Evaluation of odour impact from a landfill area and a waste treatment facility through the application of two atmospheric dispersion models.

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 different atmospheric dispersion models were employed to predict odour impact from a projected landfill area and a waste treatment facility. The first model used was a simplified Gaussian Atmospheric Dispersion model developed by the authors. Calculated odour concentrations were represented using GIS tools (Esri ®ArcMapTM software). Regarding to the second model, it was a commercial bi-Gaussian Atmospheric Dispersion one. 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 models. Concerning the landfill installation, odour concentrations were modelled for the prevailing winds. The results obtained with both models differ in the reach of odour. The maximum distance obtained by the simple dispersion model was 1.5 km, compared with the almost 5 km modelled by the commercial bi-Gaussian one. The reasons of this disparity could be caused by the difference in the dispersion coefficients employed in the two models and also an error related to ground level emission. In addition, the meteorological conditions in the Mediterranean typically present a high proportion of calm winds, which provided worse dispersion results and did not reflect the real odour dispersion. Odour emission rate seems to be overestimated, and this could explain the high distance reached by odour. Field measurements are required when landfill installation becomes operational, in order to determine the real impact of odour. Bi-Gaussian Dispersion Models may not be appropriate to quantify the odour impact from agricultural sources.