High resolution GC - MS analysis of VOCs in wastewater and sludge

Abstract

High resolution gas chromatography - mass spectrometry (GC-MS) has been widely used in the field of environmental sample analysis for volatile organic compounds (VOCs). Such a technique was applied to the analysis of VOCs at a local municipal wastewater treatment plant. The combination of purge and trap sample preparation and thermal desorption with cryofocusing technology, allows for the detection of a wide range of volatiles in wastewater and sludge samples. Results show that a large variety of organics present in samples are aliphatic and aromatic hydrocarbons. Their concentrations are in part per billion levels between 10 to 150 μg/L. Others identified using this method are chlorinated hydrocarbons, sulfides and organic acids. By comparing the chromatograms of different wastewater and sludge samples collected from various treatment process units, it can be seen that most volatiles were removed or degraded after the aeration or digestion process. Information that provides an insight to the measurement of organic compounds in sludges is also discussed in this paper.