Biological　nitrogen　removal　from　mature　landfill　leachate　is　ineffective　due　to　the　extremely　low　carbon/nitrogen　(C/N)　ratio.　Moreover,　a　large　amount　of　waste　activated　sludge　(WAS)　is　inevitably　generated　from　WWIPs　during　the　municipal　sewage　treatment　process.　In　this　study,　an　innovative　process　was　developed　to　enhance　nitrogen　removal　from　low　C/N　(1:1)　mature　landfill　leachate　and　to　reduce　the　WAS　during　a　300-day　operation.　Two　sequencing　batch　reactors　(SBRs)　were　involved　in　this　process.　Firstly,　the　mature　landfill　leachate　was　pumped　into　an　aerobic　reactor　to　undergo　partial　nitrification　(PN-SBR).　Then,　the　PN-SBR　effluent　and　WAS　were　pumped　into　an　anoxic　reactor　to　undergo　integrated　fermentation　and　denitritation　(IFD-SBR).　The　pH　profile　was　treated　as　a　real-time　parameter　to　pre-cisely　control　the　duration　of　the　PN　and　IFD　processes.　partial　nitrification　and　integrated　fermentation　denitritation　(PNIFD)　system　achieved　a　total　nitrogen　removel　efficiency　of　95.0%　and　an　average　nitrogen　removal　rate　(NRR)　of　0.63　kg/m(3).d　during　the　last　operational　phase.　Due　to　a　variety　of　refractory　contaminants,　the　effluent　COD　concentration　was　1865.9　mg/L　and　a　19.7%　COD　removal　efficiency　was　obtained　under　an　influent　concentration　of　2324.5　mg/L　Compared　with　the　traditional　nitrogen　removal　process,　PNIFD　not　only　decreased　requirements　for　oxygen　by　25%　and　the　external　or　ganic　carbon　by　100%,　but　also　achieved　simultaneous　reduction　of　external　WAS.　More　than　53.7%　of　the　external　sludge　was　reduced　during　the　IFD-SBR　operational　cycle,　with　an　average　external　sludge　reduction　rate　(SRR)　of　5.09　kg/m　(3).d.　Fermentation/denitritation　related　microorganisms,　such　as　Anaerolineaceae,　Acidimicrobiaceae　and　Thauera,　accounted　for　up　to　41.5%　of　the　total　abundance　in　the　IFD-SBR.　Based　on　the　long　and　stable　operation,　this　study　provides　a　simple　and　promising　approach　for　synchronous　nitrogen　removal　and　WAS　reduction.　(C)　2019　Published　by　Elsevier　Ltd.