[Report] Furthering Understanding of Emissions from Landfilled Waste Containing POP BFRs and PFASs (FUEL)
By Stuart Harrad, Daniel Drage, Martin Sharkey and Harald Berresheim
October 13, 2020
Brominated flame retardants (BFRs) and perfluoroalkyl substances (PFASs) have found extensive use in electrical and electronic goods, soft furnishings and building insulation foam to impart flame retardancy and stain resistance. Following concerns about their persistence and their ability to bioaccumulate and cause adverse health effects in humans and wildlife, some BFRs and PFASs have been listed under the Stockholm Convention on Persistent Organic Pollutants (POPs), an international treaty designed to eliminate POPs from the environment. While such actions have severely restricted the manufacture and new use of such contaminants, there remains a substantial reservoir that has entered the waste stream and will continue to do so for some years. Moreover, despite Irish national and EU policies severely limiting use of landfill, many items treated with BFRs and PFASs are likely to be present in Irish landfills. This is concerning, as reports from other countries show that landfill leachate contains such chemicals. In this study, we measured PFASs, polybrominated diphenyl ethers (PBDEs) and hexabromocyclododecanes (HBCDDs) in leachate from 40 landfills within Ireland. Levels detected were within the range previously reported elsewhere. Average concentrations of PFASs exceeded those of PBDEs and HBCDDs. Concentrations of some PBDEs and PFASs were significantly (p0.05) between downwind and upwind locations. The arithmetic mean concentration of perfluorooctanoic acid (PFOA) in groundwater from landfills that were not fully lined (n=4; 69ng/L) exceeded that in groundwater sourced from lined landfills (n=6; 4.1ng/L), although this was not statistically significant (p>0.1). A positive correlation (p=0.014) was observed between concentrations of PFOA in groundwater and those in leachate from the same landfills. However, this was driven substantially by one landfill that displayed the highest concentrations in both groundwater and leachate. DBDPE was detected in groundwater for the first time anywhere, in all samples at concentrations (median=9.4ng/L; arithmetic mean=78ng/L) that exceeded those of any of the other BFRs or PFASs measured. This probably reflects its use as a “drop-in” replacement for the recently restricted decabromodiphenyl ether (BDE-209). Laboratory experiments were conducted to examine leaching of BDE-209 and HBCDDs from fabrics. Concentrations in leachate were markedly higher in the first 24 hours, diminishing by an order of magnitude after 1 week. The influence of the wasteto-leachate ratio was examined, with leaching of both BDE-209 and HBCDDs significantly greater (p<0.05) at a waste-to-leachate ratio of 0.005g/mL than at one of 0.05g/mL. Using dissolved humic matter (DHM) solutions as proxies for organic landfill leachates, leaching of both BDE-209 and HBCDDs was significantly greater at higher DHM concentrations. Agitation of waste-to-leachate mixtures significantly enhanced leaching. While leaching of HBCDDs decreased significantly as leachate pH increased from 5.8 to 6.5 and to 8.5, no significant impact of pH on leaching of BDE-209 was detected. Concentrations of both BDE-209 and HBCDDs in leachate decreased significantly on increasing leachate temperature from 20°C to 60°C and then 80°C. This is considered most likely to be due to volatilisation of these contaminants into the headspace of the leaching vessel at higher temperatures. Finally, a desktop study suggests that even over the estimated 75-year aftercare timeline of most landfills, the quantities of PBDEs, HBCDDs and PFASs associated with landfill leachate represent only a very small fraction of those present overall in the Irish waste stream. The following recommendations are made:
● Concentrations of PFASs in groundwater potentially affected by unlined or partially lined landfills should be monitored closely.
● Leaching of BFRs and PFASs may be minimised by reducing the organic matter content of leachate.
● Further monitoring in landfill leachate and groundwater of concentrations of DBDPE and other chemicals designed as replacements for restricted BFRs and PFASs is recommended.
● Restrictions on the landfilling of textiles would reduce the quantity of BFRs and PFASs entering landfill.
● Further research should be conducted into methods for treating collected leachate to remove PFASs.
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