Odour Control in Slaughterhouse and Chicken Waste Rendering Plants: Indian Context and Global Practices

Introduction

Slaughterhouse and chicken waste rendering plants are integral to managing by-products from the meat and poultry processing industries in India, one of the largest meat producers and exporters in the world. With an export valuation of 2.89 billion USD in 2020 and 1,176 slaughterhouses alongside 75 modern abattoirs, India generates substantial waste, including high volumes of poultry processing waste because of the high demand for chicken. Rendering plants process these wastes into valuable products, but they produce malodorous emissions that pose environmental and public health challenges. This Blog explains the procedure of slaughterhouse and chicken waste rendering, odourous compounds in exhaust gases, world odour control practices, individual and combined odour control units, biological methods, and the advantages, disadvantages, and issues of having rendering plants near slaughterhouses, particularly collection of waste from small-scale slaughterhouses in India.

Rendering Process in Slaughterhouse and Chicken Waste Plants

The rendering process changes waste from slaughterhouses and chickens, such as inedible animal tissues (organs, bones, blood, feathers, offal, and poultry-specific materials like heads, feet, and viscera), into stable products like animal feed, fertilizers, or industrial materials.

In a rendering plant, the process begins from the collection and transportation of raw waste to the plant. The raw waste is subsequently cooked at high heat (usually 115–145°C) to separate fats, remove moisture, and eliminate pathogens. Grinding, screening, and pressing follow for the production of products such as meat and bone meal, poultry meal, feather meal, or tallow. Chicken waste rendering is supplemented with other processes to render feathers, which are hydrolyzed under pressure for the breakdown of keratin into digestible protein to create feed. Cooking and drying processes, especially for poultry waste with high protein and moisture content, create high gaseous emissions, responsible for the odour problem. Rendering is a common practice in India but the energy-intensive process and inadequate odour control are responsible for environmental problems, particularly in poultry-dominated areas.

Odourous Compounds in Exhaust Gases and Their Characteristics

Slaughterhouse and chicken waste rendering Exhaust gas is a mixture of volatile organic compounds (VOCs) and inorganic compounds which generate malodours. The primary odourous compounds are:

  1. Hydrogen Sulfide (H₂S): A highly odourous gas possessing a smell, reminiscent of rotten egg, which can be detected at 0.00047 ppm, released during decomposition of sulfur-containing proteins of meat and poultry waste.
  2. Methanethiol (CH₃SH): Sulfur compound having a pungent, cabbage odour with low olfactory threshold (0.001 ppm), present in poultry manure due to high protein content.
  3. Trimethylamine: Fishy odour nitrogenous compound, formed on protein breakdown, prominently by chicken viscera and blood.
  4. Ammonia (NH₃): Pungent nitrogenous gas from waste with high nitrogen content, detectable at 0.037 ppm, present in slaughterhouse and poultry rendering due to organic breakdown.
  5. Aldehydes (e.g., acetaldehyde, propanal): Sharp, irritating odours formed during organic matter breakdown, notably in feather hydrolysis.
  6. Volatile Fatty Acids (VFAs): Compounds such as butyric acid, with a rancid smell, generated during hydrolysis and acidogenesis, especially in poultry offal.
  7. Other VOCs: Toluene, benzene, and ketones may also be present, with varying levels of biodegradability, particularly in chicken waste from feather processing.

Rendering plant exhaust gases have high temperatures (cooking), high water content (poultry waste with 60–70% water), and badly soluble parts, so they are difficult to treat odour.  Poultry rendering, particularly feather hydrolysis, produces unique odours due to sulfur-rich keratin breakdown. Volatile compounds in India’s warm climate are enhanced causing an increase in odour intensity and dispersion.

Global Odour Control Practices for Rendering Plants

Globally, rendering plants for slaughterhouse and chicken waste employ diverse odour control technologies tailored to exhaust gas characteristics and regulatory requirements. Common practices include:

  1. Source Control: Low-emission processing and good housekeeping, such as sealed storage for poultry feathers and rapid waste processing, minimize odour generation.
  2. Physical and Chemical Methods: Adsorption (using activated carbon), absorption (via wet scrubbers), and thermal oxidation are widely used. Adsorption captures VOCs, absorption dissolves water-soluble gases, and thermal oxidation burns odourous compounds at high temperatures.
  3. Biological Methods: Biofiltration, biotrickling filters, and bioscrubbers use microorganisms to break down odourous compounds into harmless products such as carbon dioxide and water. These methods are becoming more popular because they are sustainable.
  4. Hybrid Systems: Combinations of physical, chemical, and biological methods achieve higher removal efficiencies for the complex mix of odourous compounds in emissions from slaughterhouses and poultry rendering.

In the Netherlands and Germany, biofiltration is the best available control technology, achieving up to 90% odour reduction since the 1960s. American meat rendering facilities use thermal oxidizers and wet scrubbers to meet strict emission standards. This is especially important in poultry processing facilities that deal with large amounts of feathers and offal.

Odour Control Units and Combinations

Individual Odour Control Units

  1. Wet Scrubbers: Wet scrubbers employ liquid, i.e., water or chemical solvents, in the adsorption of odourous gases such as ammonia and H₂S. Wet  scrubbers are appropriate for water-soluble chemicals but not for poorly soluble VOCs of feather hydrolysis. Wet scrubbers are typically installed in exhaust treatment stream stacks.
  2. Activated Carbon Adsorption: Activated carbon filters can readily eliminate a broad spectrum of VOCs and sulfur compounds suitable for use in slaughterhouse and poultry waste odours. Media replacement on a continuous basis is costly and restricts its usage.
  3. Thermal Oxidizers: They burn the odourous gases at 700–1,200°C to generate carbon dioxide and water. hey are effective for most VOCs, including those from feather processing, but are energy-intensive and produce greenhouse gases.
  4. Biofilters: Organic matter packed beds contain microbial decomposition of materials like H₂S, NH₃, and VFAs. They are 89–98% effective and suited for poultry rendering odours. Efficiency lies in good engineering and sizing of the unit.
  5. Biotrickling Filters: Artificial packing materials with continuous liquid flow offer a substrate for microbial growth, with high gas flow rates from rendering processes. They eliminate 88–100% for H₂S and NH₃.
  6. Bioscrubbers: These combine absorption and biological degradation , absorbing gases into a liquid for microbial breakdown. They are less effective for poorly soluble VOCs from poultry waste due to high liquid-to-gas ratios.

Combined Odour Control Systems

Combinations enhance efficiency for the diverse odorous compounds in slaughterhouse and chicken waste rendering exhaust:

  1. Wet Scrubber + Biofilter: Wet scrubbers remove water-soluble chemicals like ammonia, while biofilters degrade other VOCs, optimal for high-moisture poultry waste gases.
  2. Biotrickling Filter + Biofilter: This is aimed at biodegradable VOCs and high concentration gases, ideal for high gas flow rate large-scale poultry rendering plants.

Biological Methods

Biotechniques are of special significance in India because they are economical and environmentally friendly. Microbial degradation is the basis of biofiltration, biotrickling filters, and bioscrubbers producing minimal secondary waste. Considerations are important:

  1. Biofiltration Efficiency Determinants: Efficiency  depends on pH, temperature, nutrient availability, and watering rate. There must be sufficient gas contact time and shallow water layer over the biofilm in order for mass transfer, specifically for sulfur-containing odours from poultry waste.
  2. Advantages:Minimum cost of operation, low energy requirement, and no secondary pollutants make the biological process eco-friendly with up to 90% removal of H₂S, NH₃, and VFAs.
  3. Disadvantages: They are less effective for poorly soluble VOCs from feather hydrolysis, require large footprints

The most important factor in any treatment plant is the correct engineering of the treatment unit. In a majority of the instances, it has been observed that the plants will have some kind of odour control units but are highly undersized and are not fulfilling its intention. It involves designing a system with correct control and monitoring system.

Advantages, Disadvantages, and Challenges of Rendering Plant Location

Rendering Plants Far from Slaughterhouses

Advantages:

  1. Reduced Community Impact: Remote locations lower odour complaints. This is important in India’s crowded areas, especially for poultry rendering that has strong feather-related smells.
  2. Land Availability: Rural sites provide space for large facilities and waste storage. This is necessary for managing the large amount of poultry waste.
  3. Environmental Protection: Being far from water bodies decreases the risk of contamination from untreated waste. This is a significant issue in India, where poultry waste is often dumped into rivers.

Disadvantages:

  1. Transportation Costs: Moving slaughterhouse and poultry waste to distant plants increases expenses, especially for small-scale chicken slaughterhouses with limited resources.
  2. Logistical Challenges: Long-distance transport requires refrigerated vehicles to prevent spoilage and odour, which is difficult in India’s hot climate.
  3. Waste Degradation: Transport delays can cause decomposition, leading to stronger odour emissions, particularly in poultry waste with high moisture content.

Challenges:

  1. Infrastructure Limitations: Rural areas often lack proper roads and facilities for waste transport. This makes it hard to collect poultry waste.
  2. Regulatory Compliance: It is difficult to ensure compliance during transport and processing in remote regions where oversight is limited.
  3. Economic Feasibility: High transport costs may discourage small slaughterhouses from using distant rendering plants. This can lead to illegal dumping.

Feasibility of Rendering Plants with Waste Collection from Small Slaughterhouses

In India, small-scale slaughterhouses, especially poultry units, are common. Centralized rendering plants that collect waste from several facilities can work, but they have some challenges:

Feasibility Factors:

  1. Centralized Collection Systems: Refrigerated transport systems can keep waste fresh. This is important for poultry waste, which has a lot of moisture and feathers.
  2. Economies of Scale: Centralized plants can handle large amounts of waste. This makes it possible to use better odour control methods, like biofiltration, for poultry and meat waste.
  3. Circular Economy Potential: Rendering plants can create biogas, poultry meal, and fertilizers. This supports India’s “Swachh Bharat Abhiyan” and National Energy Policy.

Challenges:

  1. Collection Logistics: Coordinating waste collection from numerous small poultry slaughterhouses requires efficient scheduling and infrastructure.
  2. Cost Barriers: Small slaughterhouses may lack funds for transport or processing fees, necessitating subsidies.
  3. Odour During Collection: Improper storage or transport of poultry waste, especially feathers, can exacerbate odours before reaching the plant.

What Elixir Enviro Systems Can Do in Odour Control for Slaughterhouse and Poultry Rendering Plants

At Elixir Enviro Systems (EES), we recognise that odour from slaughterhouses and poultry waste rendering plants is one of the most pressing challenges for the industry. Emissions of hydrogen sulfide (H₂S), ammonia (NH₃), volatile fatty acids, and feather-processing VOCs not only lead to strong community complaints but also expose operators to strict regulatory action under CPCB and SPCB norms.

To address these challenges, EES provides customised odour control solutions designed specifically for the unique conditions of Indian slaughterhouses and poultry rendering facilities.

Advanced Biological Odour Control

  1. Biofilters, biotrickling filters, and bioscrubbers engineered to remove H₂S, NH₃, and VOCs effectively.
  2. Eco-friendly and cost-effective systems adapted to Indian climatic and industrial conditions.

Hybrid Systems for Complex Emissions

  1. Wet scrubbers + biofilters for handling high-moisture poultry emissions.
  2. Biotrickling filters + biofilters for large-scale rendering units with high gas flows and mixed odorous compounds.

Pilot Studies & Onsite Assessment

  1. Odour source identification and monitoring tailored to slaughterhouse and rendering processes.
  2. Pilot-scale testing to validate performance before full-scale installation, ensuring efficiency and long-term cost savings.

Waste-to-Energy Integration

  1. Solutions that integrate anaerobic digestion with rendering operations.
  2. Enables biogas generation while significantly reducing odour impact.

At Elixir Enviro Systems, our goal is to transform odour challenges into sustainable opportunities. By combining engineering precision with biological expertise, we help slaughterhouse and poultry rendering plants across India achieve cleaner operations, regulatory compliance, and improved community wellbeing.

Conclusion

Odour control in chicken waste-rendering and slaughterhouse facilities is crucial in India, which has a large poultry and meat industry. Rendering, cooking at high temperatures, and feather hydrolysis  generates odorous compounds like H₂S, methanethiol, ammonia, and VOCs, with high sulfur and moisture content of poultry waste. Global practices, including biofiltration, activated carbon adsorption, and thermal oxidation, offer effective solutions, with biological methods being cost-effective for India. Hybrid systems are cost-effective but have the disadvantages of high cost and maintenance. Remote rendering plants reduce community impact but have transport cost, particularly for small poultry slaughterhouses. Centralized plants receiving waste from multiple facilities are feasible with good logistics and subsidies.

FAQ

1. Why do rendering plants smell so bad?

Rendering Plants also releases pungent volatile gases like hydrogen sulfide, ammonia, and volatile fatty acids from decomposing animal and poultry waste. Feathers, blood, and viscera create especially strong odours.

2. Which odour control method works best for poultry waste in India?

Biological systems like biotrickling filters and biofilters are the most efficient and affordable for India. They can remove up to 90% of the odour if designed properly.

3. Can odour control in rendering plants also reduce pollution?

Yes. Many odour control systems also capture VOCs and harmful gases, improving air quality and reducing environmental pollution.

4. Why is it difficult to manage poultry waste odours in India?

India’s hot climate accelerates decomposition, small slaughterhouses lack resources, and many odour control systems are undersized or poorly maintained.

5. What are the benefits of centralised rendering plants?

They allow advanced odour control, support the circular economy by producing biogas and organic fertilizer, and reduce illegal dumping of poultry waste.

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.

 

 

How to Control Odour from Sewage, Fecal Sludge and Effluent Treatment Plants (STP, FSTP & ETP)?

Sewage Treatment Plants (STP), Fecal Sludge (Septage) Treatment Plants (FSTP), and Effluent Treatment Plants (ETP) are essential for managing wastewater generated from domestic, municipal, household, and industrial sources. However, these facilities are often associated with foul odour emissions, which pose a serious nuisance to the surrounding communities.

Odour generation depends on factors such as plant size, wastewater composition, retention time, aeration levels, and the design and maintenance of the treatment process. Unpleasant odours are not merely a comfort issue—they can lead to public complaints, regulatory scrutiny, and operational inefficiencies.

Elixir Enviro Systems Pvt Ltd (www.elixirenviro.in) the pioneer in odour control, Offers customised and integrated odour control solutions for STPs and ETPs across India. From proper ventilation design to advanced treatment technologies, Elixir provides systems to eliminate odour at the source, enhance air quality, and ensure regulatory compliance.

Odour Sources in STP, FSTP & ETP – What’s Causing the Smell?

Odour formation in sewage, septage, and effluent treatment plants (STPs, FSTPs, and ETPs) is primarily due to the anaerobic decomposition of organic matter. Under low or no oxygen conditions, microorganisms break down waste and release gases with pungent, foul odours. Understanding the source of these odours is essential for devising effective control measures.

  1. Inlet and Screening Chambers: Raw sewage or effluent enters the plant here and begins to break down, releasing gases such as H₂S and VOCs.
  2. Grit Chambers and Equalization Tanks: Odours may intensify in these areas due to the buildup of organic solids.
  3. Anaerobic Digesters: These units emit strong odours resulting from the biological breakdown of sludge under oxygen-deficient conditions.
  4. Sludge Handling Units: Processes like sludge thickening, dewatering, and storage can all produce pungent odours.
  5. Aeration Tanks and Clarifiers: While aeration helps reduce odours, poor oxygen transfer can create anaerobic conditions, increasing odour emissions.

What Odour Control Technologies Are Used in STP and ETP Facilities?

Odour control is not a universal solution. The technology you choose depends on the air volume that needs treatment, the level of pollutants, and the specific stages of the treatment process that produce odour. Here are the most common odour control systems used in sewage and effluent treatment plants:

Biofilter

What is a biofilter? A biofilter is a porous bed made of organic media, some are generic media and some are proprietary fomulations.  Generic media includes substances such as compost, wood chips, or synthetic materials. The proprietary media include the media manufactured by Elixir enviro systems (www.elixirenviro.in) such as Cocofil® 25 & Cocofil® 25 etc, wherein the manufacturer guarantees the removal efficiencies. It supports a microbial population that biologically degrades odourous compounds such as hydrogen sulphide (H₂S), ammonia (NH₃), and volatile organic compounds (VOCs).

The odourous air is passed through the media bed, and the microorganisms convert the pollutants into harmless by-products like CO₂ and H₂O. Biofilters are highly effective and can remove up to 95% of odours when properly maintained. However, the performance is highly dependent on media moisture content and air distribution. Few versions of biofilters offered by Elixir Enviro Systems can be seen at: Click Here

Bio-Trickling Filter

Bio-trickling filters employ inert packing media over which water and nutrients continuously trickle, creating a moist environment conducive to microbial growth. As odour-laden air passes through the filter, aerobic bacteria break down the pollutants.

These well-aerated systems can treat both volatile organic and inorganic compounds. A primary benefit is their ability to efficiently handle high odour concentrations in a compact design. However, nutrient dosing and the risk of clogging due to biomass buildup must be carefully managed.

Bio-scrubber

Also known as a bio-washer, the bio-scrubber operates in two stages. In the first stage, odourous air comes in contact with a liquid absorbent, typically water or a chemical solution, which absorbs the pollutants. In the second stage, the liquid goes into a separate tank for biological treatment. This is where microbes come in—they break down the compounds that were previously absorbed.

Bio-scrubbers are especially effective at treating highly soluble compounds such as H₂S. They are known for their high reliability and low chemical consumption, particularly when supported by proper nutrient management.

Chemical Scrubbers

Chemical scrubbers remove odourous gases using acidic or alkaline solutions. The polluted air stream is brought into contact with a scrubbing liquid in a packed tower, where chemical reactions neutralise the odourous compounds.

The pH of the scrubber is maintained based on the nature of the pollutants (acidic for ammonia, alkaline for H₂S). Although chemical scrubbers are efficient and quick acting, they require chemical handling infrastructure and periodic monitoring. This is particularly suitable where the odour characterization is done and fine removal is not expected.

Elixir Enviro’s scrubber systems are custom-built to ensure precise dosing, optimal contact time, and minimal chemical waste.

Activated Carbon Filter

A carbon filter is a highly effective solution frequently selected for its easy installation. It operates through adsorption, with activated carbon capturing and retaining odourous gases such as hydrogen sulfide (H₂S), ammonia (NH₃), and volatile organic compounds (VOCs) commonly released from wastewater treatment.

The activated carbon can come from bituminous coal or coconut shells and might be treated with chemicals to improve its ability to absorb specific pollutants. The carbon bed sits in a sealed container through which the foul air passes, letting the media absorb contaminants before clean air is released. A well-designed carbon filter system can remove up to 99% of odours. Maintenance includes regular inspections, monitoring pressure drops, and changing the carbon media every 12 to 24 months, depending on the gas load. Carbon filters are compact, quiet, and easy to fit into existing systems, but the ongoing cost, which is almost as high as the initial cost, can make them less appealing for larger units.

Process Combination

In many sewage and effluent treatment plants, using a mix of treatment techniques works better than sticking to just one method.

For instance, biofilters used with chemical scrubbers or bio-trickling filters followed by activated carbon polishing can offer multiple layers of odour removal. This helps meet strict air quality standards.

Elixir Enviro creates modular systems that fit into new or existing plants, allowing for easier adjustments as needs change.

Design Strategies for Preventing Odour Formation

Prevention is always better than cure. In addition to treatment technologies, smart plant design and operation significantly reduce odour emissions. Key approaches include:

  1. Proper Enclosure of Units: Covering tanks and channels keeps odourous gases from escaping.
  2. Efficient Ventilation Systems: Managing airflow through ducts, fans, and odour extraction points keeps air contained and directs it to treatment units.
  3. Maintaining Aerobic Conditions: Avoiding stagnant areas and ensuring enough oxygen in biological reactors reduces the formation of H₂S and NH₃.
  4. Sludge Management: Timely removal and treatment of sludge prevent the buildup of decomposing matter.
  5. Corrosion-Resistant Ducting: Especially important in environments containing acidic gases like H₂S.

Why is Odour Control in STP, FSTP & ETPs Important?

Controlling odours from sewage and effluent treatment plants is important for multiple reasons.

  1. Health and Safety: Gases like hydrogen sulphide and ammonia are dangerous. Long exposure can lead to health problems for workers and people living nearby.
  2. Environmental Compliance: Regulatory bodies such as the Central and State Pollution Control Boards have set limits for odour and gas emissions. Non-compliance can result in fines or shutdowns.
  3. Public Acceptance: Foul odours can trigger complaints and create resistance against wastewater infrastructure development, especially in urban areas.
  4. Operational Efficiency: Odours often indicate process issues such as sludge build-up or poor aeration. Fixing these problems boosts plant performance.

How Elixir Enviro Systems Controls Odour in STP & ETP Facilities

At Elixir Enviro Systems, we specialize in designing and executing custom odour control solutions tailored to the unique needs of sewage and effluent treatment plants across municipal, industrial, and residential sectors. With decades of expertise and a strong focus on innovation, our solutions are engineered to deliver maximum odour reduction, regulatory compliance, and community satisfaction.

  1. Site Assessment and Air Quality Modelling: Our experts evaluate odour dispersion patterns using advanced simulation tools.
  2. Custom System Design: Based on source identification, air volume, and contaminant loading.
  3. Installation and Commissioning: Turnkey solutions from ductwork to stack design and treatment units.
  4. Real-Time Monitoring: Integration of odour monitoring devices to track system performance.
  5. Post-installation Support: Regular maintenance, media replacement, and system audits.

Conclusion

Odour control from sewage and effluent treatment plants is not a luxury—it is a necessity. It ensures cleaner air, healthier environments, and peaceful coexistence with surrounding communities.

Elixir Enviro Systems Pvt Ltd is a trusted partner in delivering customised, cost-effective, and high-performance odour control solutions for both municipal STPs and industrial ETPs across India. With a comprehensive range of technologies—from biofilters and scrubbers to modelling and monitoring tools—Elixir ensures that your facility stays compliant, efficient, and community-friendly.

Interested in Odour Control Solutions for Your Treatment Plant?

📞 Reach out to us at info@elixirenviro.in 🌐: www.elixirenviro.in

 

🧾 FAQ

1. What causes odour in sewage and effluent treatment plants?

Odours in STPs and ETPs mainly come from the breakdown of organic matter in the absence of oxygen. This process releases gases such as hydrogen sulphide (H₂S), ammonia (NH₃), volatile organic compounds (VOCs), and mercaptans. These gases have strong, bad smells and can be harmful to health if not managed.

2. Is odour from STPs and ETPs harmful to health?

Yes, prolonged exposure to gases such as H₂S and ammonia can cause eye irritation, headaches, nausea, and respiratory problems. At high concentrations, these gases can be toxic, making affected people unconscious and sometimes causes death as well. There are several cases of people falling into the drains and lost lives, mainly due to the toxicity of gases like H2S. This can happen in STPs as well, especially when the source is in a confined zone. Effective odour control is important for the health and safety of plant workers and surrounding communities.

3. Which areas of an STP/ETP emit the most odour?

Key odour-generating zones include:

  1. Inlet works/screens
  2. Equalization tanks
  3. Anaerobic digesters
  4. Sludge handling units
  5. Primary and secondary clarifiers

These areas should be prioritised for containment and odour control systems.

4. How effective are biofilters in removing odours?

When properly maintained, biofilters can remove up to 95% of odourous compounds, especially hydrogen sulphide and VOCs. Their efficiency depends on type of media, moisture content of the media, air distribution, and microbial activity.

 

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.

Composite Without Compromise: Odour Control in GRP, SMC, and FRP Vessel Manufacturing

Proven Strategies to Keep Emissions and Nuisance Odours in Check

1. Introduction

Composite vessels made from FRP, GRP, and SMC are the backbone of many industries—offering unmatched strength, corrosion resistance, and design flexibility. But behind these advanced materials lies a quieter challenge: the odours generated during manufacturing. These emissions, primarily from resin curing and finishing operations, can affect worker health, community relations, and regulatory compliance. In this blog, we explore the sources of odour in composite vessel production and share proven strategies to control them—so manufacturers can deliver high-performance products without compromising air quality or reputation.

2. Understanding the Materials

FRP (Fiber-Reinforced Plastic) refers to a broad category of composites made from a polymer matrix reinforced with fibres such as glass, carbon, or aramid. GRP (Glass-Reinforced Plastic) is a subset of FRP, where the reinforcing fibre is glass. SMC (Sheet Moulding Compound) is a type of pre-impregnated fibre composite, usually consisting of chopped glass fibres and thermoset resins, used in compression moulding. These materials are popular for vessel manufacturing due to their excellent mechanical properties, lightweight nature, and corrosion resistance. However, many of the resins used—particularly polyester and vinyl ester—emit volatile organic compounds (VOCs) like styrene during processing. These emissions are the primary source of odour and present both environmental and health concerns if not properly managed. Let’s first dive into little more details on each material.

A. GRP: Definition and Composition

GRP (Glass Reinforced Plastic) is a composite material composed of glass fibres, such as E-glass or S-glass, embedded in a plastic resin matrix, typically polyester, vinyl ester, or epoxy. The term emphasizes the use of glass fibres as the primary reinforcement, making GRP a specific subset of fibre-reinforced composites. It is widely chosen for its balance of strength, corrosion resistance, and affordability.GRP offers good mechanical strength, excellent corrosion resistance, and moderate stiffness, though it is heavier than carbon-based composites. It is cost-effective and ideal for large structures like storage tanks, pressure vessels, pipes, and marine vessels such as boat hulls. GRP is commonly used in industries like water treatment, air pollution control, chemical storage, oil & gas, and marine applications due to its durability and resistance to harsh environments.

B. SMC: Definition and Composition

SMC (Sheet Moulding Compound) is a composite material made of chopped glass fibres (typically 25-50 mm long) mixed with a thermosetting resin, usually polyester, along with fillers like calcium carbonate and additives. Supplied as mouldable sheets, SMC is designed for compression moulding, enabling the production of complex shapes with consistent thickness and high-quality surface finishes.SMC provides good mechanical strength, dimensional stability, and an excellent surface finish, but its shorter, chopped fibres result in lower strength compared to continuous-fibre composites like GRP for high-load applications. It is well-suited for smaller, intricate components such as covers, enclosures, automotive panels, or small tanks, where high-volume production and aesthetic quality are priorities. SMC is less common for large vessels due to its structural limitations, being that said, many companies have come up with designs with steel supports making the SMC panel tanks suitable for somewhat larger applications as well.

C. FRP: Definition and Composition

FRP (Fiber Reinforced Plastic) is a broad category of composites that includes any type of fibreglass, carbon, aramid, or basalt—embedded in a plastic resin matrix. GRP is a type of FRP when glass fibres are used, but FRP also encompasses high-performance fibres like carbon or aramid. This versatility allows FRP to be tailored for a wide range of applications, from general-purpose to specialized uses.FRP’s properties vary by fibre type: glass-based FRP (like GRP) offers corrosion resistance and moderate strength, carbon-based FRP provides a high strength-to-weight ratio and stiffness, and aramid-based FRP excels in impact resistance. Glass-based FRP is used for tanks and pipes, like GRP, while carbon or aramid-based FRP is employed in aerospace, automotive, high-pressure vessels, and advanced marine structures like aircraft components or high-performance yachts. FRP’s cost ranges from affordable (glass) to expensive (carbon/aramid), depending on the fibre and manufacturing process.

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3. Why Odour Control Matters

Odour control in FRP/GRP manufacturing is far more than a matter of comfort—it’s a critical aspect of health, safety, and compliance. The Odours are largely caused by VOCs, such as styrene, a common component in polyester and vinyl ester resins. Prolonged exposure to styrene and similar compounds can lead to respiratory issues, neurological symptoms, and other health problems for workers. Additionally, regulatory agencies worldwide impose strict limits on VOC emissions to safeguard air quality and public health. Non-compliance can result in significant fines and legal challenges. Beyond regulations, persistent Odours can strain relationships with neighbouring residents and businesses, potentially damaging a company’s reputation. Effective Odour management, therefore, is essential for worker well-being, regulatory adherence, and maintaining community goodwill.

4. Odour Issues Specific to Each Material

The manufacturing of GRP (Glass Reinforced Plastic), SMC (Sheet Moulding Compound), and FRP (Fiber Reinforced Plastic) vessels involves processes and materials that can release odorous compounds. The primary sources of odours stem from the resins, solvents, and additives used, as well as specific manufacturing techniques. Below is a detailed breakdown of the odour sources for each material, organized by material type.

A. GRP Vessel Manufacturing: Odour Sources

GRP vessels are made using glass fibres and thermosetting resins (e.g., polyester, vinyl ester, or epoxy) through processes like hand lay-up, filament winding, or resin transfer moulding (RTM). Odour sources include:

(i) Resins (Styrene Emissions):

(ii) Solvents and Thinners:

(iii) Curing Agents and Catalysts:

(iv) Open-Mold Processes:

(v) Dust and Fumes:

B. SMC Vessel Manufacturing: Odour Sources

SMC is a pre-mixed composite of chopped glass fibres, polyester resin, fillers, and additives, moulded into sheets and compression-moulded under heat and pressure. Odour sources are generally less intense than GRP due to the closed-mould process but still significant:

(i) Resins (Styrene and Other VOCs):

(ii) Additives and Fillers:

(iii) Compression Moulding:

(iv) Solvents for Equipment Cleaning:

(v) Post-Moulding Finishing:

C. FRP Vessel Manufacturing: Odour Sources

FRP encompasses a broad range of composites, as an umbrella category, FRP includes both GRP and SMC, but also other forms like carbon-reinforced or aramid-reinforced plastics, or other fibres, using resins like polyester, vinyl ester, or epoxy. Odour sources depend on the fibre and process but overlap with GRP for glass-based FRP:

(i) Resins (Styrene and Epoxy Emissions):

(ii) Solvents and Cleaning Agents:

(iii) Curing Agents:

(iv) Manufacturing Processes:

(v) Fiber-Specific Odours:

5. Odour Control Strategies

The manufacturing of GRP (Glass Reinforced Plastic), SMC (Sheet Moulding Compound), and FRP (Fiber Reinforced Plastic) vessels involves resins, solvents, and additives that release odourous volatile organic compounds (VOCs), notably styrene from polyester resins. These odours, described as pungent or chemical, can affect worker health, community relations, and regulatory compliance. Effective odour control strategies are essential to mitigate these emissions, improve workplace safety, and adhere to environmental standards. The odour control strategies are categorised into two – process/product specific odour control strategies with respect each product and End of pipe solutions applicable for all the three products. First, we will cover few tailored strategies for each material, focusing on ventilation, material selection, process optimization, and followed by end-of-pipe solutions or advanced filtration methods.

A. GRP Vessel Manufacturing

(i) Ventilation and Air Extraction Systems:

GRP vessel manufacturing frequently employs open-mould techniques such as hand lay-up or spray-up, where styrene-rich polyester resins are exposed to air, resulting in significant VOC emissions. To address this, robust ventilation systems, including local exhaust ventilation (LEV) systems, are critical. These systems are installed at key emission points, such as resin application and curing stations, to capture odorous air. Regular maintenance of these systems prevents resin residue buildup, which could otherwise exacerbate odours, and ensures consistent performance in high-emission environments.

The implementation of ventilation systems not only reduces odours but also enhances workplace safety by minimizing worker exposure to harmful VOCs. For closed-mould processes like resin transfer moulding (RTM), sealing moulds tightly and integrating ventilation at demoulding stages further controls odour escape. These systems can be tailored to facility size, with smaller setups using standalone filtration units and larger plants opting for integrated HVAC solutions.

(ii) Use of Low-Styrene or Alternative Resins:

A proactive approach to odour control in GRP manufacturing involves selecting low-styrene or styrene-free resins to reduce VOC emissions at the source. Traditional polyester resins contain high styrene levels, contributing to strong odours and health risks. Low-styrene polyester resins or vinyl ester resins emit fewer VOCs during curing, significantly decreasing odour intensity. While these resins may increase material costs, they offer long-term benefits, including reduced odour complaints, improved worker safety, and alignment with environmental regulations.

The adoption of alternative resins requires careful consideration of application suitability, as vinyl ester or epoxy resins may have different mechanical properties or curing requirements compared to polyester. Manufacturers must evaluate these factors against the specific needs of GRP vessels, such as corrosion resistance for chemical storage. Pilot testing low-styrene resins can help assess performance without disrupting production. This strategy also supports sustainability goals by reducing the environmental impact of VOCs, making it appealing for facilities aiming to enhance their corporate social responsibility profile.

B. SMC Vessel Manufacturing

(i) Enclosed Mixing and Moulding Processes

SMC manufacturing involves pre-mixing chopped glass fibres with polyester resins and additives to create mouldable sheets, followed by compression moulding in closed systems, which inherently produces fewer odours than GRP’s open-mould processes. To control odours during mixing, enclosed systems with integrated ventilation or extraction units are essential. Automated mixing equipment minimizes styrene release by containing the process, while local exhaust ventilation captures any emissions during material handling. During compression moulding, closed moulds reduce odour escape, but residual styrene may be released when moulds are opened. Installing LEV systems near moulding machines ensures these emissions are captured and treated, maintaining a low-odour environment.

Enclosed processes offer significant advantages, including reduced worker exposure to VOCs and compliance with workplace safety regulations. For facilities producing high volumes of SMC components, such as small tanks or automotive parts, these systems enhance efficiency by streamlining odour control within the production line.

Additionally, Regular cleaning of mixing and moulding equipment prevents resin buildup, which could contribute to persistent odours.

(ii) Post-Curing and Off-Gassing Management

After moulding, SMC vessels may retain residual styrene, leading to odours during storage or use. Post-curing techniques, such as exposing moulded parts to controlled heat in a dedicated chamber, accelerate the off-gassing process, allowing VOCs to be released in a contained environment. This can be achieved using ovens or curing rooms equipped with ventilation systems that direct off-gassed air through and odour control unit (OCU). Alternatively, parts can be stored in well-ventilated off-gassing areas before finishing or packaging, reducing odour levels in the final product.

C. FRP Vessel Manufacturing

(i) Ventilation and Air Extraction Systems:

FRP vessel manufacturing, which includes GRP and other fibres like carbon or aramid, often involves open-mould processes that release significant styrene and other VOCs. Therefore, proper ventilation and air extraction is the key strategy.

(ii) Process Optimization and Enclosure:

Optimizing the manufacturing process for FRP vessels can significantly reduce odour emissions by minimizing solvent use, use of epoxy resins with milder odour and optimising curing times. Selecting faster-curing resins or adjusting formulations to lower styrene content decreases VOC release during production. Enclosing open-mould processes in booths or isolated areas equipped with exhaust systems allows for better control of odorous air, directing it through filtration units before release.

For closed-mould processes like filament winding or pultrusion, ensuring moulds are tightly sealed and equipped with integrated ventilation systems prevents odour escape during curing or demoulding, enhancing overall air quality management. Process enclosures offer dual benefits of odour control and improved production efficiency by reducing material waste and worker exposure to VOCs.

D. End-of-Pipe solutions or Advanced Filtration Systems

Effective odour control combines process optimization, engineering controls, and air treatment technologies. By combining enclosed systems with air treatment, manufacturers can achieve a cleaner workplace and minimize community complaints, particularly in urban settings where facilities are near residential areas.

Advanced air filtration systems are highly effective for removing these compounds from the exhausted air. These filters adsorb styrene and other organic molecules, achieving up to 99.5% reduction in odourous VOCs. Key advanced filtration strategies include:

  1. Wet Scrubbers: Use water or chemical solutions to absorb and neutralize VOCs.
  2. Dry Scrubbers: Use dry media (e.g., activated alumina or impregnated pellets) to capture specific compounds.

Employing these systems can mitigate community complaints by preventing odourous emissions from escaping the facility, which is critical for plants located near residential areas. Another factor which is overlooked in many places are the employee training; Ensuring proper storage, mixing, and application techniques minimizes unnecessary emissions. Implementing these changes requires upfront investment in equipment and process redesign, but the resulting reduction in odour complaints, improved public relations and regulatory penalties offsets these costs and justify the investment. Regular process audits and air quality monitoring ensure that optimizations remain effective, allowing manufacturers to adapt to changing production demands or regulatory requirements while maintaining a low-odour environment.

6. Regulatory and Community Considerations

Odour is not just an operational issue—it’s a community and compliance matter. Many jurisdictions have strict odour and VOC regulations. For example, styrene is a listed hazardous air pollutant (HAP) under U.S. EPA regulations. Manufacturers must monitor emissions and often report to local environmental authorities. In regions like the EU, occupational exposure limits (OELs) and industrial emissions directives (IED) govern VOC discharge. Facilities must demonstrate that Best Available Techniques (BAT) are being used for odour control.

Equally important is proactive communication with the community. Transparent environmental practices and prompt response to concerns build trust and social license to operate.

7. What EES Can Do for FRP/GRP Manufacturers

Elixir Enviro Systems Pvt Ltd (EES) offers specialized odour control solutions tailored to the unique challenges of FRP/GRP manufacturing facilities. Our services and technologies help reduce VOC emissions, improve workplace safety, and ensure regulatory compliance.

🔧 Customised Solutions We Offer:

1. Design of Ventilation systems, Enclosure and Containment Solutions

2. Process Optimisation Consulting

3. On-site Services

4. Odour Control Equipment

5. Regulatory Compliance Support

💡 Why Partner with Elixir Enviro?

8. Conclusion

Controlling odour in GRP, SMC, and FRP vessel manufacturing is not just a regulatory necessity—it’s a mark of modern, responsible manufacturing. By combining smarter material choices, better processes, and effective air treatment systems, companies can uphold product quality while protecting the environment and their communities. The result is a cleaner, more sustainable path forward for the composites industry. Partnering with Elixir Enviro Systems ensures access to industry-leading solutions for effective Odour management.

Waste to Protein, Without the Smell: Engineering Cleaner Insect Meal Plants

Introduction

Insect meal processing is emerging as a sustainable and efficient solution to meet the growing demand for high-protein products, primarily used as feed for animals like fish, pet food and poultry, and sometimes for human consumption. The larvae stage is often targeted due to its high biomass and nutritional value.

In insect meal production, several types of larvae are commonly used due to their high nutritional value and efficiency in converting organic waste into biomass. The most widely used species is the black soldier fly larvae (Hermetia illucens), known for its ability to thrive on a variety of waste materials, including food scraps and manure. These larvae are rich in protein and fat, making them ideal for animal feed, and their frass is also valued as a fertilizer. Yellow mealworms (Tenebrio molitor) are another popular choice, especially in both animal and human food products. They are typically reared on grain-based substrates and have a high protein content with a lower fat profile compared to black soldier fly larvae. Lesser mealworms (Alphitobius diaperinus), or buffalo worms, are smaller but similarly used in poultry and aquaculture feed. Housefly larvae (Musca domestica) have been used for waste decomposition and feed, though they are less common today due to biosecurity concerns. Lastly, silkworm pupae (Bombyx mori), a by-product of the silk industry, are often utilized in insect meal, particularly for fish feed, owing to their high protein content.

Each species varies in terms of rearing requirements and nutritional composition. This different rearing conditions give rise to different levels of odour potential, ranging from the decaying waste to the final frass to the storage and transportation. Irrespective of the species used for the insect meal production, the processing of insect larvae to the meal always have similar line of odour generation. The decomposition of organic waste, microbial activity, and thermal processing contribute to the emission of volatile organic compounds (VOCs), ammonia, and sulfur-based gases, leading to unpleasant smells. These odours can impact worker comfort, community relations, and environmental compliance. To address these concerns, implementing effective odour control solutions is crucial. Being said that the black soldier fly larvae generally associated with stronger odours due to the nature of their feed substrates and metabolic activity.

This article explores the sources of odour in insect meal processing, the challenges they present, and the most effective strategies for odour mitigation.

Why Odour Control Matters in Insect Meal Manufacturing

Odour is a natural byproduct of organic processing, and insect meal production is no exception. The breakdown of insect biomass, drying processes, and fermentation stages can release volatile organic compounds (VOCs) and other odorants. While these smells might not bother the insects, they can be off-putting to nearby residents or workers. Effective odour management not only ensures compliance with environmental regulations but also fosters good relationships with local communities and supports the industry’s reputation as a sustainable solution.

Sources of Odour in Insect Meal Production Plants

Insect meal processing is a highly sustainable source of protein, but it presents significant odour challenges. Understanding the sources of these odours is essential for developing effective control strategies. The primary sources of odour in insect meal production stem from raw material decomposition, insect rearing conditions, processing stages, byproduct treatment, and wastewater management.

1. Rearing Phase (Larvae Growth)

This initial stage involves growing insect larvae—such as black soldier flies, mealworms, or houseflies—on organic substrates. The odours emitted during this phase originate from the feed, the larvae themselves, and microbial activity. Feed substrates play a significant role: organic waste like food scraps or manure decomposes, releasing volatile organic compounds (VOCs) such as ammonia, hydrogen sulfide (with its characteristic rotten egg smell), and short-chain fatty acids like butyric acid, which smells like rancid butter. Grain-based feeds, such as wheat bran or oats, can undergo fermentation or fungal growth, producing odours like alcohols (ethanol) and esters that have fruity or solvent-like characteristics.

Larval metabolism contributes further to the odour profile. Frass—the combination of insect excreta and undigested substrate—produces nitrogenous compounds such as ammonia and amines, which smell sharp, fishy, or decayed. In addition, larvae release hydrocarbons through their cuticles, emitting faint waxy or oily odours. The microbial decomposition of feed, whether through aerobic or anaerobic pathways, generates sulfur compounds like mercaptans and additional organic acids, which amplify the odour intensity and complexity during this stage.

2. Harvesting Phase

During harvesting, mature larvae are separated from their substrate, often through mechanical means. This disruption enhances the release of odorous compounds. Residual wet substrate left behind after separation can undergo anaerobic decomposition, producing intensified sulfurous and putrid smells. Handling live larvae may cause stress responses, leading them to release defensive compounds like aldehydes (which have sharp, green odours) or pheromones that are often musky or acrid, depending on the species.

Cleaning processes during harvesting, such as rinsing the larvae with water or solvents, may dilute some of the odours but can also stir up stagnant, earthy smells from organic residue. The combination of biological and mechanical factors in this phase makes it one of the more dynamic contributors to the odour profile in insect meal production.

3. Processing Phase (Conversion to Insect Meal)

This phase includes the killing, drying, and grinding of larvae into meal. Different killing methods impact odour differently: freezing typically emits minimal odour at first, though thawing may release faint protein breakdown smells. In contrast, heat-based methods like blanching or boiling cause Maillard reactions (browning reactions between proteins and sugars), producing more pronounced roasted, nutty, or even meat-like aromas.

Drying, whether via oven or air, concentrates VOCs by evaporating moisture. This can result in toasted, earthy, or slightly burnt odours—especially if overheating occurs, which can create acrid or charred smells. Grinding the dried larvae into meal releases fine particulates, emitting nutty, hay-like scents. However, if the lipids in the larvae oxidize during this process, particularly in fat-rich species like black soldier flies, they can produce aldehydes such as hexanal, which carry rancid or oily smells.

4. Oil Pressing Phase (Lipid Extraction)

In facilities that separate insect oil from the protein meal—especially with species like black soldier flies—mechanical oil pressing introduces additional odour sources. When pressing is done with heat, or when heat is generated from friction, thermal breakdown of lipids can occur. This leads to the formation of aldehydes, ketones, and volatile fatty acids, producing smells ranging from grassy and paint-like to rancid or sour. If pressing temperatures are too high, acrid or burnt-oil odours may develop.

Oxidation of fats during or after pressing is another key contributor to odour. Rancid, stale-oil-like smells can emerge from unsaturated fats breaking down, particularly if the oil is not processed or stored in an oxygen-limited environment. The residual press cake may still contain fat and moisture, contributing warm, earthy, or slightly sour odours if it is not cooled and dried promptly. Emissions may also arise from hot surfaces and oil collectors, especially in enclosed spaces without adequate ventilation, resulting in a lingering oily or meaty atmosphere.

5. Storage and Packaging Phase

Once insect meal is produced, it is stored and packaged, and these post-processing conditions can influence odour stability. Properly stored dry meal usually has a mild, nutty, or toasted grain-like smell. However, if moisture infiltrates the product during storage, it can support mould growth, leading to musty or fungal odours associated with compounds like geosmin.

Packaging materials can also interact with the meal. For example, VOCs from the insect meal can adsorb onto plastic or paper packaging, subtly altering the perceived odour with synthetic or papery notes. While this phase may seem passive, it can significantly affect product perception, especially in high-value feed or food applications.

6. Wastewater Treatment Phase

Water is used at various stages of insect meal processing—for cleaning larvae, blanching, or cleaning equipment—and all of this generates wastewater rich in organic matter. The treatment of this wastewater introduces another significant odour source.

If anaerobic conditions develop in wastewater holding tanks, collection pits, or equalization tanks, foul-smelling gases such as hydrogen sulfide (H₂S), ammonia, and volatile fatty acids are released. H₂S, in particular, contributes a rotten egg odour that is often the most intense and noticeable. In addition, foaming and surfactant-rich wastewater can carry odorous compounds into the air as aerosols, especially during agitation or aeration in treatment tanks.

Further odours can arise from sludge handling—the thickened solids separated from the wastewater—which may emit earthy, septic, or musty odours, particularly if not properly stabilized or rapidly removed. Without adequate aeration or treatment, wastewater components can be a persistent and site-wide source of offensive odours, particularly in warm climates or enclosed processing facilities. If not treated properly, this wastewater can become a significant source of odour pollution.

Key Odorous Compounds to Monitor

Impact of Uncontrolled Odour

1. Environmental Concerns

Odorous emissions contribute to air pollution and can negatively impact local ecosystems. VOCs and ammonia released into the atmosphere can react with other pollutants, forming secondary air contaminants.

2. Health Hazards

Workers in insect meal plants may experience respiratory discomfort, nausea, and headaches due to prolonged exposure to odours. Strong odours can also lead to reduced air quality in surrounding areas.

3. Regulatory Compliance

Environmental regulations impose strict limits on odour emissions. Failure to comply with these standards can result in fines, operational restrictions, or shutdowns.

4. Community Complaints & Business Reputation

Foul odours can lead to complaints from nearby residents and businesses, potentially damaging the company’s reputation and straining relations with the local community.

Odour Control Strategies for Insect Meal Processing Plants

To mitigate odour challenges, insect meal processing facilities can adopt various control measures. Biofilters and scrubbers can be used to capture and neutralize odorous compounds before they are released into the atmosphere. Proper ventilation systems can help reduce indoor odour buildup. Wastewater treatment processes should be implemented to prevent the accumulation of organic waste that leads to odour formation. Additionally, optimizing rearing conditions by maintaining controlled humidity, aeration, and feed quality can help minimize metabolic odours from insect populations.

Implementing a robust odour control strategy is essential to maintaining air quality, regulatory compliance, and operational efficiency in insect meal processing plants. Below are some of the most effective odour mitigation techniques:

1. Biofiltration Systems

Biofilters are an eco-friendly solution that uses microorganisms to break down odorous compounds like volatile organic compounds (VOCs), ammonia, and hydrogen sulfide (H₂S). The process involves passing contaminated air through a biofilter medium (such as compost, peat, or wood chips), where microorganisms degrade odorous compounds into harmless byproducts like carbon dioxide and water.

2. Chemical Scrubbers

Scrubbers use liquid chemicals to neutralize odour-causing gases. The two main types include:

  1. Acid Scrubbers: Effective for ammonia removal.
  2. Alkaline Scrubbers: Target hydrogen sulfide and organic acids.  This method is highly efficient for treating large air volumes and removing multiple odorous compounds simultaneously.

3. Activated Carbon Filtration

Activated carbon filters are ideal for adsorbing VOCs and organic odour compounds. These filters trap odorous molecules within the porous carbon structure, effectively neutralizing them before they are released into the atmosphere. This method is particularly effective in handling residual odours after primary treatment.

4. Enclosed Processing & Ventilation Systems

  1. Enclosed Facilities: Sealing processing areas prevents odours from escaping into the environment.
  2. Proper Ventilation: Strategic placement of ventilation ducts and air handling systems ensures the efficient capture and treatment of odorous air before release.

5. Thermal Oxidation

Thermal oxidation or combustion-based systems break down odorous gases at high temperatures, converting them into non-odorous byproducts like carbon dioxide and water. Though effective, this method requires high energy consumption and is best suited for large-scale operations.

6. Onsite Odour Monitoring & Control Systems

Real-time odour monitoring technologies such as Oizom (www.oizom.com) help track odour levels and detect problem areas. Implementing automated odour control systems allows plants to adjust treatment processes dynamically based on odour intensity.

Elixir Enviro Systems: Your Partner in Odour Control

Elixir Enviro Systems is the pioneer in industrial Odour Control system provider in India. Have installed odour control unit in various industries such as :

  1. Biofiltration systems for VOC and odour reduction
  2. Chemical scrubbers for ammonia and hydrogen sulfide removal
  3. Advanced air purification technologies
  4. Onsite odour measurement and regulatory compliance consulting

we provide the best suited odour control systemtailored for each individual cases.

You may Consult Elixir Enviro Systems for for all your odour control and wastewater treatment related enquiries.

Conclusion

Odour control is a critical aspect of operating a successful insect meal production plant. By understanding the sources of odour and implementing a combination of ventilation, filtration, and waste management strategies, plant operators can minimize odour emissions and create a more pleasant working environment. Additionally, investing in odour control technologies not only improves the quality of life for workers and nearby communities but also enhances the overall sustainability and reputation of the insect meal industry.

As the insect meal industry continues to grow, innovative odour control solutions will play a key role in ensuring its long-term success. By prioritizing odour management, insect meal producers can contribute to a cleaner, greener future for animal feed production.

Clearing the Air: Solving Sewage Pumping Station Odour Problems for a Fresher & Healthier City

As urban areas continue to expand, the demand for efficient wastewater management systems grows with them. Sewage pumping stations are vital infrastructure elements that transport sewage from lower to higher elevations, making it possible to send wastewater to treatment facilities where gravity flow is not feasible. However, one of the most common — and often overlooked — challenges of sewage pumping stations is odour control.

Odours from sewage pumping stations are more than just an inconvenience. They are a significant environmental concern, a public health risk, and a factor that can negatively impact the social well-being of communities. In this blog, we will explore the causes of sewage pumping station odours, the challenges of managing them, technologies available for odour control, and how Elixir Enviro Systems is helping industries and municipalities solve these challenges sustainably.

1. Why is Odour Control Important in Sewage Pumping Stations?

Odour emissions are not just a public nuisance; they pose serious health and environmental risks:

  1. Respiratory Irritation: Prolonged exposure to H₂S and ammonia can cause irritation to the eyes, nose, and throat and may lead to more severe respiratory problems.
  2. Corrosion of Infrastructure: Hydrogen sulfide can convert to sulfuric acid, corroding concrete structures and metal pipelines, leading to increased maintenance costs.
  3. Environmental Degradation: Odour-causing gases contribute to atmospheric pollution and can have negative effects on nearby flora and fauna.
  4. Community Complaints and Legal Issues: Persistent odour problems lead to public complaints, social unrest, and, in some cases, environmental regulatory penalties.

2. Why Sewage Pumping Stations Stinks?

Odour emission from sewage pumping stations happens because of the way they handle wastewater. Odour to become a problem, it must leave the wastewater and enter the air. This process, known as mass transfer, is driven by concentration differences—when there’s more of a compound in the water than in the air, nature pushes for balance, causing gases to be released. Ventilation and turbulence speed up this transfer, making the sewage pumping station prone to strong odors. While Henry’s Law predicts how much gas should be in the air, real-world factors like flow rates, temperature, and facility design create much more variability.

Let’s understand various factors contributing to odour emission from sewage pumping stations, drawing on various sources to ensure a thorough understanding.

2.1. Biological Sources of Odour

Odour in sewage pumping stations primarily arises from the anaerobic decomposition of organic matter, leading to the production of hydrogen sulphide (H₂S) and other volatile organic compounds (VOCs). H₂S, known for its rotten egg smell, is generated by sulfate-reducing bacteria in conditions where oxygen is depleted, such as in stagnant sewage. This process is particularly pronounced in wet wells, where sewage accumulates before pumping, and in rising mains, where hydraulic residence time exceeds 6 hours. The decomposition is accelerated by warmer temperatures and stronger sewage, often seen during dry weather, which reduces dilution and increases organic content.

2.2. Design & Operational Factors in Pumping Stations

Sewage pumping stations are designed to collect and pump wastewater to treatment facilities, often against gravity, using wet wells and force mains. The wet well, where sewage is stored before pumping, is a critical area for odour production due to the potential for stagnation. When sewage sits for extended periods, anaerobic conditions develop, fostering H₂S production. The pumping action itself, involving turbulence, exacerbates odour emission by agitating the sewage and releasing trapped gases into the atmosphere.

The length of the force main, the pipe from the pump to the discharge, also influences odour. Longer force mains increase the residence time of sewage, allowing more time for anaerobic decomposition and H₂S production. Design guidelines for sewage works emphasize keeping force main lengths short to reduce dynamic head losses and odour production. This is particularly important at initial and design flows, where prolonged exposure can lead to significant gas buildup.

Trends in sewer system design, such as centralizing treatment and moving to separate sewer systems, can exacerbate H₂S problems. Centralization increases pumping distances, leading to more stagnant conditions and higher H₂S production, while separate systems lack rainwater dilution, increasing the risk of odour issues. These trends highlight the need for adaptive odour control strategies in modern wastewater management.

2.3. Trade Effluent Impact

An interesting factor is trade effluent—wastewater from industries—which can add odorous compounds, making the smell stronger, especially in dry weather when sewage is more concentrated. Trade effluent, may itself be odorous or increase the strength of the sewage, leading to enhanced odour generation. This is particularly relevant in urban areas where industrial discharges are common.

2.4. Maintenance Influences

Maintenance is another critical factor. Poorly maintained stations, with blockages or grease buildup, can lead to increased odour emissions. Similarly, control float switch problems can cause pumps to remain on, potentially agitating sewage excessively and releasing more gases. Regular maintenance, including clearing debris and ensuring proper operation, is essential to mitigate these issues, as advised in community guidance for living near pumping stations.

2.5. Environmental Influences

Environmental factors, such as temperature, play a role in odour intensity. Warmer seasonal temperatures increase odour generation, as bacterial activity accelerates. Additionally, the design of ventilation systems can affect how odours are dispersed. For instance, rooftop vents and mechanical ventilation are used to manage pressure and flow, but improper design can lead to odours reaching ground levels, especially under wind currents or temperature inversions.

3. What Causes the smell-Uncovering the Smelly Secrets!

Wastewater isn’t just water—it’s a complex mix of organic compounds, many of which have strong, unpleasant odours. As oxygen is depleted and anaerobic conditions take over, these odours intensify, creating a bigger challenge for treatment facilities.

3.1. The Rotten Egg Culprit: Hydrogen Sulfide

Hydrogen sulfide (H₂S) is the main offender, notorious for its rotten egg smell. It forms when sulfate-reducing bacteria thrive in oxygen-starved conditions, often inside pipe biofilms and sludge layers. Factors like low oxygen, high organic content, and long retention times boost its production. Highly toxic at high levels, H₂S can be deadly, making its control a top priority.

3.2. The Stealthy Sulfur Compounds

Beyond H₂S, other sulfur-based compounds—mercaptans, dimethyl sulfide, and dimethyl disulfide—add to the stench. These compounds are even trickier because they don’t dissolve as easily in water. High-energy areas like junction chambers, mixing tanks, and dewatering processes release them in full force, making odour control a challenge.

3.3. The Ammonia Factor

While ammonia isn’t as pungent as sulfur compounds, it can still be a problem, especially in solids processing. Dewatering, lime stabilization, and composting can trigger ammonia emissions, sometimes mixed with fishy-smelling amines. Anaerobic digestion and high-temperature processes further intensify these odours.

3.4. The Hidden Odour Offenders

Odour isn’t just about sulfur and nitrogen. Wastewater also contains volatile organic compounds (VOCs), aldehydes, ketones, and carboxylic acids, which contribute to its distinct, unpleasant scent. While not always the main culprits, they can make odour control even more complex.

Understanding these odour sources is key to managing them effectively.

4. Design Strategies to Minimize Odour Emissions from Sewage Pumping Stations

Effective design is paramount to minimizing odour emissions, and several strategies can be implemented based on engineering guidelines and best practices. The following sections outline these considerations

4.1. Location and Layout Considerations

The station’s location and layout can also influence odour impact:

  1. Site Selection: Positioning the station away from residential areas to minimize community exposure, though this may not always be feasible.
  2. Pipework Design: Minimizing bends and drops in pipework to reduce turbulence, which can release trapped gases. Avoiding long force mains is also advised, as they can increase retention time and odour production.

4.2. Minimizing Retention Time

One of the most effective ways to reduce odour is to minimize the time sewage spends in the pumping station, particularly in the wet well. This can be achieved through:

  1. Proper Wet Well Sizing: Ensuring the wet well is appropriately sized to match inflow rates, preventing overflow and stagnation. For example, operating wet wells at lower levels can reduce detention times. The Ontario guidelines, recommend more frequent pumping for fill-and-draw stations and lowering level set-points for variable speed pump stations where odour is an issue.
  2. Pump Capacity and Operation: Selecting pumps with sufficient capacity to handle inflows promptly and using variable frequency drives (VFDs) to match pumping rates with inflow, thus avoiding prolonged storage. This reduces the likelihood of anaerobic conditions developing, which is a major source of H₂S production.

4.3. Pump Selection and Operation

The type and operation of pumps can influence odour emissions:

  1. Submersible Pumps: These are often preferred as they reduce turbulence and splashing compared to dry pit pumps, minimizing gas release. In other words, the pump selection should prioritize low turbulence.
  2. Operational Practices: Ensuring pumps operate frequently to prevent stagnation, and designing for easy maintenance to allow routine cleaning, which reduces organic buildup and odour production.

4.4. Wet Well Design for Self-Cleaning and Maintenance

The wet well’s design can directly impact odour control:

  1. Sloped Bottoms and Fillets: Incorporating sloped bottoms or fillets in rectangular channels and tanks to prevent sediment accumulation. This reduces ‘dead zones’ where solids can settle and foster anaerobic conditions.
  2. Aeration Where Needed: Providing aeration to maintain solids in suspension where self-cleaning velocities cannot be achieved, though excessive aeration should be avoided to prevent increased turbulence and odour release.
  3. Access for Cleaning: Ensuring easy access for routine hosing and debris removal, which helps maintain hygienic conditions and reduces odour production.

4.5. Liquid Phase Treatment – Chemical Dosing for Odour Prevention

Liquid side treatments focus on preventing odour formation in the wastewater itself, targeting the root cause by maintaining aerobic conditions or neutralizing odorous compounds. Chemical treatment can be integrated into the design to prevent odour-causing gas formation:

  1. Oxidizing Agents: Adding substances like chlorine, hydrogen peroxide, or pure oxygen to oxidize sulphides and inhibit their production. The air injection can be successful for short to moderate force mains, though care must be taken to avoid air binding at high points.
  2. Precipitants and pH Control: Using iron or zinc salts to precipitate sulphides or raising pH with sodium hydroxide to inhibit H₂S off-gassing. These measures are effective in localized areas but require careful consideration of impacts on solids handling, such as increased sludge production.
  3. Electron Acceptors: Implementing sodium nitrate in sewers, which has advantages like slower consumption and non-hazardous properties.
  4. Other Agents: Anthraquinone inhibits sulphate-reducing bacteria, effective for several days to six weeks, but limited by low solubility for force main applications. Caustic slug dosing with sodium hydroxide shifts sulphide equilibrium, inactivating the slime layer, effective for days to weeks but not for continuous addition.

4.6. Vapour Phase (Air side) Treatments for Odour Control

In the previous point we discussed the possibilities and options to avoid odour emissions to the gas phase. Generally, without a proper air treatment, it is hard to operate the pumping station, especially since the odour threshold of the compounds causing odour are very small making it detectable at very low concentrations. So, odour emission is unavoidable in most cases and therefore odour control equipment is absolute necessary. The Air side treatments focus on capturing and treating odorous air to prevent its release into the environment. The air side treatment includes Containments, Ventilation and Odour Control Units (OCUs).

4.6.1. Sealing and Containment

Preventing odours from escaping into the environment requires robust containment measures:

  1. Airtight Covers: Designing covers for wet wells with minimal joints and using seals at all access points to contain gases. Corrosion-resistant materials, such as stainless steel or epoxy-coated aluminium, or FRP is preferred due to the corrosive nature of sulphides and sulfuric acid formed from H₂S.
  2. Avoiding Condensate Points: Ensuring covers are designed to prevent condensate collection, which can exacerbate corrosion and odour release. This is particularly important for maintaining long-term structural integrity.

4.6.2. Ventilation Systems

Ventilation is critical for removing odorous air from the wet well. Design considerations include:

  1. Forced Ventilation: Installing air extraction systems to remove odorous gases, maintaining a slight negative pressure to prevent fugitive odours and ensure that the air is treated before release.
  2. Gravity (passive) Ventilation: Employs natural ventilation for low airflow applications, such as roof vents, to equalize pressure and control odour.

4.6.3. Odour Control Units (Technologies) for Sewage Pumping Stations

1. Biofilters & Biotrickling FIlters

Use microorganisms to biologically degrade odorous compounds in the air. They can remove 99.9% of H₂S, ammonia, and other odours. They perform best with stable airflow and are eco-friendly, requiring no chemicals and have low operating costs.

2. Activated Carbon Adsorption Units

Activated carbon units are compact and effective at adsorbing odour-causing gases, particularly VOCs and H₂S. These systems are suitable for locations where space is a constraint and where moderate odour loads are encountered. Regular carbon replacement is required based on load.

3. Chemical Wet Scrubbers

Wet scrubbers use chemical solutions based on the type of compounds to be removed from the air stream. Chemicals such as sodium hydroxide or chlorine-based compounds to neutralize hydrogen sulfide and acids to remove ammonia. Therefore, it is generally called Acid and Alkali Scrubbers and are suitable for high contaminant levels.

4. Thermal Oxidation

Burns odorous air at high temperatures, though less common for pumping stations due to energy costs.

5. Monitoring and Compliance

Effective odour control doesn’t end with treatment — continuous monitoring is key:

  1. Portable H₂S Detectors: For on-the-spot odour monitoring.
  2. Continuous Online Monitoring Systems: Enable real-time tracking of gas concentrations and air quality.
  3. Olfactometry Surveys: Human sensory measurement of odour concentrations for community impact assessments.
  4. Regulatory Compliance: Many environmental regulations specify acceptable odour levels and H₂S concentration limits that must be met.

6. Elixir Enviro Systems: Your Partner in Odour Control

At Elixir Enviro Systems, we understand the complexity of sewage odour control and offer customized solutions that combine efficiency, sustainability, and long-term reliability. Our services include:

✅ Biofilter & Bioscrubber Design & Installation – Tailored systems with optimized media selection for maximum efficiency.

✅ Scrubber Systems – Wet and dry scrubber solutions for handling high-concentration odour streams.

✅ Odour Control Units (OCUs) – Different modular solutions combining biofiltration, carbon adsorption, and chemical scrubbing are available based on the client requirement.

✅ Odour Impact Assessment and Modeling – Using advanced simulation tools to predict odour dispersion and community impact.

Conclusion

Odour control in sewage pumping stations is not just a regulatory requirement — it’s a commitment to public health, environmental stewardship, and community welfare. By leveraging advanced technologies and proactive monitoring, municipalities and industries can effectively mitigate odour issues and create more liveable urban environments.

At Elixir Enviro Systems, we are proud to be part of that mission, offering reliable, innovative, and sustainable odour control solutions that protect both people and the planet.

Odour and Emission Control in Technical Rubber Manufacturing Units: A Path Toward Sustainable Operations

Introduction

Ever walked into a rubber manufacturing plant and been hit by that strong, unmistakable smell? If so, you’re not alone. The odour from technical rubber manufacturing isn’t just a nuisance, it’s a complex mix of chemicals, process emissions, and, if left unmanaged, a regulatory and community relations challenge. But here’s the good news: odour control in rubber plants is 100% solvable!

Natural Rubber or processed latex is used in different industrial applications. But generally, it is not directly used. Raw natural rubber has several limitations that make it unsuitable for direct industrial use, especially in applications like tires, gaskets, conveyor belts, and industrial rubber products. Therefore, it undergoes further processing to make it technically fit for most of the industrial applications, making it Natural Technical Rubber (NTR). Technical rubber is important as it ensures consistent performance, improved processability, meets global standard and is sustainable alternative to synthetic rubber.

The key properties of Natural Technical Rubber are the following

  1. High Elasticity & Resilience – Excellent for shock absorption
  2. Tear & Abrasion Resistance – Ideal for tires, belts, and seals
  3. Heat & Aging Resistance – Improved through processing
  4. Low Impurities – Consistent quality for industrial processing

Different countries have specific grading systems for NTR, commonly known as Technically Specified Rubber (TSR); in India it is known by the name ISNR (Indian Standard Natural Rubber), in Thailand its STR (Standard Thai Rubber), in Malaysia its SMR (Standard Malaysian Rubber) etc. TSR 20 is the most used grade worldwide, primarily in tires, industrial rubber products, and conveyor belts.

Technical rubber manufacturing supports key industries such as automotive, aerospace, construction, and healthcare. However, one persistent challenge is the emission of strong odours caused by the release of volatile organic compounds (VOCs), sulfur compounds, and other airborne contaminants during processes like vulcanization, compounding, and extrusion.

Odour emission control is essential for regulatory compliance, worker health, and maintaining harmonious community relations. Below, we explore the root causes of odours, the associated challenges, and solutions for effective odour management.

What Causes Odour in Rubber Manufacturing?

  1. Vulcanization Process: The cross-linking of rubber molecules using sulfur or peroxides releases hydrogen sulfide (H₂S), mercaptans, and other sulfur-containing compounds, which have a strong, unpleasant odour.
  2. Rubber Compounding: The addition of processing oils, resins, and chemical accelerators can lead to the release of VOCs such as benzene, toluene, and styrene, contributing to odour emissions.
  3. Mixing and Extrusion: The heating of rubber compounds during mixing and extrusion generates fumes containing hydrocarbons, ammonia, and organic acids.
  4. Solvent-Based Adhesives: The use of solvents in rubber processing and finishing results in emissions of volatile organic compounds, which can cause odour issues.
  5. Wastewater Treatment: The presence of organic contaminants and residual chemicals in wastewater can generate odorous gases such as ammonia, hydrogen sulfide, and methane.

Challenges in Odour Control

  1. Complex Chemical Composition: Odours from rubber manufacturing are caused by a mix of chemicals with varying volatility, making them difficult to capture and neutralize.
  2. High Temperature Processes: Many rubber processing steps occur at elevated temperatures, which increases the volatilization of odour-causing compounds.
  3. Regulatory Compliance: Strict environmental regulations require manufacturers to adopt effective odour control measures, necessitating investment in advanced technologies.
  4. Workplace Safety: Exposure to odorous emissions can cause headaches, nausea, and respiratory irritation, impacting worker health and productivity.
  5. Community Complaints: Persistent odour issues can lead to complaints from nearby residential areas, potentially resulting in legal and operational challenges.

Effective Odour Control Solutions

1. Process Optimization

  1. Implementing closed-system processing and efficient material handling techniques can help reduce odour emissions at the source.
  2. Using low-odour or alternative raw materials in rubber formulation can minimize the release of volatile compounds

2. Activated Carbon Filtration

  1. Activated carbon filters are highly effective in adsorbing VOCs and sulfur compounds from process air.
  2. These filters can be installed in ventilation systems to capture odorous gases before they are released into the atmosphere.

3. Biofiltration Systems

  1. Biofilters use microorganisms to break down odorous compounds into non-volatile byproducts.
  2. This eco-friendly approach is particularly effective for treating hydrogen sulfide and organic odours from exhaust air streams.

4. Chemical Scrubbing

  1. Wet scrubbers use chemical reagents to neutralize acidic and basic odorous compounds.
  2. Commonly used scrubbing agents include sodium hydroxide for acidic gases and sodium hypochlorite for organic odours.

5. Thermal Oxidation

  1. Thermal oxidizers combust VOCs and odour-causing compounds at high temperatures, converting them into harmless CO₂ and H₂O.
  2. Regenerative thermal oxidizers (RTOs) improve energy efficiency and are suitable for large-scale rubber manufacturing facilities.

Emission Control = Operational Excellence

For technical rubber manufacturers, effective odour and emission control is no longer just a compliance checkbox — it is part of being a future-ready manufacturer. From regulatory resilience to supply chain credibility to employee satisfaction, clean air initiatives deliver far-reaching operational and business benefits. The best companies aren’t just reacting to complaints; they’re proactively investing in sustainable solutions.

Elixir Enviro Systems’ Role in Odour Control

At Elixir Enviro Systems, we provide customized odour control solutions for technical rubber manufacturing units. Our expertise includes:

  1. Biofiltration Systems: We design and install biofilters that use natural microorganisms to break down odorous compounds efficiently, ensuring compliance with environmental regulations.
  2. Chemical Scrubbing: Our advanced wet scrubbers neutralize harmful sulfur compounds and VOCs, reducing odour emissions effectively.
  3. Activated Carbon Adsorption: We offer activated carbon filtration solutions to capture airborne contaminants and improve air quality in rubber manufacturing plants.
  4. Odour Monitoring & Assessment: Our onsite odour measurement and assessment services help identify odour sources and recommend targeted control strategies.
  5. Pilot Studies & Custom Solutions: We conduct pilot studies to evaluate the best odour control technologies for specific industrial processes, ensuring optimal results.

By implementing our innovative and sustainable odour control solutions, rubber manufacturers can achieve regulatory compliance, enhance workplace safety, and improve community relations.

Conclusion

Odour control in technical rubber manufacturing isn’t just about meeting regulations — it’s about creating a safer workplace, protecting the environment, and strengthening your brand’s commitment to sustainable practices. By combining process optimization with advanced treatment technologies, manufacturers can significantly reduce odour emissions and enhance operational performance.

At Elixir Enviro Systems, we specialize in comprehensive, customized odour control solutions for rubber manufacturing and other industrial sectors. From biofilters to chemical scrubbers to advanced monitoring solutions, we help you stay compliant, sustainable, and community-friendly.