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
|
|
Meat |
| 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 |
|
Seafood |
| 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.
Refrigerants
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.
Noise
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.
