COMMISSION IMPLEMENTING DECISION (EU) 2022/2508
of 9 December 2022
establishing the best available techniques (BAT) conclusions, under Directive 2010/75/EU of the European Parliament and of the Council on industrial emissions, for the textiles industry
(notified under document C(2022) 8984)
(Text with EEA relevance)
Article 1
Article 2
ANNEX
1.
BEST AVAILABLE TECHNIQUES (BAT) CONCLUSIONS FOR THE TEXTILES INDUSTRY
SCOPE
DEFINITIONS
General terms |
|
Term used |
Definition |
Air-to-textile ratio |
The ratio of the total exhaust gas volume flow (expressed in Nm3/h) from the emission point of a textile treatment unit (e.g. stenter) to the corresponding throughput of the textile to be treated (dry textile, expressed in kg/h). |
Cellulosic materials |
Cellulosic materials include cotton and viscose. |
Channelled emissions |
Emissions of pollutants to air through any kind of duct, pipe, stack, etc. |
Continuous measurement |
Measurement using an automated measuring system permanently installed on site. |
Desizing |
Pre-treatment of textile materials to remove sizing chemicals from woven fabric. |
Diffuse emissions |
Non-channelled emissions to air. |
Direct discharge |
Discharge to a receiving water body without further downstream waste water treatment. |
Dry cleaning |
Cleaning of textile materials with an organic solvent. |
Existing plant |
A plant that is not a new plant. |
Fabric production |
Production of fabric, e.g. by weaving or knitting. |
Finishing |
Physical and/or chemical treatment aiming at giving the textile materials end-use properties such as visual effects, handle characteristics, waterproofness or non-flammability. |
Flame lamination |
Bonding of fabrics using a thermoplastic foam sheet, exposed to a flame located before the laminating rolls. |
Hazardous substance |
Hazardous substance as defined in point 18 of Article 3 of Directive 2010/75/EU. |
Hazardous waste |
Hazardous waste as defined in point 2 of Article 3 of Directive 2008/98/EC of the European Parliament and of the Council(1) |
Indirect discharge |
Discharge that is not a direct discharge. |
Liquor ratio |
For a batch process, weight ratio between the dry textile materials and the process liquor used. |
n-Octanol/water partition coefficient |
The ratio of the equilibrium concentrations of a dissolved substance in a two-phase system consisting of the largely immiscible solvents n-octanol and water. |
Major plant upgrade |
A major change in the design or technology of a plant with major adjustments or replacements of the process and/or abatement technique(s) and associated equipment. |
Mass flow |
The mass of a given substance or parameter which is emitted over a defined period of time. |
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. |
Organic solvent |
Organic solvent as defined in Article 3(46) of Directive 2010/75/EU. |
Periodic measurement |
Measurement at specified time intervals using manual or automated methods. |
Pick-up |
For a continuous process, weight ratio between the liquid taken up by the textile materials and the dry textile materials. |
Process chemicals |
Substances and/or mixtures as defined in Article 3 of Regulation (EC) No 1907/2006(2) that are used in the process(es), including sizing chemicals, bleaching chemicals, dyes, printing pastes and finishing chemicals. Process chemicals may contain hazardous substances and/or substances of very high concern. |
Process liquor |
Solution and/or suspension containing process chemicals. |
Residual pick-up |
The remaining capacity of wet textile materials to take up additional liquid (after the initial pick-up). |
Scouring |
Pre-treatment of textile materials which consists of washing the incoming textile material. |
Singeing |
Removal of the fibres at the surface of the fabric by passing the fabric through a flame or heated plates. |
Sizing |
Impregnation of yarn with process chemicals aiming to protect the yarn and provide lubrication during weaving. |
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). |
Synthetic materials |
Synthetic materials include polyester, polyamide and acrylic. |
Textile materials |
Textile fibres and/or textiles. |
Thermal treatment |
Thermal treatment of textile materials includes thermofixation, heat-setting or a process step (e.g. drying, curing) of the activities covered by these BAT conclusions (e.g. coating, dyeing, pre-treatment, finishing, printing, lamination). |
Pollutants and parameters |
|
Term used |
Definition |
Antimony |
Antimony, expressed as Sb, includes all inorganic and organic antimony compounds, dissolved or bound to particles. |
AOX |
Adsorbable organically bound halogens, expressed as Cl, include adsorbable organically bound chlorine, bromine and iodine. |
BOD n |
Biochemical oxygen demand. Amount of oxygen needed for the biochemical oxidation of the organic matter to carbon dioxide in n days (n is typically 5 or 7). BODn is an indicator for the mass concentration of biodegradable organic compounds. |
Chromium |
Chromium, expressed as Cr, includes all inorganic and organic chromium compounds, dissolved or bound to particles. |
CO |
Carbon monoxide. |
COD |
Chemical oxygen demand. 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. |
Copper |
Copper, expressed as Cu, includes all inorganic and organic copper compounds, dissolved or bound to particles. |
CMR |
Carcinogenic, mutagenic or toxic for reproduction. This includes CMR substances of categories 1A, 1B and 2, as defined in Regulation (EC) No 1272/2008 of the European Parliament and of the Council(3) and amended, i.e. with hazard statement codes: H340, H341, H350, H351, H360 and H361. |
Dust |
Total particulate matter (in air). |
HOI |
Hydrocarbon oil index. The sum of compounds extractable with a hydrocarbon solvent (including long-chain or branched aliphatic, alicyclic, aromatic or alkyl-substituted aromatic hydrocarbons). |
NH3 |
Ammonia. |
Nickel |
Nickel, expressed as Ni, includes all inorganic and organic nickel compounds, dissolved or bound to particles. |
NOX |
The sum of nitrogen monoxide (NO) and nitrogen dioxide (NO2), expressed as NO2. |
SOX |
The sum of sulphur dioxide (SO2), sulphur trioxide (SO3), and sulphuric acid aerosols, expressed as SO2. |
Sulphide, easily released |
The sum of dissolved sulphides and of those undissolved sulphides that are easily released upon acidification, expressed as S2–. |
TOC |
Total organic carbon, expressed as C (in water), includes all organic compounds. |
TN |
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. |
TP |
Total phosphorus, expressed as P, includes all inorganic and organic phosphorus compounds, dissolved or bound to particles. |
TSS |
Total suspended solids. Mass concentration of all suspended solids (in water), measured via filtration through glass fibre filters and gravimetry. |
TVOC |
Total volatile organic carbon, expressed as C (in air). |
VOC |
Volatile organic compound as defined in Article 3(45) of Directive 2010/75/EU. |
Zinc |
Zinc, expressed as Zn, includes all inorganic and organic zinc compounds, dissolved or bound to particles. |
ACRONYMS
Acronym |
Definition |
CMS |
Chemicals management system |
DTPA |
Diethylenetriaminepentaacetic acid |
EDTA |
Ethylenediaminetetraacetic acid |
EMS |
Environmental management system |
ESP |
Electrostatic precipitator |
IED |
Industrial Emissions Directive (2010/75/EU) |
OTNOC |
Other than normal operating conditions |
PFAS |
Per- and polyfluoroalkyl substances |
GENERAL CONSIDERATIONS
Best Available Techniques
Emission levels associated with the best available techniques (BAT-AELs) for 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.(4) |
Emission levels associated with the best available techniques (BAT-AELs) for emissions to water
Other environmental performance levels
Indicative levels for specific energy consumption
Indicative levels for specific water consumption
Specific wool grease recovery level associated with the best available techniques
Caustic soda recovery level associated with the best available techniques
1.1.
General BAT conclusions
1.1.1.
Overall environmental performance
Note
Applicability
Applicability
Applicability
Description
Technique |
Description |
Applicability |
|||||||||||
a. |
Use of textile materials containing a minimised content of contaminants |
Criteria for the selection of incoming textile materials (including recycled textile materials) are defined to minimise the content of contaminants including hazardous substances, poorly biodegradable substances and substances of very high concern. These criteria may be based on certification schemes or standards. Regular controls are carried out to verify that incoming textile materials fulfil the predefined criteria. These controls may consist of measurements and/or verification of information provided by suppliers and/or producers of textile materials. These controls may address the content of:
|
Generally applicable. |
||||||||||
b. |
Use of textile materials with reduced processing needs |
Use of textile materials with inherent characteristics that reduce the need for processing. These materials include:
|
The applicability may be restricted by product specifications. |
1.1.2.
Monitoring
Description
Description
Substance(s)/parameter |
Standard(s) |
Activities/processes |
Minimum monitoring frequency |
Monitoring associated with |
|
Adsorbable organically bound halogens (AOX)(5) |
EN ISO 9562 |
All activities/processes |
Once every month(6) |
BAT 20 |
|
Biochemical oxygen demand (BOD n )(7) |
Various EN standards available (e.g. EN 1899-1, EN ISO 5815-1) |
Once every month |
|||
Brominated flame retardants(5) |
EN standard available for some polybrominated diphenyl ethers (i.e. EN 16694) |
Finishing with flame retardants |
Once every 3 months |
||
Chemical oxygen demand (COD)(8) |
No EN standard available |
All activities/processes |
Once every day (9) (10) |
||
Colour |
EN ISO 7887 |
Dyeing |
Once every month(6) |
||
Hydrocarbon oil index (HOI)(5) |
EN ISO 9377-2 |
All activities/processes |
Once every 3 months(11) |
||
Metals/metalloids |
Antimony (Sb) |
Various EN standards available (e.g. EN ISO 11885, EN ISO 17294-2, EN ISO 15586) |
Pre-treatment and/or dyeing of polyester textile materials |
Once every month(6) |
|
Finishing with flame retardants using antimony trioxide |
|||||
Chromium (Cr) |
Dyeing with chromium mordant or chromium-containing dyes (e.g. metal-complex dyes) |
||||
Copper (Cu) |
Dyeing Printing with dyes |
||||
Nickel (Ni) |
|||||
Zinc (Zn)(5) |
All activities/processes |
||||
Hexavalent chromium (Cr(VI)) |
Various EN standards available (e.g. EN ISO 10304-3, EN ISO 23913) |
Dyeing with chromium mordant |
Once every month |
||
Pesticides(5) |
EN standards available for some pesticides (e.g. EN 12918, EN 16693, EN ISO 27108) |
Pre-treatment of raw wool fibres by scouring |
To be decided, after effluent characterisation(12) |
||
Per- and polyfluoroalkyl substances (PFAS)(5) |
No EN standard available |
All activities/processes |
Once every 3 months |
||
Sulphide, easily released (S2-) |
No EN standard available |
Dyeing with sulphur dyes |
Once every week or once every month(6) |
||
Surfactants |
Alkylphenols and alkylphenol ethoxylates(5) |
EN standards available for some non-ionic surfactants, e.g. alkylphenols and alkylphenol ethoxylates (i.e. EN ISO 18857-1 and EN ISO 18857-2) |
All activities/processes |
Once every 3 months |
|
Other surfactants |
EN 903 for anionic surfactants |
Once every 3 months(11) |
|||
No EN standard available for cationic surfactants |
|||||
Total nitrogen (TN) |
Various EN standards available (e.g. EN 12260, EN ISO 11905-1) |
Once every day (9) (10) |
|||
Total organic carbon (TOC)(8) |
EN 1484 |
Once every day (9) (10) |
|||
Total phosphorus (TP) |
Various EN standards available (e.g. EN ISO 6878, EN ISO 15681-1, EN ISO 15681-2, EN ISO 11885) |
Once every day (9) (10) |
|||
Total suspended solids (TSS) |
EN 872 |
Once every day (9) (10) |
|||
Toxicity(13) |
Fish eggs (Danio rerio) |
EN ISO 15088 |
To be decided based on a risk assessment, after effluent characterisation(12) |
||
Daphnia (Daphnia magna Straus) |
EN ISO 6341 |
||||
Luminescent bacteria (Vibrio fischeri) |
Various EN standards available (e.g. EN ISO 11348-1, EN ISO 11348-2, EN ISO 11348-3) |
||||
Duckweed (Lemna minor) |
Various EN standards available (e.g. EN ISO 20079, EN ISO 20227) |
||||
Algae |
Various EN standards available (e.g. EN ISO 8692, EN ISO 10253, EN ISO 10710) |
Substance/parameter |
Standard(s) |
Activities/processes |
Minimum monitoring frequency(14) |
Monitoring associated with |
CO |
EN 15058 |
Singeing |
Once every 3 years |
— |
Combustion |
||||
Flame lamination |
||||
Dust |
EN 13284-1 |
Singeing |
Once every year(15) |
BAT 27 |
Combustion |
||||
Thermal treatments associated with pre-treatment, dyeing, printing and finishing |
||||
CMR (other than formaldehyde)(16) |
No EN standards available |
Coating(17) |
Once every year |
— |
Flame lamination(17) |
||||
Finishing(17) |
||||
Thermal treatments associated with coating, lamination and finishing(17) |
||||
Formaldehyde(16) |
EN standard under development |
Coating(17) |
Once every year |
BAT 26 |
Flame lamination |
||||
Printing(17) |
||||
Singeing |
||||
Finishing(17) |
||||
Thermal treatment(17) |
||||
NH3 (16) |
EN ISO 21877 |
Coating(17) |
Once every year |
BAT 28 |
Printing(18) |
||||
Finishing(17) |
||||
Thermal treatments associated with coating, printing and finishing(17) |
||||
NOX |
EN 14792 |
Singeing |
Once every 3 years |
— |
Combustion |
||||
SO2 (18) |
EN 14791 |
Combustion |
Once every 3 years |
— |
TVOC(16) |
EN 12619 |
Coating |
Once every year(19) |
BAT 26 |
Dyeing |
||||
Finishing |
||||
Lamination |
||||
Printing |
||||
Singeing |
||||
Thermofixation or heat-setting |
||||
Thermal treatments associated with coating, dyeing, lamination, printing and finishing |
1.1.3.
Water consumption and waste water generation
Technique |
Description |
Applicability |
|||||||||
Management techniques |
|||||||||||
a. |
Water management plan and water audits |
A water management plan and water audits are part of the EMS (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 water management plan and the water audits may be integrated in the overall water management plan of a larger industrial site. |
The level of detail of the water management plan and water audits will generally be related to the nature, scale and complexity of the plant. |
||||||||
b. |
Production optimisation |
This includes:
|
Generally applicable. |
||||||||
Design and operation techniques |
|||||||||||
c. |
Segregation of polluted and unpolluted water streams |
Water streams are collected separately, based on the pollutant content and on the required treatment techniques. Polluted water streams (e.g. spent process liquors) and unpolluted water streams (e.g. cooling waters) that can be reused without treatment are segregated from waste water streams that require treatment. |
Applicability to existing plants may be restricted by the layout of the water collection system and the lack of space for temporary storage tanks. |
||||||||
d. |
Processes using little or no water |
Processes include plasma or laser treatment, and processes using low amounts of water such as ozone treatment. |
The applicability may be restricted by the characteristics of the textile materials and/or product specifications. |
||||||||
e. |
Optimisation of the amount of process liquor used |
Batch processes are carried out with low-liquor-ratio systems (see Section 1.9.4). Continuous processes are carried out with low-volume application systems, such as spraying (see Section 1.9.4). |
Generally applicable. |
||||||||
f. |
Optimised cleaning of the equipment |
This includes:
|
The applicability of water-free cleaning in existing plants may be restricted by accessibility to the equipment (e.g. closed and semi-closed systems). |
||||||||
g. |
Optimised batch processing, washing and rinsing of textile materials |
This includes:
|
The use of auxiliary tanks in existing plants may be restricted by a lack of space. |
||||||||
h. |
Optimised continuous processing, washing and rinsing of textile materials |
This includes:
|
Generally applicable. |
||||||||
Reuse and recycling techniques |
|||||||||||
i. |
Water reuse and/or recycling |
Water streams may be segregated (see BAT 10 (c)) and/or pre-treated (e.g. membrane filtration, evaporation) before reuse and/or recycling, e.g. for cleaning, rinsing, cooling or in the processing of textile materials. The degree of water reuse/recycling is limited by the content of impurities in the water streams. Reuse and/or recycling of water originating from several plants operating on the same site may be integrated in the overall site water management of a larger industrial site (e.g. using common waste water treatment). |
Generally applicable. |
||||||||
j. |
Reuse of process liquor |
Process liquor, including the process liquor extracted from textile materials by mechanical dewatering (see BAT 13 (a)), is reused after analysis and make-up if needed. The degree of reuse of the process liquor is limited by the modification of its chemical composition, or by its content of impurities and perishability. |
Generally applicable. |
Specific process(es) |
Indicative levels (Yearly average) (m3/t) |
|
Bleaching |
Batch |
10 –32 (20) |
Continuous |
3 –8 |
|
Scouring of cellulosic materials |
Batch |
5 –15 (20) |
Continuous |
5 –12 (20) |
|
Desizing of cellulosic materials |
5 –12 (20) |
|
Combined bleaching, scouring and desizing of cellulosic materials |
9 –20 (20) |
|
Mercerisation |
2 –13 (20) |
|
Washing of synthetic material |
5 –20 (20) |
|
Batch dyeing |
Fabric |
10 –150 (20) |
Yarn |
3 –140 (20) (21) |
|
Loose fibre |
13 –60 |
|
Continuous dyeing |
2 –16 (20) (22) |
1.1.4.
Energy efficiency
Technique |
Description |
Applicability |
|||||||||||||||||
Management techniques |
|||||||||||||||||||
a. |
Energy efficiency plan and audits |
An energy efficiency plan and audits are part of the EMS (see BAT 1) and include:
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. |
Production optimisation |
Optimised scheduling of fabric batches to undergo thermal treatment in order to minimise the idling time of the equipment. |
Generally applicable. |
||||||||||||||||
Process and equipment selection and optimisation |
|||||||||||||||||||
c. |
Use of general energy-saving techniques |
This includes:
|
Generally applicable. |
||||||||||||||||
d. |
Optimisation of heating demand |
This includes:
|
Generally applicable. |
||||||||||||||||
e. |
Wet-on-wet dyeing or finishing of fabric |
Dyeing or finishing liquors are applied directly to the wet fabric, thus avoiding an intermediate drying step. Appropriate scheduling of production steps and dosing of chemicals need to be considered. |
May not be applicable when chemicals cannot be taken up by the fabric due to insufficient residual pick-up. |
||||||||||||||||
f. |
Cogeneration |
Cogeneration of heat and electricity where the heat (mainly from the steam that leaves the turbine) is used for producing hot water/steam to be used in industrial processes/activities or in a district heating/cooling network. |
Applicability in existing plants may be restricted by the plant layout and/or lack of space. |
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Heat recovery techniques |
|||||||||||||||||||
g. |
Recycling of warm cooling water |
See BAT 10 (i). This avoids the need for heating cold water. |
Generally applicable. |
||||||||||||||||
h. |
Reuse of warm process liquor |
See BAT 10 (j). This avoids the need for heating cold process liquor. |
|||||||||||||||||
i. |
Heat recovery from waste water |
Heat from waste water is recovered by heat exchangers, e.g. to warm up process liquor. |
|||||||||||||||||
j. |
Heat recovery from waste gases |
Heat from waste gases (e.g. from thermal treatment of textile materials, steam boilers) is recovered by heat exchangers and used (e.g. to warm up process water or to preheat combustion air). |
|||||||||||||||||
k. |
Heat recovery from steam use |
Heat, e.g. from hot condensate and boiler blowdown, is recovered. |
Technique |
Description |
Applicability |
|
a. |
Optimal design of the compressed air system |
Several compressed air units supply air with different pressure levels. This avoids the unnecessary production of high-pressure air. |
Only applicable to new plants or major plant upgrades. |
b. |
Optimal use of the compressed air system |
Compressed air production is stopped during long shutdown or idling times of equipment, and single areas can be isolated (e.g. by valves) from the rest of the system, in particular if they are associated with infrequent use. |
Generally applicable. |
c. |
Control of leakages in the compressed air system |
The most common sources of air leakages are regularly inspected and maintained (e.g. couplings, hoses, tubes, fittings, pressure regulators). |
|
d. |
Reuse and/or recycling of warm cooling water or warm cooling air from air compressors |
Warm cooling air (e.g. from air-cooled air compressors) is reused and/or recycled (e.g. for drying of coils and hanks if needed). For reuse and/or recycling of warm cooling water, see BAT 11 (g). |
Technique |
Description |
Applicability |
|||||||||
Techniques for reducing the use of heating |
|||||||||||
a. |
Mechanical dewatering of textile materials |
The water content of textile materials is reduced by mechanical techniques (e.g. centrifugal extraction, squeezing and/or vacuum extraction). |
Generally applicable. |
||||||||
b. |
Avoiding overdrying of textile materials |
The textile materials are not dried below their natural moisture level. |
|||||||||
Design and operation techniques |
|||||||||||
c. |
Optimising air circulation in stenters |
This includes:
|
Only applicable to new plants or major plant upgrades. |
||||||||
d. |
Advanced process monitoring and control of drying |
The drying parameters are monitored and controlled (see BAT 4). These parameters include:
The exhaust airflow is adjusted to optimise drying efficiency and is reduced during idle periods of drying equipment. |
Generally applicable. |
||||||||
e. |
Microwave or radio-frequency dryers |
Drying of textile materials with high-efficiency microwave or radio frequency dryers. |
Not applicable to textile materials containing metallic parts or fibres. Only applicable to new plants or major plant upgrades. |
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Heat recovery techniques |
|||||||||||
f. |
Heat recovery from waste gases |
See BAT 11 (j). |
Only applicable when the waste gas flow is sufficient. |
Process |
Indicative level (Yearly average) (MWh/t) |
Thermal treatment |
0,5 –4,4 |
1.1.5.
Chemicals management, consumption and substitution
Applicability
Description
Technique |
Description |
Applicability |
|||||
a. |
Reduction of the need for process chemicals |
This includes:
|
Generally applicable. |
||||
b. |
Reduction of the use of complexing agents |
The use of soft/softened water reduces the amount of complexing agents used in the process liquors, e.g. for dyeing or bleaching (see BAT 38 (b)). |
Not applicable to washing and rinsing. |
||||
c. |
Treatment of textile materials with enzymes |
Enzymes are selected (see BAT 14 I. (d)) and used to catalyse the reactions with textile materials to lower the consumption of process chemicals (e.g. in desizing, bleaching and/or washing). |
The applicability may be restricted by the availability of suitable enzymes. |
||||
d. |
Automatic systems for preparation and dosing of process chemicals and process liquors |
Automatic systems for weighing, dosing, dissolving, measuring and dispensing which ensure precise delivery of process chemicals and process liquors to the production machines. See BAT 4. |
The applicability to existing plants may be restricted by a lack of space, the distance between the preparation and the production machines or by frequent changes of process chemicals and process liquors. |
||||
e. |
Optimisation of the quantity of process chemicals used |
See BAT 10 (e). |
Generally applicable. |
||||
f. |
Reuse of process liquors |
See BAT 10 (j). |
Generally applicable. |
||||
g. |
Recovery and use of leftover process chemicals |
Residual process chemicals are recovered (e.g. by thoroughly purging pipes or completely emptying packaging) and used in the process. The degree of use may be limited by the content of impurities and the perishability of the process chemicals. |
Generally applicable. |
Technique |
Description |
Applicability |
|||||||||||
a. |
Substitution of alkylphenols and alkylphenol ethoxylates |
Alkylphenols and alkylphenol ethoxylates are substituted by biodegradable surfactants, e.g. alcohol ethoxylates. |
Generally applicable. |
||||||||||
b. |
Substitution of poorly biodegradable phosphorus- or nitrogen-containing complexing agents |
Complexing agents containing phosphorus (e.g. triphosphates) or nitrogen (e.g. amino polycarboxylic acids such as EDTA or DTPA) are substituted by biodegradable/bioeliminable substances, e.g.:
|
Generally applicable. |
||||||||||
c. |
Substitution of mineral-oil-based antifoaming agents |
Mineral-oil-based antifoaming agents are substituted by biodegradable substances, e.g. antifoaming agents based on synthetic ester oil. |
Generally applicable. |
1.1.6.
Emissions to water
Description
Description
Technique(23) |
Typical pollutants targeted |
Applicability |
|
Pre-treatment of individual waste water streams, e.g. |
|||
a. |
Adsorption |
Adsorbable dissolved non-biodegradable or inhibitory pollutants (e.g. AOX in dyestuffs, organophosphorus flame retardants) |
Generally applicable. |
b. |
Precipitation |
Precipitable dissolved non-biodegradable or inhibitory pollutants (e.g. metals in dyestuffs) |
|
c. |
Coagulation and flocculation |
Suspended solids and particulate-bound non-biodegradable or inhibitory pollutants (e.g. metals in dyestuffs) |
|
d. |
Chemical oxidation (e.g. oxidation with ozone, hydrogen peroxide or UV light) |
Oxidisable dissolved non-biodegradable or inhibitory pollutants (e.g. optical brighteners and azo dyestuffs, sulphide) |
|
e. |
Chemical reduction |
Reducible dissolved non-biodegradable or inhibitory pollutants (e.g. hexavalent chromium (Cr(VI)) |
|
f. |
Anaerobic pre-treatment |
Biodegradable organic compounds (e.g. azo dyestuffs, printing pastes) |
|
g. |
Filtration (e.g. nanofiltration) |
Suspended solids and particulate-bound non-biodegradable or inhibitory pollutants |
|
Pre-treatment of combined waste water streams, e.g. |
|||
h. |
Physical separation (e.g. screens, sieves, grit separators, grease separators, oil-water separation, or primary settlement tanks) |
Gross solids, suspended solids, oil/grease |
Generally applicable. |
i. |
Equalisation |
All pollutants |
|
j. |
Neutralisation |
Acids, alkalis |
|
Primary treatment, e.g. |
|||
k. |
Sedimentation |
Suspended solids and particulate-bound metals or non-biodegradable or inhibitory pollutants |
Generally applicable. |
l. |
Precipitation |
Precipitable dissolved non-biodegradable or inhibitory pollutants (e.g. metals in dyestuffs) |
|
m. |
Coagulation and flocculation |
Suspended solids and particulate-bound non-biodegradable or inhibitory pollutants (e.g. metals in dyestuffs) |
Generally applicable. |
Secondary treatment (biological treatment), e.g. |
|||
n. |
Activated sludge process |
Biodegradable organic compounds |
Generally applicable. |
o. |
Membrane bioreactor |
||
p. |
Nitrification/denitrification (when the treatment includes a biological treatment) |
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). |
Tertiary treatment, e.g. |
|||
q. |
Coagulation and flocculation |
Suspended solids and particulate-bound non-biodegradable or inhibitory pollutants (e.g. metals in dyestuffs) |
Generally applicable. |
r. |
Precipitation |
Precipitable dissolved non-biodegradable or inhibitory pollutants (e.g. metals in dyestuffs) |
|
s. |
Adsorption |
Adsorbable dissolved non-biodegradable or inhibitory pollutants (e.g. AOX in dyestuffs) |
|
t. |
Chemical oxidation (e.g. oxidation with ozone, hydrogen peroxide or UV light) |
Oxidisable dissolved non-biodegradable or inhibitory pollutants (e.g. optical brighteners and azo dyestuffs, sulphide) |
|
u. |
Flotation |
Suspended solids and particulate-bound non-biodegradable or inhibitory pollutants |
|
v. |
Filtration (e.g. sand filtration) |
||
Advanced treatment for recycling the waste water, e.g. (24) |
|||
w. |
Filtration (e.g. sand filtration, or membrane filtration) |
Suspended solids and particulate-bound non-biodegradable or inhibitory pollutants |
Generally applicable. |
x. |
Evaporation |
Soluble contaminants (e.g. salts) |
Substance/Parameter |
Activities/processes |
BAT-AEL(25) (mg/l) |
|
Adsorbable organically bound halogens (AOX)(26) |
All activities/processes |
0,1 –0,4 (27) |
|
Chemical oxygen demand (COD)(28) |
40 –100 (29) (30) |
||
Hydrocarbon oil index (HOI)(26) |
1 –7 |
||
Metals/metalloids |
Antimony (Sb) |
Pre-treatment and/or dyeing of polyester textile materials |
0,1 –0,2 (31) |
Finishing with flame retardants using antimony trioxide |
|||
Chromium (Cr) |
Dyeing with chromium mordant or chromium-containing dyes (e.g. metal-complex dyes) |
0,01 –0,1 (32) |
|
Copper (Cu) |
Dyeing Printing with dyes |
0,03 –0,4 |
|
Nickel (Ni) |
0,01 –0,1 (33) |
||
Zinc (Zn) (26) |
All activities/processes |
0,04 –0,5 (34) |
|
Sulphide, easily released (S2-) |
Dyeing with sulphur dyes |
< 1 |
|
Total nitrogen (TN) |
All activities/processes |
5 –15 (35) |
|
Total organic carbon (TOC)(28) |
13 –30 (30) (36) |
||
Total phosphorus (TP) |
0,4 –2 |
||
Total suspended solids (TSS) |
5 –30 |
Substance/Parameter |
Activities/processes |
BAT-AEL (37) (38) (mg/l) |
|
Adsorbable organically bound halogens (AOX)(39) |
All processes |
0,1 –0,4 (40) |
|
Hydrocarbon oil index (HOI)(39) |
All processes |
1 –7 |
|
Metals/metalloids |
Antimony (Sb) |
Pre-treatment and/or dyeing of polyester textile materials |
0,1 –0,2 (41) |
Finishing with flame retardants using antimony trioxide |
|||
Chromium (Cr) |
Dyeing with chromium mordant or chromium-containing dyes (e.g. metal-complex dyes) |
0,01 –0,1 (42) |
|
Copper (Cu) |
Dyeing Printing with dyes |
0,03 –0,4 |
|
Nickel (Ni) |
Dyeing Printing with dyes |
0,01 –0,1 (43) |
|
Zinc (Zn)(39) |
All processes |
0,04 –0,5 (44) |
|
Sulphide, easily released (S2-) |
Dyeing with sulphur dyes |
< 1 |
1.1.7.
Emissions to soil and groundwater
Technique |
Description |
Applicability |
|||||||||||||||||
a. |
Techniques to reduce the likelihood and environmental impact of overflows and failures of process and storage tanks |
This includes:
|
Generally applicable. |
||||||||||||||||
b. |
Regular inspection and maintenance of plant and equipment |
The plant and the equipment are regularly inspected and maintained to ensure proper functioning; this includes in particular checking the integrity and/or leak-free status of valves, pumps, pipes, tanks and containments/bunds as well as the proper functioning of warning systems (e.g. overflow detectors). |
|||||||||||||||||
c. |
Optimised storage location of process chemicals |
The storage areas are located in such a way as to eliminate or minimise the unnecessary transport of process chemicals within the plant (e.g. the transport distances on site are minimised). |
The applicability to existing plants may be restricted by a lack of space. |
||||||||||||||||
d. |
Dedicated area for unloading process chemicals containing hazardous substances |
Process chemicals containing hazardous substances are unloaded in a bunded area. Occasional spillages are collected and sent for treatment. |
Generally applicable. |
||||||||||||||||
e. |
Segregated storage of process chemicals |
Incompatible process chemicals are kept separated. This segregation relies on physical separation and on the chemicals inventory (see BAT 15). |
|||||||||||||||||
f. |
Handling and storage of packaging containing process chemicals |
Packaging containing liquid process chemicals is completely emptied by gravity or by mechanical means (e.g. brushing, wiping) without the use of water. Packaging containing process chemicals in powder is emptied by gravity for small packaging and using suction for large packaging. Empty packaging is stored in a dedicated area. |
1.1.8.
Emissions to air
Applicability
Description
Applicability
Technique |
Typical pollutants target |
Description |
|
Prevention techniques |
|||
a. |
Selection and use of mixtures of chemicals (‘recipes’) leading to low emissions of organic compounds |
Organic compounds |
Mixtures with low emissions of organic compounds are selected and used taking into consideration product specifications (see BAT 14. BAT 17, BAT 50, BAT 51). As an example, emission factors may be used for selection (see Section 1.9.1). |
Reduction techniques |
|||
b. |
Condensation |
Organic compounds excluding formaldehyde |
See Section 1.9.2. |
c. |
Thermal oxidation |
Organic compounds |
|
d. |
Wet scrubbing |
Organic compounds |
|
e. |
Adsorption |
Organic compounds excluding formaldehyde |
Substance/Parameter |
Activities/Processes (including associated thermal treatments) |
BAT-AEL (Average over the sampling period) (mg/Nm3) |
Formaldehyde |
Coating(45) |
1 –5 (46) (47) |
Flame lamination |
||
Printing(45) |
||
Singeing |
||
Finishing(45) |
||
TVOC |
Coating |
3 –40 (46) (48) (49) |
Dyeing |
||
Finishing |
||
Lamination |
||
Printing |
||
Singeing |
||
Thermofixation or heat-setting |
Technique |
Description |
|
a. |
Cyclone |
See Section 1.9.2 Cyclones are mainly used as pretreatment before further dust abatement (e.g. for coarse dust). |
b. |
Electrostatic precipitator (ESP) |
See Section 1.9.2. |
c. |
Wet scrubbing |
Substance/Parameter |
BAT-AEL (Average over the sampling period) (mg/Nm3) |
Dust |
< 2 –10 (50) |
Technique |
Description |
|
Prevention techniques |
||
a. |
Selection and use of mixtures of chemicals (‘recipes’) leading to low emissions of ammonia |
Mixtures with low emissions of ammonia are selected and used taking into consideration product specifications (see BAT 14, BAT 17, BAT 46, BAT 47, BAT 50, BAT 51). As an example, emission factors may be used for selection (see Section 1.9.1). |
Reduction techniques |
||
b. |
Wet scrubbing |
See Section 1.9.2. |
Substance/Parameter |
BAT-AEL(51) (Average over the sampling period) (mg/Nm3) |
NH3 |
3 –10 (52) |
1.1.9.
Waste
Technique |
Description |
Applicability |
|||||||
a. |
Waste management plan |
A waste management plan is part of the EMS (see BAT 1) and is a set of features aiming to:
|
The level of detail of the waste management plan will generally be related to the nature, scale and complexity of the plant. |
||||||
b. |
Timely use of process chemicals |
Criteria are clearly established associated for example with maximum storage time of process chemicals, and relevant parameters are monitored to avoid process chemicals perishing. |
Generally applicable. |
||||||
c. |
Reuse/recycling of packaging |
Process chemicals packaging is selected to facilitate its complete emptying (e.g. considering the size of the packaging aperture or the nature of the packaging material). After emptying (see BAT 21), the packaging is reused, returned to the supplier or sent for material recycling. |
|||||||
d. |
Return of unused process chemicals |
Unused process chemicals (i.e. which remain in their original containers) are returned to their suppliers. |
Generally applicable. |
Technique |
Description |
||||||||
Separate collection and storage of wastes contaminated with hazardous substances and/or substances of very high concern |
Wastes contaminated with hazardous substances and/or substances of very high concern (e.g. finishing chemicals such as flame retardants, oil-, water- and soil-repellents) are collected and stored separately. These wastes may contain high loads of pollutants such as organophosphorus and brominated flame retardants, PFAS, phthalates and chromium-(VI)-containing compounds (see BAT 18) and include in particular:
|
1.2.
BAT conclusions for the pre-treatment of raw wool fibres by scouring
Description
Type of wool |
Unit |
BAT-AEPL (Yearly average) |
Coarse wool (i.e. wool fibre diameter typically higher than 35 μm) |
kg of recovered grease per tonne of raw wool fibres pretreated by scouring |
10 –15 |
Extra- and super-fine wool (i.e. wool fibre diameter typically lower than 20 μm) |
50 –60 |
Technique |
Description |
Applicability |
|
a. |
Covered scouring bowls |
Scouring bowls are fitted with covers to prevent heat losses by convection or evaporation (see BAT 11 (c)). |
Only applicable to new plants or major plant upgrades. |
b. |
Optimised temperature of the last scouring bowl |
The temperature of the last scouring bowl is optimised to increase the efficiency of the subsequent mechanical wool dewatering (see BAT 13 (a)) and drying. |
Generally applicable. |
c. |
Direct heating |
Scouring bowls and dryers are directly heated in order to avoid the heat losses which occur in the generation and distribution of steam. |
Only applicable to new plants or major plant upgrades. |
Description
1.3.
BAT conclusions for the spinning of fibres (other than man-made fibres) and the production of fabric
Technique |
Description |
Applicability |
|
a. |
Selection of sizing chemicals |
Sizing chemicals with improved environmental performance in terms of quantity needed, washability, recoverability and/or bioeliminability/biodegradability (e.g. modified starches, certain galactomannans and carboxymethyl cellulose) are selected (see BAT 14) and used. |
Generally applicable. |
b. |
Pre-wetting of the cotton yarns |
The cotton yarns are dipped into hot water prior to sizing. This allows a reduction of the amounts of sizing chemicals used. |
The applicability may be restricted by product specifications (e.g. when high tension is required on the fibre during weaving). |
c. |
Compact spinning |
The fibre strands are compressed by suction or by mechanical or magnetic compacting. This allows a reduction of the amounts of sizing chemicals used. |
The applicability may be restricted by product specifications (e.g. level of hairiness or technical properties of the yarn). |
Description
Technique |
Description |
Applicability |
|||||||||||||||
a. |
Use of general energy-saving techniques for spinning and weaving |
This includes:
|
Generally applicable. |
||||||||||||||
b. |
Use of energy-saving techniques for spinning |
This includes:
|
Generally applicable. |
||||||||||||||
c. |
Use of energy-saving techniques for weaving |
This includes:
|
A double-width loom may only be applicable to new plants or major plant upgrades. |
1.4.
BAT conclusions for the pre-treatment of textile materials other than raw wool fibres
Technique |
Description |
Applicability |
|
a. |
Combined pre-treatment of cotton textile |
Various pre-treatment operations of cotton textiles (e.g. washing, desizing, scouring and bleaching) are carried out simultaneously. |
Generally applicable. |
b. |
Cold pad-batch treatment of cotton textiles |
Desizing and/or bleaching are carried out with the cold pad-batch technique (see Section 1.9.4). |
Generally applicable. |
c. |
Single or limited number of desizing liquors |
The number of desizing liquors for removing different types of sizing chemicals is limited. In some cases, e.g. for various cellulosic materials, a single oxidative desizing liquor may be used. |
Generally applicable. |
d. |
Recovery and reuse of water-soluble sizing chemicals |
When desizing is carried out by washing with hot water, water-soluble sizing chemicals (e.g. polyvinyl alcohol and carboxymethyl cellulose) are recovered from the washing water by ultrafiltration. The concentrate is reused for sizing, whereas the permeate is reused for washing. |
Only applicable where sizing and desizing are carried out at the same plant. May not be applicable for synthetic sizing chemicals (e.g. containing polyester polyols, polyacrylates or polyvinyl acetate). |
Technique |
Description |
Applicability |
|||||||
a. |
Chlorine-free bleaching |
Bleaching is carried out with chlorine-free bleaching chemicals (e.g. hydrogen peroxide, peracetic acid or ozone), often combined with pre-treatment with enzymes (see BAT 16 (c)). |
May not be applicable to the brightening of flax and other bast fibres. |
||||||
b. |
Optimised hydrogen peroxide bleaching |
The use of complexing agents can be completely avoided or minimised by reducing the concentration of hydroxyl radicals during bleaching. This is achieved by:
|
Generally applicable. |
Description
Applicability
Unit |
BAT-AEPL (Yearly average) |
% of caustic soda recovered |
75 –95 |
1.5.
BAT conclusions for dyeing
Technique |
Description |
|
Techniques for batch and continuous dyeing |
||
a. |
Selection of dyes |
Dyes with dispersing agents that are biodegradable (e.g. based on fatty acid esters) are selected. |
b. |
Dyeing with levelling agents made from recycled vegetable oil |
Levelling agents made from recycled vegetable oil are used in high-temperature dyeing of polyester and in dyeing of protein and polyamide fibres. |
Techniques for batch dyeing |
||
c. |
pH-controlled dyeing |
For textile materials with zwitterionic characteristics, dyeing is carried out at constant temperature and controlled by gradually lowering the pH of the dyeing liquor below the isoelectric point of the textile materials. |
d. |
Optimised removal of unfixed dyestuff in reactive dyeing |
Unfixed dyestuff is removed from the textile materials by using enzymes (e.g. laccase, lipase) (see BAT 16 (c)) and/or vinyl polymers. This reduces the number of rinsing steps needed. |
Techniques for batch dyeing |
||
e. |
Low-liquor-ratio systems |
See Section 1.9.4. |
Techniques for continuous dyeing |
||
f. |
Low-volume application systems |
See Section 1.9.4. |
Technique |
Description |
Applicability |
|
Technique for dyeing with sulphur and vat dyes |
|||
a. |
Minimised use of sulphur-based reducing agents |
Dyeing is carried out without sodium sulphide or hydrosulphite as reducing agents. Where this is not possible, partially chemically pre-reduced dyes (e.g. indigo dyes) are used so that less sodium sulphide or hydrosulphite is added for dyeing. |
The applicability may be restricted by product specifications (e.g. shade). |
Technique for continuous dyeing with vat dyes |
|||
b. |
Selection of vat dyes |
Vat dyes that are not prone to emissions during the use phase of the textile are selected. Auxiliaries (e.g. polyglycols) are used to enable dyeing with less or without subsequent steaming, oxidising and washing and to ensure appropriate colour fastness. |
May not be applicable to dyeing with dark shades. |
Techniques for dyeing with reactive dyes |
|||
c. |
Use of poly-functional reactive dyes |
Poly-functional reactive dyes with more than one reactive functional group are used to provide a high level of fixation in exhaust dyeing. |
Generally applicable. |
d. |
Cold pad-batch dyeing |
Dyeing is carried out with the cold pad-batch technique (see Section 1.9.4). |
Generally applicable. |
e. |
Optimised rinsing |
Rinsing after dyeing with reactive dyes is carried out at a high temperature (e.g. up to 95 °C) and without using detergents. The heat of the rinsing water is recovered (see BAT 11 (i)). |
Generally applicable. |
Techniques for continuous dyeing with reactive dyes |
|||
f. |
Use of concentrated alkali solution |
In cold pad-batch dyeing (see Section 1.9.4), concentrated aqueous alkali solutions without sodium silicate are used for the fixation of dyes. |
May not be applicable to dyeing with dark shades. |
g. |
Steam fixation of reactive dyes |
The reactive dyes are fixed with steam, which avoids the use of chemicals for fixation. |
The applicability may be restricted by the characteristics of the textile materials and by product specifications (e.g. high-quality dyeing of polyester/cotton blends). |
Technique |
Description |
Applicability |
|
a. |
Optimised reactive dyeing |
Wool dyeing is carried out with reactive dyes without chromium mordant. |
Generally applicable. |
b. |
Optimised metal-complex dyeing |
Dyeing is carried out with metal-complex dyes under optimised conditions in terms of pH, auxiliaries and acid used, in order to increase the exhaustion of the dyeing liquor and the fixation of the dyes. |
May not be applicable to dyeing with dark shades. |
c. |
Minimised use of chromates |
When the use of sodium or potassium dichromate as mordant is authorised, dichromates are dosed as a function of the amount of dye taken up by the wool. Dyeing parameters (e.g. pH and temperature of the dyeing liquor) are optimised to ensure that the dyeing liquor is exhausted as much as possible. |
Generally applicable. |
Technique |
Description |
Applicability |
|||||||
a. |
Batch dyeing without dyestuff carriers |
Batch dyeing of polyester and wool-free polyester blends is carried out at high temperature (e.g. 130 °C) without the use of dyestuff carriers. |
Generally applicable. |
||||||
b. |
Use of environmentally friendly dyestuff carriers in batch dyeing |
Batch dyeing of polyester-wool blends is carried out with chlorine-free and biodegradable dyestuff carriers. |
|||||||
c. |
Optimised desorption of unfixed dye in batch dyeing |
This includes:
|
The use of a reducing agent that can be used in acidic conditions may not be applicable to polyester-elastane blends. The use of dyes that are desorbable in alkaline conditions may be restricted by product specifications (e.g. colour fastness and shade). |
1.6.
BAT conclusions for printing
Description
Technique |
Description |
Applicability |
|||||||||
Selection of printing technology |
|||||||||||
a. |
Digital jet printing |
Computer-controlled injection of dye onto textile materials. |
Only applicable to new plants or major plant upgrades. |
||||||||
b. |
Transfer printing on synthetic textile materials |
The design is first printed on an intermediate substrate (e.g. paper) using selected disperse dyes and is subsequently transferred to the fabric by applying high temperature and pressure. |
|||||||||
Design and operation technique |
|||||||||||
c. |
Optimised use of printing paste |
This includes:
|
Generally applicable. |
||||||||
Recovery and reuse of printing paste |
|||||||||||
d. |
Recovery of residual printing paste in rotary screen printing |
Residual printing paste in the supply system is pushed back to its original container. |
Applicability in existing plants may be restricted by the equipment. |
||||||||
e. |
Reuse of residual printing paste |
The residual printing paste is collected, sorted by type, stored and reused. The degree of reuse of printing paste is limited by its perishability. |
Generally applicable. |
Technique |
Description |
|
a. |
Reduction of urea content in printing pastes |
Printing is carried out with a reduced amount of urea in printing pastes and by controlling the moisture content of textile materials. |
b. |
Two-step printing |
Printing is carried out without urea by two padding steps with intermediate drying and addition of fixation agents (e.g. sodium silicate). |
Description
1.7.
BAT conclusions for finishing
1.7.1.
Easy-care finishing
1.7.2.
Softening
Technique |
Description |
|
a. |
Low-volume application of softening agents |
See Section 1.9.4. Softening agents are not added to the dyeing liquor but applied in a separate process step by padding, spraying or foaming. |
b. |
Softening of cotton textile materials with enzymes |
See BAT 16 (c). Enzymes are used for softening, possibly in combination with washing or dyeing. |
1.7.3.
Flame retardance finishing
Technique |
Description |
Applicability |
|||||||
a. |
Use of textile materials with inherent flame retardance properties |
Textiles that do not require finishing with flame retardants are used. |
The applicability may be restricted by product specifications (e.g. flame retardance). |
||||||
b. |
Selection of flame retardants |
Flame retardants are selected considering:
|
Generally applicable. |
1.7.4.
Oil-, water- and soil-repellence finishing
Description
1.7.5.
Shrink-proof finishing of wool
Description
Applicability
1.7.6.
Mothproofing
Technique |
Description |
Applicability |
|
a. |
Selection of dyeing auxiliaries |
When mothproofing agents are added directly in the dyeing liquor, dyeing auxiliaries (e.g. levelling agents) that do not hinder the uptake of mothproofing agents are selected. |
Generally applicable. |
b. |
Low-volume application of mothproofing agents |
see Section 1.9.4. In the case of spraying, the excess mothproofing solution is recovered from the textile materials by centrifugation and reused. |
Generally applicable. |
1.8.
BAT conclusions for lamination
Description
Applicability
1.9.
Description of techniques
1.9.1.
Technique to select process chemicals, prevent or reduce emissions to air
Technique |
Description |
Emission factors |
Emission factors are representative values that attempt to relate the quantity of a substance emitted to a process associated with the emission of that substance. Emission factors are derived from emission measurements according to a predefined protocol considering the textile materials and the reference processing conditions (e.g. curing time and temperature). They are expressed as the mass of a substance emitted divided by the mass of textile materials treated at the reference processing conditions (e.g. grams of organic carbon emitted per kg of textile materials treated at a waste gas flow of 20 m3/h). The quantity, hazardous properties and composition of the mixture of the process chemicals and their pick-up by the textile material are considered. |
1.9.2.
Techniques to reduce emissions to air
Technique |
Description |
Adsorption |
The removal of pollutants from a waste gas stream by retention on a solid surface (activated carbon is typically used as an adsorbent). Adsorption may be regenerative or non-regenerative. In non-regenerative adsorption, the spent adsorbent is not regenerated but disposed of. In regenerative adsorption, the adsorbate is subsequently desorbed, e.g. with steam (often on site), for reuse or disposal and the adsorbent is reused. For continuous operation, typically more than two adsorbers are operated in parallel, one of them in desorption mode. |
Condensation |
Condensation is a technique that eliminates vapours of organic and inorganic compounds from a waste gas stream by reducing its temperature below its dew point. |
Cyclone |
Equipment for the removal of dust from a waste gas stream based on imparting centrifugal forces, usually within a conical chamber. |
Electrostatic precipitator (ESP) |
Electrostatic precipitators (ESPs) operate such that particles are charged and separated under the influence of an electrical field. Electrostatic precipitators are capable of operating under a wide range of conditions. Abatement efficiency may depend on the number of fields, residence time (size), and upstream particle removal devices. They generally include between two and five fields. Electrostatic precipitators can be of the dry or of the wet type depending on the technique used to collect the dust from the electrodes. |
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 scrubbing |
The removal of gaseous or particulate pollutants from a waste gas stream via mass transfer to water or an aqueous solution. It may involve a chemical reaction (e.g. in an acid or alkaline scrubber). |
1.9.3.
Techniques to reduce emissions to water
Technique |
Description |
||||||||
Activated sludge process |
The biological oxidation of dissolved organic pollutants with oxygen using the metabolism of microorganisms. In the presence of dissolved oxygen (injected as air or pure oxygen), the organic components are transformed into carbon dioxide, water or other metabolites and biomass (i.e. the activated sludge). 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. |
||||||||
Adsorption |
Separation method in which compounds in a fluid (e.g. waste water) are retained on a solid surface (typically activated carbon). |
||||||||
Anaerobic treatment |
The biological transformation of dissolved organic and inorganic pollutants in the absence of oxygen using the metabolism of microorganisms. Transformation products include methane, carbon dioxide, and sulphide. The process is carried out in an airtight stirred reactor. The most commonly used reactor types are:
|
||||||||
Chemical oxidation |
Organic compounds are oxidised to less harmful and more easily biodegradable compounds. Techniques include wet oxidation or oxidation with ozone or hydrogen peroxide, optionally supported by catalysts or UV radiation. Chemical oxidation is also used to degrade organic compounds causing odour, taste and colour nuisances and for disinfection purposes. |
||||||||
Chemical reduction |
Chemical reduction is the conversion of pollutants by chemical reducing agents into less harmful compounds. |
||||||||
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. The flocs formed are subsequently separated by sedimentation, air flotation or filtration. |
||||||||
Equalisation |
Balancing of flows and pollutant loads by using tanks or other management techniques. |
||||||||
Evaporation |
The use of distillation to concentrate aqueous solutions of high-boiling substances for further use, processing or disposal (e.g. waste water incineration) by transferring water to the vapour phase. It is typically carried out in multistage units with increasing vacuums, to reduce the energy demand. The water vapours are condensed, to be reused or discharged as waste water. |
||||||||
Filtration |
The separation of solids from waste water by passing them through a porous medium, e.g. sand or membrane filtration (see Membrane filtration below). |
||||||||
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, the biomass remaining in the tank. |
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Membrane filtration |
Microfiltration, ultrafiltration, nanofiltration and reverse osmosis are membrane filtration processes that retain and concentrate, on one side of the membrane, pollutants such as suspended particles and colloidal particles contained in waste waters. They differ in terms of membrane pore sizes and hydrostatic pressure. |
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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) may be used to increase the pH, whereas sulphuric acid (H2SO4), hydrochloric acid (HCl) or carbon dioxide (CO2) may be used to decrease the pH. Some pollutants may precipitate as insoluble compounds during neutralisation. |
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Nitrification/denitrification |
A two-step process that is typically incorporated into biological waste water treatment plants. The first step is 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. |
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Oil-water separation |
The separation of oil and water including the subsequent oil removal by gravity separation of free oil, using separation equipment or emulsion breaking (using emulsion-breaking chemicals such as metal salts, mineral acids, adsorbents and organic polymers). |
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Screening and grit separation |
The separation of water and insoluble contaminants such as sand, fibre, fluff or other coarse materials from the textile effluent by filtering through screens or gravitational settling in grit chambers. |
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Precipitation |
The conversion of dissolved pollutants into insoluble compounds by adding precipitants. The solid precipitates formed are subsequently separated by sedimentation, air flotation or filtration. |
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Sedimentation |
The separation of suspended particles by gravitational settling. |
1.9.4.
Techniques to reduce the consumption of water, energy and chemicals
Technique |
Description |
Cold pad-batch treatment |
In cold pad-batch treatment, the process liquor is applied by padding (e.g. with a foulard) and the impregnated fabric is slowly rotated at room temperature for a prolonged period. This technique allows a reduced consumption of chemicals and does not require subsequent steps such as thermal fixation and thereby reduces energy consumption. |
Low-liquor-ratio systems (for batch processes) |
A low liquor ratio can be achieved by improving the contact between the textile materials and the process liquor (e.g. by creating turbulence in the process liquor), by advanced process monitoring, by improved dosage and application of process liquor (e.g. by jets or spraying) and by avoiding the mixing of process liquor with washing or rinsing water. |
Low-volume application systems (for continuous processes) |
The fabric is impregnated with process liquor by spraying, vacuum suction through the fabric, foaming, padding, and dipping in nips (process liquor contained in the gap between two rollers) or in reduced-volume tanks, etc. |