Characteristics of Polybrominated Diphenyl Ethers Released from Thermal Treatment and Open Burning of E‑Waste

Primitive processing of e-waste potentially releases abundant organic contaminants to the environment, but the magnitudes and mechanisms remain to be adequately addressed. We conducted thermal treatment and open burning of typical e-wastes, that is, plastics and printed circuit boards. Emission factors of the sum of 39 polybrominated diphenyl ethers (∑39PBDE) were 817–1.60 × 105 ng g–1 in thermal treatment and nondetected-9.14 × 104 ng g–1, in open burning. Airborne particles (87%) were the main carriers of PBDEs, followed by residual ashes (13%) and gaseous constituents (0.3%), in thermal treatment, while they were 30%, 43% and 27% in open burning. The output–input mass ratios of ∑39PBDE were 0.12–3.76 in thermal treatment and 0–0.16 in open burning. All PBDEs were largely affiliated with fine particles, with geometric mean diameters at 0.61–0.83 μm in thermal degradation and 0.57–1.16 μm in open burning from plastic casings, and 0.44–0.56 and nondetected- 0.55 μm, from printed circuit boards. Evaporation and reabsorption may be the main emission mechanisms for lightly brominated BDEs, but heavily brominated BDEs tend to affiliate with particles from heating or combustion. The different size distributions of particulate PBDEs in emission sources and adjacent air implicated a noteworthy redisposition process during atmospheric dispersal.