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Rendering Odour
Rendering odour is one of the most intense and persistent odour challenges in any industrial sector. Rendering plants process animal by-products (including fat, bone, feathers, and offal) into materials such as tallow, meat and bone meal, and other reusable products, and the cooking and processing of this raw organic material generates the strong odours associated with the industry.
Because rendering odours are frequently described as offensive even at low concentrations, facilities are often located away from residential areas, but growth of nearby development can still bring rendering plants into conflict with neighbours. Effective odour control and reliable ambient monitoring are essential to maintaining a plant’s social licence to operate.
Major Sources of Rendering Odour
- Raw material receiving and storage of animal by-products (fat, bone, feathers, offal)
- Cooker and processing areas where raw material is rendered into tallow and meal
- Blood and stickwater handling and processing
- Storage of finished products such as tallow and meat and bone meal
- On-site wastewater treatment of process water and cooker condensate
Key Odorous Compounds
- Volatile fatty acids (VFAs) from the breakdown of fats and proteins
- Amines and other nitrogen compounds released during cooking
- Mercaptans and other reduced sulfur compounds
- Aldehydes and ketones from lipid oxidation
Rendering Odour Control Strategies
- Thermal oxidation (incineration) of cooker exhaust, the dominant control technology for rendering plants
- Condensers to capture and treat cooker vapours before release
- Wet scrubbers for acid gas and particulate removal
- Proper sealing and maintenance of cookers and process equipment
- Adequate stack height and dispersion modelling to reduce ground-level impact
- Regular ambient odour monitoring around the facility perimeter
See Also
- Point Source, for how rendering plant cookers and stacks are treated as concentrated point sources of emission
- EN13725, for the standard olfactometry method used to quantify rendering plant odour emissions
- For further technical background, see the US EPA AP-42 Emission Factor Documentation for Meat Rendering Plants.