Industrial rendering plants across India and the globe face one major environmental challenge — odour. Effective odour control in rendering plants is crucial not only for environmental compliance but also for community wellbeing and sustainable industrial growth. The rendering industry plays a crucial role in protecting the environment. Generally, a rendering plant collects animal byproducts such as offal, fat, bones and carcasses from animal slaughterhouses, butcher shops, supermarkets (markets) and farms and turn them into usable materials like tallow, grease and bonemeal. These materials are then used for the manufacturing of a variety of products soaps, animal feed (including pet-feed) and some industrial items. Yet, it carries one unavoidable challenge — odour & high strength wastewater. In this blog we would like to cover, how to handle the pungent, persistent smell from rendering operations, which is one of the most complex environmental issues industries face today. Odour emissions are not merely an inconvenience; they directly influence community relations, regulatory compliance, and the public image of the company. For progressive industries, this challenge has become a defining factor in their sustainability and ESG (Environmental, Social, and Governance) strategies.

At the forefront of this transformation are modern engineering solutions like those deployed by Elixir Enviro Systems that combine science, environmental responsibility, and innovation to create cleaner, more sustainable air treatment systems for rendering plants.

Where Does Odour Come from in Rendering Plants?

To control odour effectively, one must first understand its origin. Rendering plants handle raw animal materials such as offal, blood, bones, feathers, and fat residues. During processing, cooking, drying, and pressing, these organic materials decompose, releasing volatile organic compounds (VOCs), hydrogen sulfide (H₂S), ammonia, mercaptans, and amines. These compounds are potent even in low concentrations. For instance, hydrogen sulfide is noticeable at just a few parts per billion and produces a strong “rotten egg” smell, while mercaptans smell even stronger and are often detected far from the source. Uncontrolled odour can travel over large distances, affecting nearby communities, attracting complaints, and even halting production due to environmental violations. Hence, rendering plants increasingly rely on engineered odour control systems designed to target these compounds through physical, chemical, and biological means.

Why Odour Control Matters Beyond Compliance

The modern rendering industry is evolving. Regulations now demand comprehensive environmental management systems that align with ESG and sustainability commitments. Odour control has become a key ESG indicator because it reflects a plant’s environmental responsibility, social accountability, and operational transparency.

A robust odour control strategy brings measurable advantages:

Regulatory compliance with pollution control boards(regulatory agencies) and environmental agencies
Improved community relations by reducing complaints and promoting goodwill
Enhanced workplace safety through improved air quality
Stronger ESG reporting that aligns with global sustainability frameworks
Better brand reputation, as odour-free operations symbolize responsible industry practices

Companies like Elixir Enviro Systems have recognized that odour control isn’t just an environmental requirement — it’s an operational necessity and a reputational advantage.

Engineering the Air: How Rendering Plants Can Achieve Effective Odour Control?

Odour control in rendering plants is a multi-layered process that requires understanding of airflow patterns, pollutant chemistry, and microbial treatment. Below are the most effective engineering strategies used globally — adapted and optimized for Indian and international industries by Elixir Enviro Systems.

1. Capture and Containment

The first step in managing odour is preventing its escape. This involves designing airtight a good ventilation systems to capture emissions from:

Cookers and dryers
Pressing and decanting units
Fat and meal storage tanks
Blood drying systems

A proper ventilation system ensures that all air carrying odourous compounds is directed to a centralized treatment unit instead of being released into the atmosphere. This not only minimizes fugitive emissions but also improves the efficiency of odour control technologies.

2. Chemical Scrubbing Systems

Scrubbers are among the most reliable methods for treating high-intensity odour streams. In these systems, acidic or alkaline solutions are used to neutralize gases such as the alkaline odourous compounds like ammonia, & the acidic odourous compounds like hydrogen sulfide.

Elixir’s engineered scrubber designs optimize contact time and chemical efficiency, ensuring minimal chemical consumption with maximum odour removal. Multi-stage scrubbers are often used to treat mixed compounds, for instance, an acid scrubber followed by an oxidizing scrubber for complete neutralization.

3. Biological Odour Control Units

Biological systems utilize microorganisms to naturally degrade odourous gases into harmless compounds such as carbon dioxide and water. They are sustainable, cost-effective, and energy-efficient solutions for continuous odour control.

Biofilters:

Biofilters use organic or synthetic media to absorb and biologically degrade VOCs, ammonia, and H₂S. They achieve 85–95% odour removal efficiency and are ideal for air from enclosed conveyors, pits, and dryers. Regular media maintenance ensures consistent performance.

Biotrickling Filters:

These systems use synthetic packing material continuously irrigated with nutrient-rich water, supporting microbial activity for odour degradation. They achieve 90–98% efficiency and are suitable for high-concentration ammonia and H₂S streams, though they require controlled water and nutrient supply.

Bioscrubbers:

In bioscrubbers, odourous air passes through a liquid medium containing active microorganisms that degrade water-soluble pollutants. They achieve 80–90% efficiency, ideal for ammonia-rich odours, but require additional water treatment and energy for recirculation.

4. Thermal and Catalytic Oxidation

For rendering facilities with very high VOC loads, thermal oxidation or catalytic oxidation provides complete destruction of odourous gases. These systems operate by heating the contaminated air to high temperatures, breaking down volatile compounds into simple molecules like CO₂ and H₂O.

5. Activated Carbon Filtration

In specific sections such as product handling areas or packaging zones, activated carbon filters are used to polish residual odours. The porous carbon material adsorbs remaining organic compounds, ensuring the final discharge is nearly odourless. These systems complement biofilters and scrubbers, creating a multi-barrier odour treatment process. Activated carbon filters work as adsorption media, and therefore generally the carbon units are not recommended for high odour emission industries such as the rendering plants.

6. Plasma Technology:

Emerging non-thermal plasma systems use high-energy electrons to break down odourous molecules at 85–95% efficiency. They are compact and efficient for many contaminants. But not have seen any case study or related document showing use case in the rendering industry. but involve higher operational and maintenance costs due to electrode replacement requirements.

7. Combination Treatments for Odour Control

In many cases, combining technologies improves overall efficiency and ensures comprehensive odour removal across multiple sources.

Common hybrid systems include:

Chemical Scrubber + Biofilter:

The pretreatment with chemical scrubbers followed by the Biofilter for polishing seems ideal choice for the Odour Control from the Rendering plants. This combination can ensure the air for total efficiency up to 99%.

Thermal Oxidation + Biofilter:

Used in facilities with separate odour streams, where intense odours are treated thermally and moderate ones biologically, balancing cost and performance.

Biofilter + Activated Carbon Filter:

Biofilter removes major odorous gases (85–95%), and activated carbon filters polish the air for total efficiency up to 99% — ideal for reception pits and enclosed areas.

Chemical Scrubber + Biotrickling Filter:

This pairing achieves up to 95–98% total efficiency, handling mixed acid and alkaline gases effectively in high-odour-load plants.

Chemical Scrubber + Activated Carbon Filter:

Scrubbers neutralize H₂S and ammonia, while carbon filters remove VOCs — giving 95–99% efficiency, ideal for plants with multiple odour sources.

Though biological odour control units are very efficient, the use of biological systems alone for rendering plants is not advisable. As the load is very high from the rendering plants, the biological treatment units shall take up a very large floor space. Hence in the case of rendering plants it is always better to have a combination treatment. These hybrid systems are customized based on air volume, odour type, and emission intensity, ensuring optimized cost and performance for every rendering plant.

Integrating Wastewater and Air Odour Control

Apart from the challenges of having high strength wastewater, the wastewater treatment plants in Rendering plants also can release secondary odour during collection and treatment. By integrating wastewater treatment with air odour management, facilities can prevent odour migration from open tanks, sludge drying beds, and effluent channels.

Elixir’s integrated design approach combines:

Covered tanks and pipelines to limit volatilization
Anaerobic digesters for biogas capture and reduction of load
High rate Biological Nutrient Removal (BNR) plants to remove both COD and nutrients
Odour scrubbers for headspace gases

This holistic design ensures consistent odour control throughout the plant, maintaining compliance and environmental integrity. The details of the wastewater treatment maybe discussed in a separate blog.

Odour Control Regulations and Standards

In India, the Central Pollution Control Board (CPCB) and respective State Pollution Control Boards (SPCBs) set strict emission standards for rendering operations under the Air (Prevention and Control of Pollution) Act, 1981, but at present the CPCB doesn’t give specific regulation on Odour control in India.

Globally, regulatory bodies such as the U.S. Environmental Protection Agency (EPA) and the European Union’s Industrial Emissions Directive (IED) also enforce odour and air quality standards for animal by-product processing facilities.

Elixir Enviro Systems ensures that every system — from scrubbers to biofilters — is designed to meet or exceed these emission norms, helping clients maintain environmental compliance both in India and worldwide

Smart Monitoring and Modelling: The Future of Odour Management

Modern odour control goes beyond physical systems — it now integrates real-time data, digital simulations, and predictive monitoring for better performance and compliance. Elixir Enviro Systems utilizes advanced odour dispersion modelling to predict and assess odour behaviour under varying operating conditions. This enables engineers to optimize air capture points, ventilation strategies, and treatment system capacity with greater accuracy. Onsite odour monitoring units continuously measure parameters such as hydrogen sulphide (H₂S) and ammonia concentrations, allowing proactive intervention before odour complaints or threshold exceedances occur. This data-driven approach enhances transparency and supports ESG (Environmental, Social, and Governance) reporting by providing measurable, verifiable environmental performance indicators.

ESG in Action: How Odour Control Reflects Environmental Commitment

Rendering facilities are now integral to circular economy models, transforming waste into value. But to remain sustainable, they must operate within the boundaries of environmental stewardship. Odour control is one of the most visible reflections of ESG compliance. It demonstrates commitment to:

Environmental goals: reducing emissions and protecting air quality.
Social responsibility: improving community health and relations.
Governance: maintaining transparent, data-backed environmental performance.

Elixir Enviro Systems aligns its technologies with these ESG pillars, helping industries not only meet legal standards but also exceed them — turning odour control into an opportunity for sustainable growth.

Elixir Enviro Systems: Delivering Advanced Odour Control Solutions for Rendering Plants

Elixir Enviro Systems is a leading provider of industrial odour control solutions for the rendering industry, helping facilities eliminate nuisance emissions and meet the highest environmental standards. With decades of expertise in air treatment, wastewater management, and environmental engineering, we deliver custom-built systems that ensure cleaner air and sustainable operations. Our odour control solutions for rendering plants combine chemical scrubbers, biofilters, biotrickling filters, and hybrid systems designed to treat complex odourous compounds such as hydrogen sulfide (H₂S), ammonia, amines, and volatile organic compounds (VOCs). Each system is engineered for high efficiency, achieving up to 95–99% odour removal while minimising energy use and maintenance costs.

Key strengths of our rendering-specific systems include:

End-to-End Design and Installation: From air capture ducts and exhaust systems to treatment units and stack dispersion.
Hybrid Odour Control Systems: Combining biological and chemical filtration to manage varying odour loads efficiently.
Onsite Odour Monitoring: Continuous H₂S and ammonia measurement for real-time performance tracking and compliance.
Integrated Wastewater and Sludge Odour Control: Managing emissions from process water, condensate, and sludge handling.

By integrating these systems, Elixir Enviro Systems helps rendering facilities move beyond compliance — transforming odour control into a strategic sustainability advantage. Our goal is to engineer odour-free, community-friendly, and ESG-aligned rendering operations that reflect true environmental responsibility.

Conclusion

Odour control in rendering plants is no longer just about removing smells — it’s about engineering a cleaner, more responsible future for industries that serve the circular economy. With advanced air treatment systems, integrated wastewater solutions, and data-driven monitoring, companies can now operate efficiently, meet stringent regulations, and maintain community trust.

Elixir Enviro Systems continues to pioneer this transformation — designing and delivering odour control systems that redefine sustainability in rendering operations. By combining innovation with environmental ethics, the industry can truly render change — for the planet and its people.

Looking to Upgrade Odour Control in Your Rendering Facility?

Connect with Elixir Enviro Systems — specialists in designing end-to-end odour management solutions tailored to your process. From advanced scrubbers, biofilters, and hybrid systems to real-time monitoring and wastewater treatment, we ensure performance, compliance, and peace of mind.

Explore more about our Industrial Odour Control and Wastewater Treatment Solutions at www.elixirenviro.in.

FAQs on Odour Control in Rendering Plants

1. What is a rendering plant?

A rendering plant is a facility that processes animal by-products — such as offal, fat, bones, and carcasses — collected from slaughterhouses, butcher shops, supermarkets, and farms. The goal is to convert waste materials into valuable, reusable products like tallow, grease, and bone meal, which are later used in the manufacture of soaps, animal feed (including pet food), fertilizers, and various industrial goods.

2. What are different types of rendering?

Rendering plants are classified into edible and inedible types. Edible rendering plants process clean, food-grade by-products from slaughterhouses and meat processing facilities to produce edible fats like tallow and lard used in food and cosmetics. Inedible rendering plants, on the other hand, handle materials unfit for human consumption—such as carcasses, condemned meat, and offal—to produce non-edible tallow, grease, and meat and bone meal used in animal feed, biodiesel, and industrial applications.

Based on the processing method, rendering can also be categorized as wet rendering and dry rendering. Wet rendering uses steam or hot water to separate fat from solids, yielding higher-quality fat but consuming more energy and water. Dry rendering involves heating materials without water and separating fat mechanically—an energy-efficient process suited for inedible rendering but with stronger odour emissions. Plants may also operate in batch or continuous modes, depending on scale and production demand. Together, these variations define how rendering plants operate to balance efficiency, product quality, and environmental control.

3. What causes odour in rendering plants?

Rendering plants generate odour from the decomposition of animal by-products such as fat, blood, and offal. During processes like cooking, drying, and storage, gases containing hydrogen sulfide (H₂S), amines, and volatile organic compounds (VOCs) are released. Without proper control, these emissions can cause strong, unpleasant odours and environmental complaints.

4. What are the most effective odour control technologies for rendering plants?

The most effective odour control systems combine biological and chemical treatment methods. Technologies like biofilters, biotrickling filters, and chemical scrubbers remove odourous gases efficiently. In many facilities, hybrid systems — combining biological and non-biological units — achieve up to 99% odour removal efficiency, ensuring regulatory compliance and community satisfaction.

5. How do biofilters help in odour control?

Biofilters use naturally occurring microorganisms to degrade odorous compounds into harmless by-products such as water and carbon dioxide. They are highly effective against amines, mercaptans, and reduced sulfur compounds, offering 85–95% odour removal efficiency. Biofilters are also sustainable, low-maintenance, and ideal for continuous operation in rendering facilities.

6. What are hybrid odour control systems?

Hybrid odour control systems integrate multiple technologies—such as chemical scrubbers with biofilters, or biotrickling filters with chemical scrubbers, Thermal systems & Biological units—to handle diverse odour compounds. This multi-stage treatment ensures maximum odour removal efficiency and consistent air quality, even in high-load rendering operations.

7. How does Elixir Enviro Systems help rendering plants manage odour?

Elixir Enviro Systems provides custom-engineered odour control solutions specifically for rendering plants. Their systems include biofilters, chemical scrubbers, biotrickling filters, and hybrid combinations that effectively remove H₂S, ammonia, VOCs, and amines. Elixir also offers onsite monitoring, wastewater odour treatment, and pilot studies to ensure optimal performance and long-term sustainability.

8. Why is odour control important for sustainability and ESG compliance?

Effective odour control demonstrates a rendering plant’s commitment to environmental, social, and governance (ESG) principles. By reducing air emissions, improving workplace and community health, and ensuring transparent environmental performance, rendering facilities strengthen their sustainability credentials and public trust.

9. How can rendering facilities upgrade their existing odour control systems?

Facilities can upgrade by integrating advanced hybrid systems, adding real-time monitoring units, or improving air capture and ventilation designs. Elixir Enviro Systems offers system audits, performance analysis, and retrofit solutions to enhance odour removal efficiency and reduce operational costs.

Introduction

Industrial facilities play a vital role in the economy, but they often face challenges when it comes to odour emissions. Uncontrolled odours can impact the surrounding community, pose risks to employee health, and result in environmental regulation violations. With increasing pressure on industries to prioritize sustainability and workplace safety, odour monitoring has emerged as a critical solution.

By identifying, measuring, and mitigating odour emissions in real time, odour monitoring helps industries maintain compliance, protect their reputation, and ensure healthier environments. In this blog, we’ll explore the benefits of odour monitoring and how it can transform industrial operations.

Source of Industrial Odour ?

Industrial odour emissions stem from various processes, including:

Food, feed and Beverage Processing: Odours from fermentation, waste management, or organic residue.

Chemical Manufacturing & petrochemical industries:Emissions containing volatile organic compounds (VOCs), hydrogen sulphide, mercaptans, ammonia etc.

Pulp and Paper Industries: Odour caused by chemical pulping processes.

Pharmaceutical Facilities:Byproducts from drug manufacturing processes and bulk drug manufacturing industry have lot of solvents emission (volatile organic compounds-voc) emissions.

Ceramic manufacturing:ceramic manufacturing industries have various emissions like volatile organic compounds (VOCs), Sulphur dioxide and so on.

Wastewater Treatment Plants: Emissions caused by organic material breakdown (e.g., hydrogen sulfide, ammonia).

These odours often contain hazardous compounds like hydrogen sulfide (H₂S) and ammonia (NH₃), mercaptans (CH3-SH), which can be harmful when released in excess. This makes odour monitoring essential to detect and control emissions efficiently.

The Role of Odour Monitoring in Industrial Facilities

Odour monitoring involves using advanced tools and technologies to measure odour levels at their source, within the facility, and in surrounding areas. These tools include:

Real-time odour sensors
Portable monitoring devices
Predictive modeling software
Smart IoT-based monitoring systems

By continuously monitoring odour levels, industries can:

Detect emissions early to take corrective action.
Meet environmental compliance standards.
Enhance relationships with local communities.
Improve employee well-being and workplace air quality.

Key Benefits of Odour Monitoring

1. Early Detection and Mitigation

One of the most significant advantages of odour monitoring is its ability to detect odours in real time. With continuous monitoring, industries can identify odour sources before they escalate into larger issues. This proactive approach allows facilities to take immediate corrective measures, reducing downtime and preventing costly equipment failures.

2. Compliance with Environmental Regulations

Environmental agencies worldwide are imposing stricter air quality and odour emission regulations. Industrial facilities must adhere to these standards to avoid:

Heavy fines
Legal penalties
Operational shutdowns

Odour monitoring ensures that emissions stay within permissible limits, helping industries maintain compliance and operate without disruptions. In India, one of the major cause of company closure is the issue related to odour emissions. We at Elixir Enviro Systems Pvt Ltd, has sorted out the odour pollution related issues in many industries across the country.

3. Improving Community Relations

Uncontrolled odour emissions are a leading cause of public complaints against industrial facilities. Bad odours can negatively impact the quality of life for nearby residents and tarnish a company’s reputation.

By implementing odour monitoring solutions, industries demonstrate their commitment to environmental responsibility and sustainability. This not only reduces public complaints but also fosters trust and goodwill within the community.

4. Enhancing Workplace Safety and Employee Well-being

Persistent odours in industrial facilities can cause health issues such as:

Headaches
Nausea
Respiratory problems

Over time, exposure to harmful odour compounds like ammonia and VOCs can lead to long-term health concerns. Odour monitoring helps maintain clean air within facilities, ensuring a safe and healthy work environment for employees. This, in turn, boosts employee morale, productivity, and retention.

5. Cost Savings Through Data-Driven Decisions

Odour monitoring systems provide real-time, actionable data that helps industries:

Optimize their odour control equipment, such as scrubbers and biofilters.
Reduce energy consumption and operational costs.
Prevent expensive breakdowns by identifying issues early.

The insights gained from odour monitoring allow industries to make informed decisions that save costs while improving operational efficiency.

What Elixir Enviro Systems Does

At Elixir Enviro Systems, we are dedicated to providing comprehensive environmental solutions that address industrial challenges, improve sustainability, and ensure compliance with environmental regulations. Our services in odour monitoring and control play a pivotal role in achieving these goals.

Real-Time Odour Monitoring We provide continuous monitoring of odour levels using advanced sensors. This helps facilities detect odour problems early, before they escalate.
Odour Control Equipment We offer tailored solutions such as biofilters and scrubbers to neutralize harmful odours at their source, improving air quality and reducing emissions.
Onsite Odour Assessments Our team visits facilities to assess odour sources and recommend the best solutions for control and mitigation.

Conclusion

Odour monitoring is no longer optional for industrial facilities; it is a necessity. From early detection and regulatory compliance to improving community relations and workplace safety, odour monitoring delivers substantial benefits. It supports industries in achieving their sustainability goals while maintaining operational efficiency and protecting their reputation.

At Elixir Enviro Systems, we provide advanced odour monitoring solutions tailored to the needs of modern industries. With our expertise in odour control, you can ensure a cleaner, safer, and more sustainable environment.

Introduction

In an era where industries are under increasing pressure to adopt environmentally friendly practices, biofiltration has emerged as a standout solution for odour and air pollution control. This natural, efficient, and cost-effective technology harnesses the power of microorganisms to neutralize harmful compounds in the air, making it a sustainable choice for industries ranging from wastewater treatment to food processing.

In this blog, we’ll dive into the science behind biofiltration, explain how it works, and explore its role in controlling odours and pollutants. We’ll also look at how Elixir Enviro Systems integrates biofiltration into its suite of environmental solutions.

What Is Biofiltration?

Biofiltration is an air treatment process that uses a biological system to remove contaminants from an air stream. At its core, it involves passing polluted air through a bed of organic material, such as compost, wood chips, or peat moss, where microorganisms reside. These microorganisms break down odorous compounds and air pollutants into harmless byproducts like water, carbon dioxide, and biomass.

This eco-friendly technology is particularly effective at treating volatile organic compounds (VOCs), hydrogen sulfide (H₂S), ammonia, and other malodorous or hazardous compounds found in industrial emissions.

How Biofiltration Works

The biofiltration process involves three key stages:

1. Preconditioning the Air

Before entering the biofilter, the air stream is often preconditioned to ensure optimal conditions for microbial activity. This may involve:

Humidification: Since microorganisms thrive in moist environments, the air may be humidified to maintain the appropriate moisture level within the filter bed.
Temperature Adjustment: The air temperature is adjusted to fall within the optimal range (usually between 20°C and 40°C) for microbial activity.
Particulate Removal: Removing dust or large particles prevents clogging of the filter bed.

2. Air Passage Through the Biofilter Bed

The preconditioned air is then directed through the biofilter bed. This bed is composed of porous organic material, which provides a large surface area for microbial colonization. As the air flows through:

Pollutants dissolve into the water layer on the surface of the filter media.
Microorganisms in the biofilm (a layer of microbes) absorb these dissolved compounds.

3. Biological Degradation

Once absorbed, microorganisms metabolize the pollutants as a source of energy and nutrients. This biodegradation process converts harmful compounds into:

Carbon dioxide (CO₂): A harmless byproduct of organic compound breakdown.
Water (H₂O): Released back into the environment.
Biomass: Microbial growth that is periodically managed to maintain system efficiency.

Pollutants Treated by Biofilters

Biofiltration is effective at neutralizing a variety of odorous and harmful compounds, including:

Hydrogen Sulfide (H₂S): A common cause of the “rotten egg” smell in wastewater and industrial processes.
Volatile Organic Compounds (VOCs): Found in emissions from chemical plants, paint production, and printing industries.
Ammonia (NH₃): A sharp-smelling compound often associated with agricultural and food processing facilities.
Mercaptans and Organic Sulfides: Highly odorous compounds from petroleum refining and natural gas operations.

Advantages of Biofiltration

Biofiltration offers several advantages over traditional odour and pollution control methods:

1. Environmentally Friendly

Biofiltration relies on natural processes and does not produce harmful byproducts. It eliminates the need for chemicals or high-energy processes, making it a sustainable option.

2. Cost-Effective

Compared to technologies like thermal oxidizers or chemical scrubbers, biofilters have lower operating costs. They require minimal energy input and utilize readily available organic materials.

3. High Efficiency

Biofilters can achieve removal efficiencies of over 90% for many odorous and harmful compounds. Their effectiveness improves with proper design, operation, and maintenance.

4. Low Maintenance

With routine care, such as moisture control and periodic replacement of the filter bed, biofilters can operate efficiently for years.

5. Wide Applicability

Biofiltration is suitable for a wide range of industries, including wastewater treatment plants, food processing facilities, composting sites, and chemical manufacturing plants.

Challenges in Biofiltration

While biofiltration is highly effective, it does come with challenges that need to be managed:

Moisture Control: Maintaining the correct moisture level is critical for microbial activity. Too much or too little water can hinder performance. Elixir Enviro Systems has perfected the act of moisture control and is operating several systems across the country
Media Lifespan: Over time, the filter bed material may degrade or become clogged, requiring replacements in every 3-7 years time, depending upon the media degradation (loading rate of the system). We have few cases wherein the customer had to change the media only after 7 years.
Temperature Sensitivity: Extreme temperatures can affect microbial activity and reduce efficiency. Elixir Enviro Systems being a pioneer in the field of odour control in India, we know exactly what type of pretreatment to be done on each cases and have treated exhaust gas having over 90 degree Celsius as well.
Start-Up Time: Microorganisms need time to acclimatize to the pollutants, which can result in a slower start compared to chemical-based systems. We mostly used pre- inoculated media to avoid the slow start-up issues faced by the conventional units.
Area Requirement: The biofilter faces another issue – the large area requirement. In India, this is one of the important issue faced by many industries, not thinking about or not have not allocated space for the installation of the Odour Control Unit (OCU). With the innovative products, Elixir Enviro Systems have solutions to this problem. We have a spectrum of biofilter units ranging from conventional open Biofilters, to containerised Biofilters to High rate Biofilters.

Though there are many many challenges, Elixir Enviro Systems have solutions for odour control

Why Elixir Enviro Systems?

At Elixir Enviro Systems (EES), we specialize in turning environmental challenges into opportunities for sustainable growth. Here’s how we can help your business:

Odour Control: Our innovative biofiltration systems effectively eliminate industrial odours at the source, transforming harmful emissions into fresh, breathable air and ensuring cleaner working environments.
Wastewater Treatment: EES provides state-of-the-art wastewater treatment technologies that not only meet stringent regulatory standards but also help you reduce water consumption and promote water reuse, lowering operational costs.
Real-Time Monitoring: Our advanced real-time monitoring systems use data analytics to track and optimize the performance of your environmental systems, ensuring they run smoothly and efficiently at all times.
Consultancy Services: With our tailored consultancy solutions, we guide businesses in designing, testing, and implementing custom environmental systems that align with your specific needs and long-term goals.

Conclusion

Biofiltration represents a perfect blend of nature and technology, providing an eco-friendly and effective solution for odour and pollution control. Its ability to harness the power of microorganisms to treat a wide range of pollutants makes it an invaluable tool for industries seeking sustainable practices.

At Elixir Enviro Systems, we are dedicated to helping industries adopt biofiltration and other innovative technologies to minimize their environmental impact. If you’re looking for a reliable, sustainable, and cost-effective odour control solution, contact us today to learn more about how biofiltration can transform your operations.

Introduction

Last March, residents of Sector 28 Vashi, Navi Mumbai complained of a toxic smell from the local industrial area. The people said that the chemical manufacturers in the neighbouring Trans Thane Creek (TTC) industrial region are the source of the toxic smell. They complained that the toxic smell caused severe discomfort affecting their health and caused contamination of water (Free Press Journal- 8th March 2024)

For many years, residents of Ivy City, Northeast Washington complained of a burning stench in this area. It is only recently that they were able to find the reason behind this. Environmentalists, community activists and residents have concluded that the stench is mainly because of a manufacturing facility- National Engineering Products(NEP) Inc. that makes a sealant for the Navy, using chemicals such as formaldehyde, acetonitrile and methylene chloride. Community activists and environment activists, along with neighbours, worry that NEP’s emissions could endanger nearby families(The Washington Post- 11th April 2024).

The problems caused by Industrial odours are not just limited to India but affect the whole world. Industrial odours arise as a result of industrial processes that release different compounds as byproducts. In low concentrations, these compounds may cause discomfort, nausea, sleeplessness and physiological disturbances but at high concentrations, they can cause severe problems including respiratory diseases, increased stress and altered blood flow in the lungs. Thus, the source of these problems must be identified and steps taken to mitigate its release to the atmosphere. This improves health and ensures the overall well-being of the people.

It is observed that industrial odours mainly arise from industries and factories because of the compounds that are released into the environment. Industrial odour is mainly controlled by physical, chemical and biological methods of which the biological method is most significant, mainly due to the sustainability, low cost and feasibility of conducting at moderate temperatures and pressures. The most prominent Biological methods for odour control include use of biofilters, bioscrubbers and biotrickling filters.

Odour Generating Industries

Industrial odour are generated by variety of organisations, industries and facilities. It includes

Food & Feed Processing Industries: Cocoa processing, Coffee processing, Fish Processing, Bone meal industry, Slaughterhouses – rendering plants, Spices & bio-ingredient extraction units, Sugar manufacturing, Brewery & distillery, acetic acid fumes from bottle cleaning stations, oil mills, feed manufacturing units (fish feed, shrimp feed, pet feed, cattle feed etc) and Livestock operations
Automobile and allied Industries: It also includes foundries, manufacturing of tires, tire/rubber reclaim factories, latex/rubber processing, rubber thread manufacturing units, caprolactam manufacturing, paint manufacturing, metal pickling plants,
Other industries: Petroleum refinery, Pulp and paper, Sugar and distillery, Chemical dye and & dye intermediates, Pharmaceuticals & bulk drugs, Teflon cookware manufacturing, Plastic product manufacturing, printing, tanneries, Gelatin manufacturing, Solvent manufacturing and processing, Tobacco Processing and Other Chemical Industries.
Infrastructure Development: Ceramic production, Plywood manufacturing units, Bitumen Processing units, Wood Processing units Waste Transfer Stations, Treatment plants (Incineration plants, Pyrolysis units, Waste-to-Energy plants, Composting plants, Anaerobic Digestion Plants, Biodrying units), Wastewater lifting/Pumping Stations, and Wastewater Treatment Plants (Sewage Treatment Plants – STP and Effluent Treatment Plants- ETP).

In Ireland in 2023, 90% of the complaints made to EPA (Environmental Protection Agency) were due to noise and odour from various industries like food, recycling, creameries and waste disposal. The Kerala State Pollution Control Board (KSPCB) commissioned a study on the odour pollution-related issues at Edayar Industrial Area in September 2022. The study was done by the CSIR-National Institute for Interdisciplinary Science and Technology (NIIST), Trivandrum on behalf of KSPCB. The study found several deficiencies in the operation of odour control units installed in nearly 20 bonemeal units, chicken waste rendering plans and rubber processing units in the Edayar industrial area.

Causes

Odour from industrial establishments is caused by the chemicals present in the exhaust gas. There are many chemicals responsible for the odorous compounds. Hydrogen sulphide, Sulphur dioxide/ trioxide, nitrogen oxides, ozone, ammonia, volatile fatty acids (eg butyric acid), aldehydes and ketones (eg formaldehyde), mercaptans, amines and alcohols contribute majorly to the odour generated. These chemicals are majorly generated by various industries.

Hydrogen sulphide is a gas with a rotten egg smell. It is detectable at very low concentrations. It is colourless and found in many cleaning products, and animal waste and is a byproduct of several industrial processes like oil refining, mining, craft paper production, rayon manufacturing, food processing, wood pulp processing and tanning. People living near these kinds of industries are most exposed to hydrogen sulphide.

Ammonia and ammonium compounds are also major contributors to Industrial odour. It mainly arises from large-scale animal feed manufacturing, municipal waste treatment plants operations (generally as the byproduct of protein degradation), production of fertilizers, pharmaceutical production and food processing operations. Known for its pungent and piercing smell, ammonia (NH3) is frequently present in animal faeces and a variety of cleaning products.

Nitrogen oxides are mixture of gases composed of oxygen and nitrogen. The most significant of them include nitric oxide, nitrogen dioxide, nitrogen monoxide and nitrogen pentoxide. Oxides are nitrogen are mostly used in the manufacture of fertilizers, explosives, mining and from wastewater treatment plants. Facilities that use welding materials produce nitric acid or certain explosives and workers employed in such facilities inhale oxides of nitrogen.

Sulphur dioxide is colourless with a sharp and pungent odour and is produced by industrial processes like fertilizer manufacturing, steel making, aluminium smelting, ceramic manufacturing and combustion of fossil fuels.

VOC (volatile organic compounds) are another major source of odour and air pollution. The major contributors are the petrochemical industries, paint manufacturing, pharmaceutical and bulk drug manufacturing industries, chemical industries, rubber processing industries etc. A sub-category under the VOCs are the Volatile Fatty Acids (VFA) like butyric acid, acetic acid and propionic acid also contribute to industrial odours. Such acids are mainly generated during fermentation processes, dairy products as well as in the decomposition of fats and oils. One source of VFAs are through anaerobic degradation of organic materials.

Effects

The effects of hydrogen sulphide depend on the concentration as concentrations higher than 150 ppm can paralyse the olfactory nerve and higher than 200 ppm can be life-threatening. People with asthma may be sensitive even to its low concentrations. High H2S concentrations can induce nausea, headaches, and dizziness through inhalation. Even greater exposure levels have the potential to cause unconsciousness, coma, or respiratory arrest. There have been fatal exposures lasting 30 minutes at doses higher than 600 ppm. Severe exposures that do not cause death could result in long-term consequences such as damage to nerve tissue, paralysis of the facial muscles, or memory loss.

Sulphur dioxide has been linked to cardiovascular diseases and may cause respiratory problems like bronchitis, wheezing, phlegm and asthma attacks. Chromosome abnormalities and sister chromatid exchanges were noted in lymphocytes from workers exposed to 15.92 ppm sulfur dioxide at a fertilizer company in India. Aldehydes and ketones can irritate the eyes, nose, and throat. They can also occasionally have harmful effects on the nervous system.

Ammonia inhalation can lead to respiratory issues, skin and eye irritation, and in extreme situations, lung damage. Oxides of nitrogen can irritate eyes, nose throat and lungs at low levels. Higher exposure can result in the buildup of fluid in the lungs. Inhaling high levels of nitrogen oxides can lead to spasms, swelling of tissues in the throat, burning and even death.

Exposure to the VOCs can cause a ripple effect in the health of human being, Starting from eye, throat and nose irritation to headache and loss of coordination that may extend to damage of liver, kidneys and even the central nervous system. Some of the VOC compounds are known for its carcinogenic properties. Skin and mucous membrane discomfort may result from exposure to volatile fatty acids. These acids have the potential to negatively impact both aquatic and terrestrial creatures by contributing to air and water pollution.

Managing Industrial Odours

Industrial odours is a major cause of complaint and discomfort for people. Owing to its importance in the current age and time, proper management of odour and air emissions from any industry is of utmost importance.. Industrial odours and emissions can be controlled by either physical, chemical or biological means. Physical methods include containment methods such as odour covers, dilution methods like stacks, and site planning.

There are several chemical methods to control industrial odour. Over time many chemical formulas have been developed to treat those compounds generated by industrial processes. The chemical odour control methods include additives “claiming to neutralize the odour”, masking agent (sprays), adsorbents, ozone(ozonation), ultraviolet treatment and catalytic oxidation.

Compared to physical or chemical means, biological order control methods rely solely on bacteria and other microorganisms. These techniques include use of biofilters, bioscrubbers, biotrickling filters, and other bioreactor types. Use of these methods have been reported to be more environmentally friendly and less expensive than physical or chemical methods. It can also be conducted at normal temperatures and is simple to operate. The process is also ecologically clean as the end products are ecologically safe and oxidative in nature. Researches have shown that biological treatment methods can be considered as robust and reliable alternatives to physical or chemical treatment methods.

Biofilters

These are one of the oldest biotechnological odour pollution control techniques used to remove undesired compounds from air. They immobilise microorganisms on a solid support. Biofilters or generally used for removing hydrogen sulphide, VOCs, nitrous oxide, sulphur gases, etc. Use of biofilters can be traced back to 1920s when they were used to remove compounds emitted from animal farms and waste treatment plants. Countries like Germany and Netherlands have used this technology since the 1970s and it became popular in Western Europe and the United States in the 1980s. Europe and Japan have reported the most success in this technology.

Biofilters may be open biofilters or closed biofilters. In open biofilters, the upper part of the bioreactors is open making it more exposed to climate change whereas in closed biofilters parameters such as temperature, fluid composition and fluid flow are easier to monitor and control. The biofilters can also be classified into upflow and downflow biofilters based on the airflow through the media – if the airflow is going from top to bottom of the media, its called downflow biofilter whereas the opposite is called the upflow biofilter. The later is the common practice due to cost constraints mainly.

General Arrangement of a Biofilter System

The processes happening in the Biofilter are as follows: Initially, the pollutants are transferred from gas to liquid phase and then subjected to biodegradation by the biofilm. Bacteria constitute chunk of the microorganisms found in the biofilm. Among the bacteria, coryneforms, endospore formers (eg bacilli), pseudomonads and streptomyces are mainly used. The use of bacteria as the best candidate for use in biofilms have been after extensive research: types of microorganisms and their metabolic activities, isolation and characterization, the use of pure cultures, mixed microbial populations, effect of culture enrichment including application of specific strains and effects of external conditions on microbial activity.

Biofilters are fixed-bed bioreactors. During this operation, pollutants pass through a media bed in which active microorganisms are immobilized. This media bed causes the degradation of pollutants by biological oxidation. Good water retention capacity, presence of a dense and diverse microflora, large specific surface area, high porosity and intrinsic nutrients are some of the important requirements considered for making the media bed. The media bed is the region where the microorganism thrives and should be able to satisfy these conditions Organic materials are generally used for the preparation of bed media as these materials satisfy the requirements and are readily available at low cost. The contaminants that settle on the media bed constitute the nutrition for the biofilm by degradation. These microorganisms are generally neutrophilic, aerobic and mesophilic. Optimum moisture content is also important to ensure the survival of the biofilm ensuring that the moisture content is not too high or too low. 35- 40% of moisture is adequate for the biofilm. Pressure drop is also an important parameter and varies with the material that is used.

Biofilters are very useful and have been reported to remove many contaminants like hydrogen sulphide, dimethyl sulphide, ammonia, sulphur-containing gases and methanethiol. These are some of the common contaminants seen in wastewater treatment facilities, food waste and composting operations.

Schematic representation of biofilter

Bioscrubber

Bioscrubber is an odour treatment method said to be a combination of a gas scrubber and a biological reactor. In this process physical separation or absorption of odors in the liquid phase occurs in the gas scrubber and the biological treatment occurs in the bioreactor. The liquid leaving the bioreactor (effluent) is recirculated to the top of the column. This facilitates efficient gas cleaning of highly soluble pollutants.

Biological Odour Control

Pollutants in the air stream are removed through the bioscrubbers in the following ways: adsorption, absorption, condensation and biodegradation. It is generally preferred to use packed tower absorbers for bioscrubbers as others (wet cyclone, spray tower and venturi scrubber) show poor elimination efficiency for compounds with poor solubility in water. Generally, resistance to corrosion caused by gases and liquids, resistance to UV and thermal and mechanical resistance against temperatures are all considered while designing an absorption tower. The pollutant absorbed liquor from the scrubber undergoes continuous aeration in the bioreactor, and the active microbial culture converts the pollutant into CO2, H2O, and biomass.

The “lean” water, or bioreactor effluent, is cycled back to the absorber and used again. Bioreactors for bioscrubbing work on similar principles to activated sludge tanks used in wastewater treatment systems in terms of both design and operation. The primary distinction is that with bioscrubbing, the hydraulic retention period is typically significantly longer and equal to the sludge retention time. For this reason, bioscrubbers do not need sludge retention/separation facilities. The majority of bioscrubbers on the market today are made to remove just one type of pollutant. To give additional efficient odour management, increased operating flexibility, and other advancements in traditional designs of bioscrubbers have been examined, including the sorptive-slurry bioscrubber and the anoxic bioscrubber, airlift bioscrubber, spray column bioscrubber, two-liquid phase bioscrubber, or two-stage bioscrubber

A counter current packed tower is considered over a co-current or cross-flow towers owing to its lower pressure drop, lower energy costs and higher absorption efficiency. The ability of the bioscrubber to produce and sustain significantly larger volumes of microbial biomass in fewer process units, while retaining very high specific substrate utilization rates, is a considerable advantage over a typical biofilter and biotrickling filter. The bioreactor can be started by inoculation with activated sludge from a wastewater treatment facility and by microbial development. It relies on environmental factors like temperature, ionic strength, pH, and the presence of hazardous substances and substrate concentration. Bioscrubbers are generally used to remove ammonia, odours from wastewater treatment plants and hydrogen sulfide. The bioscrubber system is particularly advantageous when there is a good wastewater treatment plant available, thereby the load from the bioscrubber can be handled in the wastewater treatment plant and also the additional inventories such as blowers and tanks can be avoided.

Schematic diagram of bioscrubber

Biotrickling filters

This is a recent technology using more sophisticated biological waste gas treatment equipment. Like biofilters, it uses microorganisms fixed on a media and aqueous solution containing essential nutrients is trickled over the filter bed. The microorganisms grow as a biofilm and as the solution reaches the biofilm, it degrades it. The filter beds are usually made of an inert material (natural or synthetic) such as open pore synthetic foam, dump plastic packing and structure plastic packing. Other materials that have been used are TDRP (Tire-derived rubber particle), glass, ceramics and lava rock. Like biofiltration this method is simple and of low cost and is quite effective removing up to 90% of volatile organic compounds (VOCs). It is also effective for removing nitrogen components, chlorine laden components and sulphur compounds. But require sophisticated control system and continuous monitoring and makeup of nutrients to ensure the adequacy of the treatment.

Exhaust Gas Pre-treatment

Biotrickling filters are a combination of biofilters and bioscrubbers in which bacteria are immobilized on a carrier or filter material. The filter bed must be always covered with water meaning water must be uniformly sprayed. The contaminants are absorbed and decomposed by the biofilm. The circulating liquid must be checked for its nutrients (serve as feed for biofilm), pH and salt concentration. Here gas which is irrigated with an aqueous solution containing essential nutrients is carried through the filter bed. The flow of gas can be in the co-current or counter-current mechanism. Some studies suggest that co-current is better. Most of the contaminants are degraded by the biofilm. The extent of action by the filter bed depends on the activity of the microorganisms present. The filter bed will be home to a large cluster of microorganisms- aerobic and anoxic. The primary degraders constitute only a small fraction and a much larger fraction is occupied by the secondary degraders like bacteria, yeasts, fungi, and protozoa. The secondary degraders play a noteworthy role in reducing rate of biomass accumulation and recycling inorganic nutrients. Biotrickling filters are operated in temperature range of 10-40 ℃ which is the best temperature for the growth of mesophilic organisms. They are generally used to remove contaminants like hydrogen sulphide, ammonia and methanethiol.

Schematic diagram of biotrickling filter

Conclusion

Industrial odours are a major problem. The primary cause of industrial odour pollution is the airborne presence of volatile chemicals that are transported with the wind. Odorous compounds are typically volatile, corrosive and irritating, even at very low concentrations, and cause odour nuisance due to their low odour thresholds. Measurement of odour is very important and this is done by various methods like Indicator tubes, Dynamic olfactometry, Gas chromatography and electronic noses. Numerous physical-chemical and biological odour control systems have been documented in the literature to reduce the annoyance of odours emanating from the industries. The advantages of biological procedures over other methods are their efficacy, affordability, chemical-free operation, and environmental friendliness. Biological methods include use of biofilters, bioscrubbers and biotrickling filters. The biological methods are being further developed promising a remarkable future for controlling industrial odours.