A　novel　system　was　used　for　nitrogen　removal　from　reject　water.　This　system　includes　one　anoxic/oxic　reactor　for　nitrification　and　a　special　reactor　for　denitrification　in　which　primary　sludge　was　added　intermittently　as　electron　donor.　In　denitrification　reactor,　sludge　fermentation　and　denitrification　reaction　took　place　simultaneously　and　promoted　each　other.　It　was　found　that　effluent　recycle　could　improve　nitrogen　removal　efficiency　due　to　reclaiming　of　alkalinity.　Under　steady　state　conditions,　the　average　solid　retention　time　(SRT)　in　denitrification　reactor　was　12-15d,　a　total　nitrogen　loading　rate　was　0.2kgN/(m(3)　day)　and　TN　removal　efficiency　was　more　than　90%　without　extra　carbon　source　addition.　Primary　sludge　was　degraded　so　that　volatile　suspended　solid　(VSS)　decreased　by　50%.　Further　investigation　showed　that　ORP　could　be　taken　as　a　control　parameter　for　sludge　addition.