Abattoirs

See also

NSW EPA Compliance Performance Report Livestock Processing Industries - Animal Slaughter and Rendering (PDF 221KB)

DEC NSW Environmental Guidelines: Use of Effluent by Irrigation (PDF 1.5MB)

ANZECC (2000) NATIONAL WATER QUALITY MANAGEMENT STRATEGY PAPER No. 4 Australian and New Zealand Guidelines for Fresh and Marine Water Quality Volume 3 Primary Industries — Rationale and Background Information (PDF 1.4MB)

Australian Pork Limited National guidelines and sustainability indicators for effluent reuse by piggeries and cattle feedlots (PDF 229KB)

Aim of this document

This document describes the environmental problems associated with abattoirs. It recommends management strategies for minimising water, air and noise pollution, and for maintaining community amenity.

Definition of abattoirs

From Schedule 1 of the POEO Act 

Activities that occur in abattoirs

The major activities involved in the operation of an abattoir are:

• receiving and holding of livestock
• slaughter and carcass dressing of animals
• chilling of carcass product
• carcass boning and packaging
• freezing of finished carcass and cartoned product
• rendering processes
• drying of skins
• treatment of wastewater
• transport of processed material. 

Environmental problems in abattoirs

The need for a mass disposal area

A mass animal disposal area must be identified in case there is an outbreak of exotic disease. This area should be away from watercourses and groundwater. The soil should be suitably friable for digging but also as impermeable as possible.   

Liquid wastes

For hygienic reasons abattoirs use large amounts of water in animal processing operations. This produces large amounts of wastewater that must be treated.

Effective primary treatment before secondary treatment will increase the overall effectiveness and efficiency of wastewater treatment systems, as it is cheaper to remove physically the fat and solids than to treat later in secondary and tertiary treatment facilities.

Effluent salinity

Skin preservation by dry salting is a common procedure at small abattoirs that are remote from tanning operations and often export their hides and skins for tanning. After salting, often in converted cement truck mixers, the hides are hung to dry for a minimum of 5 days. During this period, the salt draws the moisture out of the hide, together with the protein-filled fluids contained in the attached flesh.

The effluent from drying sheds is therefore highly saline and has a very high biochemical oxygen demand (BOD). It contains high levels of fluoride. (The salt used contains up to 1 per cent sodium fluoride as a bactericide.) This may lead to salinity problems if the effluent is irrigated, and also to fluorosis problems with vegetation, including tree death. This waste stream should be segregated and diverted to an evaporation pond for conversion to a solid waste for potential recycling.

Wastewater

Wastewater produced in animal slaughter areas typically has a high BOD. It is also very saline and has high levels of nutrients, suspended solids and bacterial contamination. The following pond systems are commonly used for secondary treatment of meatworks effluent:

• anaerobic ponds
• facultative ponds
• mechanically forced aerated ponds
• naturally aerated ponds
• dissolved air flotation (DAF) cells
• other package treatment plants

Stormwater

Stormwater can become contaminated when it comes into contact with animal holding pens, sludge stockpiles and treated wastewater irrigation areas. This contaminated stormwater can have detrimental environmental effects on surrounding ecosystems.

Solid wastes

Sources of solid wastes generated at abattoirs include:

• animal holding areas
• slaughterhouse and processing areas
• waste treatment plant
• unwanted hide or skins and pieces, and unwanted carcasses and carcass parts

Manure is generated in animal holding areas. Materials not suitable for rendering, such as unwanted carcasses, come from the processing areas, along with paper, cardboard and plastics. Primary and secondary effluent treatment sludges are generated in the treatment ponds.

Non-process wastes

Non-process wastes originate from kitchens and offices, dispersed or uneaten feed and from general maintenance of gardens. Waste prevention and reduction, and separation of wastes for recycling or composting apply equally to these non-process wastes.

Airborne wastes

Odours

Potential sources of odours in abattoir operations are:

• the cooking and rendering process
• waste effluent treatment plants
• slaughterhouses
• product storage and handling areas
• material drying areas
• waste disposal techniques such as burning dead stock
• animal holding pens
• livestock transport vehicles
• holding of carcasses before disposal
• odours from skin handling
• odours from skin sheds

Sources of odours in the rendering plant include stale materials and fugitive emissions from cookers. Odours in animal holding pens are produced by manure and urine. Slaughterhouse odours come from solid wastes such as paunch contents and blood residues.

Anaerobic waste treatment ponds may produce gases such as methane, ammonia and hydrogen sulphide, which give rise to objectionable odours. Livestock transport vehicles entering the abattoir through residential areas may cause odour problems.

Dust

Potential sources of dust emissions at an abattoir are:

• unsealed roads
• paddocks, saleyards and holding pens
• stockpiled products and materials
• construction activities

Fuel burning emissions

Fuel burning gives rise to atmospheric emissions. Materials burned at an abattoir include:

• coal or gas fuel for boilers and steam production
• diseased animals
• sludge
• packaging
• unusable skins

Greenhouse gases

The amount of fuel used should be minimised by heat conservation and re-use strategies to limit the emission of greenhouse gases. In existing abattoirs, a strategy needs to be adopted to replace ozone depleting gases.

Diseases

In abattoirs there is a large potential for the transmission of zoogenic diseases such as Q-fever and anthrax to humans.

Noise

In abattoirs noise can be generated by several sources, including:

• animals, especially when in concentrated groups
• processing activities within the slaughterhouse
• plant machinery
• plant and service vehicles

Noise from the slaughterhouse and by-products area is generated by mechanical plant (such as conveyors), ventilation plant, air conditioning, stunning boxes, compressed air equipment, pumps and rendering plant. Some of this equipment may need to operate 24 hours a day. An abattoir is serviced by a variety of vehicles including trucks and forklifts.

Refer to the NSW Industrial Noise Policy for industrial noise criteria for abattoirs.

Typical noise levels. (T) after a noise level indicates that it is likely to have a tonal or impulsive character. No adjustments have been made to account for noise character.

Planning issues

The planning stage of any industrial activity is the best time to design the operation in a way that conforms to legal requirements, and to examine all the options for minimising waste and preventing contamination. Detailed planning may also reveal that some waste streams can be completely avoided.

Waste minimisation

There should be a full examination of process by-products and wastes to identify options for waste minimisation. In some cases, substituting raw material may lead to changes in the process. Often, re-using or recycling by-products reduces waste production. Recovering valuable materials from waste streams can be economically and environmentally sensible.

Some waste minimisation options to consider during the planning stage are:

• changing the processes or equipment
• changing the composition, packaging or durability of products
• changing or reducing raw material inputs
• improving the control of the process
• improving the materials handling and cleaning operations
• improving the maintenance and repair of equipment
• recycling waste internally
• re-using waste on site
• recovering materials from waste streams

Site selection

Site selection is the critical environmental issue for abattoirs. Careful site selection can greatly reduce the environmental nuisance. Relevant site information should include:

• the closeness to existing and future housing developments, and to land zoned to permit housing or other land uses not compatible with the proposed development
• the site hydrology: flood liability, site drainage and closeness to watercourses and groundwater resources used for domestic, agricultural or town water supply
• the prevailing wind conditions
• the landform and the likely direction of drift of odour or effects of noise
• the adequacy of the land area to house all projected activities
• the erosion hazard
• the local road network
• corridors for power and other services
• suitability of the site for possible land disposal

In areas likely to be disturbed by construction of the proposed development, the site description should include data on plants and animals, such as:

• major plant communities
• the status and conservation significance of vegetation
• the occurrence of any rare or threatened species
• the presence of any introduced species
• the heritage or cultural significance

Check heritage and sacred sites listings before making a decision on the proposed development.

Buffer zones

Buffer zones are particularly important as measures to separate conflicting land uses and to minimise any harmful effects of new developments in environmentally sensitive areas. Even if other control measures are used, odour, dust and noise emissions may still occur. Adequate buffer distances from nearby land users are the best way of avoiding nuisance from air and noise pollution. Occupiers should include buffers in management strategies, and local councils should include them in town planning approvals. New buffer zones should be created as part of the proposed development.

Buffer distances are cheap control options if additional land does not have to be bought.

A minimum buffer distance to the nearest residence or residential area of 500 m is recommended downwind of an abattoir (1000 m for a rendering plant). This depends on the prevailing winds and may need to be increased if effective and reliable odour control equipment is not installed.

The visual environment

The choice of aesthetically pleasing colours and finishes will enhance the look of premises. Features such as trees, shrubs, rock walls and grassed slopes incorporated into the landscaping will not only help with the visual impact, but also diminish the effect of operational lighting beyond the boundaries of the premises. Planting may also help control dust. Planted buffer zones can serve as wildlife corridors.

Preventing contamination

Once streams, process operations, raw materials, fuel supplies and product ranges have been identified, the methods of storing and handling materials and ways of segregating, treating and disposing of wastes must be addressed to minimise the potential for land contamination and air and water pollution. Underground tanks can leak into soils for long periods before being detected, leading to high clean-up costs.

Management strategies

Industry and control authorities should together develop management strategies that reflect good conservation practices and conform with environmental regulations. Techniques and procedures to integrate all waste management options should be adopted wherever possible. A beneficial re-use strategy should be initiated after the waste management strategy.

Cleaner production and waste minimisation aims directly at the source of the waste generation and attempts to eliminate waste before it is produced, or to reduce the amount generated. Wastes should be disposed of only after all preventive and minimisation measures have been taken.

The occupier should develop management strategies for proposed and existing premises. The strategies should aim to:

• minimise the quantity of wastes generated
• prevent pollution arising from the disposal of wastes
• prevent nuisance pollution such as odours, dust and smoke
• minimise environmental health risks
• improve the efficiency of processes through energy savings

Opportunities for recycling exist in all types of industry, in commercial and government organisations and for public groups. Operators should nominate a staff member to supervise the recycling schemes.

Environmental management plan

The operators of an abattoir need to establish an environmental management plan for the premises.

The plan needs to incorporate all the requirements of the relevant guidelines and incorporate a farm management plan for the beneficial operation of the wastewater system. Such a farm management plan would address the performance of the cropping/stocking regime, protection of the soils and ground and surface waters and the removal of nutrients.

Water pollution control measures

Water conservation

• Using high pressure water hoses will minimise the amount and therefore the cost of water used. Operators should be trained in water conservation and water monitoring.
• Provide roofing or isolate unloading areas, stockyards and processing plant so that the amount of contaminated stormwater, wastewaters and washwaters can be minimised.
• Contaminated stormwater, wastewaters and washwaters should be collected in lagoons and aerated and irrigated without any off-site runoff.
• Clean stormwater must be kept away from the contaminated areas and directed to the stormwater drainage system.
• All process areas must have concrete floors graded to wash down drains.
• All chemical storage areas and chemical-based odour control equipment must be located on impermeable concrete floors with bunding capable of containing 110 per cent of any spillage.

Wastewater treatment plant

Refer to the DEC's Environmental Guidelines: Use of Effluent by Irrigation (PDF1.5MB) for information on the size and design of ponds. Treatment ponds should service all contaminated stormwater, washwater and wastewater and be designed with the following characteristics.for information on the size and design of ponds. Treatment ponds should service all contaminated stormwater, washwater and wastewater and be designed with the following characteristics.for information on the size and design of ponds. Treatment ponds should service all contaminated stormwater, washwater and wastewater and be designed with the following characteristics. 

• Incorporate stone pitching on or grass the external walls to decrease the potential for erosion.
• Incorporate stone pitching or a concrete plinth interior on the walls to decrease the potential for erosion.
• Design anaerobic ponds for a 50 day retention time to achieve a satisfactory level of breakdown.
• Because effluent treatment plants are sensitive to overloading, design them well in the planning stage.

Treated wastewater re-use and disposal

Options for the disposal of treated wastewater are as follows.

• Irrigation to land. This is a preferred re-use strategy.
• Disposal to local sewer. This will require nutrient removal and organic loading reduction.
• Licensed disposal to a watercourse. It would normally be difficult to treat abattoir effluent to a level suitable for discharge to sewer.

For existing abattoirs in areas where there are significant land constraints, discharge to sewer or to waters may be acceptable. In these cases it should be possible to arrange a summer or dry season land disposal system coupled with a winter or wet season discharge to sewer or to waters. For green fields sites, disposal to sewer or to waters will not generally be acceptable.

Suitably treated wastewater can be used for crop production, to irrigate farmland, gardens and parks or for washing down stock holding yards.

The area of land required for irrigation disposal depends on the volume and constituents of effluent discharged, the landform soil type, the rainfall and the frequency of flooding in the area. Irrigation disposal should meet the following requirements:

• Effluent must not leave the site.
• There must be no irrigation in times of high rainfall; this could lead to contaminated stormwater runoff.
• A sampling point should be maintained on the pipe transporting to the effluent irrigation system.
• The effluent irrigation rate should be metered.

Monitoring programs are needed to ensure that long-term irrigation disposal does not affect soil and ground water quality. Irrigation sites should be chosen and/or designed so that the crop/soil system can assimilate the wastes and maintain the hydraulic balance so that surface runoff does not occur. Vegetated buffer zones help protect watercourses from potentially contaminated runoff.

Stormwater runoff

Stormwater should be controlled using the following techniques.

• Stormwater should be diverted away from intensively used holding areas, bulk chemical storage and liquid waste collection areas and treatment and disposal areas. This can be done by roofing or isolating unloading areas, stockyards and processing plant, as well as by building diversion drains and bunding.
• Contaminated stormwater should be collected in lagoons, aerated and irrigated without any off-site runoff.
• Clean stormwater must be kept away from contaminated areas and directed to the stormwater drainage system. It may be collected for stock watering or washing down.  

Solid waste disposal measures

Recycling

Composting of solid waste such as turned windrows and aerated static pile are most suited to the treatment of meat plant waste.

Disposing of industrial solid waste is arranged in several ways, including disposal to the local council's landfills.

Below are suggested appropriate techniques for disposing of solid waste generated by abattoirs.

• Manure can be spread directly on land for assimilation of wastes into soil. There is a balance between effective waste disposal and creation of pollution problems using this disposal technique. Manure needs to be mixed with surface soil to prevent fly breeding, reduce odour and avoid water pollution from surface runoff.
• Manure can also be stockpiled and dried before spreading on land. This technique needs to be managed to prevent fly strike and odours developing and to prevent seepage of the liquid phase into soil and groundwater.
• Sludge removed from treatment ponds should be allowed to dry and spread as for manure. It is best to dry out sludge in summer to quickly develop a sealing crust and prevent odour emissions.
• Paunch contents can be efficiently and economically disposed of by composting as long as offensive odours are not generated. 

Air emission control

Biofiltration

Biofiltration is very effective for managing odour problems. All odorous gases are released underneath the ground to a biofilter bed. The biofilter bed is constructed of materials such as concrete, blockwork and earth, and the beds layered with products such as compost and rice hulls, coarse gravel, sand, pinebark and woodchips. Microorganisms in the bed break down organic and inorganic odours in aerobic microbial activity under damp conditions (humidification of odours).

Odour

Below are recommended techniques for minimising odour emissions from various abattoir activities.

Rendering plants

• The building housing the rendering works must be vented to the atmosphere via a discrete stack to allow retrofitting of odour control equipment. The stack should be at least 3 m above the building roof ridge, have an efflux velocity not less than 15 m/s, and be fitted with emission sampling provisions. Retrofitting would only be permitted with existing installations. New or upgraded installations must have full odour controls installed.
• The most common odour abatement method in the cooking process is condensation and condensate subcooling, followed by incineration or afterburning of the non-condensibles.
• Alternative odour abatement methods include the use of biofilters, chemical scrubbers using hypochlorite, multi-stage acid and alkali scrubbing followed by chlorination and incineration in boilers.
• Odour control equipment should be fitted with monitoring equipment with recorders for the monitoring of key parameters.
• Good housekeeping is essential to stop odours developing. Dropped material or spilt tallow should not be left to develop odours.
• Quick processing of materials to minimise odour generated from bacterial degradation is essential.
• Rendering material should be stored in an enclosed receptacle, and any material not removed for rendering within 24 hours of production should be refrigerated below 3⁰C until it is removed from the site or processed.
• Equipment and machinery are to be kept clean of raw materials and residues.
• Effective and reliable operation of burners and chemical scrubbers is essential.
• Using continuous cookers over batch cookers can reduce odours.
• Bins for holding raw material and rendering products need to be shrouded or covered, and grinding, processing and conveying equipment must be completely enclosed.
• Receival and storage bins can be designed to prevent the accumulation of any liquid or solid wastes; the wastes should be drained or pumped from a sump on a continuous basis.
• Receival and storage bins can be designed to prevent the accumulation of any liquid or solid wastes; the wastes should be drained or pumped from a sump on a continuous basis.
• Receival and storage bins may need to be designed so that they can be cleaned with high pressure hot and/or cold water at least once a day.
• A procedure for monitoring odour as well as investigating and resolving complaints should be implemented.
• All processed fish, seafoods and poultry that have become tainted or putrid must be stored in enclosed containers and refrigerated until they are removed from the premises.
• All boilers, steam raising plant and afterburners must use clean fuels free of heavy metals and toxic wastes.
• All conveyors and pipe runs for waste animal matter transfer operations are capable of being dismantled for effective cleaning. Offal and waste animal matter must be received in a fully enclosed building.

Draft policy: Assessment and management of odour from stationary sources in NSW

For general information see the DEC's 

Slaughterhouse and processing areas

Use:

• airtight bags and bins
• enclosed conveying and filling systems
• good housekeeping.

Animal holding pens and saleyards

• Odours produced from manure and urine in animal holding areas can be greatly reduced by scraping up and removing the manures in sealed holding yards, then washing down using low volume high pressure sprays.
• Manure should be collected daily and stored in vermin-proof containers.
• Lime should be added to the soil in unsealed holding areas.

Effluent treatment plants

• During commissioning, odours produced by anaerobic waste treatment ponds can be reduced by:
  - allowing some grease and manure solids to pass through the primary treatment system, establishing a crust of 100 mm thick on the surface
  - layering straw or hay on the surface of the anaerobic pond
  - using an artificial cover (such as plastic) that breaks down over time and mixes with the fat on the surface.
• During the operational phase, all detergents and chemicals used in the abattoir should be suitable for the biological treatment process.
• An appropriate starter culture or enzyme must be used to re-establish pond equilibrium in the event of a pond failure.
• Continuous desludging of ponds by siphon prevents disturbance of the pond crust.
• Effluent treatment plants need to be adequately designed, operated and maintained to minimise emission of odours.

Skin drying areas

These areas should be vented through an odour control system. Fly strike of skins should be prevented. The normal open skillion roof sheds are well ventilated, and fly strike is usually not a major problem in them.

Dust

Below are techniques that reduce dust emissions from various abattoir operations.

• Fabric filter type dust collectors should be used for dust control.
• Surfaces of saleyards, holding pens, unsealed roads and parking areas should be sealed.
• Windbreaks (incorporating lines of trees) should be used near large coal stockpiles.
• Stockpiles should be dampened with water sprays and have their axes parallel to the direction of the strongest winds.
• Dusty process operations should be serviced by filtered ventilation hoods.
• Warehouses should use good housekeeping to alleviate dust generation.
• Dry materials, such as meat meal, must be handled in such a manner as not to give rise to dust emissions to the atmosphere.

Fuel burning activities

Some abattoirs may wish to dispose of sludge and other wastes by incineration. Coal fired boilers may also be used in the rendering process. All fuel burning equipment will release greenhouse gases.

Practical control measures needed to minimise the effects of fuel burning equipment on surrounding land users are as follows.

• All boilers, steam raising plant and after burners should use clean fuels free of heavy metals and toxic wastes.
• Combustion equipment and air pollution control equipment should be designed and operated to minimise the production and emission of air pollutants.
• Stacks should be high enough to prevent ground level concentrations of pollutants from reaching undesirable levels.

Noise control

Operating hours

Some industries operate outside normal working hours. Noise complaints may result from early or late operations and from weekend activities.

Existing premises

The following noise control measures should be considered.

• Erect noise barriers such as screens around noisy equipment and operations.
• Use visual signals and portable telephones instead of hooters and telephone bells in operational areas.
• All ventilation and extractor fans should be noise efficient or fitted with silencers, and all ducts should be lined with sound-absorbent material.
• Restrict external workshop activities and vehicle access to 7 am to 6 pm, Monday to Friday and 7 am to 1 pm on Saturdays. Generally, only work conducted inside noise-insulated workshops should be permitted during the evening (6 pm to 10 pm) and night-time (10 pm to 7 am).
• Limit vehicle movement (especially trucks) to and from the site to normal working hours only.
• Fit efficient exhaust mufflers to diesel forklift engines, other noisy vehicles and air-powered tools.
• Keep equipment in good repair and attend promptly to loose or rattling covers, worn bearings and broken equipment.
• Locate mechanical equipment on mounts designed to isolate structure-borne vibration and noise.

Noise from existing abattoir operations should not exceed the levels in the table below.

Compliance noise limits (based on background sound levels) for existing sources or places to protect existing or proposed dwellings and other noise-sensitive places or commercial areas

Compliance limit levels are measured as the average of the maximum A-weighted sound levels adjusted for noise character measured over a 15 minute time interval.

Proposed premises

The noise control measures mentioned above for existing premises can be incorporated more cheaply and efficiently into the proposed development during the design stage. Other measures worth considering are:

• installing noisy equipment into one or more plant rooms or specially designed acoustic enclosures
• positioning noisy operations as far away as possible from current or future noise-sensitive areas
• locating vehicle parking and noisy equipment away from noise-sensitive areas
• using the layout and orientation of the buildings to advantage, using buildings as noise barriers and using the natural topography as an acoustic barrier where possible.

Below are specific techniques that minimise noise from abattoir operations.

• Animal holding areas and noisy mechanical plant equipment should be located as far away as possible from the local community and employ the local topography as a noise barrier.
• Cattle being processed at abattoirs should be processed on the same day and not kept overnight in the stockyards.
• Mechanical plant noise is best controlled by good initial design and choice of equipment.
• Equipment should be maintained regularly and noisy operations should be enclosed.
• Noisy operations such as stock handling should be done during the noise tolerant periods of the day (that is, when background noise levels are highest).
• Buildings should be located so as to attenuate on-site vehicle noise.
• Heavy vehicle routes should be chosen to avoid intrusion on the local community, and if needed, restricted from operating during the noise-sensitive hours.

Noise from proposed abattoir operations should not exceed the levels in the table below when measured at any residential premises:

Compliance noise limits, based on background sound levels, for proposed sources or places to protect established dwellings and other noise-sensitive places or commercial places

Compliance limit levels are measured as the average of the maximum A-weighted sound levels adjusted for noise character measured over a 15 minute time interval.

Training employees

Training employees is a vital part of any environmental management practice. Staff should be aware of the environmental management program and environmental controls at varying levels of detail, depending on their duties. All staff need to be advised that if they fail in their duties, they are just as liable to prosecution and penalty as their employer. Further, all persons, including workers and bosses, may each be liable for a maximum fine of $250,000 and/or 7 years imprisonment. Training programs should contain common elements such as familiarisation with the company environmental policy and commitment to waste prevention, recycling and raw materials conservation. Employees should be encouraged to suggest new ideas.

It is the responsibility of the occupier of the premises to ensure all operational staff are instructed in the use of equipment, processes and emergency conditions that might result in pollution.

Summary

Abattoirs present many hazards to the environment in terms of effluent, solid wastes, odours, wastes and noise. Authorised officers should be aware of these risks and what can be done to minimise them, so that they can assess and monitor proposals properly.

Further reading

In this manual:

Department of Environment and Conservation Draft policy: Assessment and management of odour from stationary sources in NSW

Department of Environment and Conservation Environmental Guidelines: Use of Effluent by Irrigation (PDF 1.5MB)

Department of Environment and Conservation NSW Industrial Noise Policy

Others:

Department of Environment and Heritage, Queensland, 1994, Draft Environmental Guideline on Abattoirs.

First Australian Meat Technology Group of the 'AIFST' Seminar 1978, Meatworks Effluent Treatment

Green, J. M. 1993, Effluent Treatment Ponds, CSIRO Meat Research Laboratory.

New South Wales State Pollution Control Commission 1977, Environmental Guidelines for Abattoirs.

Victorian Environment Protection Authority 1991, Animal and Seafood Processors: Technical Guideline.

Western Australian Environmental Protection Authority 1991, Environmental Code of Practice: Rendering Plants.