Effect of Soot Build-Up While Sampling with the Volatile Organic Sampling Train (VOST)

Abstract

The U.S. Environmental Protection Agency's Method 00301, the Volatile Organic Sampling Train (VOST), is used to determine the destruction and removal efficiencies of volatile organic emissions from industrial boilers co-firing hazardous waste. Previous reports detailing a hysteresis effect2,3,4 for volatile organic compounds (VOCs), resulting from soot build-up on the interior surfaces of boilers and industrial furnaces, raised concerns of possible VOST measurement biases due to soot deposits within the VOST. This possibility required laboratory investigation of the method under sooty conditions. Method collection efficiency was evaluated by comparing volatile organic compound levels collected in a control VOST (using a soot-free particulate filter in the sampling probe), to VOC recoveries while using a soot-laden particulate filter in the probe. Emphasis was directed to substances in the upper range of VOC boiling points (120 to 130° C). Statistical evaluation of the data collected indicated that recoveries for two of the higher boiling VOCs (chlorobenzene and octane) appeared to be negatively influenced by the presence of soot on the VOST filter. It is not likely, however, that these findings will have a major impact on previously collected hazardous waste incinerator data, since the VOST-Soot effect was determined at moderately high soot loadings, which are atypical of properly operating hazardous waste incinerators.