Developing　eco-friendly,　economical,　and　efficient　catalytic　systems　for　pollutant　removal　has　become　an　imperative　orientation　in　water　treatment.　Conversion　of　municipal　sludge　into　multifunctional　biochar　has　been　considered　as　a　feasible　strategy　for　dual　applicability　in　water　treatment　and　sludge　management.　Herein,　municipal　biological　and　ferric　sludge　were　recycled　to　synthesize　an　iron-based　biochar　(Fe4SBC1-800)　with　great　magnetic　separation　performance　(Ms　=　29.96　emu　g−1).　The　mixed　sludge-derived　biochar　(Fe4SBC1-800)　engaged　as　an　efficient　catalyst　of　peroxymonosulfate　(PMS),　which　efficiently　promoted　the　pollutants　elimination　including　typical　azo　dye　and　several　antibiotics　and　anti-inflammatory　drugs.　The　enhanced　degradation　performance　primarily　originated　from　the　formation　of　reactive　radicals　and　non-radical　species.　The　respective　and　synergetic　mechanisms　of　biochar　and　supported　iron　species　on　PMS　activation　were　verified　based　on　experimental　results　and　theoretical　computations.　The　carboxyl　groups　served　as　the　major　active　sites　of　biochar　that　donated　electrons　to　PMS　for　•OH　and　SO4•−　formation.　The　supported　FeO　species　further　boosted　the　activation　capability:　(i)　the　enhanced　formation　of　radicals　and　FeIV　=　O　via　heterogeneous　Fenton-like　reactions;　(ii)　the　promoted　oxygen　reduction　for　O2•−　formation　by　promoting　electron　transfer　from　PMS　to　the　FeO　species　through　high　sp2-hybridized　biochar.　Overall,　this　study　innovatively　proposed　a　sustainable　and　efficient　activation　system　for　PMS　by　iron-based　magnetic　biochar,　which　systematically　probed　the　activation　mechanism　and　reconsidered　the　role　of　the　supported　iron　species　in　the　iron-based　biochar/PMS　system.　©　2024　Elsevier　B.V.