COMMISSION IMPLEMENTING DECISION (EU) 2023/2749
of 11 December 2023
establishing the best available techniques (BAT) conclusions, under Directive 2010/75/EU of the European Parliament and of the Council on industrial emissions, for slaughterhouses, animal by-products and/or edible co-products industries
(notified under document C(2023) 8434)
(Text with EEA relevance)
Article 1
Article 2
ANNEX
BEST AVAILABLE TECHNIQUES (BAT) CONCLUSIONS FOR SLAUGHTERHOUSES, ANIMAL BY-PRODUCTS AND/OR EDIBLE CO-PRODUCTS INDUSTRIES
SCOPE
DEFINITIONS
General terms |
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Term used |
Definition |
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Animal by-products |
As defined in Regulation (EC) No 1069/2009 of the European Parliament and of the Council of 21 October 2009 laying down health rules as regards animal by-products and derived products not intended for human consumption and repealing Regulation (EC) No 1774/2002 (Animal by-products Regulation)(4). |
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Channelled emissions |
Emissions of pollutants to air through any kind of duct, pipe, stack, etc. This includes emissions from open-top biofilters. |
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Direct discharge |
Discharge to a receiving water body without further downstream waste water treatment. |
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Edible co-products |
Food-grade products intended for human consumption. |
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Existing plant |
A plant that is not a new plant. |
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FDM activities |
Activities covered by the BAT conclusions for the Food, Drink and Milk Industries. |
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FDM products |
Products associated with activities covered by the BAT conclusions for the Food, Drink and Milk Industries. |
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Hazardous substance |
Hazardous substance as defined in point 18 of Article 3 of Directive 2010/75/EU. |
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Indirect discharge |
Discharge which is not a direct discharge. |
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New plant |
A plant first permitted at the site of the installation following the publication of these BAT conclusions or a complete replacement of a plant following the publication of these BAT conclusions. |
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Sensitive receptor |
Areas which need special protection, such as:
|
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Substances of very high concern |
Substances meeting the criteria mentioned in Article 57 and included in the Candidate List of Substances of Very High Concern, according to the REACH Regulation ((EC) No 1907/2006(5)). |
Pollutants and parameters |
|
Term used |
Definition |
AOX |
Adsorbable organically bound halogens, expressed as Cl, include adsorbable organically bound chlorine, bromine and iodine. |
As, Cd, Co, Cr, Cu, Mn, Ni, Pb, Sb, Tl, V |
Arsenic, cadmium, cobalt, chromium, copper, manganese, nickel, lead, antimony, thallium and vanadium. |
Biochemical oxygen demand (BODn) |
Amount of oxygen needed for the biochemical oxidation of the organic matter to carbon dioxide in n days (n is typically 5 or 7). BOD is an indicator for the mass concentration of biodegradable organic compounds. |
Chemical oxygen demand (COD) |
Amount of oxygen needed for the total chemical oxidation of the organic matter to carbon dioxide using dichromate. COD is an indicator for the mass concentration of organic compounds. |
CO |
Carbon monoxide. |
Copper (Cu) |
Copper, expressed as Cu, includes all inorganic and organic copper compounds, dissolved or bound to particles. |
Dust |
Total particulate matter (in air). |
HCl |
All inorganic gaseous chlorine compounds, expressed as HCl. |
HF |
All inorganic gaseous fluorine compounds, expressed as HF. |
Hg |
The sum of mercury and its compounds, expressed as Hg. |
H2S |
Hydrogen sulphide. |
Odour concentration |
Number of European Odour Units (ouE) in a cubic metre of gas at standard conditions for olfactometry according to EN 13725. |
NOX |
The sum of nitrogen monoxide (NO) and nitrogen dioxide (NO2), expressed as NO2. |
PCDD/F |
Polychlorinated dibenzo-p-dioxins and -furans. |
SOX |
The sum of sulphur dioxide (SO2), sulphur trioxide (SO3), and sulphuric acid aerosols, expressed as SO2. |
Total nitrogen (Total N) |
Total nitrogen, expressed as N, includes free ammonia and ammonium nitrogen (NH4-N), nitrite nitrogen (NO2-N), nitrate nitrogen (NO3-N) and organically bound nitrogen. |
Total organic carbon (TOC) |
Total organic carbon (in water), expressed as C, includes all organic compounds. |
Total phosphorus (Total P) |
Total phosphorus, expressed as P, includes all inorganic and organic phosphorus compounds, dissolved or bound to particles. |
Total suspended solids (TSS) |
Mass concentration of all suspended solids (in water), measured via filtration through glass fibre filters and gravimetry. |
Total volatile organic carbon (TVOC) |
Total volatile organic carbon (in air), expressed as C. |
Zinc (Zn) |
Zinc, expressed as Zn, includes all inorganic and organic zinc compounds, dissolved or bound to particles. |
ACRONYMS
Acronym |
Definition |
CIP |
Cleaning-in-place |
CMS |
Chemicals management system |
EMS |
Environmental management system |
FDM |
Food, drink and milk |
IED |
Industrial Emissions Directive (2010/75/EU) |
OTNOC |
Other than normal operating conditions |
SA |
Slaughterhouses, animal by-products and/or edible co-products industries |
GENERAL CONSIDERATIONS
Best Available Techniques
Emission levels associated with the best available techniques (BAT-AELs) for emissions to water
Emission levels associated with the best available techniques (BAT-AELs) and indicative emission level for channelled emissions to air
Type of measurement |
Averaging period |
Definition |
Periodic |
Average over the sampling period |
Average value of three consecutive samplings/measurements of at least 30 minutes each(6). |
Indicative emission levels for refrigerant losses
Other environmental performance levels associated with the best available techniques (BAT-AEPLs)
BAT-AEPLs for specific waste water discharge
BAT-AEPLs for specific net energy consumption
1.1
General BAT conclusions
1.1.1
Overall environmental performance
1.1.2
Monitoring
Substance/Parameter |
Activities |
Standard(s) |
Minimum monitoring frequency(001) |
Monitoring associated with |
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Adsorbable organically bound halogens (AOX)(002) (003) |
All activities |
EN ISO 9562 |
Once every 3 months(004) |
BAT 14 |
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Biochemical oxygen demand (BODn)(005) |
Various EN standards available (e.g. EN 1899-1, EN ISO 5815-1) |
Once every month |
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Chemical oxygen demand (COD)(005) (006) |
No EN standard available |
Once every week(007) |
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Total nitrogen (TN)(005) |
Various EN standards available (e.g. EN 12260, EN ISO 11905-1) |
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Total organic carbon (TOC)(005) (006) |
EN 1484 |
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Total phosphorus (TP)(005) |
Various EN standards available (e.g. EN ISO 6878, EN ISO 15681-1 and -2, EN ISO 11885) |
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Total suspended solids (TSS)(005) |
EN 872 |
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Metals |
Copper (Cu)(002) (003) |
Slaughterhouses |
Various EN standards available (e.g. EN ISO 11885, EN ISO 17294-2 or EN ISO 15586) |
Once every 6 months |
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Zinc (Zn)(001) (002) |
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Chloride (Cl-)(002) (003) |
|
Various EN standards available (e.g. EN ISO 10304-1, EN ISO 15682) |
Once every month(004) |
- |
Substance/ Parameter |
Activities/Processes |
Standard(s) |
Minimum monitoring frequency(7) |
Monitoring associated with |
CO |
Combustion (e.g. in thermal oxidisers or steam boilers) of malodorous gases, including non-condensable gases |
EN 15058 |
Once every year |
BAT 15 |
Incineration of carcasses |
- |
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Dust |
Combustion (e.g. in thermal oxidisers or steam boilers) of malodorous gases, including non-condensable gases |
EN 13284-1 |
BAT 15 |
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Incineration of carcasses |
- |
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NOX |
Combustion (e.g. in thermal oxidisers or steam boilers) of malodorous gases, including non-condensable gases |
EN 14792 |
BAT 15 |
|
Incineration of carcasses |
- |
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SOX |
Combustion (e.g. in thermal oxidisers or steam boilers) of malodorous gases, including non-condensable gases |
EN 14791 |
BAT 15 |
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Incineration of carcasses |
- |
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H2S |
Rendering, fat melting, blood and/or feather processing(8) |
No EN standard available |
BAT 25 |
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NH3 |
Rendering, fat melting, blood and/or feather processing |
EN ISO 21877 |
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Combustion (e.g. in thermal oxidisers or steam boilers) of malodorous gases, including non-condensable gases |
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Incineration of carcasses |
- |
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TVOC |
Rendering, fat melting, blood and/or feather processing |
EN 12619 |
BAT 25 |
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Combustion (e.g. in thermal oxidisers or steam boilers) of malodorous gases, including non-condensable gases |
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Incineration of carcasses |
- |
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Odour concentration |
Slaughterhouses(9) (10) |
EN 13725 |
- |
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Incineration of carcasses(9) |
- |
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Gelatine manufacturing(9) |
- |
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Fishmeal and fish oil production(9) |
BAT 25 |
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Rendering, fat melting, blood and/or feather processing(9) |
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HCl |
Incineration of carcasses |
EN 1911 |
- |
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HF |
No EN standard available |
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Hg |
EN 13211 |
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Metals and metalloids except mercury (As, Cd, Co, Cr, Cu, Mn, Ni, Pb, Sb, Tl, V) |
EN 14385 |
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PCDD/F |
EN 1948-1, EN 1948-2, EN 1948-3 |
1.1.3
Energy efficiency
Technique |
Description |
Applicability |
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a |
Energy efficiency plan and audits |
An energy efficiency plan is part of the environmental management system (see BAT 1) and entails defining and calculating the specific energy consumption of the activity (or activities), setting key performance indicators on an annual basis (for example for the specific energy consumption) and planning periodic improvement targets and related actions. Audits are carried out at least once every year to ensure that the objectives of the energy efficiency plan are met and the energy audits’ recommendations are followed up and implemented. |
The level of detail of the energy efficiency plan and audits will generally be related to the nature, scale and complexity of the plant. |
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b |
General energy-saving techniques |
These include techniques such as:
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Applicability of cogeneration to existing plants may be restricted by a suitable heat demand and/or by the plant layout/lack of space. |
1.1.4
Water consumption and waste water generation
Technique |
Description |
Applicability |
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Management, design and operation techniques |
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a |
Water management plan and water audits |
A water management plan and water audits are part of the environmental management system (see BAT 1) and include:
Water audits are carried out at least once every year to ensure that the objectives of the water management plan are met and the water audits’ recommendations are followed up and implemented. |
The level of detail and nature of the water management plan and water audits will generally be related to the nature, scale and complexity of the plant. |
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b |
Segregation of water streams |
Water streams that do not need treatment (e.g. uncontaminated cooling water, uncontaminated run-off water) are segregated from waste water that has to undergo treatment, thus enabling uncontaminated water recycling. |
Applicability to existing plants may be restricted by the layout of the water collection system and the lack of space for temporary storage tanks. |
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c |
Water reuse and/or recycling |
Recycling and/or reuse of water streams (preceded or not by water treatment), e.g. for cleaning, washing, cooling or for the process itself. |
May not be applicable due to hygiene and safety requirements. |
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d |
Optimisation of water flow |
Use of control devices, e.g. photocells, flow valves, thermostatic valves, to automatically adjust the water flow to the minimum amount needed. |
Generally applicable. |
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e |
Optimisation and appropriate use of water nozzles and hoses |
Use of correct number and position of nozzles; adjustment of water pressure of nozzles and hoses. |
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Techniques related to cleaning operations |
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f |
Dry cleaning |
Removal of as much residual material as possible from raw materials and equipment, e.g. by using compressed air, vacuum systems or catchpots with a mesh cover. |
Generally applicable. |
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g |
High-pressure cleaning |
Spraying of cleaning water at pressures ranging from 15 bar to 150 bar. |
May not be applicable due to health and safety requirements. |
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h |
Optimisation of chemical dosing and water use in cleaning-in-place (CIP) |
The amounts of hot water and chemicals used are optimised by measuring for example turbidity, conductivity, temperature and/or pH. |
Generally applicable. |
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i |
Low-pressure foam and/or gel cleaning |
Use of low-pressure foam and/or gel to clean walls, floors and/or equipment surfaces. |
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j |
Optimised design and construction of equipment and process areas |
The equipment and process areas are designed and constructed in a way that facilitates cleaning. When optimising the design and construction, hygiene requirements are taken into account. |
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k |
Prompt cleaning of equipment |
Cleaning is applied as soon as possible after use of equipment to prevent hardening of residual material. |
1.1.5
Harmful substances
Technique |
Description |
|
a |
Proper selection of cleaning chemicals and/or disinfectants |
Avoidance or minimisation of the use of cleaning chemicals and/or disinfectants that are harmful to the aquatic environment, in particular those that contain priority substances considered under the Water Framework Directive(11). When selecting the cleaning chemicals and/or disinfectants, hygiene and food safety requirements are taken into account. This technique is part of the CMS (see BAT 3). |
b |
Reuse of cleaning chemicals in cleaning-in-place (CIP) |
Collection and reuse of cleaning chemicals in CIP. When reusing cleaning chemicals, hygiene and food safety requirements are taken into account. |
c |
Dry cleaning |
See BAT 10 (f). |
d |
Optimised design and construction of equipment and process areas |
See BAT 10 (j). |
1.1.6
Resource efficiency
Technique |
Description |
Applicability |
|
a |
Minimisation of biological degradation of animal by-products and/or edible co-products |
Animal by-products and/or edible co-products are promptly collected in slaughterhouses and are stored in closed vessels or rooms in SA installations, for as short a time as possible, before further treatment. Raw materials intended for human consumption (e.g. fat, blood), feed material or pet food may require refrigeration. |
Generally applicable. |
b |
Residues separation and recycling/recovery |
Residues are separated, e.g. using accurately positioned screens, flaps, catchpots, drip trays and troughs, for recycling and recovery. |
|
c |
Anaerobic digestion |
Treatment of biodegradable residues by microorganisms in the absence of oxygen, resulting in the generation of biogas and digestate. The biogas is used as a fuel, e.g. in a gas engine or in a boiler. The digestate may be used, e.g. as a soil improver, on site or off site. |
May not be applicable due to the quantity and/or nature of the residues. |
d |
Phosphorus recovery as struvite |
See Section 1.4.1. |
Only applicable to waste water streams with a high total phosphorus content (e.g. above 50 mg/l) and a significant flow. |
1.1.7
Emissions to water
|
Technique(12) |
Typical pollutants targeted |
Applicability |
Preliminary, primary and general treatment |
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a |
Equalisation |
All pollutants |
Generally applicable. |
b |
Neutralisation |
Acids, alkalis |
|
c |
Physical separation, e.g. screens, sieves, grit separators, fat separators, primary settlement tanks |
Gross solids, suspended solids, oil/grease |
|
Physico-chemical treatment |
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d |
Precipitation |
Precipitable dissolved non-biodegradable or inhibitory pollutants, e.g. metals |
Generally applicable. |
e |
Chemical oxidation (e.g. with ozone) |
Reducible dissolved non-biodegradable or inhibitory pollutants, e.g. AOX, antimicrobial-resistant bacteria |
|
Aerobic and/or anaerobic treatment (secondary treatment) |
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f |
Aerobic and/or anaerobic treatment (secondary treatment), e.g. activated sludge process, aerobic lagoon, anaerobic contact process, membrane bioreactor |
Biodegradable organic compounds |
Generally applicable. |
Nitrogen removal |
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g |
Nitrification and/or denitrification |
Total nitrogen, ammonium/ammonia |
Nitrification may not be applicable in the case of high chloride concentrations (e.g. above 10 g/l). Nitrification may not be applicable when the temperature of the waste water is low (e.g. below 12 °C). |
Phosphorus removal |
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h |
Precipitation |
Total phosphorus |
Generally applicable. |
i |
Enhanced biological phosphorus removal |
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j |
Phosphorus recovery as struvite |
Only applicable to waste water streams with a high total phosphorus content (e.g. above 50 mg/l) and a significant flow. |
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Final solids removal |
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k |
Coagulation and flocculation |
Suspended solids and particulate-bound non-biodegradable or inhibitory pollutants |
Generally applicable. |
l |
Sedimentation |
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m |
Filtration (e.g. sand filtration, microfiltration, ultrafiltration, reverse osmosis) |
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n |
Flotation |
Substance/Parameter |
Unit |
BAT-AEL(13) (14) |
|
Chemical oxygen demand (COD)(15) |
mg/l |
25 –100 (16) (17) |
|
Total organic carbon (TOC)(15) |
7 –35 (17) (18) |
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Total suspended solids (TSS) |
4 –30 (17) (19) (20) |
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Total nitrogen (Total N) |
2 –25 (17) (21) (22) |
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Total phosphorus (Total P) |
0,25 –2 (17) |
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Adsorbable organically bound halogens (AOX)(23) |
0,02 –0,3 |
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Metals |
Copper (Cu)(23) |
0,01 –0,2 (24) |
|
Zinc (Zn)(23) |
0,05 –0,5 (24) |
Substance/Parameter |
Unit |
BAT-AEL(25) (26) |
|
Adsorbable organically bound halogens (AOX)(27) |
mg/l |
0,02 –0,3 |
|
Metals |
Copper (Cu)(27) |
0,01 –0,2 (28) |
|
Zinc (Zn)(27) |
0,05 –0,5 (28) |
1.1.8
Emissions to air
|
Technique |
Description |
Main compounds targeted |
Applicability |
a |
Optimisation of thermal oxidation or combustion in boilers |
Optimisation of design and operation of boilers or thermal oxidisers to promote the oxidation of organic compounds, as well as to reduce the generation of pollutants such as NOX and CO. |
CO, NOX |
Generally applicable. |
b |
Removal of high levels of dust, NOX and SOX precursors |
Removal (if possible, for reuse) of high levels of dust, NOX and SOX precursors prior to combustion of malodorous gases or thermal oxidation, e.g. by condensation. Additional post-combustion removal of dust, NOX and SOX may be carried out using wet scrubbing for example. |
Dust, NOX, SOX |
|
c |
Fuel choice |
The use of fuel (including support/auxiliary fuel) with a low content of potential pollution-generating compounds (e.g. low sulphur, ash, nitrogen, fluorine or chlorine content in the fuel). |
Dust, NOX, SOX |
|
d |
Low-NOX burner |
The technique is based on the principles of reducing peak flame temperatures. The air/fuel mixing reduces the availability of oxygen and reduces the peak flame temperature, thus retarding the conversion of fuel-bound nitrogen to NOX and the formation of thermal NOX, while maintaining high combustion efficiency. This may be associated with a modified design of the furnace combustion chamber. |
NOX |
Applicability to existing plants may be restricted by design and/or operational constraints. |
Substance/Parameter |
Unit |
BAT-AEL (average over the sampling period) |
Dust |
mg/Nm3 |
< 1 –5 (29) |
NOX |
50 –200 (29) (30) |
|
SOX |
6 –100 |
Substance |
Unit |
Indicative emission level (average over the sampling period) |
CO |
mg/Nm3 |
3 –30 |
1.1.9
Noise
Technique |
Description |
Applicability |
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a |
Appropriate location of equipment and buildings |
Increasing the distance between the emitter and the receiver, by using buildings as noise screens and by relocating equipment and/or buildings’ exits or entrances. |
For existing plants, the relocation of equipment and buildings’ exits or entrances may not be applicable due to lack of space and/or excessive costs. |
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b |
Operational measures |
These include techniques such as:
|
Generally applicable. |
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c |
Low-noise equipment |
This includes techniques such as low-noise compressors, pumps and fans. |
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d |
Noise control equipment |
This includes techniques such as:
|
May not be applicable to existing plants due to lack of space. |
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e |
Noise abatement |
Inserting obstacles between emitters and receivers (e.g. protection walls, embankments). |
Generally applicable. |
1.1.10
Odour
Technique |
Description |
Applicability |
|
a. |
Regular cleaning of installations and equipment |
Regular cleaning (e.g. daily) of installations and equipment including areas where animal by-products and/or edible co-products are stored and processed. |
Generally applicable. |
b. |
Cleaning and disinfection of vehicles and equipment used to transport and deliver animal by-products and/or edible co-products |
Transport vehicles and delivery equipment (e.g. containers) are cleaned and disinfected after being emptied. |
|
c. |
Enclosure of animal by-products and/or edible co-products during transport, reception, loading/unloading and storage |
Loading/unloading and reception areas are situated in enclosed ventilated buildings. Appropriate equipment is used for transport and storage of the animal by-products and/or edible co-products. |
May not be applicable to existing plants due to lack of space. |
d. |
Minimisation of biological degradation of animal by-products and/or edible co-products |
See BAT 12 (a). |
Generally applicable. |
e. |
Air extraction as close as possible to the point of odour generation. |
Air extraction as close as possible to the point of odour generation with full or partial enclosure. Extracted air may be treated (see BAT 25). |
Generally applicable. |
1.1.11
Use of refrigerants
1.2
BAT conclusions for slaughterhouses
1.2.1
Energy efficiency
Technique |
Description |
Applicability |
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a |
Refrigeration management plan |
See Section 1.4.3. |
Generally applicable. |
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b |
Techniques for efficient scalding of pigs and/or poultry |
These include techniques such as:
|
Applicability to existing plants may be restricted by the plant layout/lack of space. |
Slaughtered animals |
Unit(31) |
Specific net energy consumption (yearly average)(32) |
Cattle |
kWh/tonne of carcasses |
116 –240 (33) |
kWh/animal |
30 –80 (34) |
|
Pigs |
kWh/tonne of carcasses |
65 –370 (35) |
kWh/animal |
4 –35 (35) |
|
Chickens |
kWh/tonne of carcasses |
170 –490 (35) |
kWh/animal |
0,25 –0,90 (35) |
1.2.2
Water consumption and waste water generation
Technique |
Description |
Applicability |
|
a |
Dry emptying of cattle/pig stomachs |
Cattle/pig stomachs are emptied by using machines without water. |
Generally applicable. |
b |
Dry collection of the contents of pigs’ small intestines |
Pigs’ small intestines are emptied by pulling them between a pair of rollers. Their content is collected in a tray and pumped to a container. |
|
c |
Techniques for efficient scalding |
See BAT 21 (b). |
Applicability to existing plants may be restricted by the plant layout/lack of space. |
Slaughtered animals |
Unit(36) |
Specific waste water discharge (yearly average)(37) |
Cattle |
m3/tonne of carcasses |
1,85 –3,90 (38) |
m3/animal |
0,30 –1,30 (39) |
|
Pigs |
m3/tonne of carcasses |
0,70 –3,50 |
m3/animal |
0,07 –0,30 |
|
Chickens |
m3/tonne of carcasses |
1,45 –6,30 |
m3/animal |
0,002 –0,013 |
1.2.3
Use of refrigerants
Technique |
Description |
|
a |
Refrigeration management plan |
See Section 1.4.3. |
b |
Preventive and corrective maintenance |
The correct operation of the refrigeration equipment is regularly reviewed and any deviations/malfunctions are corrected/fixed in a timely manner. |
c |
Use of refrigerant leak detectors |
A centralised alarm system is used in order to promptly identify refrigerant leaks. |
Type of refrigerant |
Unit |
Indicative emission level (rolling average over 3 years) |
Any type of refrigerant |
Percentage (%) of the total amount of refrigerant contained in the cooling system(s) |
< 1 –5 |
1.3
BAT conclusions for installations processing animal by-products and/or edible co-products
1.3.1
Energy efficiency
Type of installation/process(es) |
Unit |
Specific net energy consumption (yearly average) |
Rendering, fat melting, blood and/or feather processing |
kWh/tonne of raw material |
120 –910 |
Fishmeal and fish oil production |
420 –710 |
|
Gelatine manufacturing |
1 380 –2 500 (40) |
1.3.2
Water consumption and waste water generation
Type of installation/process(es) |
Unit |
Specific waste water discharge (yearly average) |
Rendering, fat melting, blood and/or feather processing |
m3/tonne of raw material |
0,2 –1,55 |
Fishmeal and fish oil production |
0,20 –1,25 (41) |
|
Gelatine manufacturing |
16,5 –27 (42) |
1.3.3
Emissions to air
Technique |
Description |
|
a. |
Condensation |
See Section 1.4.2. The technique is used together with one or a combination of the techniques (b) to (g) for the treatment of non-condensable gases. |
b. |
Adsorption |
See Section 1.4.2. |
c. |
Biofilter |
|
d. |
Combustion in a steam boiler of malodorous gases, including non-condensable gases |
|
e. |
Thermal oxidation |
|
f. |
Wet scrubber |
|
g. |
Bioscrubber |
Substance/Parameter |
Unit |
BAT-AEL |
Odour concentration |
ouE/m3 |
200 –1 100 (43) (44) |
TVOC |
mg C/Nm3 |
0,5 –16 |
NH3 |
mg/Nm3 |
0,1 –4 (45) |
H2S |
< 0,1 –1 (46) |
Substance/Parameter |
Unit |
BAT-AEL |
Odour concentration |
ouE/m3 |
400 –3 500 (47) |
TVOC(48) |
mg C/Nm3 |
1 –14 |
NH3 (48) |
mg/Nm3 |
0,1 –7 |
1.4
Description of techniques
1.4.1
Emissions to water
Technique |
Description |
Activated sludge process |
A biological process in which the microorganisms are maintained in suspension in the waste water and the whole mixture is mechanically aerated. The activated sludge mixture is sent to a separation facility from where the sludge is recycled to the aeration tank. |
Aerobic lagoon |
Shallow earthen basin for the biological treatment of waste water, the content of which is periodically mixed to allow oxygen to enter the liquid through atmospheric diffusion. |
Anaerobic contact process |
An anaerobic process in which waste water is mixed with recycled sludge and then digested in a sealed reactor. The water/sludge mixture is separated externally. |
Chemical oxidation (e.g. with ozone) |
Chemical oxidation is the conversion of pollutants by chemical-oxidising agents other than oxygen/air or bacteria into similar but less harmful or hazardous compounds and/or to short-chained and more easily degradable or biodegradable organic components. Ozone is one example of a chemical-oxidising agent applied. |
Coagulation and flocculation |
Coagulation and flocculation are used to separate suspended solids from waste water and are often carried out in successive steps. Coagulation is carried out by adding coagulants with charges opposite to those of the suspended solids. Flocculation is carried out by adding polymers, so that collisions of microfloc particles cause them to bond to produce larger flocs. |
Equalisation |
Balancing of flows and pollutant loads by using tanks or other management techniques. |
Enhanced biological phosphorus removal |
A combination of aerobic and anaerobic treatment to selectively enrich polyphosphate-accumulating microorganisms in the bacterial community within the activated sludge. These microorganisms take up more phosphorus than is required for normal growth. |
Filtration |
The separation of solids from waste water by passing it through a porous medium, e.g. sand filtration, microfiltration and ultrafiltration. |
Flotation |
The separation of solid or liquid particles from waste water by attaching them to fine gas bubbles, usually air. The buoyant particles accumulate at the water surface and are collected with skimmers. |
Membrane bioreactor |
A combination of activated sludge treatment and membrane filtration. Two variants are used: a) an external recirculation loop between the activated sludge tank and the membrane module; and b) immersion of the membrane module in the aerated activated sludge tank, where the effluent is filtered through a hollow fibre membrane, with the biomass remaining in the tank. |
Neutralisation |
The adjustment of the pH of waste water to a neutral level (approximately 7) by the addition of chemicals. Sodium hydroxide (NaOH) or calcium hydroxide (Ca(OH)2) is generally used to increase the pH, whereas sulphuric acid (H2SO4), hydrochloric acid (HCl) or carbon dioxide (CO2) is generally used to decrease the pH. The precipitation of some substances may occur during neutralisation. |
Nitrification and/or denitrification |
A two-step process that is typically incorporated into biological waste water treatment plants. The first step is the aerobic nitrification where microorganisms oxidise ammonium (NH4 +) to the intermediate nitrite (NO2 -), which is then further oxidised to nitrate (NO3 -). In the subsequent anoxic denitrification step, microorganisms chemically reduce nitrate to nitrogen gas. |
Phosphorus recovery as struvite |
Phosphorus contained in waste water streams is recovered by precipitation in the form of struvite (magnesium ammonium phosphate). |
Precipitation |
The conversion of dissolved pollutants into insoluble compounds by adding chemical precipitants. The solid precipitates formed are subsequently separated by sedimentation, air flotation, or filtration. Multivalent metal ions (e.g. calcium, aluminium, iron) are used for phosphorus precipitation. |
Sedimentation |
The separation of suspended particles by gravitational settling. |
1.4.2
Emissions to air
Technique |
Description |
Adsorption |
Organic compounds are removed from a waste gas stream by retention on a solid surface (typically activated carbon). |
Bag filter |
Bag filters, often referred to as fabric filters, are constructed from porous woven or felted fabric through which gases are passed to remove particles. The use of a bag filter requires the selection of a fabric suitable for the characteristics of the waste gas and the maximum operating temperature. |
Biofilter |
The waste gas stream is passed through a bed of organic material (such as peat, heather, compost, root, tree bark, softwood and different combinations) or some inert material (such as clay, activated carbon, and polyurethane), where it is biologically oxidised by naturally occurring microorganisms into carbon dioxide, water, inorganic salts and biomass. A biofilter is designed considering the type(s) of waste input. An appropriate bed material, e.g. in terms of water retention capacity, bulk density, porosity, structural integrity, is selected. Also important are an appropriate height and surface area of the filter bed. The biofilter is connected to a suitable ventilation and air circulation system in order to ensure a uniform air distribution through the bed and a sufficient residence time of the waste gas inside the bed. Biofilters can be divided into open-top biofilters and enclosed biofilters. |
Bioscrubber |
A packed tower filter with inert packing material which is normally continuously moistened by sprinkling water. Air pollutants are absorbed in the liquid phase and subsequently degraded by microorganisms settling on the filter elements. |
Combustion in a steam boiler of malodorous gases, including non-condensable gases |
Malodorous gases, including non-condensable gases, are burned in a steam boiler in the installation. |
Condensation |
The removal of vapours of organic and inorganic compounds from a process off-gas or waste gas stream by reducing its temperature below its dew point so that the vapours liquefy. |
Thermal oxidation |
The oxidation of combustible gases and odorants in a waste gas stream by heating the mixture of contaminants with air or oxygen to above its auto-ignition point in a combustion chamber and maintaining it at a high temperature long enough to complete its combustion to carbon dioxide and water. |
Wet scrubber |
The removal of gaseous or particulate pollutants from a gas stream via mass transfer to a liquid solvent, often water or an aqueous solution. It may involve a chemical reaction (e.g. in an acid or alkaline scrubber). In some cases, the compounds may be recovered from the solvent. |
1.4.3
Use of refrigerants
Refrigeration management plan |
A refrigeration management plan is part of the environmental management system (see BAT 1) and entails:
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