Dispersion modeling of air pollutant emissions of Lakvijaya Power Plant, Sri Lanka

Abstract

Air quality models play an important role in providing information for verifying permitting conditions and for exposure assessment purposes. Measured field air quality data was compared with model predictions to show that AERMOD air dispersion model is capable to identified located the maximum air concentration in the study area, provided representative or conservative air concentration estimates, and demonstrated bias and scatter not significantly different than that reported for other compounds. In general, AERMOD was a useful screening tool for modeling dispersion of major criteria pollutants SO2, NO2 and, Particulate Matter (PM) are generated from coal power plant. This assessment was carried out to investigate the ambient air quality at the surrounding environment when considering the three criteria pollutants such as SO2, NO2 and PM emitted from the 900 MW coal power plant situated at Norochcholai. The Air Dispersion modelling software, AERMOD was used for the assessment to find the ground-level concentration of three criteria pollutants. The assessment period is two years, 2020 & 2021, average level of stack emission measurement data during the study period were used as source input data and metrological data obtained by Department of Metrology, Puttalam in same years and terrain data downloaded by webgis were used for the dispersion analysis. The concentration of Pollutants at three locations, which were selected to measure the in-situ ambient air quality, were compared with the measure data. The air dispersion modeling study shows that the concentration of selected criteria pollutants in surrounding environment is well below The National Environmental (Ambient Air Quality) Regulations, 1994, published under Gazette Extraordinary No. 850/4 of December 1994. The measured data at particular locations was also well below the standard levels. The calculated AQI values for maximum predicted ground-level concentrations of Particulate Matter for each monsoon and selected locations are in good condition for year 2020 and 2021. However, AQI values for the measured data at selected locations are always greater than the predicted values of ADM since prediction values indicate only the emission by the power plant but measured levels include air emission by other local sources such as open burning of waste and garbage, vehicular emission, domestic emissions and small industries in the area etc. The pollution control devices such as ESPs, FGDs and Low NOx burner technologies of the coal power plants play a major role in protecting the ambient air quality levels in the surrounding environment. The functioning of the pollution control devices in optimum conditions at all-time is more important to maintain the standard ambient air quality. Monitoring of ambient air quality in the surrounding environment is a mandatory requirement to identify the changes, if any.