污泥液化生物炭中重金属的长期释放特征及其机理

污泥中重金属的存在对环境构成严重的威胁。液化既能处理污泥又能回收能源，但所产生的生物炭中可氧化态重金属（具有潜在且长期生态毒性）的含量和比例都上升了。目前研究生物炭中重金属的长期环境行为较少。本项目拟考察不同液化参数下制备的生物炭中重金属化合物的抗氧化性。结合培养实验和土柱淋溶实验，研究生物炭中重金属在土壤中的长期释放特征与影响因素；通过重金属的释放动力学模型，建立重金属化学形态与长期释放能力之间的关系。采用加速淋溶和加速老化实验来模拟研究更长时间（1-30年）生物炭中重金属的释放特征。通过模拟重金属化合物在土壤中氧化过程的研究，阐明生物炭中重金属在土壤中的释放机制。利用BCR法、Dold法和FTIR、XRD、XAFS和μ-XRF等分析手段为重金属的长期释放规律提供机理层面的解释。最终为合理评估和控制生物炭中重金属的长期环境风险，为绿色高效应用生物炭提供初步的理论基础和数据支撑。

The existence of heavy metals in the sludge poses a serious threat to environment. The liquefaction technology had the benefits of treatments of sludge and energy. However, the concentrations and proportions of oxidizable heavy metals (potential but long-term eco-toxicity) in biochar derived from liquefaction of sludge were both increased. There were few researches regarding long-term environmental behavior of heavy metals in biochar. In this project, researches will be focused on characteristics of resistance to oxidation of heavy metal components in biochars produced under different liquefaction conditions. The long-term release behaviors of heavy metals and their influencing factors in biochars will be carried out combined with incubation experiment and leaching experiment of soil columns. The relationship between chemical speciation of heavy metal in biochars and long-term releasing amount will be established by the kinetic models of heavy metal release behaviors of leaching experiment of soil columns. The longer-term (1-30 years) release behaviors of heavy metals in biochars will be predicted by accelerated leaching experiment and artificial accelerated aging method. Then, the release mechanism of heavy metals in biochars in soils will be revealed through the study of the oxidation process of simulated heavy metal components. Mechanisms for long-term release behaviors of biochars will be revealed by European Community Bureau of Reference sequential extraction, method of Dold, Fourier transform infrared spectrum, X-ray diffraction measurement, X-ray absorption fine structure spectroscopy and X-ray fluorescence microanalysis. The implement of this research project will provide preliminary theoretical and data support for long-term risk evaluation and management of heavy metals in biochar, and guiding the highly effective and environmental application of biochar.