Abstract
ABSTRACT For real-time monitoring of VOCs in wastewater discharged from high-tech industries, an automatic sampling device, process sampling module (PSM) connected with PT-GC-FID system was developed. The system was designed to simultaneously monitor 17 compounds, including one polar compound, acetone, and 16 non-polar compounds, such as benzene, toluene, chloroform, etc. The trapping tube designed is 20 cm in length and 1/8” in O.D, and was packed with two adsorbents, carbopackB and carbosieve III, to trap the target compounds. For the purpose of in-situ monitoring, the flush of sampling tube composed of two two-way valves and one time controller to prevent the absorption interference of the residual. The optimum condition for the analytical system was 12min of purge time at 60℃ (purge temperature) and 4min of desorption time at 260℃ (desorption temperature). Good chromatograms were obtained with the developed analytical system even if cryogenic device and de-mist process were not used. The precision was high (RSD 1.99%~13.35%) and the accuracy was achieved at the level between 0.27% to 23.54%. The method detection limits ranged from 0.32 to 2.39 ppb. Variations of the VOCs concentration in wastewater discharged from high-tech industries were obtained and recorded from two times three day sampling campaign during 2004/05/26 to 2004/05/28 and 2004/06/15 to 2004/06/17.