«EUROPEAN COMMISSION Integrated Pollution Prevention and Control (IPPC) Reference Document on Best Available Techniques for the Textiles Industry July 2003 ...»
Ø start/stop control of cleaning of the printing belt Ø re-use of the cleanest part of the rinsing water from the cleaning of the squeegees, screens and buckets Ø re-use of the rinsing water from cleaning of the printing belt · use digital ink-jet printing machines for the production of short runs (less than 100 m) for flat fabrics, when product market considerations allow (see Section 4.7.9). It is not considered BAT to flush with solvent to prevent blocking while the printer is not in use · use digital jet printing machines described in Section 4.7.8 for printing carpet and bulky fabrics, except for resist and reserve printing and similar situations.
BAT is to avoid the use of urea by either:
· the one-step process with the controlled addition of moisture, where the moisture is applied either as foam or by spraying a defined quantity of water mist (see Section 4.7.1) OR · the two-steps printing method (see 4.7.2).
xvi Textiles Industry Executive Summary For silk and viscose, with the one-step process, the spraying technique is not reliable due to the low moisture add-on required for these fibres. The foaming technique with complete elimination of urea is proven for viscose, but not yet for silk. There is a high initial investment cost of about 200000 euros for a foaming machine related to a production capacity of up to about 80000 linear metres per day. The technique has been operated under economically viable conditions in plants of capacity of about 30000, 50000 and 140000 linear metres per day. There is a question whether the technique is economically viable for smaller plants.
Where the foam technique is not used, the amount of urea consumed can be reduced to about 50 g/kg of printing paste for silk and to 80 g/kg for viscose.
BAT is to use optimised printing pastes that fulfil the following requirements (see 4.7.3):
· thickeners with low-emission of volatile organic carbon (or not containing any volatile solvent at all) and formaldehyde-poor binders. The associated air emission value is
0.4 g Org.-C/kg textile (assuming 20 m3 air/kg textile) · APEO-free and high degree of bioeliminability · reduced ammonia content. Associated emission value: 0.6 g NH3/kg textile (assuming 20 m3 air/kg textile).
Process in general
BAT is to:
· minimise residual liquor by:
Ø using minimal application techniques (e.g. foam application, spraying) or reducing volume of padding devices Ø re-using padding liquors if quality is not affected
· minimise energy consumption in stenter frames by (see Section 4.8.1):
Ø using mechanical dewatering equipment to reduce water content of the incoming fabric Ø optimising exhaust airflow through the oven, automatically maintaining exhaust humidity between 0.1 and 0.15 kg water/kg dry air, considering the time taken to reach equilibrium conditions Ø installing heat recovery systems Ø fitting insulating systems Ø ensuring optimal maintenance of the burners in directly heated stenters · use low air emission optimised recipes. An example for classification/ selection of finishing recipes is the “Emission factor concept” described in Section 4.3.2.
Easy-care treatment BAT is to use formaldehyde-free cross-linking agents in the carpet sector, and formaldehydefree or formaldehyde-poor (0.1 % formaldehyde content in the formulation) cross-linking agents in the textile industry (see 4.8.2).
Mothproofing treatments · Process in general
BAT is to:
Ø adopt appropriate measures for material handling as described in Section 126.96.36.199 Ø ensure that 98 % efficiency (transfer of insect resist agent to the fibre) is achieved Ø adopt the following additional measures when the insect resist agent is applied from a dye
§ ensure that a pH4.5 is reached at the end of the process and if this is not possible, apply the insect resist agent in a separate step with re-use of the bath § add the insect resist agent after dye bath expansion in order to avoid overflow spillages § select dyeing auxiliaries that do not exert a retarding action on the uptake (exhaustion) of the insect-resist agent during the dyeing process (see Section 188.8.131.52).
Textiles Industry xvii Executive Summary · Mothproofing of yarn produced via the dry spinning route
BAT is to use one or both of these techniques (described in Section 184.108.40.206):
Ø combine acid aftertreatment (to increase the uptake of mothproofer active substance) and reuse of the rinse bath for the next dyeing step Ø apply proportional over-treatment of 5 % of the total fibre blend combined with dedicated dyeing machinery and waste water recycling systems to minimise active substance emissions to water.
· Mothproofing of loose fibre dyed / yarn scoured production
BAT is to (see Section 220.127.116.11):
Ø use dedicated low-volume application systems located at the end of the yarn scouring machine Ø recycle low-volume process liquor between batches and use processes designed specifically to remove active substance from spent process liquor. These techniques may include adsorptive or degradative treatments Ø apply mothproofer directly to the carpet pile (when mothproofing during carpet manufacture) using foam application technology.
· Mothproofing of yarn dyed production
BAT is to (see Section 18.104.22.168):
Ø use a separate aftertreatment process to minimise emissions from dyeing processes which are carried out under less than optimum conditions for mothproofer uptake Ø use semi-continuous low-volume application machinery or modified centrifuges Ø recycle low-volume process liquor between yarn batches and processes designed specifically to remove active substance from spent process liquor. These techniques may include adsorptive or degradative treatments Ø apply mothproofer directly to the carpet pile (when mothproofing during carpet manufacture) using foam application technology.
· Softening treatments BAT is to apply the softening agents by pad mangles or better, by spraying and foaming application systems, instead of carrying out this treatment by exhaustion directly in the batch dyeing machine (see Section 4.8.3).
BAT is to:
· substitute overflow washing/rinsing with drain/fill methods or “ smart rinsing” techniques as described in Section 4.9.1
· reduce water & energy consumption in continuous processes by:
Ø installing high-efficiency washing machinery according to the principle described in Section 4.9.2. The associated values for high-efficiency continuous washing of cellulosic and synthetic fabric in open-width are reported in Table 4.38 Ø introducing heat recovery equipment · when halogenated organic solvent cannot be avoided (e.g. with fabrics that are heavily loaded with preparations such as silicone oils that are difficult to remove with water), use fully closed-loop equipment. It is essential that the equipment fulfil the requirements described in Section 4.9.3 and provisions be taken for in-loop destruction (e.g. by advanced oxidation processes) of the persistent pollutants in order to avoid any possible contamination of groundwater arising from diffuse pollution and accidents.
Waste water treatment
Waste water treatment follows at least three different strategies:
· central treatment in a biological waste water treatment plant on site · central treatment off site in a municipal waste water treatment plant · decentralised treatment on site (or off site) of selected, segregated single waste water streams xviii Textiles Industry Executive Summary All three strategies are BAT options when properly applied to the actual waste water situation.
Well-accepted general principles for waste water management and treatment include:
· characterising the different waste water streams arising from the process (see Section 4.1.2) · segregating the effluents at source according to their contaminant type and load, before mixing with other streams. This ensures that a treatment facility receives only those pollutants it can cope with. Moreover, it enables the application of recycling or re-use options for the effluent · allocating contaminated waste water streams to the most appropriate treatment · avoiding the introduction of waste water components into biological treatment systems when they could cause malfunction of such a system · treating waste streams containing a relevant non-biodegradable fraction by appropriate techniques before, or instead of, a final biological treatment.
According to this approach, the following techniques are determined as general BAT for the
treatment of waste water from the textile finishing and carpet industry:
· treatment of waste water in an activated sludge system at low food-to-micro organisms ratio as described in Section 4.10.1, under the prerequisite that concentrated streams containing non-biodegradable compounds are pretreated separately · pretreatment of highly-loaded (COD5000 mg/l) selected and segregated single waste water streams containing non-biodegradable compounds by chemical oxidation (e.g. Fenton reaction as described in Section 4.10.7). Candidate waste water streams are padding liquors from semi-continuous or continuous dyeing and finishing, desizing baths, printing pastes, residues from carpet backing, exhaust dyeing and finishing baths.
Certain specific process residues, such as residual printing pastes and residual padding liquors are very strong and, where practicable, should be kept out of waste water streams.
These residues should be disposed of appropriately; thermal oxidation can be one suitable method because of the high calorific value.
For the specific cases of waste water containing pigment printing paste or latex from carpet backing, precipitation/flocculation and incineration of the resulting sludge is a viable alternative to chemical oxidation (as described in Section 4.10.8).
For azo-dyes, anaerobic treatment of padding liquor and printing pastes as described in Section 4.10.6 before a subsequent aerobic treatment can be effective for colour removal.
If concentrated water streams containing non-biodegradable compounds cannot be treated separately, additional physical-chemical treatments would be required to achieve equivalent
overall performance. These include:
· tertiary treatments following the biological treatment process. An example is adsorption on activated carbon with recycling of the activated carbon to the activated sludge system: this is followed by destruction of the adsorbed non-biodegradable compounds by incineration or treatment with free-radicals (i.e. process generating OH*, O2*-, CO2*-) of the excess sludge (biomass along with the spent activated carbon) (see plant 6 in Section 4.10.1) · combined biological, physical and chemical treatments with the addition of powdered activated carbon and iron salt to the activated sludge system with reactivation of the excess sludge by “wet oxidation” or “wet peroxidation” (if hydrogen peroxide is used), as described in Section 4.10.3 · ozonation of recalcitrant compounds prior to the activated sludge system (see plant 3 in Section 4.10.1).
Textiles Industry xix Executive Summary For effluent treatment in the wool scouring sector (water-based process)
BAT is to:
· combine the use of dirt removal / grease recovery loops with evaporative effluent treatment, with integrated incineration of the resulting sludge and full recycling of water and energy for: 1) new installations 2) existing installations with no on-site effluent treatment 3) installations seeking to replace life-expired effluent treatment plant. This technique is described in Section 4.4.2 · use coagulation/flocculation treatment in existing mills already using it in conjunction with discharge to sewerage system employing aerobic biological treatment.
Whether or not biological treatment can be considered as BAT must remain an open question until better information on its costs and performance can be assembled.
Sludge disposal For sludge from waste water treatment of wool scouring effluent
BAT is to:
· use sludge in brick-making (see 4.10.12) or adopt any other appropriate recycling routes · incinerate the sludge with heat recovery, provided that measures are taken to control emissions of SOx, NOx and dust and to avoid emissions of dioxins and furans arising from organically bound chlorine from pesticides potentially contained in the sludge.
The main general conclusions are:
· the information exchange was successful and a high degree of agreement was reached following the second meeting of the TWG · due to the nature of the textile industry (very complex and variegated sector) the impact of the implementation of the BAT identified will depend on the characteristics of each mill.
The speed of implementation will therefore be a particularly sensitive issue for this industry · mindful of the current difficulties that certain companies may have in controlling/ selecting the source of the fibre raw material, it was recognised that a quality assurance system for incoming textile material is necessary in order to produce an adequate application for an IPPC permit. BAT is therefore to seek collaboration with upstream partners in the textile chain, not only at site-specific level, but also at industry sector level, in order to create a chain of environmental responsibility for textiles.
The main recommendations for future work are:
· more systematic collection of data is needed about the current consumption and emission levels and about the performance of techniques to be considered in the determination of BAT, especially for water effluents · a more detailed assessment of the costs and savings associated with techniques is needed to further assist the determination of BAT · the collection of information about areas that have not been properly covered by the BREF due to a lack of information. More details about specific areas in which data and information are lacking are mentioned in Chapter 7.
The EC is launching and supporting, through its RTD programmes, a series of projects dealing with clean technologies, emerging effluent treatment and recycling technologies and management strategies. Potentially these projects could provide a useful contribution to future BREF reviews. Readers are therefore invited to inform the EIPPCB of any research results which are relevant to the scope of this document (see also the preface of this document).
1. Status of this document Unless otherwise stated, references to “the Directive” in this document means the Council Directive 96/61/EC on integrated pollution prevention and control. As the Directive applies without prejudice to Community provisions on health and safety at the workplace, so does this document.
This document forms part of a series presenting the results of an exchange of information between EU Member States and industries concerned on best available techniques (BAT), associated monitoring, and developments in them. It is published by the European Commission pursuant to Article 16(2) of the Directive, and must therefore be taken into account in accordance with Annex IV of the Directive when determining “best available techniques”.
2. Relevant legal obligations of the IPPC Directive and the definition of BAT
In order to help the reader understand the legal context in which this document has been drafted, some of the most relevant provisions of the IPPC Directive, including the definition of the term “best available techniques”, are described in this preface. This description is inevitably incomplete and is given for information only. It has no legal value and does not in any way alter or prejudice the actual provisions of the Directive.