When industrial odours aren’t controlled they pollute the local environment. This is unpleasant for members of the public and other local businesses. It can also create poor working conditions that affect employee health and morale.
From an environmental perspective, air pollution is bad news because it affects the quality of the air we breathe. While certain odours are nothing more than a nuisance, hazardous air pollutants have the potential to cause health problems.
So, what can we do? We can implement odour control measures to prevent odour pollution or minimise it when prevention is not possible.
Here’s how you can determine if odour control is required for your operation:
Odour monitoring builds a complete picture of the scale of your odour problems and the root causes. The types of odour your operation produces, and the extent of the pollution, will be determined so we can design a solution.
At OSIL, we use on-site data loggers and olfactometry to detect and measure odours. The data collected allows us to build a complete picture of your odours. This in turn allows us to appropriately specify the correct odour control system.
Dispersion modelling helps us understand how your emissions impact the wider environment. These surveys are used to estimate whether your emissions could harm the environment and cause a nuisance for members of the public.
Our dispersion models take into account a range of factors like exit velocity, thermal rises, airflow and external factors like meteorological patterns to build a complete picture of the environmental impact of your industrial odours.
Olfactometry is a useful tool for evaluating and validating odour complaints. It involves collecting air samples and testing them in an accredited laboratory.
The difference between olfactometry and odour monitoring is that olfactometry is a single process in the wider odour monitoring process. It is a test and result service, used to identify the type of odours you produce so we can recommend the right solutions.
LEV and GEV Surveys
LEV and GEV Surveys are necessary to visually inspect and test extraction systems to determine if they are fit for purpose and functioning as intended. These surveys are a legal requirement to ensure fit-for-purpose extraction.
During an LEV / GEV survey, each piece of ventilation equipment in a system is inspected to ensure it is functioning within its design specifications. The system is then tested to make sure it is providing the specified level of exposure control.
Odour control systems
Adequate odour control depends on purpose-designed odour control plant. These are processes that prevent or abate pollution. They include:
Odour control systems can be simple (e.g. single-stage system.) or complex (e.g. a multi-stage systems) to meet the specified level of odour control performance. In some situations, it’s possible to design systems that vent nothing but clean air, while other times odour minimisation is the best outcome.
Want to know more about industrial odour control? Feel free to call us on (0) 1543 506855 for a chat about how we can help you.
Service and maintenance is key to ensuring that your odour control system continues to work as intended and is safe to use.
Without service and maintenance, your odour control system will be susceptible to problems like failing components, a build-up of residue (limescale, sludge, etc.) in scrubbers and vessels and electrical and mechanical bugs.
These problems could be disruptive to your operation by causing unscheduled downtime and they could even cause a breakdown.
It’s also important to note that some odour control systems have serviceable parts. For example, the filters in some odour control systems need cleaning or replacing during routine servicing to maintain optimal system performance.
Service and maintenance is essential to catch disruptive problems early and ensure your odour control systems continue to operate optimally.
Monthly health checks
The best way to maintain an odour control system is to have routine service and maintenance health checks. These checks should form part of a planned maintenance schedule that’s designed for your system.
Health checks involve visual and physical checks of the odour control system extending beyond process plant to all associated equipment. These checks can vary from one system to another depending on the size and complexity of the system.
A monthly health check will generally include:
A visual inspection of plant and associated equipment
Physical tests, including:
Measurement of inlet and outlet odour levels.
Measurement of air velocities.
Check fans are running correctly, drive belts are ok, grease bearings, check hours run meters and other mechanical components.
Check ducting, check for any UV degradation, check the supports are ok, check the dampers are operating correctly, drain condensate.
Check and recalibrate instrumentation.
Biological systems – Check media health, irrigation inspection including spray pattern and nozzles.
Chemical scrubbers – Check media quality, look for evidence of calcium build-up, traces of sludge build-up, check chemical dosing system including inspection of pumps, valves, instruments and pipework. Dry media systems – inspect media, carry out media analysis if appropriate.
Other checks depending on the system – water softener salt levels, chemical storage and dosing equipment.
Examples of maintenance
Multi-stage odour control systems should be inspected once per month and smaller or more basic systems may be inspected quarterly or every six months depending on your needs.
Mechanical components like fan drive belts are serviceable parts that should be replaced periodically when worn. Filters should also be cleaned and replaced when spent, spray nozzles should be checked and cleaned regularly, and scrubbers and other vessels should be cleaned when required.
Pipework and ductwork may need replacing or resealing over time. Vessels may corrode or become contaminated and need replacing or deep cleaning. Scrubbers may have a build-up of sludge that needs removing.
You may need to replace or optimise your bio-media. Biological systems may need biologically rebalancing to promote a healthy biomass. You may experience pressure drops in the system or abnormalities if the system is not maintained correctly.
You may detect odour coming from the system. This is often the first sign that there’s something wrong. This could be caused by a blockage, media deterioration, a leak, chemical dosing malfunction or a problem with the ductwork.
At OSIL, we believe that service and maintenance is essential for every odour control system, so we make maintaining your odour control system easy with Gold, Silver & Bronze packages. These packages can cover everything from scheduled maintenance to call outs, so that your odour control system always runs at its best.
Want to know more about odour control system maintenance? Feel free to call us on (0) 1543 506855 for a chat about how we can help you.
Problem odours are a by-product of many industrial processes such as wastewater treatment, incineration and chemical processing.
These odours must be controlled to minimise their impact on the environment. The common problems in odour control include:
How to define and characterise what odours are being produced
Selecting and sizing the correct odour control system
Creating the correct microbiology in biofiltration systems
Controlling the build-up of limescale (calcium carbonate) within chemical scrubbers
When problem odours are a nuisance they are considered pollution. Odour control is all about reducing the amount of odour that is released into the environment. We can do this with chemicals treatment, dry media filters or biological treatment.
However, before an odour control system is specified, it is first necessary to define and characterise what odours are being produced.
How to define and characterise what odours are being produced
Odour surveys are used to determine the character and concentration of odours so that the correct odour control solution can be designed.
Olfactometry surveys answer the question of what odours are produced; dispersion modelling surveys answer the question of how odours from your operation are likely to travel when released into the environment. Good odour control relies on both surveys so that we can design systems that work and don’t cause a nuisance.
When evaluating and validating odour complaints the correct survey is an olfactometry survey. Olfactometry involves collecting air samples and sending them to accredited laboratories where the odours can be analysed and identified. This process defines and characterises what odours are being produced.
At OSIL, we also have the expertise to evaluate olfactometry results for you. This reduces the time to finalise results and makes the process more efficient.
Dispersion modelling surveys
When we need to understand the effects odours have on the environment the correct survey is a dispersion modelling survey. Dispersion modelling simulates odour dispersion so that environmental risks can be categorised.
This is useful when upgrading odour control systems and determining the root cause of odour pollution complaints. It may be the case that your existing odour control system is not up to the job or has improper ventilation.
The most relevant survey when designing odour control systems is olfactometry because for an odour control system to be effective it has to be designed for the identified odours. No two systems offer the same performance.
An incorrectly specified odour control system will not perform as intended and it could be extremely costly to your business by forcing further investment.
Selecting and sizing the correct odour control system
Odour control is all about reducing the amount of odour that is released into the environment and there are several systems we can use to achieve this.
Odour control systems include chemical scrubbing, biological treatment and dry media filters. These systems are intended for different applications.
Chemical (wet) scrubbers
These systems make contact between a liquid absorbent and a contaminated air gas stream for simple applications. Single-stage chemical scrubbing systems are used where only a basic scrubber is all that’s needed – but you can also specify multi-stage chemical scrubbers that target a more diverse range of odours and pollutants for bigger tasks.
Biological (biofiltration) systems
These systems can treat a higher volume of odours without the addition of chemicals using a media bed colonised by microorganisms.
Biological systems can remove a wide range of contaminants without the need for chemicals, and unlike chemical scrubbers, they produce no contaminated water as a by-product. This may suit your operation better.
Dry media systems
These systems can be designed to treat a wide range of odours, including H2S, organic sulphides, mercaptans, ammonia and VOCs.
Dry media systems are inherently simple in operation and their performance is determined by the specification of filters. These include activated carbon, impregnated carbon, oxidising alumina media, and hybrid, multi-media filters.
Using these systems together
It’s important to recognise the individual limitations of these systems, with the primary limitation being that some are better than others at removing certain contaminants. You also have to consider the space available to you on-site.
Sometimes, more than one process is needed. Biological and dry media solutions can be used as complementary technologies for polishing another primary technology (such as chemical scrubbing) or as standalone treatment systems.
Biological systems – getting the microbiology right
The most common problem when designing biological odour control systems is getting the microbiology right. We need to create an environment where microorganisms can not only thrive but also degrade the odours as efficiently as possible.
The variety of microorganisms depends on the nature of the odours. Biological systems often contain the following types of bacteria:
Sulphur oxidising bacteria
Heterotrophs for VFA degradation
Nitrifying bacteria for ammoniacal odours
Biological diversity is essential to capture the maximum number of pollutants. The spatial distribution is also important for consistency.
When designing microbiology for biofiltration systems, we have to consider the odours and the microorganisms in terms of capture and emission.
The biology of the biofiltration system also depends on the type of bio filtering used. There are two main types of technology in question:
Biotrickling filters / Bioscrubbers
With biotrickling filters / bioscrubbers, odours are forced through a media bed colonised by microorganisms in a liquid medium. As contact is made between the odours and microorganisms, the microorganisms capture the odours and degrade them. The contaminated water is recirculated to achieve excellent results. When the microbiology is correct, bioscrubbers can be 100% effective at removing odours.
Biofilters are extremely effective in applications where the odours are mostly organic. The air flows through the living biomass where microorganisms absorb pollutants. This technology requires a sufficient surface area for biomass growth. When the correct microbiology is specified, biofilters are extremely effective at filtering VOCs.
What’s the key difference?
The difference between biotrickling and biofilters is that biofilters do not recirculate the water as biotrickling filters do. Bioscrubbers are best for highly water-soluble compounds, while biofilters are best for volatile organic and inorganic compounds.
When specifying a system, the space available to you on-site will also need to be considered. Fixed bed biofilters have the greatest physical footprint while drained bed biofilters have the smallest footprint. Bioscrubbers sit in the middle.
Chemical scrubbing – controlling the build-up of limescale
The build-up of limescale (calcium carbonate) in chemical scrubbing systems is a common problem. A simple solution is to use water softeners to stop the build-up of limescale. This is a cost-effective solution that prevents further build-up.
Limescale can become a serious problem if it is allowed to consolidate. This is why it’s important to clean the system with descaling agents periodically.
Biodegradable cleaning agents are available for this task. These should be run through the system during maintenance. Pipes, components and tanks should all be cleaned, and it may be necessary to do this every few months.
The risk of limescale build-up is blockages in the system and damage to components. This will increase maintenance costs. We recommend descaling your chemical scrubbing system at least once a quarter and using water softeners during cycles.
Sewage treatment plants must route odours through odour control systems to control air pollution. Ventilation systems are useless on their own for odour control if all they do is vent odours out into the atmosphere.
This setup would only pollute the atmosphere and cause a nuisance with the local population. It may even get you in trouble with the local council. For these reasons, odour control should be a top priority for all treatment works.
Getting to the root of your odour problem
The most common cause of a foul odour in sewage treatment plants is the release of hydrogen sulphide (H2S). This offensive odour is also known as “sewer gas” and it can cause health problems.
Other types of odours include amines which possess an ammonia smell and mercaptans which give off the stench of rotting food.
Sewage moves through pipes and is treated by a number of processes contained in large tanks. This environment is contained. The screenings and sludges are separated and pumped away into containers. Again, the environment is contained. So, you might be wondering how odours escape and make a plant smell?
The main cause is biological overload and odour overload. Quite simply, tanks and process rooms have to be ventilated and sludge has to be removed at least once a year and tanks have to be cleaned. This can allows odours to escape. Plants can also have spills and accidents that can also cause significant odour problems.
Odour control systems in sewage plants
Controlling odours so that they are not a problem for the local population is important for several reasons, chief of which is a social responsibility to ensure that your operation does not impact on the lives of local residents.
Thankfully, there are a number of odour control systems we can use in sewage treatment plants so that the air vented is clean and odourless.
Some of these systems include:
Tube vents and a passive filter
These are an activated carbon-based, passive odour control unit. They are commonly utilised to absorb vent gases from sewerage processes.
One stage carbon filtration
Our CuCarb® activated carbon dry scrubbers can operate as a single standalone unit or as a polishing unit downstream of biological or chemical treatment systems. OSIL’s selected activated carbons serve as media to purify air streams by concentrating and retaining odorous gases and vapours.
Single-stage chemical scrubbing
Our ChemKlean® Scrubbing System has no moving parts to reduce maintenance. This system works by using a liquid to absorb odour-causing components in gasses. The gas is then released into the atmosphere.
Dual systems combine two systems for odour control, such as biofiltration + carbon filtration or chemical scrubbing + carbon filtration. We call this process multi-stage filtration, and it is used to control powerful odours.
What’s the right solution for your sewage plant?
The scale of your operation, the types of equipment you use, and the design of your building and ventilation system will determine the right solution. There is no one-size-fits-all approach. It’s important to note that the size of the systems used in odour control vary. You need bigger systems for higher air volumes. We can recommend a few options if you’d like. Feel free to call us on (0) 1543 506855 for a chat.
Where a business produces airborne contaminants in the workplace, there is a legal and insurance-based requirement to protect workers’ health by controlling exposure to contaminants. Control is achieved with an LEV or GEV system.
LEV and GEV systems are used to extract and ventilate airborne contaminants and pollutants (e.g. dust, fumes and gas). These systems require regular checks to ensure they are fit for purpose, and surveys enable compliancy to be checked.
LEV & GEV survey process
Health and safety law, says you must assess the risks to your workers from hazardous substances – dusts, fumes, vapours, etc. – and decide what measures to use to protect their health.
If the measures you adopt include extraction systems (LEV) to remove the dusts, fumes, vapours etc. produced by your work processes or activities, then you must maintain the LEV in efficient working order, so it continues to provide the necessary protection. You should also have a periodic thorough examination and test (at least every 14 months) and must keep this record for at least 5 years. In addition, you should have information on the installed LEV system to confirm it provides adequate protection, which should be kept for the life of the equipment.
You must ensure that your LEV is still working as effectively as originally intended and is helping to protect your employees’ health. To be able to tell if it is still working as it should, you should be able to provide the examiner with information about the intended or designed performance of your system.
An examination will test:
Process flow functionality and comparison against the design intent
Hoods, seals and ductwork
Parts that deteriorate, such as filters
Parts that need attention, such as volume control dampers and their settings
Each piece of LEV / GEV equipment in a system is inspected to ensure system conformity with design specifications. The system is then tested to establish if it provides an adequate level of exposure control.
This information might be in the form of an initial appraisal or commissioning report, if one was carried out, or for simple ‘standalone’ systems it could have been provided as standard operating data by the suppliers of the extraction equipment. Alternatively, it might be found in recognised guidance (including that from HSE) on simple processes/systems (For example LEV Guidance hsg258 ). If none of this is available, you could consider getting someone competent to advise you.
During a survey, extraction systems are visually inspected and tested to determine if they are fit for purpose and functioning as intended.
LEV and GEV surveys produce a report that highlights defects, problems and advises where maintenance is recommended. Businesses must implement critical recommendations to comply with health and safety standards.
For example, the survey may find an issue with ducting that leaks. The ducting would need to be repaired or replaced for the system to pass the test.
Businesses must also keep records of all examinations and tests for at least five years. A logbook or dedicated LEV/GEV file is the standard way of doing this. Following a survey, the survey report should be read, and any queries/actions addressed. A presentation of the survey should be carried out to the client from the examiner, if possible. If a logbook is used, then this should be stamped so the business has a record of compliance.
Another important aspect of surveys is ensuring the people who use the extraction system know how it functions and what settings have been established during the commissioning process. Training should be provided by the installer in this respect. Adjustments to any settings should not be made by anyone except the company’s maintenance engineer, the commissioning engineer or the LEV system examiner.
Routine checks (maintenance)
Know the parts of the LEV system and their function.
How the LEV system should be used.
How to recognise a damaged part.
Simple checks to show that the LEV system is delivering its design performance and what to do if it is not.
The importance of regular surveys
Regular LEV and GEV surveys are a legal requirement, so you are breaking the law if you have a ventilation system that isn’t regularly tested.
To put it another way, surveys are necessary to determine the ventilation system is functioning as intended and providing the necessary protection against airborne contamination. They will also detail the requirements to prove compliance with health and safety legislation.
If you require assistance with your LEV or GEV surveys OSIL would be pleased to discuss your requirements.
Wastewater treatment, chemical processing, waste incineration and food production can all contribute to industrial odours.
Many industrial sectors and municipal wastewater treatment works can release unpleasant odours into the air which can travel for miles before becoming a nuisance. Different environmental factors can also play a key role in increasing the effect of offensive odours. One of the common examples that intensifies odour at the source is an increase in the air temperature and air distribution can also transfer odours from one place to another.
What are the impacts of Odour emissions?
Continuous odour emissions of a pungent type can be categorised as a part of air pollution and such odours can have a detrimental effect on local neighbourhoods. Constant exposure to offensive and aggressive odours inside a factory, food manufacturing facility or waste treatment plant can cause severe mental and physical health problems to the employees as well as causing detrimental corrosion to plant and machinery.
A large number of research studies have suggested that odour emissions could be more dangerous to the most susceptible sections of the population. It can particularly affect; children, the elderly and asthmatic sufferers. The correct type of odour control can lead to a better and a healthier environment for people living in the neighbourhood of a plant that is producing foul odour.
The offensive release of harmful gases like hydrogen sulphide, ethyl methyl sulphide and trimethylamine can result in serious health issue. These health issues can produce symptoms that range from mild discomfort, to being extremely serious. Chemicals with strong odour have the capacity of causing lung, eyes, nose and throat irritation. Employees working inside factories can experience a mild burning sensation in their throat that eventually leads to coughing, wheezing and other breathing problems.
What can be done to eliminate odour emissions?
There are a comprehensive range of odour abatement processes that can be used to maintain an odour free environment both internally or externally.
Here is a list of multiple processes that can be used for eliminating odour problems:
Wet Scrubbing: Often the technology of choice for companies seeking a flexible and efficient way to eradicate unwanted odours.
Biological Treatment:OSIL’s LavaRok biological systems which is often the favoured solution for clients looking for a reliable and flexible process for treating high volumes of odour – without the addition of chemicals.
Photo- ionisation: This process involves applying a high intensity UV light combined with a specialised catalyst to eliminate odours from contaminated air.
Activated Carbon: This adsorption process is ideal for treating VOCs and other organic contaminants.
Misting and Dosing System: This is a process for masking odours with the careful use of essential oils, surfactants and organic compounds.
With the continual development of towns and cities, foul odour emissions are becoming more and more problematic for all types of manufacturing, production and treatment processes as well as for the conurbations surrounding these facilities.
Odour elimination has gradually become one of the primary concerns that need to be resolved. It is imperative that odour is controlled so as not to materially affect people’s enjoyment of their property or outdoor space and decrease their legitimate use of the environment.
If problems do occur, or are likely to occur in the near future, it is important that the appropriate actions to prevent or minimise the risk are taken. While for some activities it may not be practicable to avoid all odours, any neighbourhood has the right to expect that there must not be any odour produced that will detract from their quality of life. It is unlikely; however, that action will be taken over occasional or slight odours.
By “neighbourhood” we mean anyone living, working, visiting or making use of public space outside a site that is producing odour. It means any sensitive receptor.
Rather than simply installing turnkey equipment, OSIL is one such odour controlling partner that focuses on finding the right solution to resolve odour problems.
It is a common misconception that these two terminologies are identical to each other but in reality, they are poles apart. We at OSIL are here to guide you through the differences.
The simplest comparison of industrial Odour Masking is the domestic air-fresheners when introduced into a room at a high concentration they mask the unpleasant pungent odour present in the room or particular area. As a result, the human nose detects the highly concentrated fragrance and not the bad odour. The drawback to this technique is that the odour still exists in the background and when the masking fragrance fades away, the bad odour resumes its presence, thus demonstrating that it is a short-term solution.
Industrial Odour Masking differs only slightly from the above but is not an entirely unique concept. In the industrial sector, odour masking is achieved by releasing a highly concentrated masking agent in numerous kinds of fragrant odours. The process is used on Industrial Waste, Sewage, Farming, and similar industries to mask the odours being generated. Large areas like septic tanks, sewage ponds, refuse tips, offal processing plants, often use masking agents to deodorise the noxious odour, being produced which would otherwise make the surrounding local area very unpleasant.
There are special odour masking products for the industrial sector that are easy-to-use and can be mixed with water in a range of varying dilutions. As a result, these can be applied by mist machines, sprayers or direct drip-feed into the water source.
Numerous facilities such as sewage treatment plants are prone to odour issues due to the residual components from the treated wastewater. These screenings and sludges can produce an excessive amount of hydrogen sulfide gas which smells like rotten eggs. To control this type of odour, various odour control technologies are used:
Micronutrient Dosing- A healthy way to combat this type of odour is by adding micronutrient additives as they biologically breakdown the organic waste and reduce the amount of odour released. These additives increase the growth of facultative bacteria, which prohibits the emission of Hydrogen Sulfide (H2S).
Extraction and Filtration- Extracting the odorous vapours from waste treatment is another method via which the odour in the sewage treatment plants can be controlled. This is an effective method that prevents the odour from infiltrating the surrounding neighbourhoods. Activated carbon filters and biofilterscan be used to treat the extracted vapours.
The above details the differences between these two odour treatment solutions. We at OSILcan ensure that your employees work in an environment with the best possible atmosphere, one that is odourless and safe from noxious gases. We can help create a workplace environment that employees deserve, reach out to our engineering staff for assistance in removing your odour problems.
New storm tanks have been installed in and around Oldham. Vents were needed to allow air to be drawn in when the storm tanks were been emptied and air to be pushed out when they fill up. When this air leaves the storm tank it could be odorous and this needed to be prevented from being released into the air where people are as this would be very unpleasant.
The challenges were:
To meet the client’s requirements of designing and manufacturing a passive carbon filter unit. The client required the units to be installed above the new Storm Tanks and treat the odour from the odorous air that left the Storm Tank through a carbon filter designed to remove the odorous compounds before the air is expelled into the surrounding atmosphere.
Concern on manual handling when it came do media changes.
Very short lead time.
How did OSIL approach the challenge?
Based on the volume of air that would be displaced, the diameter and the height of each tube vent was decided on after a dispersion model had been created. The construction material that was decided upon was uPVC/GRP. Each tube vent stack was designed with manual handling in mind with the height from the ground level to center of the carbon media pod/shuttle being 1305mm from ground level. In addition, the position on the media pod/ shuttle was sized to be no more 20kg. The weight along with the position allows the carbon media to be manual handled safely when doing a media change but equally still effective at removing the odour from the odorous air.
Following design approval, the tube vents were manufactured to a very tight timeline. We kept the client informed throughout regarding the progress being made which enabled them to plan their own works in a timely manner
This design ensures that the tube vent effectively allow fresh air to be drawn in and odourless air to be expelled into the surrounding area while also ensuring that the future maintenance can be undertaken on each unit with as little risk to the operatives as practicable.
An Operations & Maintenance manual was produced for the Tube Vent Units to help the Clients Engineers understand the system and perform regular maintenance themselves.
“We would be pleased to have the opportunity of working with Lima employees again as it was a pleasure on this project with the communication between both parties being regular which enabled us to work effectively together. We would welcome other opportunities for OSIL to do future work for Lima.”
About the OSIL Blog
Here you’ll find news, company information, research and thought leadership on all aspects of Odour and Air Pollution control.
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