Leaching of decabromodiphenyl ether and hexabromocyclododecane from fabrics under simulated landfill conditions

A series of laboratory experiments were conducted to examine the leaching of decabromodiphenyl ether (BDE-209) and hexabromocyclododecane (HBCDD) from a mix of three fabrics. Consistent with previous reports that such leaching is governed by second order kinetics, concentrations in leachate were markedly higher in the first 24 h of leaching, and diminished by an order of magnitude after 1 week. The influence of the waste:leachate ratio was examined for the first time, with leaching of both BDE-209 and HBCDD significantly greater (p < 0.05) at a waste:leachate ratio of 0.005 g/mL than at 0.05 g/mL. Using dissolved humic matter (DHM) solutions as proxy for simulating organic landfill leachates we found that leaching of both BDE-209 and HBCDD was also significantly greater at a DHM concentration of 1,000 mg/L in leachate compared to that observed at DHM values of 100 and 0 mg/L. Agitation of waste:leachate mixtures significantly enhanced leaching. While leaching of HBCDD decreased significantly as leachate pH increased from 5.8, through 6.5, to 8.5; no significant impact of pH on leaching of BDE-209 was detected. Concentrations in leachate of both BDE-209 and HBCDD decreased significantly on increasing leachate temperature from 20 °C to 60 °C and 80 °C. This is considered most likely due to volatilisation of these contaminants into the headspace of the leaching vessel at higher temperatures.