The　recovery　of　vivianite　through　the　anaerobic　digestion　of　waste-activated　sludge　has　attracted　considerable　attention　due　to　its　operational　simplicity　and　the　high　economic　value　of　vivianite.　This　study　concentrated　on　the　recovery　of　vivianite　from　anaerobic　fermentation　systems　through　a　strategy　combining　sludge　pre-　fermentation　with　the　waste　agricultural　and　forestry　biomass-derived　biochar　(ZBC).　In-depth　analyses　of　the　structure　and　functionality　of　ZBC　were　conducted　using　techniques　such　as　Fourier-transform　infrared　spectroscopy　(FTIR),　X-ray　photoelectron　spectroscopy　(XPS),　and　Raman　spectroscopy.　The　sediment　produced　after　the　experiment　and　the　changes　in　microbial　community　composition　were　characterized.　The　results　indicated　that　pre-fermentation　promoted　phosphorus　release,　enhancing　the　synthesis　of　vivianite　while　selectively　enriching　respiratory　and　fermentative　Fe　(III)-reducing　microorganisms.　When　FeOOH　was　used　as　the　Fe　(III)　source,　ZBC,　through　its　dual　action　of　redox　functional　groups　and　graphitization　structure,　increased　the　Fe2+　production　by　243.6　%　in　the　system　dominated　by　respiratory　Fe　(III)-reducing　bacteria.　The　optimal　dosage　of　ZBC　for　the　simultaneous　recovery　of　vivianite　resources　and　methane　energy　was　2.5　g/L.　The　combined　application　of　pre-fermentation　and　ZBC　provides　a　novel　approach　for　the　efficient　recycling　of　vivianite　and　offers　new　insights　into　the　reuse　of　agroforestry　waste　biomass　resources.