Annex 50 Complementary information to source category 7g Textile Production
Of the 635,000 metric tons of dyes produced annually worldwide, about 10-15% of the dye is disposed of in effluents from dyeing operations. However, dyes in wastewater may be chemically bound to fabric fibers. The average wastewater generation from a large, centralized industrial U.S. dyeing facility is estimated at between 3.8 and 7.5 million liters per day (one and two million gallons per day). Dyeing and rinsing processes for disperse dyeing generate about 100-140 L of wastewater per kg of product (12-17 gallons of wastewater per pound). Similar processes for reactive and direct dyeing generate even more wastewater, about 125-170 L of wastewater per kg of product (15-20 gallons per pound of product) (USEPA 1997a).
Based on the analyses of 16 samples from Germany, it was concluded that, the PCDD/PCDF concentration will not increase significantly during these finishing processes: mean concentrations found in finished cotton were at 0.21±0.10 ng I-TEQ/kg with a median of 0.20 ng I-TEQ/kg (Horstmann 1994).These results were confirmed by random sample analyses of raw and pre-treated cotton arriving at the Hamburg harbor, which contained 0.03-0.2 ng I-TEQ/kg (Hutzinger et al. 1995).
Whereas there are many data for PCDD/PCDF concentrations in final products (textiles), there are no data for residues and wastewater. Therefore, emission factors can be given only as upper bound and lower bound limits for the final product.
Derivation of emission factors
Release to Air
In the only study of PCDD/PCDF air emissions from textile production processes that could be found, the following five processes were investigated (Sedlak et al. 1998):
- Crosslinker finish with MgCl2, as catalyst;
- Flame retardant finish on fleece on the basis of Sb203/Hexabromocyclododecane;
- Flame retardant finish on upholstery material on the basis of ammonium bromide;
- Flame retardant finish on fleece on the basis of ammonium bromide; and
- Flame retardant finish on upholstery material on the basis of PVC, Sb2O3, hexabromocyclododecane.
PCDD/PCDF concentrations in air emissions from these processes were low, ranging from 1.7 to 2.6 pg TEQ/m³. However, relatively high concentrations of PXDD/PXDF were found in associated textiles and in chimney deposits. Data are not sufficient to derive emission factors.
Release to Water
Only one study was found in which the PCDD/PCDF content of textile production wastewater was determined. In this study, a PCDD/PCDF concentration of 0.44 ng TEQ/L was measured in wastewater from a Slovenian textile-dyeing facility engaged primarily in wet-process dying of polyester yarns with disperse dyes (Marechal et al. 2012). Data are not sufficient to derive emission factors.
Release in Products
Whereas in most samples of raw textiles, concentrations below 1 ng I-TEQ/kg were detected (means around 0.2 ng I-TEQ/kg), highly contaminated samples were also found. For example, 244 ng I-TEQ/kg were detected in bleached polyester, 370 ng I-TEQ/kg in blue cotton (Horstmann 1994), and 86 ng I-TEQ/kg in wool (Mayer 1997). The homologue profiles of all highly contaminated samples were dominated by the higher chlorinated PCDD and PCDF (Cl7 and Cl8), which are indicators for PCP or chloranil-based dyes and pigments as the source of the contamination. However, several analyses confirmed that there is no correlation between PCP and PCDD/PCDF concentrations in textiles although the congener patterns gave strong indications that PCP should be the source. These findings make sense as PCP is water-soluble and will be removed in the finishing process and final washing processes whereas the PCDD/PCDF adsorb to the fiber and will stay in the textile (Horstmann and McLachlan 1995, Klasmeier and McLachlan 1997).
The problem of PCDD/PCDF contamination of textiles is not yet resolved, as evidenced by a recent Swedish study that found textiles and leather to account for 90-95% of total PCDD/PCDF in source-separated combustible domestic waste (Hedman et al. 2007).
EFProduct of 100 μg TEQ/t is presented as a reasonable upper limit value, based on values reported in existing studies.
EFProduct of 0.1μg TEQ/t is presented as a reasonable lower limit value, based on values reported in existing studies.
EFProduct of NA for textiles manufactured without formation or transfer of PCDD/PCDF (BAT Technology).
Release in Residues
PCDD/PCDF have been reported in textile mill sludge (Wright 1996). However, data were not sufficient for the derivation of an EFResidue. The occurrence of PCDD/PCDF occur in wastewater treatment sludge from textile mills that use PCDD/PCDF-contaminated dyes and biocides is supported by the presence of PCDD/PCDF in the wastewater of such facilities, as reported by Marechal et al. (2012).