Evaluation of odour impact from a landfill area and a waste treatment facility through the application of two approaches of a Gaussian dispersion model

Odour emission from landfill areas has a high potential to cause significant annoyance to people living in their surroundings. In order to avoid odour nuisance, it is crucial to select the best location in the project phase of these facilities. In the present work, two approaches of the Gaussian atmospheric dispersion model were employed to predict odour impact from a projected landfill area and a waste treatment facility. The first approach was a simplified bi-Gaussian Atmospheric Dispersion model developed by the authors. Calculated odour concentrations were represented using GIS tools (Esri ®ArcMapTM software). Regarding the second approach, a commercial bi-Gaussian Atmospheric Dispersion one was used. The odour impact of the waste treatment facility is expected to be low, because of the high efficiency of air biofiltration treatments and the dispersion effect of the stack. The shape and the reach of odour percentile contours were quite similar, providing coherent results between two approaches. Concerning the landfill installation, odour concentrations were modelled for the prevailing winds. The results obtained with both approaches differ in the reach of odour. The maximum distance obtained by the simple dispersion model was 1.5 km, compared with the 3.3 km modelled by the commercial one. Both approaches seem to overestimate the distance reached by odour. Meteorological conditions in Mediterranean areas typically present a high proportion of calm winds, and in these situations Gaussian models may present high errors. Field measurements are required when landfill installation becomes operational, in order to determine the real reach of odour. Bi-Gaussian Dispersion Models may not be appropriate to quantify the odour impact from agricultural sources.