In this study, the effectiveness of an industrial byproduct that contained ethylene and propylene glycols to serve as a denitrification carbon source was investigated. Use of the byproduct was compared to methanol on the basis of denitrification rate and yield. Three sequencing batch reactors (SBR) were studied; one was fed methanol, the other two were fed with low and high dosages of the byproduct separately. The low dosage reactor (GLYL) exhibited the highest denitrification rate of 11.55 mg NOx-N/g MLVSS•h and the lowest yield of 0.21 mg VSS/mg COD, while the high dosage reactor (GLYH) had the lowest denitrification rate of 8.56 mg NOx-N/g MLVSS•h and the highest yield of 0.55 mg VSS/mg COD. The results of this study showed that the industrial byproduct can be used to effect efficient nitrogen removal, but excess dosage can cause poor performance.