【作者】 杜颖哲；

【导师】 严建华； 李晓东； 陆胜勇；

【作者基本信息】 浙江大学 ， 工程热物理， 2013， 博士

【摘要】 随着我国国民经济和工业化的不断发展,由垃圾焚烧、金属冶炼、农药过度使用等造成的二噁英排放问题日益严重,并得到民众更广泛的关注。同时,上壤污染问题(有机污染物、重金属等)也日益突出,应用超累积植物修复污染土壤后必须进行二次处理,而超累积植物热处理过程中将会排放大量高浓度的重金属和二嗯英等有毒污染物。目前,二嗯英排放的研究主要应用国际黄金法则——HRGC/HRMS作为检测手段,但该方法因其分析费用高、分析周期长以及操作步骤复杂,无法适应二噁英检测新时期的特点——大量样品、低成本和快速检测,因此,为了适应大量复杂组分(例如,富含重金属)环境样品中二嗯英含量的检测,CALUX快速生物检测方法作为一种灵敏度高、准确性好、分析费用低、分析周期短以及操作步骤简单的分析技术,得到专家学者们越来越多的关注。针对CALUX生物检测方法在重金属超累积植物污染物排放特性研究方面的应用问题,本文开展了锌镉超累积植物热处置后重金属、二噁英的排放特性、控制技术以及CALUX快速生物检测技术在污染物分析检测中应用的一系列基础实验研究,得到一些具有现实指导意义的研究结果和结论。本文的主要研究内容如下：(1)验证了CALUX快速生物检测方法的质量控制系统,并且研究了不同前处理方法对CALUX生物检测系统的影响,为将来优化改善生物检测前处理步骤奠定实验基础。依托我国典型土壤、飞灰等样品,证明利用CALUX生物检测方法和HRGC/HRMS分析检测环境样品的PCDD/Fs结果线性相关性都很高,验证了CALUX快速生物检测方法针对环境样品可以作为HRGC/HRMS化学分析方法的替代方法,对大量复杂环境样品中PCDD/Fs进行筛选或半定量快速检测。(2)本文对超累积植物热处理后重金属的排放控制特性进行了较详细的实验研究。实验证明以焚烧作为最终手段,或者将热解—焚烧两种热处置方式联合应用更具有优势。重金属回收率随熔点的升高而增长,而且高熔点重金属的回收率随反应温度升高相应增加。重金属在底渣中主要以元素形态累积,而且高熔点重金属易于富集于底渣中。高岭土为控制烟气中重金属排放以及富集重金属于灰渣的最佳添加剂。(3)在研究植物热处理过程中重金属排放特性的基础上,开展了二噁英排放特性的研究。随焚烧温度的升高烟气中二噁英浓度不断增加,加入活性碳明显降低了PCDD/Fs的排放,因此,考虑到控制烟气中重金属和PCDD/Fs排放的共同目标,活性炭是一种最有效的吸附剂。烟气中PCDD/Fs和Cu的排放浓度变化规律相同,这说明铜氯化物可能会催化PCDD/Fs的生成,而且铜氯化物浓度的增加可能会更有效地增加PCDD/Fs的生成。随着焚烧温度的升高,飞灰中二噁英浓度也随之增加,但是底渣中二嗯英浓度随之降低,且其浓度极低,说明二噁英易于富集于飞灰中。(4)重金属超累积植物热处理所得环境样品中富含重金属,利用CALUX快速生物检测方法分析样品中PCDD/Fs时,重金属离子可能对检测结果具有影响效果。从总体趋势来看,重金属离子种类越多,对荧光素酶活性的削弱影响越大。五种重金属离子中对荧光素酶活性影响较大的可能为两种重金属离子——Hg2+与Cu2+。随Hg2+浓度的增加相对荧光素酶活性逐渐减弱,而且CALUX生物检测系统的H1L6.1细胞系对Hg2+容许能力较弱,而细胞系对Cu2+容许能力较强。重金属离子单独作用时对细胞存活率影响较小,Hg2+和Cu2+共同作用对细胞的存活影响最大,<0.5μg/ml-medium为细胞存活率的最大重金属离子容忍浓度。此外,实验结果表明较高浓度硝酸对CALUX生物检测系统的运行会造成实质上的影响。然而,不同浓度硝酸对细胞存活率的影响不明显且并无特定规律,可能是促进作用,也可能是抑制作用。更多还原

【Abstract】 Along with accelerated economic and industrialization development, waste combustion, metal smelting, and overuse of pesticide have led to increasingly serious problem of PCDD/Fs emissions, and more widespread attention. Meanwhile, the issue of contaminated soil (organic pollutants, heavy metals) has been increasingly outstanding, but thermal treatment of hyperaccumulators, which remedy the contaminated soil, will discharge the flue gas and fly ash with high concentration of heavy metals, PCDD/Fs and other toxic pollutants. At present, the detection technology of PCDD/Fs is mostly HRGC/HRMS, which is the international gold method of dioxin assay, but this method can not adapt to the detection process with low cost and fast assay, because of high cost, long period and complication of the assay. Therefore, in order to adapt to the PCDD/Fs detection in environmental samples with a large number of complex components (e.g., rich in heavy metal), CALUX bioassay, as an analysis method with high sensitivity, good accuracy and low cost, short analysis period, and simple operation steps, has raised more attention of experts. This dissertation launched a series of fundamental experiment studies in the issue of application of CALUX bioassay on pollutants emission derived from thermal treatment of Zn-Cd hyperaccumulators. The objectives of the current research involved as follows:(1) The quality control system of CALUX bioassay has been validate, and the influence of different pretreatment methods on CALUX bioassay system has been studied in this dissertation, in order to lay the experimental groundwork for improving and optimizing the pretreatment steps of bioassay. The results of PCDD/Fs contents in typical soil and fly ash samples by CALUX bioassay and HRGC/HRMS prove that CALUX-TEQs and MS-TEQs are highly linear correlated, and CALUX bioassay, which can be the alternative method for HRGC/HRMS, can screen or semi quantitatively detect PCDD/Fs contents in a great number of environmental samples.(2) This dissertation is launched a series of experiment studies in the issue of emission control characteristics of heavy metals derived from hyperaccumulators thermal treatment. The results indicate that incineration, or joint application of pyrolysis and incineration, have more advantages. The recovery rates of heavy metals increase with the elevatory melting points, moreover, the recovery rates of heavy metals with high melting points raise with the increasing reaction temperatures. The heavy metals forms accumulated in bottom ash are elemental speciation, and heavy metals with high melting points tend to accumulate in bottom ash. Furthermore, kaolin is the best additive to control heavy metal emissions and to accumulate heavy metals in ashes.(3) Based on the study of emission characteristics of heavy metals derived from hyperaccumulators thermal treatment, the PCDD/Fs emission characteristics have been studied. PCDD/Fs concentrations in flue gas are raised with the increasing combustion temperatures, and the PCDD/Fs concentrations with activated carbon significantly decrease, but PCDD/Fs increase with kaolin as additive, so activated carbon is the most effective adsorbent, in order to control the emissions of heavy metals and PCDD/Fs. Moreover, the emission rules of PCDD/Fs and Cu in flue gas are same, so copper chlorides may catalyze the PCDD/Fs generation, and the increase of copper chlorides concentrations may further promote the generation. Considering the fly ash, PCDD/Fs concentrations also increase with the raised temperatures, but the concentrations in bottom ash are on the contrary and extremely low, which proves that PCDD/Fs tend to accumulate in fly ash.(4) The environmental samples derived from thermal treatment of hyperaccumulators are rich in heavy metals, so when CALUX bioassay analyzes PCDD/Fs in samples, heavy metal ions may influence the results. In general, adding more kinds of heavy metal ions will cause greater impact on luciferase activity, and the luciferase activity expression decreases. Hg2+and Cu2+are the most influential ions on luciferase activity:the increasing Hg2+concentration will reduce relative luciferase activity, and the effect of Hg2+on the luciferase activity expression is remarkable, but the effect of Cu2+is less. Five different heavy metal ions, when isolated from the mix, will inferiorly affect the relative survival ratio. The combined action of Hg2+and Cu2+most affects cell survival ratio, and their maximum tolerance concentration to relative survival ratio is<0.5μg/ml-medium. Furthermore, the results indicate that higher concentration of nitric acid solution will actually affect CALUX bioassay system, but different concentrations of nitric acid solution have no obvious effect on cell activity, and the influence may be stimulative, or may be inhibiting.更多还原