Determination of odour emission rate from area sources

National Research-Development Institute for Industrial Ecology ECOIND

Pollution Control Department 

Air Pollution Control Laboratory

Determination of odour emission rate from area sources

Direct measurement of odour concentration in ambient air is most of the time not sufficient to establish an odour pollution level.

For this reason, the Air Pollution Control Laboratory has developed and optimized sampling methods for determining odour emission rates from liquid or solid area sources, expressed in odour units per second (ouE/s) and obtained as the product of the odour concentration and the air flow associated with the source.

For diffused area sources characterized by the lack of air flow to the outside, the extraction equipment consists of a type hood (wind tunnel), with an area of 0.5 m2, automatically ventilated by two radial fans with a constant volumetric flow, thus simulating the passage of air currents over the sampled source (figure 1).

For active area sources characterized by the presence of an outside air flow greater than 0.008 m/s but not greater than 3 m/s sampling equipment consist of a dedicated hood with a covered area of 1 m2 is used. The hood is pyramid-shaped and join with a cylindrical exhaust pipe. (figure 2)

Samples uses to determine odour concentration are vacuumed in containers made of certified nalophan materials through a vacuum pump shown in the figures 1 and 2. The odour concentration is determined through dynamic olfactometry using a dynamic olfactometer with 4 human assessors (figure 3) and is expressed in ouE/m3. Then is reported to the specific type of volumetric flow of the  sampled sources resulting in the emission rate.

Through these methods for determining odour emission rates, several types of simulations of the dispersion of odour concentrations in the surrounding air can be carried out, depending on climate parameters over short or long periods of time, using the emission rate as input data associated with the sampled source in the specialized dispersion programs of atmospheric pollutants.