Gaussian Dispersion Behavior of Odorous Gases
Sunil Kumar Pariyar (1), Bhupendra Devkota (PhD)(2), Rohini Devkota (3), Sunil Babu Khatry (4)
Tribhuvan Univsrsity, Nepal
Abstract Number: 481
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Last modified: January 23, 2010
Working Group: sq1
Among the different gaseous pollutants generated from the landfill site, ammonia and hydrogen sulfide are well known for their characteristic odor. The dispersion of gas is generally determined by the meteorological parameters. This study aims to find out the concentrations of characteristic odorous gases (Ammonia and Hydrogen sulfide) through spot measurement and addresses the dispersion pattern through Gaussian Dispersion Model, which links meteorological process and the odor pollution in the micro climatic condition of Sisdol landfill Site.
Diurnal variation of wind speed and direction were analyzed through wind rose diagram and from the analysis it was found that NEE (Koru Gaon), NE (Kagati Gaon), SEE (Rampurthumki), SE (Sanogaon) and NNW (Aletar) are prevailing wind directions with average wind velocity of 2.6m/s. Correlation analysis of wind velocity and air temperature has shown high significant value. Early morning and late evening were found very sensitive for odor pollution due to low wind velocity (high accumulation) as compared with mid day period (high dispersion). From the Gaussian Dispersion Modeling the dispersion of gases were found exponential in nature and significant concentrations of both ammonia (205.52 micro-g/m3) and hydrogen sulfide (41.09 micro-g/m3) were observed up to 20m distance from the source indicating very vulnerable area for odor pollution.
From the analysis it was found that the dispersion rate of ammonia is greater than that of hydrogen sulfide. The air sampling results entails that, up to 20m distance the measured concentration of both gases are higher than the odor threshold values. Similarly the water sampling results indicates that, the measured concentration of ammonia and hydrogen sulfide in water are above the prescribed odor threshold values. Hence the people working inside the landfill sites are chronically prone to odor pollution especially hydrogen sulfide and ammonia so Personnel health & safety measures should be adopted and practiced to maintain the safety health for landfill professionals.