Use of a residue containing chromium(VI) for dye decomposition using an advanced oxidative process

•Chromium(III) oxide was recovered from an organic matter analysis residue.•Recovered chromium(III) oxide used as a photocatalyst for Advanced oxidation processes (AOPs) to degrading dyes in effluents.•The recovered Cr2O3 showed high catalytic activity compared to the other processes for Dye-discoloration and dye-degradation.•This approach minimizes the costs of dye treatment via AOPs by reducing the expenses associated with the addition of reagents.