基于渗滤液修饰矿物吸附剂捕集垃圾焚烧过程中重金属研究

Heavy metal emission from waste incineration is usually in the form of metal vapor and particulate matter which can cause many problems to people's health. The infurnace mineral sorbents can control the heavy metal emission effectively, so this technology is considered to have a good prospect for development. However, the disadvantage of large addition amount of sorbents constrain the industrial application, so how to reduce the addition amount and increase the capture efficiency of heavy metal are critical problems in recent research. This project try to combine the infurnace sorbent and leachate injection technologies and propose a new metal capture method during the waste incineration in the basis of mineral's eutectic melting and leachate's component characteristic. First, the capture mechanisms of the heavy metal irons in leachate and the heavy metal vapor by sorbents in flue gas will be studied throuth the analysis of crystal structure changes and the quantum chemistry calculation. Accordint to the mechanism study, the alternative sorbents can be narrowed in a shorter list. Then, the capture ability and the capture rule of minerals will be studied in a lab-scale fluidized bed incinerator. The particulate matters are sampled in different size classification for Plasmid DNA Damage test to study the effect and mechanism of metals' toxicity reduction by sorbents. Finally, the sorbents will be evaluated according to the toxicity emission control effect to find the sorbents with excellent performance and their optimal operation conditions. Based on the above research, a integrated new method of heavy metal emission control by mineral sorbent modified by leachate during waste incineration will be established successfully.

垃圾焚烧过程中排放的重金属通常以气态和颗粒物形态进入大气，对人体健康造成严重危害。炉内添加矿物吸附剂可有效控制重金属排放，被广泛认为具有良好的发展前景，但吸附剂添加量大的缺点严重制约了该技术的应用，如何以更少的吸附剂添加量获得更好的重金属捕集效果成为研究重点。本项目利用硅铝酸盐共晶融化原理和垃圾渗滤液的组分特性，将炉内添加吸附剂与渗滤液回喷工艺相结合，提出一种捕集垃圾焚烧过程中重金属的新方法。拟首先通过晶体构型分析和量子化学理论，研究吸附剂捕集渗滤液中离子态重金属和炉膛内气态重金属机理，缩小吸附剂筛选范围；然后在小型流化床焚烧炉上研究不同吸附剂的捕集性能和规律，并对分级采样颗粒物进行质粒DNA损伤分析，研究吸附剂对重金属的降毒效果和降毒机理；最后基于毒性排放总量评价吸附剂，找到合适的矿物吸附剂及焚烧炉最优运行工况，最终形成一套完整的渗滤液修饰矿物吸附剂回喷炉膛捕集焚烧过程中重金属的新方法。

为克服用天然矿物吸附剂捕集垃圾焚烧过程中重金属用量大的缺点，本项目对吸附剂筛选，吸附剂使用的最佳工况，吸附剂吸附机理及改性机理进行了深入研究和探讨。首先在水平管式炉上，在综合吸附效率与浸出毒性的基础上进行吸附剂的评价与筛选，最终选定天然高岭土为最佳吸附剂。在小型流化床焚烧炉上，考察了在两种模式下（模式1： 高岭土与固体燃料一起加入炉膛； 模式2： 高岭土随二次风喷入炉膛）高岭土对铅的捕集效率随温度、高岭土添加量变化而变化的规律，得到最优高岭土添加方式和焚烧工况为：随二次风与固体燃料一同添加，添加量为3%，温度为850℃。在确定最佳焚烧工况后，在小型流化床上对比考察喷射模拟渗滤液与否对高岭土吸附铅的影响，实验表明喷射模拟渗滤液可促进高岭土对铅的吸附，降低烟气中铅的排放量。运用量子化学计算，基于密度泛函理论研究了Pb和Cd的原子态、一氧化物分子、二氯化物分子在高岭土表面吸附情况，具体指吸附系统的结构、吸附物和吸附面之间的成键状况、吸附能及吸附反应活化能，深入理解高岭土Pb和Cd蒸汽的高温吸附原理，揭示了高岭土对铅和镉的吸附机理。考虑到脱羟基后高岭土中Si环表面的惰性以及Al环表面的活性，煅烧，酸碱浸渍，渗滤液以及其他旨在产生游离Si和高活性Al的改性方法，均可用以提升焚烧炉内高岭土化学吸附Pb和Cd蒸汽的性能，揭示了吸附剂的改性机理。用两段式竖直管式炉考察了高岭土和偏高岭土对PbCl2的吸附性能和浸出毒性，探究了温度、水蒸气对吸附效率和浸出毒性的影响；利用了IR、XRD、SEM等表征手段探究了高岭土及偏高岭土分别与PbCl2之间的吸附产物类型和熔化机制。本研究创新性地提出基于暂定耐受摄入量进行重金属毒性因子的计算，将环境释放效应置于毒性因子外部参与计算吸附剂捕集多重金属效率。. 本项目以第一标注发表相关论文12篇，其中SCI收录6篇、EI收录2篇（不含双收录）、国内会议2篇；培养博士生2名、硕士生4名；授权国家发明专利1项，申请国家发明专利3项。