Recently,　the　combination　of　anammox　and　post　heterotrophic　partial　denitrification　(nitrate　to　nitrite)　was　increasingly　popular　to　treat　anammox　effluent　with　excessive　nitrate,　whereas　achieving　nitrite　accumulation　stably　was　a　major　bottleneck　for　post-denitrification.　This　work　focused　on　the　performance　of　heterotrophic　partial　denitrification　under　acetate　feast-famine　condition.　The　results　showed　that　readily　biodegradable　COD　to　nitrate　(RBCOD/NO3-)　ratio　of　2.5　facilitated　an　ideal　nitrite　accumulation　ratio　(NAR)　of　71.7%　under　complete　nitrate　reduction.　When　RBCOD/NO3-　ratio　was　below　3.5,　in　terms　of　efficiency　and　nitrite　accumulation,　higher　NAR　obtained　during　exogenous　denitrification　identified　that　the　external　acetate　depletion　was　the　optimal　ending　point　of　denitrification,　which　could　be　indicated　by　pH　accurately.　The　indication　of　pH　realized　NAR　of　60%　ideally　under　batch-flow　mode　with　RBCOD/NO3-　ratio　of　2.7,　which　might　promote　the　scale-up　of　partial　denitrification.　Furthemore,　alkaline　environment　(pH　9.0-9.6)　repressed　N2O　emission　even　during　endogenous　denitrification.　(C)　2012　Elsevier　Ltd.　All　rights　reserved.