Empirical modeling of aerosol transport from sprinkler irrigation | Modélisation empirique du transport d’aérosol par irrigation en aspersion

International audience

إنجليزي. Transport of aerosols resulting from sprinkler irrigation of treated wastewater is a complex phenomenon due to the combined effect of several parameters including fine droplets (<0.15 mm) and wind speed, which are the most important vectors for pathogen transmission. The objectives of the present study were (1) to characterize the distribution of the fine droplet plume emanating from a sprinkler head in the horizontal and vertical axes under different meteorological conditions and (2) to model (i) the short-range airborne transport and (ii) sedimented transport based on the combination of meteorological and spatial parameters. Nine experiments have been conducted outdoor under different environmental conditions. By injecting a fluorescent dye (Acid Brilliant Flavine) into the water, the distribution of aerosols emanating from an impact sprinkler under 350 kPa operating pressure was measured vertically (1-10 m above the ground) downwind and horizontally within a perimeter equivalent to 4 times the sprinkler range (20-40 m). Crosswind distribution of the droplet plume from a sprinkler was found to be Gaussian, and its dispersion rate depended on wind speed and the standard deviation of the wind direction. From the distance of 20-40 m from the sprinkler head, and 1 m above the ground, airborne transport fell from 20.8 and 3.43 mL m −2 h −1 to below 2.89 and 0.13 mL m −2 h −1 for wind speeds of 3.6 and 1.1 m s −1 , respectively. Moreover, different models have been evaluated by varying the factors considered. It was found that two empirical models, which combine spatial variables, and the key meteorological parameters, including wind speed, the standard deviation of wind direction, temperature, and relative humidity (for airborne transport), provide the best correlations between the simulated transport values and the observed data (R 2 = 0.9). Therefore, these models can be used for future studies to evaluate the risks linked to treated wastewater reuse for irrigation.