The speciation of heavy metals, besides the total concentrations, urgently need to be considered when assessing the eco-toxicity and the bioavailability of heavy metals in environment. This paper aims to investigate the distribution and chemical speciation (e.g. the acid extractable fraction (F1), the reducible fraction (F2), the oxidizable fraction (F3), and the residual fraction (F4)) of heavy metals during the anaerobic digestion process of swine manure. The majority of six heavy metals from the manure was located in biogas residue in the order of decreasing concentration Zn > Cu > Ni > As > Pb > Cd. The transformation of heavy metals among four fractions was observed during the digestion process, and the change of bioavailable fraction of Zn, Cu, Ni, Cd, As and Pb were 9.71%, −6.04%, −19.24%, 13.62%, −16.48% and −7.22%, respectively. The heat map of correlation coefficients and the stepwise linear regressions model were established to describe the correlation between the bioavailability of the metals and the given digestion variables to predict the influence of the selected variables on the bioavailability of heavy metals. The variations of heavy metal bioavailable fractions are attributed to three key digestion variables, NH₄⁺-N concentration, CH₄% in biogas daily yield and pH. These results provide a new perspective for analysis and control of heavy metals during the anaerobic digestion process.

在评估环境中重金属的生态毒性和生物利用度时，除总浓度外，还急需考虑重金属的形态。本文旨在研究厌氧消化过程中重金属的分布和化学形态（例如，酸可萃取级分（F1），可还原级分（F2），可氧化级分（F3）和残留级分（F4））。猪粪。粪便中的六种重金属中的大多数以浓度> Zn> Cu> Ni> As> Pb> Cd递减的顺序位于沼气残渣中。消化过程中观察到重金属在四个馏分之间的转化，锌，铜，镍，镉，砷和铅的生物利用度变化为9.71％，-6.04％，-19.24％，13.62％，-16.48。 ％和−7.22％，分别。建立相关系数的热图和逐步线性回归模型，以描述金属的生物利用度与给定的消化变量之间的相关性，从而预测所选变量对重金属生物利用度的影响。重金属生物利用分数的变化归因于三个关键的消化变量NH₄ ⁺ -N浓度，沼气中CH ₄％的日产量和pH值。这些结果为厌氧消化过程中重金属的分析和控制提供了新的视角。