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Herein, we anchored Cu atoms with four N atoms into waste adsorbent-based biochar (SACu 30 @NC) containing both Cu(I) and Cu(II) to explore the role of different Cu valences for PDS activation mechanism. The atomic Cu was identified as the active site, and Cu(III) and electron shuttle process dominated organics degradation in SACu 30 @NC/PDS system. Therein, Cu(I) preferred to activate the adsorbed PDS to produce Cu(III) (Cu(I)N 4 -PDS→Cu(II)N 4 -SO 4 •-→Cu(III)N 4 -SO 4 2-), whereas PDS adsorbed on Cu(II) surface was more likely to extract electrons from organic pollutants directly. Benefiting from non-radical process, SACu 30 @NC exhibited selective and anti-interference performance for organic pollutants in complex matrixes. The promising catalytic activity of SACu 30 @NC (BPA=50 mg/L, 100% within 180 min) with low Cu leaching (<0.1 mg/L) in continuous-flow experiments further revealed the potential of SACu 30 @NC for practical applications. This work provides new insights into the PDS activation mechanism by single-atom Cu catalysts and develops an efficient approach for practical wastewater purification. [Display omitted] • High-performance and low-cost SACu@NC was prepared from waste biosorbent. • Cu-N4 sites were identified as the key sites in SACu@NC/PDS system. • Cu(I) in SACu@NC preferred to activate the adsorbed PDS to produce Cu(III) species. • Electron shuttle process was more possibly caused by Cu(II) in SACu@NC. • SACu@NC showed superior catalytic activity and stability in continuous-flow tests. [ABSTRACT FROM AUTHOR]