Recently,　the　short-chain　fatty　acids　(SCFAs)　production　with　carbon　recovery　from　waste　activated　sludge　has　received　increasing　attention.　Despite　that　numerous　approaches　have　been　investigated,　the　divalent　cation　chelation　towards　enhancing　anaerobic　fermentation　and　the　carbon　migration　fates　has　been　rarely　reported.　This　work　attempted　to　chelate　structural　divalent　cations　from　sludge　flocs　by　sodium　pyrophosphate　(SP)　at　the　dosages　of　0–0.6　g/g　SS,　facilitating　sludge　disintegration　and　hydrolysis　with　particulate　organic　matters　solubilization.　At　the　optimal　SP　dosage　of　0.4　g/g　SS,　the　chemical　oxygen　demand　(COD)　and　carbon　source　content　in　sludge　solid　were　reduced　by　45.24　%　and　35.50　%　within　1-day　treatment,　leading　to　considerable　sludge　hydrolysis　and　carbon　release　performances　with　soluble　COD/total　COD　of　23.21　%　and　carbon　release　rate　of　26.94　%　in　2-day　anaerobic　fermentation,　respectively.　Numerous　SCFAs　of　237.43　mg　COD/g　VSS　were　produced　by　4-day　anaerobic　fermentation,　with　the　overall　carbon　recovery　rate　of　21.19　%,　which　were　dominantly　composed　by　acetate　and　propionate.　Meanwhile,　the　SP-inhibited　biogas　generation　also　contributed　to　SCFAs　accumulation.　The　divalent　cation　chelation　obviously　improved　rate　constant　and　equilibrium　performances　of　anaerobic　fermentation　process,　which　were　1.81–5.21　and　1.36–2.82　times　higher　than　those　without　SP,　respectively.　The　carbon　migration　pattern　was　proposed　by　interphase　carbon　source　balance　and　the　mechanism　was　also　illustrated.　The　crucial　novelty　was　to　propose　an　innovative　and　economic　sludge　hydrolysis　pattern　by　divalent　cation　chelation　towards　improving　carbon　recovery.　©　2023　Elsevier　B.V.