Industrial odours can be a source of conflict between production facilities and residential areas. The issue particularly affects companies operating in waste treatment, wastewater treatment, sludge treatment, composting, chemicals and the food industry. Depending on atmospheric dispersion conditions, odorous emissions can affect areas some distance from the facilities themselves.
Odour nuisance is particularly difficult to manage because the disturbance experienced by residents depends not only on the concentration of the substances present, but also on the frequency and duration of events, odour intensity and character, weather conditions and individual olfactory sensitivity. Both channelled emissions and fugitive emissions can contribute to the problem.
From a technical perspective, one mistake to avoid is treating odour as a secondary parameter compared with other air pollutants. Some substances, such as hydrogen sulphide and certain mercaptans, can be detected at concentrations in the parts-per-million (ppm) range or even lower. Odour thresholds vary considerably between compounds: ammonia thresholds are generally in the ppm range, while those for volatile organic compounds (VOCs) depend on the specific substance.
This means that a plant may comply with chemical emission limits and still cause odour-related problems in the surrounding area.
For this reason, odour abatement systems must address both treatment efficiency and the overall management of emissions:
- effective capture of fugitive sources;
- maintaining adequate negative pressure in the relevant areas, where required;
- controlling openings in industrial buildings;
- managing emission peaks during unloading or material-handling operations.
Depending on the pollutants and operating conditions, integrated configurations may include:
- multistage chemical scrubbers;
- biofilters sized according to the pollutant load and required contact time;
- activated carbon systems;
- process-parameter monitoring and, where appropriate, instrumentation for odour monitoring.
Odour concentration is determined by dynamic olfactometry in accordance with EN 13725. Continuous instrumental monitoring systems can complement measurement campaigns, provided they are properly calibrated and validated for the application.
The design of air-handling duct networks is also essential. Inadequate air velocities, condensate accumulation and organic deposits can lead to build-up and material degradation inside ducts, contributing to odour problems.
Odorous-emission management is an environmental, social and reputational issue. Companies that invest in effective source capture and suitable treatment systems can reduce the risk of nuisance, improve operational continuity and lower the risk of complaints and restrictions related to odour impact.
