Odour Control in Mixed Waste Composting Plants: Indian Context and Global Practices

Introduction

Municipal solid waste (MSW) composting is an important way to manage the large amount of organic waste in India, where organic matter makes up 60 to 70% of total waste. This process turns organic materials into nutrient-rich compost, providing a sustainable waste management option. However, composting produces smelly compounds that can create environmental and public health issues, especially in India’s crowded urban areas. The use of mechanical equipment like trommels, belt conveyors, and large reception pits in Indian composting facilities makes odour emissions worse due to more waste handling and exposure. Effective control of odours is essential for successful operations and community support. This document details the characteristics of mixed waste in India, identifies key odorous compounds, outlines Indian regulations for odour control, describes global odour control practices, explores odour control technologies, and highlights effective strategies.

Characteristics of Mixed Waste in India

Municipal solid waste in India consists of 60 to 70% organic material. This includes food waste, vegetable peels, garden trimmings, and other biodegradable items. The rest includes recyclables such as paper, plastic, glass, and metals, along with hazardous household waste like batteries, paints, and chemicals, as well as inert materials such as sand, grit, and construction debris. The waste has a high moisture content, often over 50%, due to wet organic waste like kitchen scraps. It also has a low calorific value of 800 to 1,000 kcal/kg, which makes composting a better option than thermal processing. The quick breakdown of the organic part, along with the high moisture and poor airflow, leads to anaerobic conditions. This creates unpleasant smells during decomposition, especially in large pits where waste is stored before processing.

Odorous Compounds in Mixed Waste Composting

The decomposition of organic matter in MSW composting generates various odourous compounds due to microbial activity under varying oxygen conditions. Key compounds include:

  1. Volatile Organic Compounds (VOCs): These include alcohols (e.g., ethanol), aldehydes (e.g., acetaldehyde), and ketones (e.g., acetone),. They form when carbohydrates and proteins break down and create strong, solvent-like smells.
  2. Ammonia (NH₃): Released during the decomposition of nitrogen-rich materials such as food waste and manure, ammonia produces a sharp, irritating odour, especially in high-pH environments.
  3. Hydrogen Sulfide (H₂S): Formed under low-oxygen conditions, hydrogen sulfide emits a characteristic rotten egg smell. This odour is common in poorly aerated compost piles or reception pits.
  4. Mercaptans: Organic sulfur compounds such as methyl mercaptan produce a strong, skunk-like odour, resulting from the anaerobic breakdown of proteins.
  5. Volatile Fatty Acids (VFAs): Compounds such as acetic, propionic, and butyric acids are produced during anaerobic fermentation, contributing to sour or rancid odours.
  6. Amines: Compounds like trimethylamine, derived from protein degradation, produce fishy or ammonia like smells.

These compounds are released during waste handling, preprocessing (e.g., trommel screening, conveyor transport), and storage in reception pits, requiring targeted odour control measures.

Indian Regulations for Odour Control in MSW Composting

The Ministry of Environment, Forest and Climate Change (MoEF&CC) notified the Solid Waste Management Rules, 2016, which regulate the management of MSW in India for urban agglomerations, census towns, notified industrial townships, and other such areas. Major provisions for odour control are:

  1. Source Segregation: The regulations require source segregation of waste into biodegradable, non-biodegradable, and hazardous types in order to minimize contamination, enhance quality of compost, and reduce odour-generating substances. For example, plastics and metals can be used to hold moisture, forming anaerobic micro-environments that release volatile fatty acids (VFAs), hydrogen sulfide (H2S), and mercaptans to some but not the only cause of odour production.
  2. Standards for Processing: Urban local governments (ULBs) need to set up composting or bio-methanation plants for biodegradable waste, with controlled conditions to restrict odours. Plants must have sanitary conditions and control emissions properly.
  3. Standards of Quality for Compost: Schedule II defines standards for compost so that it is free from harmful substances, indirectly controlling odours by encouraging good processing practices.
  4. Monitoring and Compliance: ULBs should report to the Central Pollution Control Board (CPCB) by April 30 of every year about compliance with waste treatment and odour control. The CPCB compiles these reports for the Central Government on or before December 15 every year.
  5. Environmental Protection: The regulations focus on avoiding environmental pollution, such as odour release, through handling and processing waste appropriately. Treatment facilities with over 5 metric tonnes of waste per day must be approved by the State Pollution Control Board (SPCB) and must have provisions for odour control.

The technical guidelines of the CPCB suggest aeration, control of moisture, and technologies such as biofilters to control odours. Inconsistent follow-up due to financial limitations, infrastructural constraints, and lack of awareness leads to ongoing odour issues, especially in centres with big reception pits. Nevertheless, it is practically difficult to control the odour with the change in process only.

Global Odour Control Practices in MSW Composting Facilities

Globally, MSW composting facilities use process optimization and advanced technologies to manage odours, especially in systems with mechanical equipment and reception pits:

  1. Process Optimization: Maintaining aerobic conditions through aeration (e.g., aerated static piles with blowers) and controlling moisture levels (50–60%) minimize anaerobic decomposition. Source separation and mechanical screening reduce contaminants, improving feedstock quality and reducing odours. For reception pits, forced aeration and rapid turnover are essential.
  2. Technological Interventions: Enclosed systems like in-vessel composting contain odours, while air treatment technologies capture and treat emissions from preprocessing and pits. Enclosed trommels and conveyors with negative-pressure systems are standard in developed countries, with extracted air treated using various technologies.

Odour Control Technologies

Biological Odour Control Units

Biological systems use microbial activity to break down odorous compounds. They provide cost-effective and sustainable solutions:

  1. Biofilters: These systems use organic materials to absorb and break down VOCs, ammonia, and H2S. They achieve 85 to 95% odour removal efficiency. Biofilters work well for treating air from enclosed trommels, conveyors, and reception pits. They need moisture control for the media and require media replacement every 3 to 5 years.
  2. Biotrickling Filters: These use synthetic packing materials that get irrigated with nutrient-rich liquid to support the breakdown of pollutants by microbes. They effectively handle high concentrations of ammonia and H2S, reaching 90 to 98% removal efficiency. Their compact design makes them suitable for enclosed preprocessing areas. However, they require a constant supply of water and nutrients, which increases costs.
  3. Bio-scrubbers, These systems channel odorous air through a liquid medium filled with microorganisms that break down pollutants. They achieve 80 to 90 percent efficiency for water-soluble compounds like ammonia. Bioscrubbers can handle high odor loads, but they need a lot of energy for air and liquid circulation. They also require a dedicated water treatment system, which limits their use in places with limited resources.

Non-Biological Odour Control Units

Non-biological systems are utilized for pungent smells or where biological systems are unavailable:

  1. Chemical Scrubbers: Wet scrubbers utilize chemical solutions (sodium hydroxide, sulfuric acid) to neutralize ammonia and H2S with 85–95% removal efficiency. They can be used in reception pit and preprocessing air but require expensive chemical inputs and maintenance.
  2. Activated Carbons Filters: These adsorb VOCs and other odor-causing compounds and, when used alone or in combination with biofilters, are 90–99% effective. They are suitable for polishing biologically treated air but need frequent replacement, so they are expensive.
  3. Thermal Oxidation: Burning of the malodourous gases at elevated temperatures (800–1200°C) with almost complete odour annihilation. Used in large plants where a lot of odour is generated but is energy intensive and generates secondary emissions, so usage is limited.
  4. Plasma Technology: Non-thermal plasma systems use high-energy electrons to break down odorous molecules, achieving 85–95% efficiency. They are emerging technologies suitable for compact facilities but are costly and require technical expertise and are generally comes with very expensive annual maintenance cost for the electrode replacement and thereby higher operational costs, limiting the use in large facilities.

Combination Treatments for Odour Control

Combining odour control technologies enhances efficiency and addresses a broader range of compounds:

  1. Biofilter + activated carbon filter: Biofilters deliver primary VOCs, ammonia, and H2S treatment with 85–95% removal, and polishing the remaining odours using activated carbon filters to 95–99% total efficiency. This occurs in enclosed trommel and reception pit plants with optimal cost and performance.
  2. Biotrickling Filter + Chemical Scrubber: Biotrickling filters remove high levels of ammonia and H2S (90–98% efficiency), and chemical scrubbers remove remaining acid or alkaline gases, 95% total efficiency. It is suitable for high-odour-load plants but increases the cost of operations.
  3. Biofilter + Thermal Oxidation: This combination is generally used in facilities having separate streams of odour with extremely high intensity odour and moderate indensity odour. the high intensity odour is treated in the thermal oxidation stage as this will reduce high dependence on the secondary fuel, achieving near-complete removal. Whereas the odour from the moderate sources will be handled in Biofilters (85–95% efficiency). This is used in large-scale facilities with stringent regulations but is energy intensive.
  4. Chemical scrubber + Activated Carbon Filter: Ammonia and H2S are scrubbed out by chemical scrubbers (85–95% effective), with the best removal with activated carbon filters for VOCs, providing 95–99% total effectiveness. This is appropriate for plants with multiple odour sources but is costly in terms of replacement requirements for chemicals and carbon.

These blends are designed according to the character and volume of the odour of the plant, with air from trommels, reception pits, and conveyors blown to the main treatment unit (e.g., biofilter) and then to a secondary unit (e.g., activated carbon) for further removal.

Elixir Enviro Systems: Your Partner in Odour Control for Composting Plants

At Elixir Enviro Systems, we specialize in designing and delivering comprehensive odour control solutions tailored for municipal solid waste (MSW) composting plants across India. With deep domain expertise in biological air treatment and solid waste handling, we offer:

✅ Biological Odour Control Units

  1. Biofilters: Engineered for high odour removal efficiency (85–95%), ideal for reception pits, trommels, and conveyor enclosures. Our biofilters use specially selected media for longer lifespan and consistent performance.
  2. Biotrickling Filters: Compact and highly effective for treating high concentrations of ammonia and H₂S, with up to 98% removal efficiency. Designed for enclosed preprocessing zones and pit ventilation systems.
  3. Bioscrubbers: Liquid-phase biological systems for high-load applications, particularly effective in treating water-soluble odorous compounds.

✅ Non-Biological & Hybrid Systems

  1. Chemical Scrubbers: High-efficiency wet scrubbers for tough odour streams, especially from reception pits and shredders.
  2. Activated Carbon Filters: For VOC polishing and secondary treatment stages, especially useful after biological filtration.
  3. Hybrid Systems: Combining technologies like Biofilter + Carbon Filter or Biotrickling Filter + Chemical Scrubber for comprehensive odour coverage across all process stages.

✅ Comprehensive Services

  1. Odour Mapping & Onsite Assessment: We conduct detailed odour audits and dispersion modeling to identify emission hotspots and quantify odour loads.
  2. Custom System Design & Turnkey Execution: From engineering to commissioning, we provide end-to-end odour control system solutions customized to plant layout, budget, and odour profile.
  3. Annual Maintenance & Performance Monitoring: Our AMC services include media replacement, efficiency testing, and performance tuning to ensure regulatory compliance and system longevity.

Conclusion

Odour control in mixed waste composting plants is a serious concern in India because of high organic load, non-segregation, high moisture, and use of mechanical systems like trommels, conveyors, and large reception pits. Segregation, effective processing, and emission control are mandated under the Solid Waste Management Rules, 2016, but the gaps in implementation persist because of non-availability of resources. Significant odourous compounds like VOCs, ammonia, H2S, mercaptans, VFAs, and amines are released during handling of wastes, and specific interventions like enclosed preprocessing, aeration, and pit management are necessary. Internationally, technologies like in-vessel composting, biological systems (biofilters, biotrickling filters, bioscrubbers), and non-biological systems (chemical scrubbers, activated carbon filters, thermal oxidation, ozone treatment, plasma technology) are useful in odour control, and combination treatments enhance efficiency. For India, using low-cost biological technologies like biofilters, along with better segregation, pit aeration, and enclosing mechanical systems, may improve odour control and support sustainable composting operations.

FAQ

Q1: Why does municipal solid waste composting produce strong odours?

Municipal solid waste composting involves the decomposition of high-moisture, organic-rich waste. Under anaerobic conditions—often caused by poor aeration or excess moisture—this generates volatile organic compounds (VOCs), ammonia, hydrogen sulfide (H₂S), volatile fatty acids (VFAs), and other malodorous gases.

Q2: What are the main sources of odour in Indian composting plants?

The key sources include large reception pits with poor ventilation, trommel screening equipment, and open conveyor systems. These areas facilitate anaerobic conditions and release odorous compounds during waste handling and storage.

Q3: What is the best odour control technology for MSW composting in India?

Biological systems like biofilters and biotrickling filters are the best in cost terms for Indian conditions. They provide high odour removal efficiency (85–98%) with relatively lower running cost, especially when combined with appropriate enclosures and pit aeration systems.

Q4: Are Indian composting plants required to control odour under law?

Yes. The Solid Waste Management Rules, 2016, control odour by proper segregation of waste, standards for processing, and measures for controlling emissions. A permission from the State Pollution Control Boards is required for plants with more than 5 metric tonnes per day with special provisions for odour control.

Q5: Can process adjustments alone eliminate odour emissions?

No. While process improvement like aeration and moisture control reduces odour formation, odour formation cannot be eliminated. Effective odour control relies on the application of a combination of biological or chemical treatment processes, equipment enclosures, and efficient management of sound reception pits.

 

 

Controlling Odour from Milk, Ghee and Dairy Processing: A Complete Guide

Introduction

In the dairy industries maintaining a clean hygienic and Odour free environment is critical not only for regulatory compliance but also for employee health and brand image. From milk pasteurization to ghee carification, each stage in dairy processing can emit various smell that, if left unchecked can cause discomfort , environmental concerns and even neighbour complaints. This blog guides you to explore the cause of odour in dairy, milk and ghee processing plants and effective strategies to control and eliminate them.

Why Odour Control Matters in Dairy Plants

Dairy processing involves the handling of large amounts  of organic materials such as raw milk, cream, curd and butter, which are subjected to spoilage and fermentation. If not managed properly, the by-products of these processes can lead to the release of unpleasant smells. Here’s why odour control  should be a top priority:

  1. Compliance with Environmental Norms: Pollution control boards across many countries mandate odour management as part of environmental compliance.
  2. Community Relations: Plants located near residential areas need to ensure they do not disrupt the local environment.
  3. Employee Health and Morale: Persistent foul odours can reduce workplace satisfaction and may even lead to health complaints.
  4. Brand Reputation: An unpleasant smell near your processing unit can negatively impact your brand image and consumer trust.

What Causes Foul Smell in Dairy and Ghee Factories?

Understanding the sources of odour helps in deploying targeted solutions. Some of the most common odour sources in a dairy or ghee processing facility include:

1. Raw Milk Storage

Psychrophilic (bacteria with optimal growth rate below 15°C) and Mesophilic (bacteria with optimal growth rate between 20-40°C) bacterial growth can make the milk processing plant smell awful. This happens, If the milk is stored for extended periods at improper temperatures, it can ferment and can produce sour or putrid odours.

2. Pasteurization and Heating Processes

The heating of milk and cream releases volatile organic compounds (VOCs) that contribute to strong smells, especially during ghee production. Also improper processing like Overheating butter during clarification can cause burnt odours, while incomplete removal of milk solids can lead to spoilage-related smells.

3. Whey and Sludge Disposal

Whey, a by-product of curd and cheese making, contains organic matter that decomposes quickly. Improper disposal leads to foul smells.

4. Spillage and Floor Cleaning

Milk spills or leftover residue on floors can rot and produce odour if not cleaned thoroughly.

5. Wastewater Treatment

Effluents containing milk solids, fats, and detergents from cleaning-in-place (CIP) systems can create anaerobic conditions, emitting hydrogen sulfide and other gases.

Effective Odour Control Strategies

Managing odour in dairy processing plants requires a multi-pronged approach combining engineering, chemical, and biological controls. Here are some proven strategies:

1. Proper Housekeeping and Hygiene Practices

  1. Regular cleaning schedules
  2. Immediate cleanup of spills
  3. Use of cleaning agents

2. Ventilation and Air Filtration

  1. Air quality management is critical to prevent airborne contamination. High-efficiency particulate air (HEPA) filters, with 99.97% efficiency for 0.3-micron particles, can remove microbial contaminants
  2. Installing air curtains in high-odour zones
  3. Installation of exhaust fans to ensure air circulation

3. Enclosed Processing Units

Whenever possible, ensure that odour-generating processes like ghee clarification or cheese ripening are enclosed and equipped with fume extraction systems. Also its always better to use the enclosed crate washing units and so on to avoid the spillage milk speading all over and acting as a fugitive source of odour.

4. Biological Treatment Systems

These eco-friendly systems use microbial activity to neutralize odours.

✅ Biofilters (Cocofil™ or Organic Media)

A mixture of coconut husk, compost, and soil traps and degrades VOCs biologically. These are perfect for continuous, low-concentration odour sources.

✅ Bioscrubbers

In this setup, odourous air is washed with water in a tower where bacteria are suspended. The scrubbing media absorbs odourous gas, and which is later transferred to an aeration-based treatment unit. At this aeration tank the microbes digest compounds like H₂S and ammonia and making it odourless compounds. This liquor is later circulated again in the absorption/scrubbing column to as a continuous system.

✅ Biotrickling Filter

In this setup, odourous air is passed through a column where the microbes are attached on a packing medium like in the trickling filter. Unlike trickling filter, which is used for wastewater treatment, here the case of biotrickling filter, air is being treated. Similar to that in the scrubber, the mass transfer of odourous2 compounds first happens from waste gas to the liquid that is being trickled over the media containing bacteria. Then the compounds gets taken up by the bacteria from the liquid and neutralize them.

All the above systems are low-maintenance, energy-efficient, and are highly effective for odour control.

5. Chemical Scrubbers

Ideal for point-source odours with high gas concentrations. Here, odourous air is passed through a packed column or spray scrubbers where it reacts with acid/alkali solutions.

✅ Acid Scrubbers

Used for ammonia control (uses acidic solution as scrubbing liquid)

✅ Alkaline Scrubbers

Used for hydrogen sulfide and other acid gas control (alkaline solutions are used as scrubbing liquid).

Always include mist eliminators to prevent chemical carryover.

6. Activated Carbon Filters

These are compact, plug-and-play systems that adsorb odourous gases using porous carbon media. Suitable for:

  1. Packaging rooms
  2. Ghee storage areas
  3. Smaller plants or urban units

They offer high removal efficiency and minimal maintenance, making them a popular choice.

7. Composting and Sludge Management

Instead of letting organic waste rot in open containers, convert it into compost or manage it through covered anaerobic digestion tanks.

8. Odour Mapping and Monitoring

Managing odour effectively starts with knowing when, where, and how it’s being released. One of the smartest ways to do this is by using real-time odour mapping and monitoring with advanced sensor technology.

By placing sensors and data loggers in key areas around the facility, plant operators can keep an eye on odour levels, spot unusual changes, and identify problem spots quickly. This steady flow of data helps teams take action early—before odour becomes a regulatory issue or leads to complaints from the community.

How Oizom Helps with Odour Monitoring

Oizom (www.oizom.com), a leader in environmental monitoring, provides innovative tools like Polludrone and Odosense to tackle odour challenges. These smart, IoT-enabled devices are designed to accurately detect a variety of odourous gases, including hydrogen sulfide (H₂S), ammonia (NH₃), methane (CH₄), and VOCs, giving operators the insights they need to stay ahead of potential problems.

Environmental and Legal Compliance

In India and many other countries, dairy processing units—including those producing milk, curd, butter, and ghee—must adhere to stringent odour emission norms laid out by their respective Pollution Control Boards. The Central Pollution Control Board (CPCB) and State Pollution Control Boards (SPCBs) have specific environmental guidelines aimed at minimizing nuisance odours that can affect local communities. To stay on the right side of regulations, facilities need to run regular environmental audits, keep current records of their emissions and cleanup efforts, and work with certified experts in odour control. Why go through all that? Because staying compliant doesn’t just help avoid fines or legal trouble—it also builds public trust and shows that the company genuinely cares about the environment.

What Can Elixir Enviro Systems Do for Odour Control in Dairy Plants?

Elixir Enviro Systems is a leading name and pioneer in India in industrial odour control, providing end-to-end solutions that help dairy processing units stay compliant, efficient, and community-friendly. With extensive experience in managing odour emissions across diverse industries, Elixir offers specialized services tailored for dairies, milk processing units, and ghee manufacturing plants, where organic waste, fermentation processes, and effluent treatment systems often result in strong and persistent odours.

Our offerings include:

  1. Odour Assessments & Dispersion Modelling – Site-specific odour studies using     advanced modelling tools to identify emission sources and predict odour spread.
  2. Custom-Engineered Odour Control Systems – Design and installation of biofilters, chemical scrubbers, and activated carbon units specifically suited to dairy-related emissions.
  3. Turnkey ETP Upgrades & Sludge Handling – Enhancing existing effluent treatment plants to reduce odour-causing compounds and improve sludge management.
  4. Layout Optimization & Engineering Support – Smart facility design and airflow optimization to prevent fugitive emissions and reduce odour hotspots.
  5. Ongoing Monitoring & AMC – Real-time odour monitoring, annual maintenance contracts.

With over 1 million m³/hr of treated air capacity across India, Elixir Enviro Systems is the trusted partner for sustainable, scalable, and proven odour control in the dairy industry.

Conclusion

Odour control in dairy, milk, and ghee processing plants is not a luxury—it’s a necessity. Persistent odours don’t just affect your plant’s environment; they can compromise employee health, community relations, and compliance with environmental regulations. A proactive, well-engineered odour management strategy enhances operational efficiency, reduces legal risk, and strengthens your brand’s reputation.

Elixir Enviro Systems helps dairy processors take odour control from an afterthought to a core operational priority. With industry-specific expertise, cutting-edge technologies, and end-to-end support, we empower your facility to operate cleaner, safer, and more sustainably.

📞 Need help with odour control at your facility?

Partner with Elixir Enviro Systems to implement reliable, compliant, and sustainable odour control solutions tailored to your dairy operations.

👉 Contact us today

📧 Email: info@elixirenviro.in  🌐 Visit:www.elixirenviro.in

 

FAQs

1. What causes foul odours in dairy and ghee processing plants?

Foul odours can result from the fermentation of spoiled milk (raw material handling), heating of fats (processing), waste accumulation, whey disposal, and inefficient cleaning processes. Also, wastewater treatment plant collection tanks and headworks creates big odour nuisance issues. In many places, the emissions from the spray drying column also creates huge odour nuisance. In short, the odour from dairy can be the following places

  1. Raw milk storage tanks
  2. Milk spillage and floor washings
  3. Ghee clarification and fat separation
  4. Whey disposal units
  5. Effluent treatment plant (ETP) including the Sludge handling units
  6. Storage of expired or rejected dairy products
  7. Cleaning-In-Place (CIP) system discharges

2. How is odour measured in dairy plants?

Odour perception is subjective but measurable using sensory and instrumental techniques. Commonly detected smells in dairy operations include sour milk, rotten eggs (hydrogen sulphide), rancid butter, and ammonia-like scents. Odour monitoring includes both qualitative and quantitative approaches:

  1. Sensory methods: Human olfactometry (e.g., dynamic dilution olfactometry)
  2. Chemical analysis: Gas chromatography-mass spectrometry (GC-MS), H2S meters
  3. Real-time sensors: Ammonia, VOC, and sulphide detectors
  4. Odour dispersion modelling: Using tools like AERMOD or CALPUFF to predict impact

3. What are the key odourous compounds in a dairy?

Several key compounds are responsible for malodour in dairy operations:

  1. Hydrogen sulphide (H₂S): Produced in anaerobic environments
  2. Volatile fatty acids (VFAs): Resulting from the decomposition of milk solids
  3. Ammonia (NH₃): Released from protein breakdown and cleaning agents
  4. Methyl mercaptan and dimethyl sulphide: Emitted from ghee and fat residues
  5. Skatole and indole: Found in biological waste streams

4. What are operational optimization strategies for odour control in Dairy industries?

Operational changes can significantly reduce odour:

  1. Preventing anaerobic conditions in wastewater holding tanks
  2. Immediate treatment of whey and curd waste
  3. Reducing fat/protein accumulation in drains
  4. Optimising Clean-in-Place (CIP) systems to avoid residue build-up
  5. Segregation of high-strength waste streams

5. How to Reduce Odour from Milk and Ghee Manufacturing Units

Use enclosed heating systems, make sure the area is well-ventilated, and use air scrubbers or odour-neutralizing products. Keeping the space clean and removing waste regularly also makes a big difference.

6. Are there eco-friendly solutions for odour control?

Yes, Biofilters, Biotrickling filters, Bioscrubbers and plasma ionization are sustainable, environmentally friendly options that effectively neutralize odours. Generally, the Biological  systems such as Biofilter, Biotrickling filters and Bioscrubbers turns out to be the lowest lifetime cost system. Require low energy and offer high removal efficiency for H2S and VOCs

Key considerations:

  1. Media selection and life span
  2. Moisture and pH control
  3. Prevention of clogging and biomass overgrowth

7. What are the best Practices for Dairy Units

  1. Conduct odour audits and risk assessments regularly
  2. Install containment and ventilation systems at emission points
  3. Automate cleaning processes to reduce manual handling and spillage
  4. Provide odour complaint registers and response protocols
  5. Use odour control units such as Biofilters or other technologies and maintain them well.

8. What are the challenges in odour control from dairy

  1. Variability in odour emission sources, this can be easily managed by well-engineered Odour Control Unit (OCU).
  2. High capital and operational cost for advanced systems; Capital (CAPEX) is a requirement for any OCU to be in place. Operation expense (OPEX) can be minimized by selecting the right technology; for instance the biological system.
  3. Inconsistent odour perception among stakeholders; to an extent it can be controlled by designing a well designed system wherein the odour perception outside the boundary become next to impossible.
  4. Lack of trained personnel for system operation. This is true for complex systems like thermal oxidation, cold plasma systems and so on. The biological system, generally require minimal or no requirement of operation personal.
  5. Integration with legacy plant designs. This is true especially for the plants with minimal land availability. Otherwise, integration of OCU to the plant design in not at all a challenge.

9. Can odour control improve compliance with regulations?

Absolutely. Most environmental boards require odour management plans, and effective odour control helps meet these compliance standards

Odour Control in Fish and Shrimp Feed Manufacturing: Strategies for a Cleaner Production Process

Introduction

The fish and shrimp feed manufacturing industry plays a vital role in aquaculture, providing essential nutrition for farmed species. However, one of the major challenges faced by feed producers is odour emissions during processing. Strong, unpleasant odours can arise from raw materials like fishmeal, fish oil, and other protein-rich ingredients, leading to environmental concerns and potential regulatory issues.

Effective odour control is crucial not only for maintaining a healthy work environment but also for ensuring compliance with environmental regulations and fostering good community relations. In this blog, we will explore the sources of odour in fish and shrimp feed production and discuss practical strategies to mitigate them

Common Sources of Odour in Fish and Shrimp Feed Manufacturing

1. Raw Materials

  1. Fish Meal: Made from whole fish or fish byproducts; has a strong, pungent odour due to the presence of volatile nitrogen compounds like trimethylamine.
  2. Shrimp Shell meal: Often contains chitin, protein residues, and fats that decompose quickly and emit foul smells.
  3. Other Marine Ingredients: Algae, krill, squid, and crustacean byproducts all contribute to the distinctive odour due to high protein and oil content.
  4. Animal Fats and Oils: These can oxidize and emit rancid smells.

2. Processing Stages

  1. Grinding and Mixing: Releases dust and odorous particles from protein-rich materials.
  2. Cooking/Extrusion: High temperatures volatilize amines, sulfur compounds, and fatty acids, leading to a cooked or burnt protein smell.
  3. Drying: Moisture evaporation carries volatile organic compounds (VOCs) into the air, intensifying odour.
  4. Cooling and Packaging: Residual heat and exposed feed particles can continue to release odours if not quickly cooled or sealed.

3. Storage and Waste Handling

  1. Spoiled Raw Materials: Decomposition of ingredients in storage can produce ammonia, hydrogen sulfide, and VOCs.
  2. Wastewater and Solid Waste: Effluents from wash water and organic solids (like sludge or leftover ingredients) decay and emit unpleasant odours.

4. Microbial Activity

Bacteria and fungi acting on proteins and fats in raw materials and waste streams produce odorous compounds such as:

  1. Ammonia
  2. Hydrogen sulfide
  3. Volatile fatty acids
  4. Putrescine and cadaverine (from protein decay)

Environmental and Community Impact of Odour in Fish and Shrimp Feed Manufacturing

Odour emissions from fish and shrimp feed manufacturing plants are a significant environmental concern affecting air quality and local communities. These odours, mainly caused by volatile organic compounds (VOCs) and nitrogenous compounds released during processing, contribute to air pollution and can lead to frequent community complaints. Persistent and strong odours from aquafeed production can also negatively impact local biodiversity by disturbing nearby ecosystems and sensitive wildlife.

Effective odour control in fish feed manufacturing not only reduces these environmental impacts but also helps improve relations with surrounding communities. By managing odour emissions proactively, feed manufacturers can prevent complaints, avoid costly fines, and reduce the risk of legal action. Strong odour management practices enhance a company’s reputation and demonstrate a commitment to sustainable and responsible aquaculture production.

Regulatory Framework and Compliance for Aquafeed Odour Control

The fish and shrimp feed manufacturing industry must comply with strict environmental regulations related to odour emissions and air pollution control. In India, agencies like the Central Pollution Control Board (CPCB) enforce standards for odour limits and air quality that feed producers must meet. Globally, regulations from bodies such as the United States Environmental Protection Agency (EPA) and the European Union (EU) provide guidelines for industrial odour control and emissions management in aquafeed production.

Compliance with these odour regulations is essential for legal operation and plays a vital role in corporate social responsibility (CSR) and sustainability reporting. Meeting regulatory requirements helps aquafeed manufacturers avoid penalties, ensures operational continuity, and supports environmental stewardship goals. Integrating advanced odour control technologies and following regulatory frameworks enable companies to reduce volatile organic compounds (VOCs) and improve air quality, fostering sustainable fish and shrimp feed production.

Proven Odour Control Strategies in Aquafeed Production

To address these challenges, manufacturers can adopt the following strategies:

1. Optimize Raw Material Handling

  1. Proper Storage: Store fish meal and oil in sealed, temperature-controlled environments to minimize oxidation and VOC release.
  2. Quality Control: Use fresh, high-quality raw materials to reduce the presence of odorous compounds.
  3. Inventory Management: Implement first-in, first-out (FIFO) systems to prevent spoilage.

2. Install Odour Control Systems

  1. Biofilters: These use microorganisms to break down odourous compounds. They are cost-effective and environmentally friendly for treating exhaust air from processing areas.
  2. Scrubbers: Wet scrubbers can neutralize odours by passing exhaust gases through a liquid solution, capturing VOCs and amines.
  3. Thermal Oxidizers: For high-odour loads, thermal oxidizers burn off volatile compounds, converting them into less harmful substances like carbon dioxide and water.

3. Enhance Processing Techniques

  1. Low-Temperature Processing: Use lower temperatures during drying and extrusion to reduce the release of volatile compounds.
  2. Enclosed Systems: Design processing equipment with enclosed systems to contain odours and direct them to treatment units.
  3. Ventilation: Install high-efficiency ventilation systems to capture and treat odourous air before release.

4. Waste Management

  1. Effluent Treatment: Treat wastewater and processing byproducts promptly to prevent odor generation. Anaerobic digesters can convert waste into biogas, reducing odour and generating energy.
  2. Regular Cleaning: Clean equipment and storage areas regularly to prevent residue buildup, which can contribute to odours.

5. Monitor and Maintain

  1. Odour Monitoring: Use sensors to detect and measure odour levels in real-time, allowing for quick adjustments to control systems. Electronic noses and gas sensors such as Odosnese of Oizom provide continuous monitoring, enabling rapid response to odour spikes.
  2. Maintenance of Equipment: Regularly maintain odour control systems like biofilters and scrubbers to ensure optimal performance.

Case Study: How Elixir Enviro Systems Helped a Shrimp Feed Plant Achieve 4 OU/m3 at outlet

A leading shrimp feed manufacturer with a production capacity of 400 tons per day was facing persistent and intense odour emissions at its facility. The primary raw materials—fishmeal, fish oil, soybean meal, vitamins, and minerals—generated strong, fishy odours, particularly during cooking, drying, and cooling phases. Additional odour sources included the grinder unit and material conveying systems.

The company approached Elixir Enviro Systems Pvt. Ltd. for an end-to-end odour control solution. After a detailed site audit and airflow assessment, Elixir designed and installed a high-performance odour abatement system consisting of:

  1. Dust scrubbers to remove particulates and pre-condition the exhaust air
  2. Two high-rate Ultrafil biofilters in parallel to biologically treat odourous compounds like trimethylamine, diamines, and ammonia
  3. A blower system rated at 75,000 CMH, equipped with a Variable Frequency Drive (VFD) for optimal flow control

The system was engineered to handle a process airflow of 75,000 CMH, blending hot air from the dryer and directing it efficiently into the biofilters. Performance testing revealed a remarkable odour removal efficiency with final odour concentration at the outlet measuring just 4 OU/m3 (Odour Units), when tested using field olfactometry—well below industry standards

💡 Outcomes:

This successful implementation not only eliminated odour-related complaints but also helped the client align with environmental norms, boosting their sustainability credentials.

Elixir Enviro Systems – Experts in Aquafeed Odour Control

If you’re seeking reliable odour control solutions for fish and shrimp feed manufacturing, Elixir Enviro Systems is your trusted partner. We specialize in industrial odour treatment, wastewater management, and biofiltration systems for factories and processing plants.

With years of experience, Elixir offers complete turnkey solutions—from design and installation to testing and long-term maintenance. Whether your facility requires wet scrubbers, biofilters, regenerative thermal oxidizers (RTOs), or real-time odour monitoring systems, Elixir has you covered.

Why Choose Elixir Enviro?

✅ Pioneer in Industrial Odour Control in India

✅ Largest player in India, treating about 1 Million cubic meters of air per hour

✅ Experts in aquafeed manufacturing odour control

✅ Custom solutions tailored to your industrial odour challenges

✅ In-house R&D and advanced simulation tools

✅ Onsite odour audits and pilot testing for optimized solutions

✅ Solutions designed to meet all local and global environmental regulations

Our expertise and innovative technology ensure your facility operates with minimal odour impact while maintaining productivity and compliance

Conclusion

As the aquafeed industry continues to grow, so does the responsibility to operate sustainably and sensitively—especially when it comes to odour emissions. Effective odour control in fish and shrimp feed manufacturing is not just about meeting regulations; it’s about protecting the health and well-being of plant workers, maintaining good relationships with surrounding communities, and upholding your company’s environmental integrity.

By implementing smart engineering controls, modern treatment technologies, and best operational practices, facilities can significantly reduce their odour footprint while improving overall efficiency and compliance.

At Elixir Enviro Systems, we specialise in designing and delivering tailored odour control solutions that work—from raw material intake to final air discharge. Whether you’re upgrading an existing system or planning a new facility, we’re here to help you create a cleaner, safer production environment.

📞 Ready to tackle odour challenges at your aquafeed plant?

💬 Contact Elixir Enviro Systems today for expert consultation, onsite assessment, or a custom solution that meets your regulatory and operational goals.

FAQ

Q1: Why is odour control important in fish and shrimp feed manufacturing?

Odour control helps reduce environmental pollution, ensures compliance with regulations, protects worker health, and maintains good relations with nearby communities.

Q2: What are the main sources of odour in aquafeed production?

Odour mainly originates from raw materials like fishmeal and shrimp meal, processing stages (grinding, cooking, drying), storage of raw materials and waste, and microbial activity breaking down organic compounds.

Q3: Which technologies are effective for odour control in feed plants?

Common technologies include biofilters, wet scrubbers, thermal oxidizers, enclosed systems, and advanced ventilation combined with real-time odour monitoring.

Q4: How can wastewater treatment help with odour control?

Treating wastewater and organic solids promptly prevents decomposition that generates odours. Methods like anaerobic digestion reduce odours and produce useful biogas.

Q5: How often should odour control equipment be maintained?

Regular maintenance is essential and should be conducted based on manufacturer guidelines and site-specific needs to ensure continuous effective performance.

How to Manage Odour in Pet Food Manufacturing: Proven Technologies & Regulatory Insights

Introduction

The pet food manufacturing industry has grown significantly in recent years, driven by increasing pet ownership and demand for high-quality, specialized pet nutrition. However, one of the persistent challenges in this sector is managing odours generated during production. The processing of animal proteins, fats, and other organic materials creates volatile organic compounds (VOCs), sulfur compounds, and amines, which produce strong, often unpleasant odours. These odours can affect worker safety, community relations, and regulatory compliance. Effective odour control is thus critical for operational success, environmental responsibility, and maintaining a positive public image.

This article explores the sources of odours in pet food manufacturing, their impact, and the technologies and strategies available for effective odour management. It also examines Regulations, industry best practices, and emerging innovations, providing a comprehensive guide for manufacturers seeking to mitigate odour-related challenges.

What Causes Odours in Pet Food Manufacturing?

Pet food manufacturing involves several processes that contribute to odour emissions, including raw material handling, cooking, extrusion, drying, and packaging. Understanding these sources is the first step in designing effective control measures.

1. Raw Material Handling

Pet food production often begins with the receipt and storage of raw materials such as meat, fish, poultry by-products, grains, and fats. These materials, particularly animal-based ingredients, can emit odours during unloading, storage, and preprocessing. Decomposition of organic matter, especially if storage conditions are suboptimal, exacerbates the issue.

2. Batching and Grinding

The raw materials or all the ingredients defined based on the formulation of the company, including protein sources such as fishmeal, chicken-meal etc. are grinded along with the other materials. During this time there will be VOC and dust generation, which will be handled in a bag filter. The dust gets trapped in the bag filter but the exhaust air after the bag filter will be having VOCs and that causes odour emission from the process.

3. Cooking

A key process in which animal by-products are cooked at high temperatures (often exceeding 120°C), leading to the release of VOCs, including aldehydes, ketones, and sulfur-containing compounds like hydrogen sulfide (H₂S). These compounds have low odour thresholds, meaning even small concentrations are detectable and potentially offensive.

4. Extrusion and Drying

Extrusion involves mixing, cooking, and shaping pet food under high pressure and temperature. The process releases steam and volatile compounds, contributing to odour emissions. Drying, used to reduce moisture content in kibble or treats, further volatilizes organic compounds, releasing them into the exhaust air.

5. Packaging and Storage

While less intense, odours can also arise during packaging if residual volatile compounds are released from freshly processed products. Improperly sealed storage areas may allow odours to escape into the surrounding environment.

Odour control solutions for pet food manufacturing plants using biofilters and scrubbers

Why Odour Control Matters in the Pet Food Industry

Odour emissions from pet food manufacturing have wide-ranging implications:

Given these impacts, effective odour control is not just a technical necessity but a strategic priority for pet food manufacturers.

Regulations Governing Odour Emissions

Odour regulations vary by region but generally aim to limit nuisance and protect air quality. In the United States, the Environmental Protection Agency (EPA) and state-level agencies enforce standards under the Clean Air Act, which may include limits on VOCs and hazardous air pollutants (HAPs). Facilities must also comply with local zoning laws and nuisance ordinances.

In the European Union, the Industrial Emissions Directive (2010/75/EU) sets guidelines for managing emissions, including odours, from industrial processes. Member states often have additional requirements, such as Germany’s Technical Instructions on Air Quality Control (TA Luft), which specify odour thresholds.

In Australia, the Environmental Protection Authority (EPA) in each state regulates odour emissions, often requiring facilities to conduct odour impact assessments and implement control measures. Similar frameworks exist in Canada, where provincial governments oversee compliance.

Pet food manufacturers must stay informed about applicable regulations and engage with regulatory bodies to ensure compliance. This often involves monitoring emissions, modeling odour dispersion, and reporting to authorities.

Top Odour Control Technologies for Pet Food Manufacturing

A range of technologies is available to control odours in pet food manufacturing, each suited to specific processes and compounds. These can be broadly categorized into physical, chemical, and biological methods, often used in combination for optimal results.

1. Physical Methods

2. Chemical Methods

3. Biological Methods

Best Practices for Pet Food Manufacturing Odour Management

Beyond installing control technologies, pet food manufacturers can adopt operational and strategic practices to minimize odours:

1. Process Optimization

2. Facility Design

3. Monitoring and Modeling

4. Community Engagement

5. Training and Maintenance

Elixir Enviro Systems – Experts in Pet Food Odour Control

If you’re looking for reliable pet food odour control, Elixir Enviro Systems is your trusted partner. We specialize in industrial odour treatment, wastewater management, and biofiltration systems for factories and processing plants.

With years of experience, Elixir offers complete solutions—from design and installation to testing and maintenance. Whether your facility needs scrubbers, biofilters, RTOs, or real-time odour monitoring, we’ve got you covered.

Why Choose Elixir Enviro?

✅ Pioneer in Industrial Odour Control in India

✅ Largest player in India having treating about 1 Million cubic meter of air each hour

✅ Experts in pet food manufacturing odour control

✅ Custom solutions for industrial odour problems

✅ In-house R&D and simulation tools

✅ Onsite odour audits and pilot testing

✅ Solutions that meet all local and global regulations

Visit www.elixirenviro.in to learn more or contact us for a custom consultation on odour control for your facility.

Conclusion

Odour control in the pet food manufacturing industry is a multifaceted challenge requiring a combination of advanced technologies, operational best practices, and community engagement. By understanding the sources of odours—raw materials, batching-Grinding, extrusion, and wastewater—manufacturers can deploy targeted solutions like scrubbers, biofilters, and oxidizers. Regulatory compliance, worker safety, and environmental sustainability further underscore the importance of effective odour management.

As industry continues to grow, so too will the need for innovative, cost-effective, and eco-friendly odour control strategies. Manufacturers that invest in these solutions will not only mitigate risks but also strengthen their reputation as responsible corporate citizens. By prioritizing odour control, the pet food industry can ensure a harmonious coexistence with communities and a sustainable future for pet nutrition.

📌 FAQ Section

Q1. What causes odour in pet food manufacturing?

A: Odours are primarily caused by raw material handling, grinding & batching of ingredients, extrusion, drying, and improper wastewater management. These processes release VOCs, sulfur compounds, and amines.

Q2. How can odour emissions be controlled in pet food factories?

A: Odour control can be achieved using technologies like biofilters, wet scrubbers, regenerative thermal oxidizers (RTOs), and proper ventilation systems. Process optimization and regular maintenance also play a crucial role.

Q3. Are odour control systems mandatory for pet food manufacturers?

A: In many regions, yes. Regulatory bodies like the US EPA, EU’s Industrial Emissions Directive, and local environmental agencies require odour emissions to be controlled and monitored. Other locations around the globe mostly have nuisance law, meaning if the neighborhood complains, the factory might need to shut down until the issue is rectified. Considering this, the cost of installation of the Odour Control Unit surpasses the disadvantages of legal penalties, factory-closures and poor neighborhood relationships.

Q5. What role does Elixir Enviro Systems play in odour control?

A: Elixir Enviro Systems offers turnkey odour control solutions tailored to pet food manufacturing, including biofilters, scrubbers, oxidizers, and real-time monitoring. They also provide audits and pilot testing to ensure effectiveness.

The Science Behind Biofiltration: How does Biofilter for Odour Control System works?

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:

  1. Humidification: Since microorganisms thrive in moist environments, the air may be humidified to maintain the appropriate moisture level within the filter bed.
  2. Temperature Adjustment: The air temperature is adjusted to fall within the optimal range (usually between 20°C and 40°C) for microbial activity.
  3. 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:

  1. Pollutants dissolve into the water layer on the surface of the filter media.
  2. 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:

  1. Carbon dioxide (CO₂): A harmless byproduct of organic compound breakdown.
  2. Water (H₂O): Released back into the environment.
  3. 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:

  1. Hydrogen Sulfide (H₂S): A common cause of the “rotten egg” smell in wastewater and industrial processes.
  2. Volatile Organic Compounds (VOCs): Found in emissions from chemical plants, paint production, and printing industries.
  3. Ammonia (NH₃): A sharp-smelling compound often associated with agricultural and food processing facilities.
  4. 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:

  1. 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
  2. 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.
  3. 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. 
  4. 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. 
  5. 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:

  1. 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.
  2. 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.
  3. 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.
  4. 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.

Biological Odour Control – What is it?

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

  1.  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 
  2. 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, 
  3. 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. 
  4. 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.

Bioscrubber

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. 

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.