The　Anaerobic-Anoxic/Nitrification　(A(2)N)　system　is　a　continuous-flow,　two-sludge　process　in　which　Poly-P　bacteria　are　capable　of　taking　up　phosphate　under　anoxic　conditions　using　nitrate　as　an　electron　acceptor.　The　process　is　very　efficient　because　it　maximizes　the　utilization　of　organic　substrate　for　phosphorus　and　nitrogen　removal.　An　experimental　lab-scale　A2N　system　fed　with　domestic　sewage　was　tested　over　a　period　of　260　days.　The　purpose　of　the　experiment　was　to　examine　phosphorus　removal　capacity　of　a　modified　A2N　two-sludge　system.　Factors　affecting　phosphorus　and　nitrogen　removal　by　the　A2N　system　were　investigated.　These　factors　were　the　influent　COD/TN　ratio,　Sludge　Retention　Time　(SRT),　Bypass　Sludge　Flow　rate　(BSF)　and　Return　Sludge　Flow　rate　(RSF).　Results　indicated　that　optimum　conditions　for　phosphorus　and　nitrogen　removal　were　the　influent　COD/TN　ratio　around　6.49,　the　SRT　of　14　days,　and　the　BSF　and　RSF　were　fixed　at　about　26-33%　of　influent　flow　rate.