The　in–situ　recycling　technique　offers　a　promising　solution　for　the　efficient　management　of　the　escalating　volumes　of　waste　muck　or　slurry　generated　during　shield　tunneling.　While　foam　is　extensively　utilized　for　soil　conditioning　in　earth　pressure　balance　(EPB)　tunneling,　the　effects　of　organic　and　inorganic　flocculants　on　the　in–situ　recycling　potential　of　waste　EPB　shield　muck　containing　residual　foams　remain　underexplored.　To　bridge　this　gap,　laboratory　experiments　were　conducted　using　four　flocculants:　cationic　polyacrylamide　(CPAM),　nonionic　polyacrylamide　(NPAM),　anionic　polyacrylamide　(APAM),　and　polyaluminum　chloride　(PACL),　with　an　enhanced　flocculation　and　press–filtration　apparatus.　The　defoaming–flocculation–dewatering　behavior　of　waste　EPB　shield　muck　was　systematically　investigated　by　evaluating　key　parameters,　including　residual　foam　height,　defoaming　ratio,　antifoaming　ratio,　total　suspended　solids,　turbidity,　moisture　content,　and　zeta　potential,　while　accounting　for　both　muck　dry　mass　and　fines　content.　Moreover,　the　microscopic　structure　of　flocculates　and　filter　cakes　was　characterized　using　nanoparticle　size　analysis　and　scanning　electron　microscopy.　The　experimental　results　reveal　that　CPAM　exhibits　constrained　flocculation　and　dewatering　efficiency,　primarily　attributed　to　diminished　charge　neutralization　resulting　from　residual　anionic　surfactants.　In　contrast,　PACL　demonstrates　superior　dewatering　performance　compared　to　NPAM　and　APAM,　but　exhibits　the　lowest　flocculation　and　foam–suppression　efficiency.　Additionally,　a　consistent　linear　negative　correlation　is　identified　between　the　flocculation　and　dewatering　indices　of　EPB　shield　muck,　independent　of　the　flocculant　type,　whether　organic　or　inorganic.　©　2025　Japanese　Geotechnical　Society