Legislation in odour nuisance

Olfactometric measurements

It is impossible to calculate odour reduction efficiencies without olfactometric measurements. This is because the odour-components with the lowest concentrations (sub-ppb-range) cannot be detected by GC or GCMS but the human nose could very well notice them.

The way to predict the efficiency is comparison of a certain situation with a “similar” reference site, perform a pilot test or to “simply” try the deodorising system full scale in your site. This last option is the best way.

Atmospheric conditions and odour

The required efficiency can vary for every situation, because of atmospheric conditions, surrounding area conditions, raw material quality, recipe and process-conditions.

Odour could leave out of windows and doors and during outside loading/unloading. This may be an issue in the summer, when too much doors/windows are open. The complaints in the near vicinity of the factory are “premises-odours”. Complaints from a greater distance are mostly “stack-odours”.

With a low odour concentration out of the stack it can still give complaints during nice weather: high temperatures and low wind speed. The high ambient air temperature causes the (humid) flume to go down and the low wind speed reduces the dilution. (Dilution is wind speed times flume cross-section at ground level).

Efficiencies

Aerox® as well as most other technologies will show higher odour-reducing efficiencies with high odour concentrations then with low concentrations. This is mostly no problem because the absolute odour emission (odour units per hour) is the most important and with lower odour concentrations also lower reduction efficiencies are allowed.

Odour measurements are expensive and do have a large tolerance on the results. Also if they are executed by certified laboratories according the best available standards.

Odour measurements

Odour immission in the surrounding area is occurring within 1 to 10 minutes after emission out of the stack or building. Odour measurements are officially allowed to be analysed within 28 hours after sampling (according European standard). Odour concentrations are mostly decreasing in time and this effect is normally not determined.

Odour immission can be calculated from emission measurements, but are based on (standard) general methods. The actual situation can cause differences with respect to the outcome of the standard calculations due to the unique area situation (location of high buildings, etc.) and weather conditions (long hot summer, unusual wind direction etc.) This makes it necessary to evaluate a system during a long period.

Guarantees

Odour measurements are expensive, the odour issue is very complicated and it takes a lot of time to evaluate the “odour problem” with all concerned. It is very hard or impossible to even maintain a steady odour concentration during a certain period. The odour emission cannot be accurately specified in terms of components, concentration, fluctuation, etc. A supplier however always demands this when a purchaser demands process-guarantees. Only a supplier with experience and know-how related to the specific application can advice an optimal solution.

The current European standard for odour assessment recognises that the "occurrence of odour nuisance is highly complex and profoundly influenced by atmospheric processes determining the dispersion of odours, the quality of the odour and finally the receptor characteristics of those exposed to it".

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