BTEX emission inventory and modeling of impacts on air quality for The Map Ta Phut Petrochemical Complex

Abstract

The aromatic compounds benzene, toluene, ethylbenzene and xylene (BTEX), all found at the Map Ta Phut Petrochemical Complex were studied. Ambient air samples were actively collected by personal air samplers attached to charcoal adsorbent tubes during the dry (22-28 February), the semi-wert (28 April-5 May) and the wet (19-25 June) periods in 2002. These samples were extracted by carbon disulfide and quantified for BTEX using GC/FID technique. Daytime and less commonly nighttime data from all monitoring sites were statistically analyzed. For daytime data, the average mean concentrations at two downwind sites were higher than those at two upwind sites but lower than those at two sites within the industrial area. The ambient measurement data indicated that BTEX concentrations at the industrial and downwind monitoring sites were affected by emission sources situated within the complex. Consequently, an emission inventory of BTEX in the complex was compiled and the air dispersion model ISCST-3, was used to predict its effects. The predicted values were compared with corresponding field measurement values and reasonable agreement was obtained. BTEX emission inventories were then simulated by ISCST-3 using 2002 meteorological data (as it is considered to result in higher BTEX concentrations than 2000 or 2001 data) to determine annual average predicted concentrations. The results at all monitoring sites were lower than their chronic benchmarks set by other studies. Benzene was found its high concentration at two monitoring sites within the complex and one downwind site but they were still lower than the ambient air quality guideline (5 ppb) set by WHO. Two refineries and two upstream aromatic petrochemical plants were identified as major BTEX emission sources and should be managed in order to maintain local ambient concentrations of benzene within the WHO guideline