污泥热解炭化工程污泥炭重金属含量及形态特征分析

Characteristics of heavy metal content and speciation distribution in sludge-based biochar from sludge pyrolysis project

以某市政污泥热解炭化工程的污泥炭产物为对象,对Cu、Zn、Mn、Co、Ni、Cd、Cr、Pb 8种重金属总量以及4种形态(弱酸提取态、可还原态、可氧化态及残渣态)的分布特征进行研究,各形态提取测定采用改进BCR顺序提取方法。结果表明,重金属元素Zn总量最高7192.49 mg/kg,不同重金属元素的固化率从高到低依次为Cu>Cr>Ni>Co>Cd>Mn>Pb>Zn,除Zn以外的固化率均达到了50%以上,Cu和Cr固化率均超过90%。在污泥热解炭化工程设计、工程运行、污泥炭资源化利用时,应重点关注Zn含量,研究炭化工程不同参数如热解温度对重金属元素形态迁移转化的影响。对污泥炭土地利用重金属的限值标准,应更加关注不同重金属形态及其在环境中的迁移转化特征。

Sludge-Based Biochar(SBB)from a municipal sludge pyrolysis and carbonization project was collected as research object,total contents and speciation distribution(exchangeable and acid-soluble fraction,reducible fraction,oxidizing fraction,residue fraction)of eight heavy metals(Cu,Zn,Mn,Co,Ni,Cd,Cr,Pb)were investigated.Extraction of each heavy metal form was determined by improved sequential extraction method of BCR.The results showed that the total content of Zn in SBB was the highest as 7192.49 mg/kg,the stabilization rate of different heavy metals shows a decreasing trend as CuCrNiCoCdMnPbZn.The stabilization rates of all heavy metals except Zn reached more than 50%,Cu and Cr reached more than 90%.In sludge pyrolysis project design,operation and SBB utilization,attention should be paid to the content of heavy metal element Zn and the influence of different parameters such as pyrolysis temperature on the migration and transformation of heavy metals.For the limit standard of heavy metals in SBB land use,more attention should be paid to the migration and transformation characteristics of different heavy metals in the environment.