It is widely accepted that incineration can permanently eliminate plastic waste. However, unburned material still exists in the bottom ash that is a solid residue from incinerators. In this study, microplastics exacted from bottom ash in 12 mass burn incinerators, one bottom ash disposal center and four fluidized bed incinerators were identified by micro-Fourier transform infrared spectroscopy. The results showed that bottom ash was a neglected microplastics source with an abundance of 1.9–565 n/kg, which indicated that per metric ton waste produce 360 to 102,000 microplastic particles after incineration. Nine types of plastics were identified, of which polypropylene and polystyrene were the predominant types. Microplastics sized between 50 μm and 1 mm accounted for 74 %. Granules, fragments, film, and fibers accounted for 43 %, 34 %, 18 %, and 5 % of the microplastics, respectively. The abundance of microplastics differed significantly with whether the local waste was source-separated, the local gross domestic product per capita, and the types of furnace. The global microplastics emission from incineration bottom ash was then estimated. Our observations provide empirical evidence proving that incineration is not the terminator of plastic waste, and bottom ash is a potential source of microplastics released into the environment.

焚化可以永久消除塑料废物已被广泛接受。但是，未燃烧的物质仍存在于底灰中，是焚烧炉的固体残渣。在这项研究中，通过微傅里叶变换红外光谱法鉴定了在12台大规模燃烧式焚烧炉，一个底灰处理中心和四个流化床焚烧炉中从底灰中提取的微塑料。结果表明，底灰是一种被忽略的微塑料来源，其丰度为1.9–565 n / kg，表明焚烧后每公吨废物产生360至102,000个微塑料颗粒。确定了9种塑料类型，其中主要是聚丙烯和聚苯乙烯。尺寸在50μm和1 mm之间的微塑料占74％。颗粒，碎片，薄膜和纤维占43％，34％，18％，和5％的微塑料。微塑料的丰富程度与当地垃圾是否按来源分类，当地人均国内生产总值以及熔炉类型有显着差异。然后估算了焚烧底灰的全球微塑料排放量。我们的观察提供了经验证据，证明焚烧不是塑料废物的终结者，底灰是释放到环境中的微塑料的潜在来源。