Top 5 Reasons for Odour Control System Failures

Odour Control Unit

Today’s odour control systems are engineered intricately to maximise removal rates from high air flows with efficient, compact designs.

System failures are primarily caused by engineering and design issues and odour control systems’ incorrect sizing and specification.

This article will explore the top five reasons for odour control system failures.

Specifying solutions based on guesswork

When odour control decisions are based on guesswork, this often results in incorrectly specified odour control systems. No two sites are the same, so past experiences and best practices are no guarantee of success.

When odour control systems are specified, decisions must be made based on data, samples, and research. We need to understand the nature of odours, including their type, offensiveness, frequency and intensity.

Working with an odour control expert like OSIL is crucial to collecting the correct data and specifying and designing the right solutions.

Incorrect system configuration

In multi-stage treatment systems, upstream and downstream odour control processes cleanse the air for the following process. The order and configuration of these processes are essential to maximising performance and uptime.

For example, in a multi-stage treatment system consisting of a biofilter and a wet scrubber, the wet scrubber should come first to remove inorganic contaminants that would damage the microorganisms in the biofilter. Dry media is generally a final polishing stage or an initial polishing stage with a venturi scrubber to remove dust.

Limescale build-up in wet scrubbers

Limescale build-up is a common problem in wet scrubbers. It decreases performance, reduces operational capacity and breaks machines when the build-up is thick. Unfortunately, limescale build-up is not preventable, but it is manageable.

Cleaning is easy; all you do is run a biodegradable cleaning agent through the system following a set number of cycles. Using water softeners during cycles will reduce limescale build-up, helping the cleaning agent do its job.

Incorrect microbiology in biological systems 

Biological odour control systems are self-contained and self-sufficient. The lead cause of failures in biological systems is incorrect microbiology – we need an environment where microorganisms can survive and thrive.

When designing biological systems, we partner with leading academia covering key microbiological aspects: selecting and cultivating tailored bacteria and specialist seeding and population health monitoring.

A worst-case scenario for a poorly designed biomass is a complete failure, i.e. the microorganisms don’t survive. This can happen because the air flowing through the filter is toxic to the microorganisms, or the organic compounds are not assimilated, so the microorganisms starve and wither away.

Not following recommended maintenance cycles 

Odour control systems need scheduled service and maintenance cycles to prevent reactive maintenance and reduce costs and disruption.

A lack of maintenance, such as failing to clean and lubricate parts and not replacing filters at recommended intervals, invites problems. Without maintenance, odour control systems will be less efficient and could suffer breakdowns.

Here are a few examples of maintenance:

  • 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.

Find out more

Speak to one of our odour control experts today to find out more about how we help keep odour control systems working at their best.

How To Estimate the Odour Control Unit Capacity?

Implement Odour Control

Whether we’re talking about chemical storage tanks, lagoons of slurry or food manufacturing, we design every odour control system to achieve a measured removal rate in ouE/m3. Additionally, every odour control system has a flow rate measured in m3/hr, which lets us calculate the system’s treatment capacity.

This article will explore these odour control measurements so you can estimate the odour unit capacity and removal rates of your systems.

Odour control unit capacity

Odour control systems process a maximum airflow volume measured in m3/hr (cubic meters per hour). We estimate m3/hr requirements based on the operational capacity of the plant/site.

Another unit of measurement is ouE/m3 (One European Odour Unit per hour), which is the number of odorants evaporated into one cubic metre of gas. ouE/m3 sets the target for the odour removal efficiency, defining outlet concentration.

Understanding m3/hr

Simply, m3/hr is how many cubic metres of air the odour control unit will process in an hour. A higher m3/hr means it has a higher capacity.

However, a higher capacity is not always desirable, especially in smaller systems, because a higher capacity means a more extensive, more complex system, which increases cost. Thus, finding a balance between capacity and size is crucial.

A standard odour control unit has a capacity of 50 m3/hr to 1,000 m3/hr, which sounds like a lot. Still, it is nothing relatively speaking – OSIL’s CCU (Containerised Carbon Unit) treats 6,000 m3/hr to 45,000m3 /hr with a stackable design.

The ability of an odour control system to treat airflow volumes depends on four key factors:

•  System size

• Adsorbent selection

• Adsorptive capacity

• Process conditions – temperature, chemical constituents, moisture

There is more to satisfying a required m3/hr than pumping lots of air through an extensive system; the odour control system needs to treat the air effectively and achieve a desired ouE/m3 (odour concentration).

Understanding ouE/m3

Simply, ouE/M3 is how we measure odour control unit capacity. It is an objective measure of odour concentration (the amount of odour).

All odour control systems take contaminated air gas and treat it mechanically, chemically, or biologically. ouE/M3 can be measured before and after treatment to determine the efficiency of odour removal.

OSIL and most other odour control experts use ouE/m3 because it is the European standardised method of conducting olfactometry. It accurately tells us the concentration of odours, so we can measure removal rates and efficacy.

In odour monitoring and olfactometry, ouE/m3 measurements are usually described with the following notation:

C98, 1-hour = x ouE/m3 w

• x: Limit concentration in ouE

•1-hour: the average time the concentration is calculated

• 98: the percentile that is used to derive concentration value

This notation is used in odour monitoring to define odour concentrations, allowing us to measure tiny concentrations. This is helpful when designing mitigation measures and fine-tuning the performance of odour control systems.

Find out more

Want to find out more about odour control solutions? Contact us today and speak with one of our experts. Just call +44 (0)1543 506855.

Wastewater Treatment: Are your odour controls optimal?

Wastewater treatment plants are treating more wastewater than ever, and processing volumes are growing each year.

As processing volumes grow, treatment works get upgraded or extended, and odour controls should follow suit. However, it is common for a gap to form between wastewater treatment and odour control, creating inefficiencies in the odour removal process. 

If your odour control process is not working at its optimal performance, your treatment plant will produce nuisance odours and possibly generate complaints 

which could result in legal action.

Odour complaints are a serious matter!

Stricter environmental controls and increased processing volumes mean the encroachment of odours on residential areas is a now severe concern.

Unfortunately, nuisance odours like Hydrogen Sulphide (H2S) generate public complaints because they can impact on people’s lives in the area. 

A loss of reputation and souring relationships with residents and other local businesses is possible, not to mention fines from the local council, who can serve an abatement notice if your treatment plant does not address complaints effectively.

Integrated Approach

There is a need for an integrated approach to odour control on wastewater treatment plants to make the processing of odour efficient by design.

What does an integrated approach mean? It means reviewing the odour source, taking the appropriate samples, determining the characterisation, carry out impact assessments, and control techniques to design a totally integrated solution.

The minimisation and abatement of unpleasant odours is a significant challenge for wastewater treatment plants. By taking an integrated approach, you can make sure your odour control process 

meets your requirements completely.

Odour monitoring and sampling

Odour Sampling

Odour monitoring and sampling are crucial for the detection and measuring of essential odour-generating compounds in wastewater treatment emissions.

By collecting this data, we can size and specify odour control solutions that are not only fit for purpose but designed to maximise removal rates.  

A simple example is using on-site data loggers to measure the odours produced by different holding tanks. For more complex odours, we might use Gas Chromatography-Mass Spectrometry (GC/MS), which tells us the gas’s molecular components

Odour control technologies

Odour control technologies are systems that physically, chemically, or biologically remove odorous compounds from gaseous air streams.

The right technology depends on how odours are formed in the wastewater treatment process, the source of the odours and their characterisation. These factors also determine the size of the system and the number of treatment stages.

Because wastewater treatment plants produce a complex range of odorous compounds, they sometimes require multiple treatment stages.

For example, odours might pass through a wet scrubber to remove acidic compounds, then a  biofilter to remove biodegradable compounds and then a carbon filter as a final polishing stage before venting to the atmosphere.

OdaCompact is an elegant solution with a centralised odour control system offering a two-stage odour control system in a single tower. It combines LavaRok biofiltration with CuCarb Dry Media filters – the biofilter scrubs organic odours while the carbon filter neutralises VOCs and chlorinated compounds, producing a cleansed air stream.

Find out more

Are your wastewater odour control systems working to their optimum? Contact us today to arrange a site survey and for helpful advice from our experts.

How To Choose the Right Odour Control Technology?

Implement Odour Control

To choose the right odour control technology, first, we need to identify the types of odour you produce and the concentration of the odours.

Many processes produce predictable odorous compounds as by-products, like hydrogen sulphide and ammonia. However, we still need to figure out the makeup of the compounds to choose the right odour control solution.

Odour monitoring and sampling

For existing processes, we use odour monitoring, a scientific process that detects and collects data about odours such as concentration and type.

The following data sets are useful:

  • F – Frequency
  • I – Intensity
  • D – Duration
  • O – Offensiveness
  • L – Location / R – Receptor

Techniques for acquiring data include olfactometry, which requires physical sampling and analysis in a lab, instrumental odour monitoring systems (electronic noses that collect data and send it to a control centre) and the human nose using trained experts.

Odour sampling and analysis is taken further by Gas Chromatography-Mass Spectrometry (GC/MS), which tells us the gas components at a molecular level. GC/MS is crucial when odours are complex and not easily identifiable.


Pre-build processes 

For pre-build processes, odour control should be built into the process to integrate the technology and solution fully.

When specifying odour control systems for new processes, we consider the types and concentrations of odours that are predicted to be produced, air and flow rate, available site space, maintenance requirements and treatment location.

We know what technologies work for odours through experience and fieldwork, not to mention the vast scientific research over the years. Your build will have specifications, so we’ll specify technologies that meet your demands.

Available technologies

Once we know more about the odours you produce, we can look at specifying technologies that will deal with them. Here are a few available technologies:

  • ChemKlean (wet scrubbing) – Removes odours from air gas streams using a liquid chemical absorbent. Specified for basic odour control applications like inlet works. 
  • LavaRok (biofiltration) – A biological filter made from pumice stone with bacteria that turns biodegradable compounds into food.
  • Tube vents and a passive filter – Specified for vent gases and tanks to absorb hydrogen sulphide and other noxious odours produced in sewage treatment.
  • OdaCompact (two-stage treatment) – Two stages of odour treatment in a single tower, combining LavaRok biofiltration with CuCarb dry media filters
  • CCU (Containerised Carbon Unit) – A stackable, containerised odour control system that uses activated carbon adsorption with CuCarb filters.  

Localised vs centralised odour control

Sometimes, the right technology setup depends on the floorplan of the site, with site space also a factor in sizing and specifying odour control systems.

Localised odour control includes several smaller odour control systems located close to the emission source, eliminating complex pipes and ductwork.

Centralised odour control includes ductwork to move contaminated air into a central, large odour control system, which can be located externally.

For multi-stage treatments, we can also combine localised and centralised odour control. In this setup, localised systems might scrub non-organic odorous compounds to prepare the air gas stream for final polishing in a larger biological system.

Speak to one of our odour control experts today to find out more about how we size and specify the right odour control solutions for our customers.

How Odour Control Depends on Service and Maintenance

Odour control systems require regular service and maintenance to prevent equipment failures and assure system performance. 

Service and maintenance are crucial parts of an odour control system’s life cycle because they manage wear and maximise lifespan.

It’s important to note that all odour control systems, biological or chemical, have specific needs that can only be managed with service and maintenance, so their uptime and performance depend on S&M.

Examples of requirements

With chemical scrubbers, a build-up of limescale (calcium carbonate) can block and damage the system. Water softeners must be used to manage limescale, with pipes and components (including tanks) cleaned extensively during maintenance.

With dry media filters (activated carbon and impregnated carbon, oxidising alumina media, and hybrid, multi-media filters), old media needs replacing with new media when spent, so routine maintenance is necessary to assure performance.

With biological scrubbers (both biotrickling and biofilter types), the microbiology of the biomass can get knocked out of whack if the biofilter isn’t managed. Microorganisms in the filter need to be fed the right odorous substances to survive, so changes inlet stream can directly affect removal efficiency and biomass health.

Assuring total system performance

When an odour control system uses a variety of technologies/processes to remove different odorous compounds in a cycle, we have to consider the system as a single unit, where the performance of one technology affects the other.

For example, a wet scrubber might remove inorganic compounds from  the contaminated air streams to prepare them for biofiltration, which will remove organic, biodegradable compounds. Dry media can then be used as a final polishing stage.

Consider these odour control systems like links in a chain. Service and maintenance keep each link in optimal condition, so the systems function as one. If one fails, the whole cycle is broken, causing costly downtime.

Managing carbon emissions

Another important reason for service and maintenance in odour control is reducing total carbon emissions from odour control processes.

Inefficiencies brought about by a lack of maintenance, like failing to clean and lubricate parts and not replacing filters at recommended intervals, can significantly increase  emissions from operations. Systems could use more power, or you might have breakdowns that create an increase in emissions.  

Do you need help with S&M?

We recommend monthly checks for all odour control systems. During a monthly health check, a visual inspection of the plant and associated equipment will be performed, and physical tests will be conducted to measure and monitor performance.

Here are a few examples of maintenance:

  • 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.

Preventive maintenance is necessary to prevent larger problems, and it is cheaper than repairing damaged equipment. Every business should have a service and maintenance plan, and we can help if you need one.  

OSIL offers a full range of service and maintenance packages to suit all requirements and budgets. Gold, Silver & Bronze packages are available, and we service and maintain our systems and equipment from other supplies.

Feel free to call us on (0) 1543 506855 for a chat about how we can help you.

Get rid of odours at petrol and fuel refineries


Petrol and fuel refineries produce a variety of odorous compounds including sulphides, mercaptans and hydrocarbon compounds.

These refinery odours can seep into the atmosphere and cause nuisance complaints, damaging the refinery’s reputation.

Inevitably, completely getting rid of petrol and fuel refinery odours isn’t possible – like all odours, we can only control and manage them.   

Thankfully, petrol and fuel refinery odours can be efficiently dealt with using modern filtration systems that remove, absorb and adsorb odorous compounds.

Such systems need to be properly sized and specified for the application, but first, it is necessary to analyse odours and monitor them so that we can evaluate odour problems and devise accurate, efficient and effective solutions.

Odour monitoring

Data logging

Odour monitoring involves using sensors to monitor the sources of odours so we can evaluate the extent and types of odour produced. Armed with this information, we can at least offer basic advice on appropriate solutions.


Olfactometry is an in-depth, lab-based odour analysis that detects and measures key odour-generating compounds. It measures the concentration of odours with an odour number that determines the strength of the odour.


Gas Chromatography Mass Spectrometry (GC-MS)

GC-MS combines gas chromatography (which tells us the various components of an odour) with mass spectrometry (which tells us the mass-to-charge ratio of one or more molecules present in a sample), giving us an odour breakdown.

Odour control systems

To get rid of odours at petrol and fuel refineries, we can use a variety of odour control systems in either single or multi-stage treatment processes:

Passive filters (adsorption)

High-quality ‘passives’ offer effective hydrogen sulphide and VOC removal. Oil and chemical storage tanks, vents and containers are prime applications.

Our passive filters have a disposable/refillable filter, and the carbon media can be tweaked to remove different odours. For example, impregnated carbon can be used to remove NH3 (ammonia) with high efficacy.

Passive Filters and Tube Vents

Dry scrubbing (adsorption)

OSIL’s activated carbon dry scrubbers offer effective hydrogen sulphide, VOC and ammonia removal at high flow rates. Dry scrubbers are a good solution for petrol and fuel refineries that produce significant volumes of organic odours.

Our dry scrubbers can operate as a single standalone unit or as a polishing unit downstream of biological or chemical treatment systems.

Dry Scrubbing

Wet scrubbing (absorption)

Wet scrubbers remove contaminants from air gas streams with a liquid absorbent (water with chemical additives). Our ChemKlean® Scrubbing System can be utilised for inlet works and exhaust gases for petrol and fuel production processes.

Wet scrubbing is often paired with a biological treatment, or the OdaCompact® system, a space-saving system that combines LavaRok® biofiltration dry media.

Wet Scrubber

Biological systems (degradation)

Biotrickling filters and biofilters are two types of biological system that use a biomass to remove organic compounds from air gas streams.

Our systems use LavaRok® for the media bed. The big benefit of LavaRok® biofiltration for refinery odour control is it produces no contaminated sludge as a by-product, so it significantly reduces waste.

Biological System

Providing odorous compounds are biodegradable, biological systems will treat large volumes of air with excellent efficiency.

Biological treatments can be used in refineries to remove odours from gas flaring systems, bitumen production and septic water areas.

Find out more

If your refinery is looking into odour control solutions, contact us today for a chat about how we can help you meet your goals.

Odour management guidance for refineries


Refineries have their work cut out to control odours and reduce noxious, unpleasant emissions, but with good strategy and advice from experts, it’s possible to abate odours while minimising waste and energy usage. 

The following odour management guidance for refineries provides an introduction to odour management. For personalised advice, please contact us.


In the United Kingdom, the following legislation applies to odour control:

  • Environmental Protection Act, (EPA)
  • Town & Country Planning Act, (TCPA)
  • Environmental Permitting Regulations, (EPR)
  • Industrial Emissions Directive, (IED)

Before embarking on any odour control investment and upgrades, you must review the legislation that places obligations on your refinery.

It’s important to note that while existing regulatory frameworks for controlling and managing odour issues exist, they are not specific to refineries.

Odour Management Strategy

An Odour Management Strategy (OMS) will define your refinery’s direction and goals for odour control. It will describe what you want to achieve, for whom, and what you need to do to achieve those goals with a division of responsibilities.

Your odour management strategy should consult several experts, including an odour control specialist, to determine what is achievable.

Odour Management Plan

An Odour Management Plan (OMS) is created from the odour management strategy. It will outline the procedures for reducing odours and the impacts associated with emissions from sources, so they can be mitigated effectively.

An odour management plant has four core parts:

  • Plan – Identify odour sources and potential new sources of odour and detail prevention, control and mitigation strategies. Plan training for staff, plan preventative maintenance and detail odour complaint response protocols.
  • Do – Identity the prevention, control and mitigation strategies that need to be implemented, put in place training, establish odour complaint response protocols and implement administrative controls.
  • Check – When everything is running, verify that the measures you planned and put in place are effective. Monitor odours and inspection protocols and keep records.
  • Act – Review and revise your odour management plan as needed to ensure your refinery continues to deal with odours effectively.

Measuring odours


To deal with odours effectively, refineries must understand the odours they produce to empower their odour management policy.

An odour impact assessment should be performed to measure odour levels and create a clear picture of the odours produced. 

Odour impact assessments can use various quantitative and semi-quantitative techniques, including sniff surveys, sensor and data loggers, chemical concentration measurement and olfactometry with results measured in a lab.

Olfactometry analysis is used to quantify the concentration of odours with an odour number that determines the

strength of the odour.

Odour control systems

Odour Control Solutions

Odour control systems in refineries include:

  • Biofiltration: Applications include gas flaring systems, bitumen production, septic water areas. Removes organic contaminants effectively, with no effluent waste and no secondary air pollution.
  • Wet scrubbing: Applications include alkylation, bitumen production, storage (facilities) and loading. Removes soluble compounds like SO2, ammonia, H2S and VOCs with high efficacy.
  • Passive filters: Applications include oil and chemical storage tanks and tube vents that vent odorous gases. Filters H2S and VOCs. Impregnated carbon media can filter NH3, boosting potential chemical applications.

Find out more

If your refinery is looking into odour control solutions, contact us today for a chat about how we can help you meet your goals.

Refinery Odour Control – Key Systems and Technologies


Odour control is an ongoing requirement for industrial oil refineries. Unavoidably, oil refineries produce strong nuisance odours from handling, storing and processing oils, as well as manufacturing fuels, greases and lubricants.

Refining crude oil down into its various components releases sulphides, mercaptans and hydrocarbon compounds. Oil refineries also have to contend with odours from combustion, gas flaring systems and contaminated wastewater.

These odours are unpleasant and also noxious, so they must be controlled to minimise their impact on the environment.

Thankfully, odour control in oil refineries is made possible with correctly sized and specified odour control solutions. This article will run through the key technologies, so you can figure out the next steps in your odour management strategy.


Application: Gas flaring systems, bitumen production, septic water areas.


Biofiltration is an effective single-stage and multi-stage treatment with adsorption and absorption for organic odours. It has a high efficiency for odorous substances and produces no contaminated waste (sludge) for disposal.

Our LavaRok® biofiltration systems use pumice stone as the support material on which the micro-organisms grow and establish a viable biomass. Pumice is an alternative to woodchip and shells with a lifespan of around 25 years.

With LavaRok®, there is no secondary air pollution, so no CO2 or NOx is produced. The only requirement is a power supply.

For multi-stage treatment in tight spaces, we recommend the OdaCompact® system, a space-saving system that combines LavaRok® biofiltration with CuCarb dry media filters to remove organic contaminants and VOCs in one system.

Passive filters

Application: Oil and chemical storage tanks

Passive Filters and Tube Vents

When oil and chemical tanks are filled and drained, odorous air is released. Passive filters effectively remove organic odorous compounds from air with a removal efficiency rate over 99% with the right media and density.

The most common medias are activated carbon and impregnated carbon with the removal efficiency determined by the media’s surface area.

Passive filters are commonly used to filter the following contaminants:

  • Hydrogen sulphide (H2S)
  • Volatile organic compounds (VOCs)
  • Ammonia (NH3) *Impregnated carbon needs to be specified for NH3.

With passive filters on oil storage tanks, vent gases can be purified and released directly  into the atmosphere. The treatment process is discrete and automated, with air treated as it flows through the filter with no manual intervention.

Wet scrubbing

Applications: Alkylation, bitumen production, storage (facilities) and loading.


Wet scrubbing is the mass transfer of soluble gases to a solvent in a chamber. The contaminated air gas stream is injected through the chamber, and soluble contaminants are absorbed by the liquid and dissolved.

Wet scrubbing is highly effective for scrubbing highly soluble compounds like SO2, ammonia, H2S and VOCs. The downside to wet scrubbing is it produces waste effluent, and chemicals may be needed to remove certain contaminants.

Because it’s simple and robust, wet scrubbing is the most common odour control system used in refineries today. The removal efficiency can be as high as 99%, dependent on stack design, compound solubility and gas concentration.

Find out more

We can recommend solutions and size and specify the right odour control systems for your refinery. Contact us today for a chat.

Odour Impact Assessment – what’s involved?


An odour impact assessment is a survey assessment that provides a qualitative analysis of the impacts of odours within a local vicinity.  

Odour impact assessments are a critical part of odour control policy because they provide unique information on the impact of industrial and commercial activities, enabling operators to take action by resolving identified problems.

Some industrial and waste activities also operate under an Environmental Permit, which requires ongoing assessment for odour management.

The following legislation controls odours in the UK:

  • Environmental Protection Act, (EPA)
  • Town & Country Planning Act, (TCPA)
  • Environmental Permitting Regulations (EPR)
  • Industrial Emissions Directive (IED)

Your organisation may fall under one or more of these legislations.

How does the odour impact assessment process work?

There are five steps in an odour impact assessment:

  • Briefing
  • Planning
  • Sampling
  • Testing
  • Reporting

Stage 1 – Briefing

We will consult with you on the nature of your operations, the extent and types of odour you produce, and the odour control systems, technologies and processes you use in your industrial or commercial operation.

Stage 2 – Planning

Once the basic details of your site and odour control policy are ascertained, we will visit your site and plan the assessment. We will look at your site design, space and odour control systems and design the assessment based on these.

An odour impact assessment can use various scientific techniques, including sniff surveys, dispersion modelling and olfactometry, which measures odour levels with sampling and analysis. With these three techniques, we will establish if you have any problems and what can be done to resolve them effectively.

Stage 3 – Sampling

Sampling involves using specialised equipment to take odour samples which are then analysed in a lab – this is a critical part of odour impact assessments because it is the only way to ascertain the measure the following data sets:

  • Frequency
  • Intensity
  • Duration
  • Offensiveness
  • Location / R – Receptor

Our technicians will take samples in line with environmental and health and safety guidelines.

Stage 4 – Testing

Testing of the samples takes place in accredited laboratories following UK-EU standards for testing. The most common type of testing is olfactometry, which provides an odour number that objectively determines the strength of the odour.

By understanding the intensity, offensiveness, duration and frequency of odours, we can ascertain the impact on local environments from leakage and what control measures need to be in place for sound odour management.

An odour impact assessment will also measure your systems and vents for odours with onsite data loggers, with results provided in real-time to our technicians.

Stage 5 – Reporting

OSIL’s experience in sampling and testing means we can interpret laboratory test results, advise you on outcomes, and provide recommendations.

It’s important to note that all modelling exercises monitor approximate how odours will behave in the environment. The value in modelling comes from our expertise, like the nature of odours and how they behave at ground level.

Find out more

Odour impact assessments are necessary to fulfil your odour pollution obligations and to ensure any odour removal solutions are appropriately specified. Contact us today for a chat about how we can help you.

Everything You Need to Know About Odour Control System Performance Testing

Odour Control Unit

Odour control system performance testing involves physical and automated tests of odour control systems to find problems and assure performance. 

Performance tests are conducted following the installation, upgrade and repair of odour control systems to certify performance, design and capabilities. Periodic tests can also be performed to track system degradation.  

The importance of performance testing

Performance tests are used to evaluate the behaviour of odour control systems in real conditions. The behaviour of the system is measured and analysed, giving us a picture of its performance, efficiency and technical capabilities.

Odour control system performance testing helps us:

  • Measure performance
  • Measure efficiency
  • Assure equipment safety
  • Identify problems
  • Measure degradation over time
  • Test and approve repairs
  • Identify upgrades and improvements
  • Assure performance against manufacturer specifications

Types of odour control system performance testing

Flow and load surveys

Flow and load surveys measure the flow and load of odour control systems to certify installations and identify works that are failing. Tests are designed to accommodate all flow velocities and test maximum system input/output.  

The purpose of these tests is to measure the flow and load of odours into the system, so the system’s efficiency can be measured.  

System performance evaluation

System performance evaluations are used to measure treatment efficiencies and recommend improvements that could yield better results. The performance evaluation will include a test of the system and the final product.

Another critical aspect of performance evaluation is identifying problems. Test results are compared to previous results or manufacturer baselines to identify performance problems, perhaps related to the quality of the treated gas.

Running tests

Running tests are automated tests performed while the odour control system is running to measure emissions, energy use, and machine performance. Software collects data, which is fed back to central control and stored in the cloud.

Running tests are important to monitor system performance and assure operational efficiency. Data from tests is stored for analysis. Some of the newest odour control systems have smart features built-in, simplifying the process.  

Technology review and sector-specific advice

Another kind of performance test involves a review of your technology and a comparison with alternative technologies available. Odour control systems become obsolete every few years, so there are significant opportunities available.

Sector-specific advice could include recommendations for odour control policy based on legislation, upgrades to equipment, new installations that would transform the efficiency of your operation, and how to invest with an asset-light strategy.

How we can help

As an independent operator, OSIL offers unbiased odour control advice with comprehensive services, including system design and build, system refurbishment and upgrades, service and maintenance, air pollution control and testing.

We have extensive experience across all sectors, particularly in the water, waste and recycling sectors, as well as the food and beverage and process industries. This experience means we can deliver unique value to your business.

To find out more about odour control systems and performance testing, contact us today to have a chat with one of our lead engineers.  

Solutions and Technologies for Odour Management in Organic Waste Facilities

Odour Control and Management

With organic waste levels increasing in line with a growing population, organic waste facilities have their work cut out to meet capacity.

Investment in in-vessel composting facilities, including containers, silos, agitated bays and enclosed halls has soared. Still, an often unspoken aspect of organic waste treatment – odour control – has seen soaring investment too.

Organic waste facilities produce various odorous gases because of the decomposition of different types of organic waste, emitting organic gases, aromatics, nitrogenous compounds and S-compounds like hydrogen sulphide (H2S).

Due to increasing volumes of organic waste, organic treatment facilities need increasingly large and efficient odour management systems, which can be as simple as passive filters or tube vents or as complex as multi-stage treatments.

Here’s a run-down of the main technologies used in organic waste facilities:

Biofiltration systems

Biofiltration System

The most prevalent and effective odour control technology for organic waste facilities is biofiltration. Biofiltration systems are low-maintenance, use no chemicals, and produce no sludge, helping to reduce waste further.

In a biofiltration system, microorganisms feed on odorous compounds in air gas streams, assimilating them into the biomass. The microbial action can degrade biodegradable contaminants into CO2, H2O, mineral salts and organic compounds (food for the biomass).

OSIL biofiltration systems use LavaRok®, a modern substitute for woodchip and shells in biofiltration units. LavaRok® is made from pumice stone, which has a 25-year lifespan and promotes a healthy, diverse ecosystem.

Biofiltration systems are used as a primary treatment technology in organic waste facilities because they effectively treat all organic odours.

OdaCompact® (two-stage treatment)

OdaCompact® is a two-stage treatment tower combining biofiltration with CuCarb® Dry Media filters, such as activated carbon filters.

We specify OdaCompact® when a space-saving design is required, and a two-stage treatment is desirable. Each dry media filter is tailored to treat specified odours, with H2S, organic sulphides, ammonia, amines, and VOCs treatable.

Dry media is a good match for biofiltration because it polishes the process, capturing odours the biomass can’t, perhaps because of capacity.

Dry media filters work through adsorption, a process that sees atoms, ions and molecules from targeted gases adhere to the media, producing scrubbed air. The filter media need replacing when spent to maintain the efficiency of the system.

Passive filters  or tube vent filters

Passive Filters and Tube Vents

Passive / tube vent filters are the simplest odour control technology, typically specified for containers, holding tanks and pump sumps under positive pressure to adsorb gases.

A passive filter is designed into a system called a passive odour control unit , a self-contained system. .

Passives are effective at removing hydrogen sulphide and other S-compounds from air gas streams. They use activated carbon in granular or pellet form, which is easily replaced using the refillable filter mounted at the top of the unit.

Passive filters are mostly used in wastewater treatment works, however, organic waste facilities also use them to treat gases from containers, silos and agitated bays. Passives are mostly used as a final polishing stage for treated gases.

Find out more

We can recommend, size and specify the right odour control solutions for your organic waste facilities. Contact us today for a chat.

Odour control for industrial emission treatment

Implement Odour Control

When not controlled adequately, industrial emissions cause significant air pollution, and odorous compounds in these emissions can lead to community complaints and abatement notices from your local council. This makes odour control a key consideration for industrial emission treatment, no matter the scale of the operation.

The following odorous compounds are common in industrial emissions:

  • Amines
  • H2S (hydrogen sulphide)
  • NH3 (ammonia)
  • HCl (hydrochloric acid)
  • SO2 (sulphur dioxide)
  • RHS (mercaptans or thiols)
  • CH2O (formaldehyde, formaline)

These compounds are a by-product of industrial processes like wastewater treatment, chemical processing, food manufacturing and animal rendering.

To control odours, odorous components must be separated from exhaust gases so that emissions can eventually be exhausted out into the atmosphere without causing an odour nuisance. This requires  dedicated odour control treatment.

Odour Control for Industrial Emissions

The most efficient odour control treatment for industrial emissions is a gas scrubber, also known as a wet scrubber or chemical scrubber.

This technology separates odorous compounds out of air gas streams using a liquid absorbent. Wet scrubbers are ideal for removing a wide range of pollutants from air gas streams. They require no operator intervention and have no working parts. They offer up to 99% removal efficiencies in most applications.

Here are some typical applications:

  • Wastewater treatment plants to remove hydrogen sulphide
  • Fertiliser production facilities to remove ammonia from exhaust gases
  • Glass production plants to remove hydrogen fluoride from air gas streams
  • Chemical processing plants to remove water-soluble solvents like acetone

How It Works

A wet scrubber brings a contaminated air gas stream into contact with a liquid absorbent (water with special chemical additives). The air gas stream moves through the chamber where the liquid is misted or finely sprayed through the gas. The odorous compounds in the gas are dissolved into the liquid absorbent.

Wet Scrubber

The treated air then flows out of the scrubber where it can be vented, stored, or undergo secondary treatment downstream with a dry filter or carbon absorber. This is a multi-stage treatment, most often used to target lead (Pb) and/or dioxin and furans (D/F), which may be present in your industrial emissions.

The removal efficiency of a wet scrubber can be as high as 99%. Removal efficiencies are dependent upon stack design, compound solubility and gas concentration.

Key Advantages of OSIL Scrubbing Systems

Our wet scrubbers have no moving parts and require little or no operator intervention, making them ideal for large-scale industrial emissions treatment. They are ‘self-contained’ systems designed to be easy to use and maintain.

All of our odour control scrubbers have the following features:

  • Easy to start up and shut down.
  • Easy to monitor and control.
  • Lowest in class pressure drop.
  • Tolerate a wide variations in odour concentration.
  • Low requirement for recirculation (lower water usage).
  • Up to 99% removal efficiencies across most emission types.

Our wet scrubbers can be used as a single primary treatment or as part of a multi-stage treatment process. We provided an example of this above using a dry media filter or carbon absorber downstream.

Want to find out more about how you can use OSIL wet scrubbers for industrial emission treatment? Contact us now and speak to one of our experts. Just call +44 (0) 1543 506855 or email and we’ll get back to you. 

Odour Management for Organic Waste Facilities

Implement Odour Control

Organic waste facilities produce a variety of foul odours, with gaseous ammonia (NH3) and hydrogen sulphide (H2S) being the biggest culprits.

Potential sources of odour in organic waste facilities include:

  • Composting activities
  • Foul surface water
  • Residual wastes for landfill
  • Storage prior to processing

Odour management for organic waste facilities involves reducing odorous gases that are produced from activities (e.g. with better aeration when composting), monitoring odours, and treating contaminated air so it can be vented safely.

At OSIL, we provide a range of odour management solutions that will help you reduce, control and manage odours in your organic waste facility. We will work closely with you to specify odour management solutions that are fit for purpose.

Odour monitoring, sampling and analysis

Odour monitoring involves detecting and measuring key odour-generating compounds and observing changes that may occur over time. It should form part of your odour management plan in order to assess the following areas:

Odour Sampling
  • How effective your operational practices are
  • The nature of odours and the extent of problems if they arise

The methods used to measure odours are determined by the odour source. This can be an area source (e.g. storage areas, composting zones) or a point source (e.g. a stack or a vent). It’s important to measure odours at all sources.

There are several techniques we can use to monitor odours:

  • Olfactometry
  • Data loggers
  • Gas Chromatography Mass Spectrometry

You may also choose to perform your own activities in the following areas:

  • Complaints monitoring
  • Odour diaries (when necessary)

Using on site data loggers to detect and measure odorous compounds, Olfactometry, and data collected from samples processed using Gas Chromatography Mass Spectrometry (GC/MS), we can build a complete picture of your organic waste facility’s odours, so that we can specify the correct odour control solutions.

You can find out more about how odour monitoring, sampling and analysis works here.

Odour removal

Scrubbing will be necessary to reduce odorous compounds in air gas streams so that contaminated air can be safely released into the atmosphere. We offer a wide range of odour removal solutions to suit your needs.

In organic waste facilities, biological systems are extremely effective for odour removal because odours are forced through a packed media bed colonised by microorganisms. The microorganisms degrade organic odours with excellent efficiency.

Our LavaRok® systems use pumice stone as the support material on which the micro-organisms grow and establish a viable biomass. Pumice is a modern alternative to woodchip and shells with a lifespan of around 25 years.

Odour Control and Removal

Passive filters and tube vents can be used for vent gases. These use activated carbon or impregnated media to absorb H2S and NH3. The filters are disposable/refillable, and we offer a fast turnaround activated carbon resupply service.

Passive Filters and Tube Vents

In organic waste facilities, we typically specify passive filters for storage and waste holding tanks and pump sumps under positive pressure.

Another option is OdaCompact, a space-saving single tower that offers a two-stage treatment, combining LavaRok® biofiltration with CuCarb® Dry Media Systems. This solution is ideal for organic waste facilities that have limited space.

We also offer standardised capital equipment, including Containerised Hi-Flow CuCarb® Odour Control Units, which can be purchased on finance. These filter organic gases with a pre-configured design. Choose a lease or hire to suit your business’s needs.

Find out more

To discuss odour management solutions for your organic waste facility, call us on (0) 1543 506855 to have a chat with our experts.

Passive Filter in Industrial Odour Control

Passive Filters and Tube Vents

If your industrial operation generates noxious/toxic organic gases, passive filters are the simplest way to filter vent gases on storm, sludge, sewage and waste holding tanks, fume exhaust cupboards and pump sumps under positive pressure.

We typically specify passive filters when there is a need to vent otherwise noxious and unpleasant gases out into the atmosphere. We call these systems ‘passive odour control units’  because they are self-contained units.  

OSIL is a leading provider of activated carbon-based, passive filters. We can specify the correct media for your use case. Our filters are disposable/removable and can be placed in the middle or at the top of the pipe stack.

How Passive Filters work

Passive filters are made from activated carbon. The contaminant removal process is adsorption; when contaminated air passes through the filter, certain gases react chemically with the carbon and stick to the media.

Due to the cavernous surface area of the activated carbon, the removal rate of organic gases with passive filters is extremely high. The carbon is extremely porous, so there’s a lot of surface area for the organic gases to cling to.

Passive filters are commonly used to filter the following contaminants:

  • Hydrogen sulphide (H2S)
  • Volatile organic compounds (VOCs)
  • Ammonia (NH3) *Impregnated carbon needs to be specified for NH3. This is specially impregnated to remove ammonia from air gas streams.

Passive filter in industrial odour control

One of the big benefits of our passive filters is they can be disguised as inanimate objects, like bollards, lamp posts and trees. They can also be coated in any colour with textured and matte coatings, so they reflect no light and draw no attention.

The removal efficiency rate with passive filters can exceed 99%. This is dependent on the surface area of the filter, the specification of the carbon, and how contaminated the air is (the first two points are determined by the last point).

Here are a few examples of how passive filters are used:

  • Food factories use passive filters on storage tanks and tube vents
  • Pharmaceutical companies, laboratories and medicine manufacturers use passive filters for fume cupboards
  • The oil and fuel industries use passive filters for vent gases on oil storage tanks and for vapour control in tube vents
  • Wastewater and sewage treatment plants use passive filters for vent gases on storm, sludge, sewage and waste holding tanks
  • Sewage pumping stations use passive filters on  pump sumps under positive pressure so that pumping activities do not generate odour complaints.

Odours that cannot be controlled with broad spectrum media can be controlled with impregnated media, allowing passive filters to be used in many applications. The removal rate of passive filters is measured in ouE/m3.

Talk to OSIL about passive filters

We are a leading supplier of activated carbon-based passive filters and tube vents and we provide a low-cost, fast turnaround activated carbon resupply service. We can design your OCUs to treat a specified ouE/m3. Call us on +44 (0) 1543 506855 to find out more.

Servitisation and Financial Models for Odour Control Systems

Odour Control

When you buy plant outright, you are tasked with looking after it. This puts a barrier between you and the manufacturer, limiting the value you could get from working more closely with them to make your plant work better. 

A solution to this is servitisation, an asset procurement model where instead of buying assets outright, you purchase them with fully integrated services.

The simplest way to explain this concept is with an example. We design, manufacture and sell odour control systems. With servitisation, these products are available on contracts with monthly or quarterly payments and maintenance and servicing included.

This long-term relationship can benefit your business in several ways:

  • Cut costs.
  • Improve performance.
  • Keep your plant in working order.
  • Get access to upgrades and new innovations.
  • Get aftercare, including emergency call outs.
  • Spread the cost of integrated services with monthly payments.
  • Multiple finance models, including lease hire and lease purchase options.

The servitisation aspect of this comes from the integrated services, such as maintenance, servicing, spare parts, call outs, and so on.

With servitisation, you get the products your business needs and the services you want in a single integrated solution that works for you.

Who is servitisation for?

Servitisation is ideal for businesses that require a fully integrated odour control system, including predictive maintenance and service packages, to keep equipment running to optimum levels throughout its lifecycle.

The key feature of servitisation is that rather than just buy equipment outright, you get it looked after by the very experts who designed it. This ensures maximum performance and uptime, not to mention efficiency and reliability.

Traditionally, manufacturers focused on products with little thought given towards the significant value services can bring to customers.

By adding services to products, you get to acquire a state-of-the-art odour control system and get it look after by our experts. Everything can be integrated into a single solution so all you need to do is make your monthly or quarterly payments.

There are two main servitisation levels:

  • Basic aftersales — this typically includes predictive maintenance, repairs and condition monitoring.
  • Advanced services — this typically includes pay-per-use and hire contracts, integrated solutions, call outs and spares.

We can build a servitisation package that suits your needs. Everything will be included in a single contract for your convenience.

Lease purchasing and servitisation

Leasing and servitisation is a match made in heaven for pre-configured odour control systems. Our Containerised Hi-Flow CuCarb Odour Control Units can be purchased through a lease purchase and servitisation forms part of this.

Inclusive service and maintenance is a benefit of lease purchases, which provides a clear advantage over outright purchasing. Service and maintenance is offered to ensure these systems  maintain an optimal flow and perform as intended.

For standardised odour control systems, a lease purchase works very well because you have a route to ownership at the end of your lease agreement.

Servitisation is important for  odour control systems to ensure they function properly. These systems were designed by us, so we are the best people to look after them for you. A lease purchase will guarantee the quality of your odour control system.

Servitisation can also extend beyond your lease purchase agreement after you complete your purchase. This will allow you to maintain your odour control system for years to come, in line with the manufacturer standards that we set.

Lease hiring and servitisation

By its very nature, a lease hire agreement is a model of servitisation because you hire equipment on subscription. In other words, you pay to use equipment you need rather than buy it.

Additional servitisation features with a lease hire typically include repairs, parts, emergency call outs, servicing and predictive maintenance. Some or all of these can be included within a contract to ensure  your particular service requirements are met.

A lease hire is available with our Containerised Hi-Flow CuCarb Odour Control Units, which are plug and play odour control units that use dry media filters. They are delivered ready to use and can be setup on the same day for immediate use.

Containerised Hi-Flow CuCarb Odour Control Units can be used as standalone odour control systems for polishing another primary technology (such as wet scrubbing and biofilters) or as a standalone treatment system for off-gases.

By hiring this equipment, you get to use it for a period that covers your operational needs, and because service and maintenance is included, you don’t have to do anything but use it and make sure it doesn’t sustain damage in your care.

Servitisation opens the door to a long-term relationship

At OSIL, we design and manufacture state-of-the-art odour control systems that are used across most sectors. We can sell these outright, but we are much happier working with our customers to make our solutions work even better.

The odour control systems we manufacture work like clockwork, but our customers get much more from them when we provide integrated services like servicing, maintenance, monitoring and consulting. We will not only sell you an odour control system but create the best package of solutions that benefit your business.

Servitisation can include:

  • Service and maintenance
  • Call outs and repairs
  • Spare parts
  • Upgrades
  • Odour monitoring
  • Odour control strategy
  • Troubleshooting/optimisation

You will only get this scope of servitisation with OSIL. We have designed our business model to move on from one-time investments to “lease of services”.

We can build a servitisation package that includes everything you need on a lease purchase or lease hire. Our design and build services give you a turn-key solution to your air pollution issues, or you can choose one of our containerised solutions.

We provide a complete product and service solution, allowing our customers to use one company for their odour control requirements.

We are focused on leading the market through innovation, collaboration, flexible finance plans and customer service. To find out more, we invite you to speak with one of our odour experts today about how we can help you.

Odour Monitoring in Biogas Projects

Odour monitoring in biogas projects is an essential stage of odour management. It is necessary to ensure that biogas production does not impact the local population. It can also help us locate and identify inefficiencies in equipment.

Biogas and odours

Because modern biogas production takes place in a hermetic environment, biogas plants shouldn’t produce unpleasant odours. However, as most plant operators would attest to, odours are a natural by-product of biogas production which can lead to disgruntled locals and regular complaints.

There are several reasons why biogas plants can smell:

  • The use of non-hermetic equipment, especially during transportation, storage, loading and unloading of organic waste
  • Old and outdated tanks and pipelines, especially those installed over a decade ago made from a metal prone to corrosion
  • Poorly specified odour control systems, including inadequate filtration and wrongly specified odour control technologies
  • Poorly maintained odour control systems, especially those that utilise carbon filters that need replacing after a set time
  • Poorly planned and coordinated biogas plant activities, such as storage tanks being left open and logistics issues that expose waste to the environment.

For those in charge of odour management at biogas plants, there is a clear need to take an analytical approach to odour control. The correct procedure for enabling this in your biogas odour control strategy is odour monitoring.

Biogas and odour monitoring

Odour monitoring provides a reliable evaluation of the odours you produce so that the correct odour control solutions can be specified.

There are a variety of techniques we use for biogas odour monitoring:

Gas Chromatography Mass Spectrometry (GC/MS)

With GC/MS monitoring, we can study odours from liquids, gases and solids. Odours are monitored continuously over time so that data is collected from all biogas production processes across different cycles. This ensures we can collect all available data, not just a snapshot of available data from a moment in time.

Based on the collected data, we can understand the elements that need to be managed, how prevalent they are, and identify options for effective solutions.


In biogas plants, olfactometry is used to measure odour levels and validate odour complaints. We offer industry-leading analysis where we work with accredited laboratories to identify odour thresholds. This allows us to provide an odour number that determines the strength of the odour in the collected sample.

Dispersion modelling

Dispersion modelling helps us understand how odours produced by your biogas plant impact the wider environment. You can think of this process as a series of surveys and tests that determine how odours cause air pollution.

Dispersion modelling will be necessary to build a complete picture of the environmental impact of your biogas production. We will test a variety of factors, including exit velocity, thermal rises, airflow and external factors like meteorological patterns. This will give us a clear picture of how your odours impact the environment.

Biogas and odour control

Odour monitoring eliminates guesswork by providing clear answers to questions regarding odour type, activity and dilution. This enables us to specify the right odour control solutions, so that nuisance odours become a thing of the past.   

The standard odour control technology for biogas is biofiltration, which is extremely effective in applications where odours are mostly organic. Carbon filtration (dry media) can be added upstream for multi-stage odour control. 

Want to find out more about odour monitoring in biogas projects? Contact us today and speak to one of our experts. Just call +44 (0) 1543 506855.

Wastewater Odour Control: An Evolution of Technologies

waste water odour control

Wastewater treatment plants produce significant volumes of odour that must be treated before contaminated air can be exhausted outdoors.  

Most odours produced during wastewater treatment result from anaerobic decomposition of organic matter. Sulphur, nitrogen and methane are released during this process, as are H2S and ammonia. The result is a potent mix of gaseous compounds that if released without treatment would cause significant local unrest.

As the attention paid to odour control has increased with environmental concerns, odour control technologies have become more efficient. There are now several solutions available that can treat wastewater odours efficiently.


Wastewater treatment facilities are tasked with treating wastewater so that some parts can be reused in other processes and the final effluent is suitable for final discharge into the associated river or sea. This process produces several by-products, including noxious air and gases that need to be controlled.

Without adequate odour control processes in place, wastewater treatment plants will cause a nuisance and can generate odour complaints from locals. This can damage the reputation of the company and attract the attention of the local council.

There are several different technologies available to treat odour-causing compounds in gases produced from wastewater treatment and storage. These technologies tend to be used as part of a multi-stage treatment process consisting of a primary and final polishing stage. It is also not unheard of for gases to go through three or more treatments. It depends on the level of filtration required to achieve the desired discharge results.

In this article, we will evaluate the technologies available to wastewater treatment plants to control odours in an efficient and effective way.

Single-stage systems

Single-stage systems

Single-stage systems use only one odour treatment technology. Any single technology can be used. This is most often a wet scrubber, biological filter or passive filter. Single-stage treatment is suitable for basic applications and low levels of odour. For example, you could use a passive filter to reduce odours from a small pumping station.

Multi-stage systems

Multi-stage systems use more than one odour treatment technology. The most common format is a two-stage treatment consisting of a wet scrubber and a carbon filter. However, biofiltration with a carbon filter is also common. Multi-stage systems are more complex but are capable of treating a wide range of odours.

Wet Scrubbers

Wet scrubbers treat contaminated air by bringing the gas into contact with a liquid absorbent. The gaseous compounds pass from the gas to the liquid. A 99% removal rate is possible if the compounds easily dissolve in liquid. A few system designs are available, such as packed tower and atomised mist configurations.

Wet scrubbers are an ideal solution for basic applications in wastewater odour control like inlet works and exhaust gases. Multi-stage scrubbers can remove higher concentrations of odours. A venturi scrubber can be added to remove dust and a dry media filter can be added for insoluble VOC removal and final polishing. 

Acid gases, water soluble inorganic contaminants and volatile organic compounds can be removed with the right absorbent and system. Our ChemKlean® Scrubbing Systems boast outstanding efficiency, offering up to 99% removal rates.


Wet Scrubbers

Wet Scrubber

Biofiltration systems treat large streams of contaminated air. They oxidise odorous compounds from air gas streams using a living biomass of microorganisms with an engineered microbiology. The microorganisms degrade odorous compounds into CO2, H2O, mineral salts and other organic compounds.

Biofiltration systems are most widely used to treat off-gas in wastewater treatment facilities. Providing that odorous compounds are biodegradable, biofiltration treats large volumes of air with outstanding efficiency. There is also no secondary waste because the degraded products feed and form additional biomass.

Our technology, LavaRok®, is a modern substitute for woodchip and shells in biofiltration. It uses pumice stone which has a 25-year lifespan.

OdaCompact® (two-stage treatment)

OdaCompact®  is a new, innovative, two-stage odour control system in a single tower. It combines LavaRokbiofiltration with CuCarb® Dry Media filters. The biofilter neutralises organic odours while the carbon filter neutralises VOCs and chlorinated compounds. This is a space-saving system that’s easy to run and use.

OdaCompact®  is a popular choice in wastewater treatment facilities because it combines two technologies into a single tower. This not only saves space but also simplifies deployment and reduces design and build time. OdaCompact® requires minimal maintenance.

Passive Filters & Tube Vents

Passive Filters and Tube Vents absorb vent gases from sewerage processes. They use an activated carbon, oxidising alumina or hybrid filter to absorb hydrogen sulphide and other noxious odours produced in sewage treatment to reduce environmental pollution. The filters trap odours through adsorption, where odour molecules attach to the filter and bond with it.

Passive Filters and Tube Vents are most widely used for odour control on storm, sludge, sewage and waste holding tanks. Airborne gaseous chemicals (specifically volatile organic chemicals, or VOCs) can be filtered effectively. These systems can be disguised as bollards, lamp posts and trees for use in sensitive areas.

Passive Filters and Tube Vents

Carbon Adsorption

Carbon Absorption

Carbon adsorption is the simplest of all odour control technologies. It captures odour-causing compounds in a filter. This is achieved with an activated carbon, impregnated carbon, or hybrid, multi-media filter. These filters are specified to target different types of odorous compound, but mostly H2S and sulphur-based compounds.

Carbon adsorption is most often used as a polishing stage in a multi-stage odour control system. However, carbon adsorption can also be used as a standalone treatment, so long as the correct type of filter is specified. Different filters treat different odours, including VOCs, H2S, mercaptans, organic sulphides, ammonia and amines.

Our CuCarb® Dry Media Systems are deployed in wastewater treatment facilities through-out the UK.

Want to find out more about wastewater odour control technologies? Contact us today and speak to one of our experts. Just call +44 (0) 1543 506855.

Industrial Odour Control Systems And Solutions

Industrial Odour Control system and Solution

We might be pointing out the obvious, but the best odour control system is the one that works. Different odours call for different solutions and the type of work you do, including the equipment you use, will determine the design of your system.

Design and Build

We offer a complete design and build service to ensure your industrial odour control system is correctly sized and specified.

Our turnkey design service includes:

  • Project feasibility
  • 3D design
  • Equipment supply (including lease hire or lease purchase)
  • Installation
  • Commissioning
  • Training & aftersales support

Why choose OSIL? Because we put quality first. This extends from the quality of our customer service to the expert design and build of your odour control system. We get things right and take care of our customers as a key partner.

Industrial Odour Control Systems

We offer the most complete range of systems to treat every kind of odour, from single-stage wet scrubbers and single stage biofiltration systems to highly complex multi-stage systems.

Our industrial odour control systems include:



Biofiltration systems or biofilters oxidise odorous compounds from air gas streams using a living biomass of microorganisms.

The microbial action degrades contaminants into CO2, H2O, mineral salts or organic compounds. Biofilters are efficient at treating numerous gaseous compounds, including hydrogen sulphide (H2S) and ammonia (NH3).

Our LavaRok® systems use pumice stone as the support material on which the micro-organisms grow and establish a viable biomass. Pumice is a modern alternative to woodchip and shells with a lifespan of around 25 years.

Dry Media

Dry Media Odour Control

Dry media systems use carbon filters that act as an adsorbent to trap odours and retain them. This process filters contaminants from the air.

We offer a range of carbon filters that can be used as a primary treatment or as a polishing stage in a multi-stage treatment system.

Filters include activated carbon, impregnated carbon, oxidising alumina media, and hybrid, multi-media filters. These are used to remove different types of pollutants from the air, such as Volatile Organic Compounds (VOCs) and odorous gases.

Wet Scrubbing

Wet Scrubbing

Wet scrubbers remove contaminants from air gas streams with a liquid absorbent. The contaminated air makes intimate contact with the liquid, and contaminants from the air pass to the liquid, producing non-contaminated air.

Our ChemKlean® Scrubbing System can be utilised as a single-stage odour control treatment for inlet works and exhaust gases.

For more intensive applications, ChemKlean® Scrubbers can circulate more than two liquid absorbents to remove a wider range of contaminants. They can also be paired with a venturi scrubber to remove dust and dry media filters.

Servicing and Maintenance

Odour Servicing and Maintenance

Service and maintenance is necessary to keep your odour control system working as intended. A service will include a health check of the system including a mechanical test and the replacement of serviceable parts where necessary.

We offer Gold, Silver & Bronze S&M packages to suit your system’s requirements. Most large systems require monthly S&M visits while simpler or smaller systems can make do with  quarterly visits or visits twice a year.

OSIL provides a seamless S&M experience with scheduled maintenance available as well as same day call outs for breakdowns and problems. You can trust us to look after your system because we’re the same fantastic team who built it.

Want to find out more about our industrial odour control solutions? Contact us today and speak to one of our experts. Just call +44 (0) 1543 506855.

How To Control Food Factory Odours

Food Factory Odour Control

Food factories generate significant volumes of odour the most offensive of which is hydrogen sulphide gasses (H2S). This smells like rotting eggs and is intolerable.

Food processing also generate VOCs, aldehydes, ketones, alcohols, acids, ammonia, amines and mercaptans which can be equally offensive. Add fats, greases, sludges, slurries and high temperatures to the mix, and you have a breeding ground for unpleasant odours.

Ductwork and extraction

To create a tolerable work environment, food processing odours like garlic, onion, marinated sauces and spices need to be vented efficiently. This makes extraction and the design and quality of ductwork important.

For odour control, traditional systems in food processing utilise a biological or chemical process that breaks down odours through oxidation. Examples of such technologies include LavaRok® biological filters and ChemKlean® scrubbing systems.

Controlling odours in a food factory requires a correctly sized odour control system. These can only be designed with an understanding of the type and size of odour problems you’re experiencing. This starts with odour monitoring.

Odour monitoring

Odour monitoring is the process of collecting data about the types of odour produced and the characteristics and volumes of those odours.

The techniques we use include data logging, Olfactometry, and Gas Chromatography Mass Spectrometry (GC/MS), which combines gas-chromatography and mass spectrometry to identify odours. GC/MS builds a complete picture of odorous compounds so we can select and size the correct odour control solution.

Once we understand the type and size of the odour problem you’re experiencing we can design a solution to manage your odours.

Odour control systems in food processing

There are several technologies available for odour control. These include:

Biological filters

Biofilters have a living biofilm of microorganisms (bacteria) that consume odorous compounds for energy. The microbiology of the biomass is carefully designed to capture specific odorous compounds.

Our technology, LavaRok®, is a modern substitute for woodchip and shells in biofiltration. It uses pumice stone which has a 25-year lifespan.

There are two main types of technology: bioscrubbers, where odours are forced through a media bed colonised by microorganisms in a liquid; and biofilters, where air flows upwards through living biomass where microorganisms absorb pollutants.

Chemical scrubbers

Chemical or wet scrubbers use a liquid absorbent to remove odorous compounds from air gas streams. These systems can be simple for inlet works or form part of a multi-stage filter process that removes higher concentrations of odours.

Wet scrubbers are useful in food factories because extracted substances are often hygroscopic. Wet scrubbers use no pump and can have an integrated water supply. This reduces maintenance and makes cleaning easy.

Multi-stage wet scrubbers often use two or more liquid absorbents, the benefit being that we can target a wider range of compounds. Little to no operator intervention is needed and removal efficiencies can be as high as 99%.

Chemical scrubbers

Dry media systems

Dry media filters include activated carbon, impregnated carbon, oxidising alumina media, and hybrid, multi-media filters. These are used as a standalone filter for polishing another primary technology such as wet scrubbing.

OdaCompact is a good example of such a system. This space-saving single tower offers a two-stage treatment, combining LavaRokbiofiltration with CuCarb® Dry Media Systems. It’s a top choice for food factories with limited space.  

Dry media filters can control H2S, organic sulphides, mercaptans, ammonia and VOCs to a specified ouE/m3. This makes them a good choice in food processing, although they sometimes need to be paired with another process like biofiltration or wet scrubbing.

Want to know more about odour control in food processing? Feel free to call us on (0) 1543 506855 for a chat about how we can help you.

Where can odour control be used?

Where can odour control be used

Odours are a by-product of many industrial processes, including wastewater treatment, incineration, crude oil refinement, chemical processing and food production.

These odours become a problem when they cause a nuisance. This can lead to complaints and attract attention from councils who can serve an abatement notice.

There are several technologies we can use to control odours. Air scrubbing systems, wet scrubbing systems, biological systems and dry media systems are examples of solutions that can remove, reduce and neutralise odours with great efficiency.

Odour control can be used in most applications to mitigate odours. Here are some of the common applications where odour control is used:

Wastewater and sewerage  

Foul odours in wastewater treatment plants are most often the result of anaerobic decomposition of organic compounds. This decomposition produces hydrogen sulphide, mercaptans, amines, and volatile organics. Wet scrubbing is the most flexible technology for this problem. Our solution is called ChemKlean®. Another solution is LavaRok® biofiltration.

Incineration plants

Incineration plants produce flue gas that is vented into the atmosphere. The gas (smoke) must not be dense or noxious. Unpleasant odours are often the result of old-style incinerators. Activated carbon (adsorption) can be used to treat flue gas before atmospheric release, to effectively remove mercury, furans and dioxins.

Food processing plants

Odour Control in Food Processing Plant

The odours produced by food processing plants are among the most potent which is why some have a dedicated odour treatment plant to treat their odours. We can remove or reduce odours at the generation sources or from collected emissions, using a multi-stage scrubber consisting of a wet and dry media filter.

Chemical processing

The manufacturing and processing of chemicals produces odours and fumes that must be controlled for safety. Chemical plants can control odours with chemical scrubbers where the odorous vapours are soluble in a liquid. Activated carbon can be used where the odours are not soluble in a liquid, or these systems can be used together.

Oil refineries and petrochemical plants

Odour Control in Oil refineries and petrochemical plants

Oil refineries and petrochemical plants produce odours from refining crude oil and manufacturing fuels. This process releases sulphides and hydrocarbons. Adsorption with activated carbon is the best filtration solution for removing hydrogen sulphide (H2S) during refinement.

Which odour control method is right for you?

Proven methods for odour control include masking, absorption, and combustion, which work with varying degrees of success depending on the sizing and specification of the odour control system.

The correct odour control system for any application depends on the types of odorous compounds produced. This is normally determined by the industry sector. For instance, wastewater treatment produces a different range of odours to incineration, so requires a different air pollution and odour control solution.

Want to find out more about our odour control solutions? Contact us today to speak with one of our experts. Just call +44 (0) 1543 506855.

How Industrial Companies Can Use Odour Control To Reduce Negative Impact On The Environment

Odour Control Unit

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

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

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.

How to Maintain an Odour Control System

Odour Control System

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

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

Example 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.

Common Problems in Odour Control

Common problems in Odour Control

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.

There are two main types of odour control survey: olfactometry surveys and dispersion modelling surveys, which are utilised for different tasks.

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.

Olfactometry surveys

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.