Currently,　there　are　well-operated　iron　removal　water　plants　in　the　northeast　region　of　China.　Among　them,　the　backwash　process　produces　a　large　amount　of　iron-containing　sludge　(IS)　year　by　year,　which　can　cause　some　harm　to　the　environment　if　not　treated.　The　main　form　of　existence　for　IS　is　amorphous　γ-FeOOH,　and　this　work　demonstrates　that　IS　is　a　natural　and　highly　active　catalyst　for　periodate(PI).　Moreover,　IS　showed　strong　stability　in　environmental　factor　effects　and　reproducibility　experiments.　EPR　with　quenching　experiments　proved　that　IS　could　activate　PI　to　produce　•OH,　O2•−,　1O2,　and　IO3•.　In　the　degradation　experiments　where　methylene　blue　was　chosen　as　the　model　pollutant,　IO3•,　and　1O2　were　the　substances　that　served　the　prominent　role　in　degradation.　This　work　provides　an　inexpensive　and　feasible　way　to　dispose　of　waste　iron-containing　sludge　from　water　plants　and　provides　fundamental　insights　into　the　degradation　mechanism　of　organic　pollutants　through　the　activation　of　PI　by　IS.　©　2024　Elsevier　Ltd