THE DEVELOPMENT OF A SAMPLING SYSTEM FOR THE DETERMINATION OF ODOR EMISSION RATES FROM AREAL SURFACES .2. MATHEMATICAL-MODEL

An improved design for an odor emission hood was examined in the laboratory using ammonia emission from a water surface. The experimental ammonia convective mass transfer coefficients from a diluted ammonia solution were determined at velocities of 0.3 m/s to 0.8 m/s using the odor emission hood. The theoretical ammonia convective mass transfer coefficients were also predicted by boundary layer theory under laminar flow conditions. It was found that experimental data were only 10% below theoretical predictions at an air velocity of 0.3 m/s to 0.6 m/s. The maximum velocity was limited to 0.6 m/s by the geometric size, shape and aerodynamic stability of the hood. At 0.33 m/s, the smallest variation of mass transfer coefficients was measured. The odor emission rate was found to be a function of air velocity to the power 0.5 in accordance with boundary layer theory. An odor sampling system based upon the odor emission hood provides a way to quantify the potential odor emission strength in sewage treatment plants, for odor dispersion modeling and odor control.