium, the effects of process parameters such as temperature parameters (250-500 ℃), pressure (16.5-24.5 MPa), residence time (35-76 s) and peroxide multiplicity of the oxidising agent (1.0-2.0) on the removal of the organic matter were systematically investigated to achieve the purpose of waste to waste treatment. The experiments were carried out by univariate analysis and combined with a porous nickel foam reactor for system optimisation. The results show that the three-dimensional porous structure of the reaction system significantly improves the removal rate of ADBS by about 10% compared with the non-reactive core filling system, and the activation temperature reduces to 400 ℃ at the same time. The surface oxidation of nickel foam in supercritical environment is found to form a Ni/NiO heterogeneous interface structure by XRD and XPS characterization. The metal matrix in this interface enhances the electron conduction ability, and the Ni²⁺ active sites on the NiO surface can specifically adsorb oxygen-containing functional groups (C=O, C-O), effectively weakening the C-H/C-C chemical bonds in organic molecules. The multi-stage pore structure of the reactor can significantly shorten the diffusion path of substances, and combined with the low viscosity of supercritical water, it realizes efficient mass transfer of reactants. Mechanistic analyses show that Ni/NiO system accelerates the oxidation reaction by promoting the generation of hydroxyl radicals, and the porous structures provide favourable conditions for the exposure of active sites. This study provides a theoretical basis and technical reference for the treatment of surfactant-based pollutants, and confirms the key role of the foam nickel reaction core in the SCWO process.