生物质辅料对污泥热解炭中重金属的协同钝化效应及其机制研究

To stabilize the heavy metals is one of the top issues for safe application of pyrolytic sludge biochar (PSB) in an attempt to substantially minimize its potential ecological risk after use, which is of great significance in promoting the development of sludge pyrolytic technology of engineering level and thereafter realizing the “reduction, stabilization, harmlessness and resource utilization” of sewage sludge. Our preliminary results have manifested that the addition of auxiliary biomass material (such as rice husk and bamboo sawdust) was able to enhance the immobilization of heavy metals in PSB, however, the interactions among organic carbon(OC), inorganic component(IC) and heavy metals in the co-pyrolysis process of sewage sludge and auxiliary biomass materials have not systematically studied yet. In this project, the 3-dimensional spatial structure and surface characteristics of complex of OC-IC-metals will be illustrated via EDX, XRD, FTIR, XRAM and TEM advanced instruments. In addition, the quantitive correlations between the H/C, O/C and aromatic cluster groups and the stability of heavy metals will be explored through elemental analyses and BCR extraction technology. The outcomes will be essential for revealing the behind mechanisms in relation to synergistic stabilization effect due to the addition of auxiliary biomass and providing the scientific support to the mitigate the ecological risk of PSB.

实现污泥生物炭重金属的钝化稳定化，使污泥生物炭利用的潜在生态风险降到最低，是关系污泥生物炭安全利用的核心问题，对推动污泥热解处理技术工程化应用，实现污泥减量化、稳定化、无害化和资源化处理具有重要意义。申请人前期的研究结果证实生物质辅料对污泥热解生物炭重金属的钝化具有显著的促进作用，但未就生物质辅料与污泥共热解过程中有机碳-无机组分-重金属的内在作用机制进行深入研究。本项目中申请人通过综合运用能量色散X射线光谱仪、X射线衍射仪、傅里叶变换红外光谱仪、X射线分析显微镜和透射电子显微镜等仪器设备，定性表征污泥生物炭-矿物组分-重金属复合体的三维可视化立体空间形貌变化，通过运用元素分析、BCR提取等分析手段，建立污泥生物炭H/C、O/C和芳香簇结构大小与稳定态重金属含量之间的定量关系，阐明生物质辅料对污泥热解炭中重金属的协同钝化效应及其机制，为消除污泥生物炭资源化利用的重金属风险提供理论依据。

随着我国经济社会的快速发展，城镇化进程不断加快，每年污水处理量不断上升，直接造成市政污泥产生量的逐年增加。大量的剩余污泥成为了新的环境问题。由于污泥中含有氮磷钾等营养元素，可以作为一种良好的肥源，然而对环境有害的重金属在污水处理过程中大都转移到了污泥中。若污泥直接进入土壤环境，污泥中的重金属在土壤中累积将会对土-水-植物等环境系统造成潜在的生态风险。大量研究表明，热解能有效固定污泥中的重金属，但热解后大多数重金属依然存在于污泥炭中，这限制了污泥炭的资源化增值安全利用。.实现污泥炭重金属的钝化稳定化，使污泥炭利用的潜在生态风险降到最低，是关系污泥炭资源化增值安全利用的核心问题，对推动污泥热解处理技术工程化应用，实现污泥减量化、稳定化、无害化和资源化处理具有重要意义。.本项目通过研究生物质辅料对污泥热解生物炭重金属元素分布及赋存形态的影响、生物质辅料对污泥热解生物炭分子结构和官能团演变的影响和污泥生物炭结构与重金属负载关系，评价污泥生物炭土壤环境重金属生物有效性与生态风险，探明了污泥生物炭H/C、O/C和芳香簇结构大小与稳定态重金属含量之间的定量关系；明确了生物质辅料对污泥热解炭中重金属的协同钝化效应及其机制；推算出了污泥热解炭结构与重金属负载关系的可能的立体空间形貌结构。从而阐明了生物质辅料对污泥热解炭中重金属的协同钝化效应及其机制，为实现“以废治废”，消除污泥生物炭资源化安全利用的重金属风险提供了理论依据。