For　efficient　energy　consumption　and　control　of　effluent　quality,　the　cycle　duration　for　a　sequencing　batch　reactor　(SBR)　needs　to　be　adjusted　by　real-time　control　according　to　the　characteristics　and　loading　of　waste-water.　In　this　study,　an　on-line　information　system　for　phosphorus　removal　processes　was　established.　Based　on　the　analysis　for　four　systems　with　different　ecological　community　structures　and　two　operation　modes　anaerobic-aerobic　process　and　anaerobic-anaerobic　process,　the　characteristic　patterns　of　oxidation-reduction　potential　(ORP)　and　pH　were　related　to　phosphorous　dynamics　in　the　anaerobic,　anoxic　and　aerobic　phases,　for　determination　of　the　end　of　phosphorous　removal.　In　the　operation　mode　of　anaerobic-aerobic　process,　the　pH　profile　in　the　anaerobic　phase　was　used　to　estimate　the　relative　amount　of　phosphorous　accumulating　organisms　(PAOs)　and　glycogen　accumulating　organisms　(GAOs),　which　is　beneficial　to　early　detection　of　ecology　community　shifts.　The　on-line　sensor　values　of　pH　and　ORP　may　be　used　as　the　parameters　to　adjust　the　duration　for　phosphorous　removal　and　community　shifts　to　cope　with　influent　variations　and　maintain　appropriate　operation　conditions.