Due to the fast growth of cities and populations, residential areas are increasingly close to Waste Water Treatment Plants (WWTPs), causing odour impact on neighbourhood and complaints. The present study focuses on assessing the impact on the residential vicinity of a WWTP in Valencia (Spain) of different superficial odour sources using Computational Fluid Dynamics (CFD) simulations. Together with other software, CFD simulation is used as a complementary study to model pollutant dispersion. Unlike other simulation tools, CFD is bounded to smaller domains (1 or 2km). However, it performs more meaningful calculations and provides more detailed results, which allow obtaining resolutions at a scale below centimetre. The precise mesh generated in this work facilitates the study of the effect of the turbulence and the eddies caused by different obstacles (buildings, walls, etc.).