Assimilative capacity of air pollutants in an area of the largest petrochemical complex in Thailand

Abstract

Assimilative capacities of sulfur dioxide (SO2) and oxides of nitrogen (NOx) in the largest petrochemical industrial complex in Thailand were evaluated in this study. AERMOD dispersion model was simulated to compute for ground level concentrations and spatial distributions of SO2 and nitrogen dioxide (NO2) within a radius of 5 km from Maptaphut industrial area. Emission input consisted of 419 stacks which total amount of 2,071.82 and 2,163.66 g/s of SO2 and NOx were used as baseline emissions. Maximum hourly average and annual concentrations predicted at 8 ambient air quality monitoring stations in the study domain were used to evaluate an assimilative capacity of these pollutants. Emissions of SO2 and NOx were adjusted to the limit that predicted concentrations will not exceed their ambient air quality standards. Results indicated that in order to achieve both hourly and annual standards, NOx emissions must be reduced by at least 40% from its baseline value. As for SO2, emissions can be increased up to about 130% from current level. Results of this study indicated that an existing regulation in controlling individual emission source by using emission standard is insufficient. Analysis of air pollution as area-based approach by taking into consideration entire emission sources can support for better planning and management of pollution.