Air Quality Modeling and Health Risk Assessment of Air Pollutants Generating from Khulna Power Plant

Abstract

Clean air is seriously affected by the atmospheric emissions generating from industrial sectors. Power plants contribute significantly among these emissions of air pollutants. This study describes the air pollutants emission from Khulna Power Company Limited (KPCL), the distribution of emitted pollutants with time and space, the contribution of power plant emission to the ambient air, and finally the estimation of health risk.

This Study reveals that KPCL (225 MW power generation capacity) using Heavy Fuel Oil (HFO) that contains C (83.42%), H (10.02%), S (0.7%), O (0.05%) and N (0.1%) by weight and the chemical formula of HFO was derived as C2230H3211S7N2.5O. The energy content of HFO was determined 17.76 MJ/kg and it contains Amino (-NH), Hydroxyl (-OH) and Aliphatic Carbon (-CH), Esters (S-OR) and Sulphate (S=O) bonds. The atmospheric emission from KPCL Power plants was estimated as 197.4 t/yr of SO2, 84 t/yr of NOX, 9 t/yr of CO, 12.46 t/yr of PM10, 9.30 t/yr of PM2.5 and 2.7 kg/yr of Lead compounds. The dominant air pollutants from KPCL were found SO2 (62.04%) and NOx (26.35%).

This study also shows that the dispersion of air pollutants from KPCL during September month mostly travelled towards the northern direction in a long distance (>300 km) covering the area of Jessore, Chuadanga, magura, Jhenaidah in Khulna division; Pabna, Shirazgonj, Bogra in Rajshahi division and in some cases dispersed over Dinazpur, Rangpur, Thakurgaon in Rangpur division. During the period of November 2014 to February 2015 the plume travelled long distance of more than 200km covering the area of Mongla, Bagerhat Shundarbans, Potuakhali, Borguna, Gopalgonj, Pirozpur and over Bay of Bengal. Plume also travel over Sundarbans about one- fourth (4 months) period of a year. Back trajectory of long range transport showed that air pollutants from India, Bhutan and Nepal were also contributed to the airshed of Khulna city. Due to the location Himalayan Mountains the massive air pollution of china seems not transported to Khulna airshed.

Air Quality Index (AQI) results showed that during the September 2013the AQI for SO2 (15) and NOX (21) indicating the ‘good’ category (1-50) which pose little or no short term health risk. During this month comparing with the available local air quality monitoring station data, it was found that 18.5% of total ambient SO2 and 12.36% of total ambient NOX contributed by KPCL emission respectively. From dispersion modeling of November 2014 to February 2015, it was found that, 2km surrounding area of KPCL is mostly affected by SO2 and NOX. Average concentrations of SO2in that area were 7.04μg/m3 in November 2104, 7.7μg/m3 in December 2014, 6.62μg/m3 in January 2015 and 7.92μg/m3and the average concentrations of NOX were 2.94μg/m3 in November 2014, 3.13μg/m3 in December 2014, 2.81μg/m3 in January 2015 and 3.42μg/m3 in February 2015. Due to the exposure of SO2 and NOX in this area the DALYs for chronic respiratory disease obtained 0.15 and for cardiovascular disease it was obtained 0.35 per 10 Lac which indicates that 10 Lac inhabitants surrounding the KPCL area will lose their life expectancy by 128 days due to cardiovascular disease and 55 days due to chronic respiratory disease.