Department of Chemical and Biochemical Engineering, College of Chemistry and Chemical Engineering, Xiamen University, Xiamen 361005, China.
Department of Chemical and Biochemical Engineering, College of Chemistry and Chemical Engineering, Xiamen University, Xiamen 361005, China.
J Environ Sci (China). 2021 Mar;101:361-372. doi: 10.1016/j.jes.2020.08.032. Epub 2020 Sep 15.
Chemical speciation can fundamentally affect the potential toxicity and bioavailability of heavy metals. The transformation of heavy metal speciation and change of bioavailability were investigated in an anaerobic digestion (AD) system using four different substrates (pig manure (PM), cattle manure (CAM), chicken manure (CHM) and rice straw (RS)). The results obtained indicated that the total contents of heavy metals in PM, CHM and CAM were higher than in RS and decreased in the order Zn > Cu > Ni > Pb > As > Cd in all substrates. Moreover, the speciation with the largest proportion for each heavy metal was the same both in the different substrates and the biogas residues. Among them, Zn, Ni, Cd and As were mainly in the reducible fraction (F2), while Cu was mainly in the oxidizable fraction (F3) and Pb occurred predominantly in the residual fraction (F4). Our results further indicated that the AD process had a greater effect on the speciation of heavy metals in CHM and PM, but less on CAM and RS. The rates of change in bioavailability followed the order PM > CHM > CAM > RS. Changes in organic matter, humic acid or local metal ion environment as a result of AD were inferred as likely mechanisms leading to the transformation of heavy metal speciation. These results enhanced our understanding of the behavior of heavy metals in AD and provided a new perspective for the treatment and disposal of the substrates.
化学形态能从根本上影响重金属的潜在毒性和生物可利用性。本研究采用四种不同的底物（猪粪（PM）、牛粪（CAM）、鸡粪（CHM）和稻草（RS）），在一个厌氧消化（AD）系统中研究了重金属形态的转化和生物有效性的变化。结果表明，PM、CHM 和 CAM 中的重金属总量高于 RS，且 Zn＞Cu＞Ni＞Pb＞As＞Cd。此外，在所有底物中，每种重金属的形态比例最大的都是相同的，无论是在不同的底物还是沼气残留物中。其中，Zn、Ni、Cd 和 As 主要以可还原态（F2）为主，Cu 主要以可氧化态（F3）为主，而 Pb 主要以残渣态（F4）为主。我们的研究结果进一步表明，AD 过程对 CHM 和 PM 中重金属的形态有更大的影响，但对 CAM 和 RS 的影响较小。生物有效性的变化顺序为 PM＞CHM＞CAM＞RS。推断 AD 导致的有机物、腐殖酸或局部金属离子环境的变化可能是导致重金属形态转化的原因。这些结果增强了我们对 AD 中重金属行为的理解，为底物的处理和处置提供了新的视角。
