The　aim　of　this　study　is　to　investigate　the　denitrification　potential　enhancement　by　addition　of　external　carbon　sources　and　to　estimate　the　denitrification　potential　for　the　predenitrification　system　using　nitrate　utilization　rate　(NUR)　batch　tests.　It　is　shown　that　the　denitrification　potential　can　be　substantially　increased　with　the　addition　of　three　external　carbon　sources,　i.e.　methanol,　ethanol,　and　acetate,　and　the　denitrification　rates　of　ethanol,　acetate,　and　methanol　reached　up　to　9.6,　12,　and　3.2　mgN/(g　VSS.h),　respectively,　while　that　of　starch　wastewater　was　only　0.74　mgN/(g　VSS.h).　By　comparison,　ethanol　was　found　to　be　the　best　external　carbon　source.　NUR　batch　tests　with　starch　wastewater　and　waste　ethanol　were　carried　out.　The　denitrification　potential　increased　from　5.6　to　16.5　mg　NO3-N/L　owing　to　waste　ethanol　addition.　By　means　of　NUR　tests,　the　wastewater　characteristics　and　kinetic　parameters　can　be　estimated,　which　are　used　to　determine　the　denitritication　potential　of　wastewater,　to　calculate　the　denitrification　potential　of　the　plant　and　to　predict　the　nitrate　effluent　quality,　as　well　as　provide　information　for　developing　carbon　dosage　control　strategy.