Industrial odour control, a solution for reducing odour pollution

Industrial odour control is a best practice. After all, odour pollution, depending on its frequency and intensity, can trigger various health-related disorders such as insomnia, headaches or dizziness. This type of pollution is, in fact, a common cause of complaint among people living close to industrial areas.

Basically, because smell is one of the most sensitive senses and helps us to detect toxic or annoying substances that are often characterised by an unpleasant odour.

But how can you reconcile the well-being of your neighbours with the maintenance of industrial activities that release bad odours?

Read on because we have a solution for measuring and control so that this invisible pollution is no longer a source of discord.

What is odour pollution?

The quality of the air we breathe is a precious asset, often taken for granted. However, in the industrial environment, the presence of unpleasant odours can be an indicator of a deeper problem: odour pollution. This phenomenon, although less visible than other types of pollution, has significant negative implications for our health and well-being.

Odour pollution is a phenomenon that affects air quality and public health and is caused by activities that release volatile molecules into the environment. These compounds, although not toxic in themselves, can cause discomfort and psychological disturbances. Our highly sensitive sense of smell detects these molecules, alerting us to the presence of potentially harmful substances.

The compounds responsible include sulphides, ammonia and esters, among others. Not only does it affect air quality, but it can also have adverse effects on human health, respiratory diseases and other health problems such as insomnia, irritability, headaches, and reactions such as loss of concentration and changes in breathing. This occurs because odoriferous substances affect the nasal mucosa and respiratory function, increasing stress and altering blood flow in the lungs.

To mitigate these effects, it is crucial to implement effective solutions that not only neutralise odours, but also allow the source of the pollution to be identified. Bioremediation (biotechnological process using micro-organisms, fungi, plants or their derived enzymes to restore a disturbed environment), real-time monitoring industrial air and its environment to measure and control pollutant molecules and the use of odour inhibitors are valuable techniques that can help neutralise odours and address the source of the contamination. In addition, it is important that strict regulations and sustainable practices are an integral part of the strategy to improve environmental quality and protect public health.

What chemicals cause odours?

Odour pollution is a phenomenon that affects both people and the environment and is caused by the release of tiny odorous molecules into the environment that are not visible to the naked eye, but have a tangible impact on our daily lives and the fabric of our planet. Industry, agricultureand everyday human activities are all behind odour pollution.

In the following, we take a closer look at the chemicals responsible for this problem and their influence on our health and ecological balance.

Hydrogen sulphide

It is known for its strong, pungent odour, similar to rotten eggs. Hydrogen sulphide (H₂S) is a colourless gas commonly found in animal waste and many cleaning products. It is also a by-product of various industrial processes, which contributes to its presence in the environment. Exposure to H₂S can cause irritation to the eyes, nose and throat, and at higher concentrations, it can be toxic to the nervous system. In addition, its release into the environment can contribute to the acidification of soil and water, adversely affecting local flora and fauna.

Ammonia

Ammonia (NH₃), known for its strong and penetrating odour, is commonly found in animal waste and many cleaning products. It is also a sub-product of a number of industrial processes. Inhalation of ammonia can cause respiratory problems, eye and skin irritation, and in severe cases, lung damage. Ammonia can contribute to the eutrophication of water bodies, promoting excessive algal growth that depletes oxygen and damages the biodiversity of aquatic ecosystems.

Volatile fatty acids

These acids, such as butyric acid, are also responsible for unpleasant odours. These acids have a rancid odour and are generated during the decomposition of fats and oils, as well as in fermentation processes. Exposure to these acids can cause irritation of the skin and mucous membranes. These acids can contribute to air and water pollution, adversely affecting aquatic and terrestrial organisms.

Aldehydes and ketones

Volatile organic compounds (VOC) are a diverse mixture of chemicals that can have odours ranging from sweet to musty. These compounds are released during the decomposition of organic matter and in various industrial processes. For example, formaldehyde (CH₂O) is a VOC with a pungent odour and is found in products such as paints and building materials. Exposure to aldehydes and ketones can cause irritation to the eyes, nose and throat, and in some cases, toxic effects on the nervous system. In addition, they can contribute to the formation of ground-level ozone (O₃), a pollutant that affects human health and ecosystems.

 

These chemicals are frequently found in places such as landfills, sewage treatment plants, food industries and areas with intense agricultural activity. Each of them plays an important role in the generation of odours, which can negatively impact our quality of life and the balance of the environment.

How is industrial odour measured?

Odour pollution of industrial origin arises mainly from the presence of volatile chemicals transported and diluted in the air.

The assessment of unpleasant odours emitted by industries is a highly relevant issue, as they can have a significant impact on air quality and public health. To address this problem, several methods and systems have been developed to measure and control odours effectively.

Gas chromatography combined with olfactometry

It is one of the most widely used methodologies as it takes advantage of both the precision of technology and human judgement to establish a relationship between the detected compounds and the intensity of the odour.

Dynamic olfactometry

This method uses a panel of selected persons, known as an olfactory panel, which sniffs air samples to determine the odour concentration. The concentration is measured in European odour units per cubic metre (ouE/m³), following the EN 13725:2022 standard. This method is widely used due to its accuracy and reliability.

Electronic noses

It is another technological breakthrough in odour measurement and mimics the human sense of smell and can monitor odours continuously. Electronic noses are particularly useful for detecting and analysing odours in real time, allowing a rapid response to any contamination problem.

Chemical analysis is another key technique in odour measurement. Using gas chromatography and mass spectrometry (GC/MS), it is possible to identify and quantify the chemical compounds responsible for unpleasant odours. In addition, specific analysers are used for gases such as hydrogen sulphide (H₂S) and ammonia (NH₃), which are common in many odour sources. This method is offered by some air quality stations based on electrochemical sensors such as the Kunak AIR Pro and Kunak AIR Lite.

Wet chemical techniques

These techniques also play an important role in odour measurement as they are used to measure specific compounds, such as mercaptans, which are known for their strong odour. The results obtained by these techniques are essential to understand the chemical composition of odours and their impact on the environment.

Indicator tubes

These are portable devices that allow the measurement of the concentration of certain gases in the air by a colour change in the tube. These tubes are easy to use and provide fast results, making them a valuable tool for odour monitoring in the field.

In summary, the combination of these methods and technologies allows for an accurate and continuous assessment of odour pollution, helping to mitigate its impact on the environment and people’s quality of life.

It is crucial to consider aspects such as the nature of the odour (simple or complex), the minimum threshold for human detection, and the levels of exposure that can cause annoyance. These tools are fundamental to monitor and mitigate odour pollution, thus ensuring a healthier and more pleasant environment for communities affected by industrial emissions.

The mere presence of the different chemical compounds does not imply that an odour is considered pleasant or unpleasant, as this is a qualification that is subjective. Other more or less measurable factors related to odours are also relevant in this characterisation, such as:

• Whether it is a simple or compound odour;
• The amount of odour, defined as the intensity of a single or compound odour to be perceived;
• The minimum odour concentration required to be detected;
• The threshold of perception of a compound that can be detected by olfaction;
• The exposure threshold, which relates the concentration and time of exposure to the occurrence of annoyance;
• Short-term exposure limit value (SELV), set at 15 minutes;
• Average Exposure Limit Value (AELV) for 8 hours; and
• European Odour Unit, which is defined as the number of odorous substances that, when evaporated in 1 m³ of a neutral gas under normal conditions, causes a physiological response. About the latter concept, Kunak is currently working to be able to offer odour units soon.

Human response to increasing concentrations of H₂S.
Source: Bermúdez, Ramos and Rojas, 2018 (translated)

Which activities are potential sources of pollution?

Odour pollution is a type of air pollution that, although invisible, has a significant impact on quality of life and environmental well-being. This form of pollution comes from various industrial activities that release volatile and malodorous compounds into the air, affecting not only the air we breathe but also the perceived cleanliness and liveability of our cities. The industries most likely to generate odour are:

Agri-food industry

Incluye mataderos, empresas azucareras y producción de cerveza. Estas actividades liberan compuestos orgánicos volátiles y azufrados que resultan en olores desagradables.

Chemical industry

Refinerías y plantas de producción de amoniaco y fertilizantes son conocidas por emitir compuestos de nitrógeno como el amoniaco y aminas, que contribuyen a la contaminación odorífera.

Paper industry

El proceso de fabricación del papel puede generar compuestos sulfurados, especialmente durante la cocción de la pulpa de madera.

Textile and footwear industry

These industries use solvents and adhesives that can emit volatile organic compounds with strong and persistent odours.

Livestock exploitations

Slurry and manure, as well as offal and carcasses of dead animals, generate a high load of organic compounds that result in bad odours.

Wastewater Treatment Plants (WWTP)

Wastewater treatment can release gases such as hydrogen sulphide, which has a characteristic rotten egg odour.

Composting facilities

In these reuse facilities, odor control is particularly important due to the nature of the process and its potential to generate unpleasant odors. Strategies to mitigate these problems include the use of biofilters, humidification systems, and proper compost management techniques. By ensuring that compost is maintained in optimal conditions, the emission of unpleasant odors is significantly reduced.

The measurement and control of these odours is not only essential for the comfort and health of nearby communities, but also for the preservation of the environmental balance. The implementation of effective odour removal techniques and the continuous monitoring of environmental impact are crucial steps to ensure a cleaner and more sustainable future. Legislation and public policies should put emphasis on the regulation of these emissions, thus promoting a healthier environment for all.

Odour pollution is an environmental problem where measuring the environmental impact of these industrial activities is essential to develop mitigation strategies and to raise awareness of the importance of clean air free of odorous pollutants.

Regulation of odour pollution in the environment

Firstly, it should be made clear that beyond the monitoring and control operations that may be imposed by particular environmental licences or current regulations related to air quality or the prevention and control of pollution, countries such as Spain lack specific laws that deal with the problem of odour emissions.

However, the lack of legislation is no excuse for not taking measures to minimise environmental problems. After all, the fact that a company is a source of constant conflict is not the best way to present itself.

In this regard, there are guides that can serve as a reference for the adoption of measures aimed at reducing the problems of industrial odour, in addition to the experiences of countries and regions that are working on its standardisation, such as Chile and Ontario.

Environmental monitoring is a key component of odour management. Through advanced systems such as Kunak’s air quality stations, companies can continuously monitor odour emissions, enabling a quick and effective response to any unexpected odour pollution episodes. This type of technology not only helps to keep odour levels within acceptable limits, but also provides valuable data for analysis and continuous process improvement.

Industrial odour is, in short, an issue that can cause problems of coexistence between companies and people. Its regulation continues to be one of the great forgotten issues in many legislations, but it seems that the administration is slowly starting to move to solve this atypical situation. To this end, measures such as odour monitoring in sewage treatment plants or from the paper industry are helping to pave the way.

“A key component of regulation is monitoring, as only through continuous measurement are we able to see the volume of emissions before the introduction of restrictions and use past readings as a criterion for future performance.” (Envirotech Online, 19/01/2022).