The　laboratory　scale　anaerobic-anoxic　-aerobic　(A(2)O)　process　fed　with　synthetic　brewage　wastewater　was　designed　to　investigate　the　effects　of　changing　feed　C/P　ratio　on　the　performance　of　biological　nutrient　removal　(BNR)　processes.　In　the　experiment,　the　influent　chemical　oxygen　demand　(COD)　concentration　was　kept　at　approximately　300　mgL(-1)　while　the　total　phosphorus　concentration　was　varied　to　obtain　the　desired　C/P　ratio.　Results　showed　that　when　the　C/P　ratio　was　lower　than　32,　phosphorus　removal　efficiency　increased　as　C/P　ratio　increased　linearly,　while　when　the　C/P　ratio　was　higher　than　32,　the　P　removal　efficiency　was　maintained　at　90-98%,　and　effluent　P　concentration　was　lower　than　0.5　mg　L-1.　However,　regardless　of　the　C/P　ratio,　excellent　COD　removal　(90%　or　higher)　and　good　total　nitrogen　removal　(75-84%)　were　maintained　throughout　the　experiments.　It　was　also　found　that　very　good　linear　correlation　was　obtained　between　COD　uptake　per　unit　P　released　in　the　anaerobic　zone　and　C/P　ratio.　In　addition,　the　P　content　in　the　wasted　activated　sludge　increased　with　the　decrease　in　the　C/P　ratio.　Based　on　the　results,　it　was　recommended　that　the　wastewater　C/P　ratio　and　its　effects　be　incorporated　into　BNR　design　and　operational　procedures,　appropriate　C/P　ratios　were　used　to　achieve　the　effluent　treatment　goals.　(c)　2005　Society　of　Chemical　Industry.