A sludge-derived heterogeneous catalyst (Fe-SDBC) was prepared by using sludge-derived biochar (SDBC) -loaded with iron. Fe-SDBC was used to activate persulfate (PS) for orange G degradation (OG). The Fe-SDBC/PS system showed an excellent performance for the degradation of OG. The effects of several key parameters (metal oxides-biochar ratio, Fe-SDBC dosage, initial pH value, PS concentration) on the degradation process were systematically evaluated. Subsequently, Fe-SDBC was characterized by X-ray fluorescence spectrometer (XRF), Fourier transform infrared (FT-IR) and Raman spectroscopy (Raman). The radical scavenger experiments suggested that Both SO₄^·- and OH·contributed to the degradation process and the radicals were mainly generated through heterogeneous mechanism. The mechanism of the Fe-SDBC/PS system was investigated. Apparently, different forms of iron were the main contributors to PS decomposition, and the circulation of Fe²⁺/Fe³⁺ increase the effectiveness of the catalyst to activate the PS. Eventually, recycle tests showed that Fe-SDBC had excellent reusability in activating PS for OG removal. It could still play a role in the degradation of high concentration OG for three successive 24h degradation cycles. In summary, Fe-SDBC was capable of perpetually activating PS and achieved satisfactory OG degradation efficiency