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Meat Processing: Environmental Impacts
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Environmental Impacts from Meat and Fish Processing

Meat and fish processors must operate in a manner that protects human health and the environment while maintaining the highest food safety standards. If not minimized and properly managed, these operations can create enormous negative impacts on the environment. The primary environmental issues associated with meat and fish processing are water use, high-strength effluent discharge, and energy consumption. The meat and poultry processing industry (excluding rendering) uses an estimated 150 billion gallons of water annually. Although a portion of the water used by the industry is reused or recycled, most of the water becomes wastewater. Noise, odor and solid wastes are additional significant impacts that can detrimentally affect the environment if not adequately addressed.  

The amounts and types of wastes generated depend upon a variety of factors including: 

  • animal type, size and shape;
  • transportation and conveyance methods;
  • receiving and handling of animals;
  • processing times and  technologies;
  • amount of carcass washing;
  • wash temperatures;
  • cleaning/sanitation procedures; and
  • rendering operations. 

The information contained in this section includes environmental impacts for beef, pork, poultry and fish processing and associated rendering activities. The upstream processes of distribution and post-consumer packaging management are not covered. The manufacture of specialty meats and associated products are also not included in this topic hub. This sector focuses on activities that occur at a slaughterhouse and the related processes. The following table lists common wastes generated from specific processing areas. 

Meat & Seafood Processing Area Wastes

Process Area

Process Area Wastes 


Transportation, receiving and holding   manure, hair, feathers, grit, mortalities
Slaughter blood, fluids
Cleaning feathers, skin, bone, hides, beaks
Bleeding blood
Trimming and evisceration trim scrap, offal, paunch material
Inspection contaminated and rejected materials
Further Processing meat scraps, cheeks, hides, feet, offal, bone and fat
Cooling and storage contaminated ice, damaged product, off-spec inventory
Prepared foods additives, oils, grease, sauces, damaged product
Fermented, smoked, pickled foods spices, brines, sauces, spoiled materials, drippings


Catch by-catch
At-sea treatment cuttings, bones, blood, off-spec product
Transport and marketing off-spec, spoiled product
Receiving and thawing Spoiled materials, thaw-water, melted ice
Butchering and processing, including canning Off-cuts, viscera, bones, skins, suspended and dissolved solids, sauces, brines, fish oils other oils
Quarantine, storage and distribution Off-spec. materials, spoiled materials, damaged cans

Meat Processing Water Consumption: Like many other food processing activities, the necessity for hygiene and quality control in meat processing results in high water usage and consequently high wastewater generation. Volumes of wastewater from meat processing are generally 80-95 percent of the total freshwater consumption (MRC, 1995). The United Nations Environmental Program, Cleaner Production Assessment in Meat Processing (2000), estimates a range of 1,100 to 4,400 gallons of water are used per live weight ton of slaughtered animal in the United States. Between 44-60 percent of water is consumed in the slaughter, evisceration and boning areas (MRC, 1995). The following table illustrates the breakdown of water consumption in beef and pork processing based on a study of Australian abattoirs. 

Water Consumption in Meat (Beef and Pork) Processing Operations

Meat Processing Activity

Percent of Usage

Stockyard washdowns and animal watering 7-22 percent
Slaughter, evisceration and boning 44-66 percent
Casings production 9-20 percent
Rendering 8-38 percent
Domestic uses 2-5 percent
Chillers 2 percent
Boiler losses 1-4 percent

Meat Research Corporation (MRC), 1995

In poultry processing plants, in addition to being used for carcass washing and cleaning, water is also consumed for hot water scalding of birds prior to defeathering; in water flumes for transporting feathers, heads, feet and viscera; and for chilling birds. As a result, poultry processing tends to be more water intensive on a per unit  production basis than red meat processing (Wardrop Engineering, 1998). Water consumption rates vary from 4,000 to 24,000 gallons per 1,000 birds processed (Hrudey, 1984). 

Meat Processing Wastewater Generation: Freshwater consumption has a major impact on the volume and pollutant load of the resulting wastewater. Wastewaters generally have high organic loads and are also high in oils and grease, salt, nitrogen and phosphorous. At red meat abattoirs, water is used primarily for washing carcasses during the various process stages and for cleaning at the end of each shift. Eighty to 95 percent of water used in abattoirs is discharged as effluent (MRC, 1985). 

The wastewater from a slaughterhouse typically contains blood, manure, hair, fat, feathers and bones and may be at high temperatures. Untreated effluent may be as high as 8,000 mg/L BOD with suspended solids at 800 mg/L or greater. The wastewater may also have pathogens, including Salmonella and Shigella bacteria, parasite eggs and amoebic cysts. Pesticide residues may be present from treatment of animals or their feed. Chloride levels may be very high (up to 77,000 mg/L) from curing and pickling processes. Cooking activities also greatly increase the fat and grease concentration in the effluent. 

Fish Processing Water Consumption: Most seafood processors have a high baseline water use for cleaning plant and equipment. Therefore, water use per unit product decreases rapidly as production volume increases. Major sources of wastewater include: fish storage and transport; cleaning, freezing and thawing; preparation of brines; equipment sprays; offal transport; cooling water;  steam generation; and equipment and floor cleaning. 

Water consumption in fish processing operations has traditionally been high to achieve effective sanitation. Industry literature indicates that water use varies widely throughout the sector, from one to four gallons per pound of product. Several factors affect water use, including: the type of product processed, the scale of the operation, the process used, and the level of water minimization in place (Environment Canada, 1994a). General cleaning contributes significantly to total water demand so smaller-scale sites tend to have significantly higher water use per unit of production. Reducing wastewater volumes tends to have a significant impact on reducing organic loads, as these strategies are typically associated with reduced product contact and better segregation of high-strength streams.

Fish Processing Wastewater Generation: Wastewater from seafood processing operations can be very high in BOD, oil and grease, and nitrogen content. Literature data for seafood processing operations shows a BOD production of two to145 pounds of BOD per ton of product (Environment Canada, 1994a). White fish filleting processes typically produce 25 to 75 pounds BOD for every ton of product (UNEP, 1998). BOD comes primarily from the butchering process and from general cleaning and nitrogen originates -- predominantly from blood in the wastewater stream (Environment Canada, 1994a). Thawing operations can also account for up to 50 percent of the wastewater generated. 

Rendering Wastewater Generation: Rendering, while it recovers raw materials for beneficial use, raises the production of high-strength wastewater. Similarly, other byproduct recovery such as offal collection and hide treatment increase wastewater generation. Conveyance by fluming, carcass cleaning and general cleaning and sanitation also create significant quantities of wastewater.

Organic loads can vary considerably depending on whether the site incorporates a rendering operation. Rendering plants, where installed, are the largest single source of wastewater contamination. The wastewater from rendering (often referred to as stickwater) contains approximately 60 percent of the plant?s total COD output while being typically only 10 percent of the volume (MRC, 1995). As a general rule, red meat abattoirs with rendering will generate approximately 100 pounds COD/ton HSCW (hot standard carcass weight)*, whereas operations without rendering will generate only about 30 pounds COD/ton HSCW (MRC, 1998). 

Energy Consumption
Energy consumption depends upon the age and scale of the plant, level of automation, and range of products manufactured. Processes involving heating, such as cooking and canning, are very energy-intensive, whereas filleting requires less energy. Thermal energy, in the form of steam and hot water, is used for cleaning, heating water, sterilizing and for rendering.  Electricity is used for the operation of machinery and for refrigeration, ventilation, lighting and the production of compressed air. 

Like water consumption, the use of energy for refrigeration and sterilization is important for ensuring good quality meat and fish products.  Storage temperatures are often specified by regulation.  As well as depleting fossil fuel resources, the consumption of energy causes air pollution and greenhouse gas emissions, which have been linked to global warming. Typical ranges for energy use are 330 to 1330 kW per ton of hot standard carcass weight. Representative figures for ton of fish processed range from 65 to 87 kW for filleting, 150-190 kW for canning, and about 32 kW for fish meal and oil production. The following table provides a breakdown of electricity consumption at a meat processing facility.

Meat (Beef & Pork) Processing Energy Consumption

Meat Processing Activity

Percentage of Usage

Refrigeration 59%
Boiler Room 10%
Rendering 9%
Slaughter 6%
Compressed Air 5%
Boning Room 3%
Others 8%

Energy Authority of New South Wales, 1985

Air Emissions and Odor:

The U.S. EPA has identified air emissions from meat and fish processing and rendering operations in the following documents.


For meat processing, the above report did not quantify VOC (volatile organic compound), HAP (hazardous air pollutant), or PM (particulate matter) emissions; however, engineering judgment and comparison of similar processes in other industries may provide an estimation of the exact types of emissions expected from meat processing plants. Potential sources of PM are animal holding areas, feed storage, singeing operations and other heat sources (boilers). VOCs and HAPs may be generated from scalding tanks, animal holding areas, sanitizing operations, wastewater systems and heating sources. Control methods for VOCs and particulates include wet scrubbers, dry sorbants and cyclones. Air emission controls will vary from facility to facility and depend upon the nature of the emissions and the pollutant loading in the gas stream.

Although smoke and dust can be a problem in fish processing, the most objectionable emissions are odors.  Processing fish byproducts results in more of the odorous contaminants than cannery operations because of the greater state of decomposition of the materials processed. The fishmeal driers are the largest odor sources. Reduction cookers emit less offensive odors than meal driers; however, these emissions consist primarily of hydrogen sulfide and trimethylamine, which are not currently listed as HAPs.  Almost no particulate emissions result from reduction cookers. Fish cannery and reduction odors can be controlled with afterburners, chlorinator-scrubbers and condensers.  Drier dust can be captured using centrifugal collectors. 

VOCs are the primary air pollutants emitted from rendering operations, which have historically been an odor nuisance in residential areas located in close proximity to the facility. Emission controls are directed to odor control and elimination. Particulate matter is also emitted from grinding and screening of the solids (cracklings) and other operations such as blood and feather drying. Boiler incinerators are a common control technology for rendering emissions because the boilers can be used to generate steam for cooking and drying operations. Multistage wet scrubbers are the primary alternative to incinerators. These scrubbers can be used to remove particulate matter as well as odors from rendering waste streams.

Biological treatment systems, commonly used to treat abattoir effluent, are another common source of odors.  Insufficient capacity of treatment systems or shock-loadings to the system can upset the microbiological balance of the system, resulting in the release of hydrogen sulfide and other odorous compounds.

Solid Waste
For many food processing plants, a large fraction of the solid waste produced by the plant comes from the separation of the desired food constituents from undesired ones in the early stages of processing. In some cases, the materials are composted. Due to their potential to carry disease, animal-derived solid wastes are often regarded as industrial waste. The availability of suitable licensed waste disposal sites needs to be assessed. 

Other significant solid wastes include packaging materials such as waxed corrugated boxes, pallets, shrink wrap, strapping ties, drums and polystyrene. Packaging waste accounts for about one-third of municipal solid waste. Many of these products can be reused or recycled. Markets exist nationwide for most of these materials. 

The main purpose of refrigeration is to cool the meat after slaughter and to maintain it in a chilled state for shorter or longer storage periods and for cutting and further processing. For operations that use refrigeration systems based on chlorofluorocarbons (CFCs), the fugitive loss of CFCs to the atmosphere is an important environmental consideration, since these gases are recognized to be a cause of ozone depletion in the atmosphere.  For such operations, the replacement of CFC-based systems with non- or reduced-CFC systems is important.

If an abattoir is located close to residential areas or other noise-sensitive receptors, the noise generated from various items of equipment and the maneuvering of trucks delivering livestock and removing byproducts can cause a nuisance.  These potential problems should be taken into consideration when determining plant location.

* Note: Units of Production

Commonly used units to describe the scale of production in abattoirs are live carcass weight (LCW) and hot standard carcass weight (HSCW). LCW represents the weight of an animal prior to slaughter. HSCW represents the weight of the carcass after evisceration and hide removal and before further processing.  HSCW is typically 75 percent of the original LCW. 


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Pollution Prevention Resource Exchange
Pollution Prevention Resource Exchange
Contact email: abray@newmoa.org

Hub Last Updated: 3/11/2008