MSWI底灰中重金属迁移转化的模拟试验研究

发布时间：2018-03-01 08:10

本文关键词： 底灰重金属迁移性形态　出处：《河北工程大学》2015年硕士论文　论文类型：学位论文

【摘要】：垃圾焚烧技术的应用带来了新的问题,焚烧灰渣的安全处置成为新的热点。垃圾焚烧底灰占焚烧灰渣总重量的80%左右,有相当一部分重金属富集在底灰中。所以填埋场中,底灰受到地球化学等因素的影响,重金属的形态和迁移性会发生变化,因此研究底灰中重金属迁移性及转化机理是有必要的。本文对新鲜底灰的基础理化性质进行了分析,包括底灰的物理组成、含水率、总孔隙率、矿物形态以及重金属含量等。实验数据表明底灰属于多孔介质,呈强碱性,主要矿物质为石英和方解石。在实验室条件下对MSWI底灰进行了为期64周的模拟填埋试验,并对产生的渗滤液的性质进行了分析。模拟试验包括缺氧柱和好氧柱,分别测定了两个柱中产生的渗滤液的p H、ORP、TP、TN、COD和TOC等指标。根据试验结果,发现渗滤液的性质随时间和模拟降雨次数的增加而不断发生变化,其中p H值持续下降,而ORP则逐渐升高然后下降;COD、TOC、TN和TP可分为急速上升、快速下降、缓慢下降和基本稳定四个阶段。从整个试验过程来看,p H在试验结束时仍维持在强碱性。在试验结束时两组试验中产生的渗滤液的p H、TOC和COD等三个水质指标均超出《城镇污水处理厂污染物排放标准》(GB18918-2002)一级A排放标准。对新鲜底灰和试验过程中从取样口采集的底灰进行检测,发现新鲜底灰中Cu、Zn和Cd含量是超出标准值的,缺氧条件和好氧条件下底灰中Cu、Zn和Cr含量变化趋势不明显;缺氧条件下Pb含量呈上升趋势,而好氧条件下Pb含量波动变化;缺氧条件下A取样口Ni含量呈上升趋势,B取样口则呈下降趋势,好氧条件下A、B取样口的底灰均呈下降趋势;好氧条件下的As含量随时间延长而减少,缺氧条件下明显变化。试验初始阶段,渗滤液中含有Cd、Pb、Zn、Cr、Ni和Cu等重金属离子,其中Cd低于《污水综合排放标准》(GB8978-2002)浸出限,而Pb,Zn,Cr,Ni,Cu均高于浸出。底灰中重金属含量较高,但不同重金属的含量和渗出总量差异较大。主要的几种重金属渗出总量从高到低为:CuCrNiZnPb,同种元素在不同条件下的渗出量不同但渗出率差异较小,渗出率从高到低为:NiCuCrPbZn,Ni的渗出率在20%左右,Cu和Cr在3%~8%之间,Pb和Zn的渗出率低于0.12%。利用XAFS技术对试验底灰中Zn的形态进行测试并采用Ifeffit软件进行拟合分析,发现新鲜灰中存在Zn2Si O4、Zn Fe2O4、Zn O和Zn SO4四种Zn的化合物。
[Abstract]:The application of waste incineration technology has brought new problems, the safe disposal of incineration ash has become a new hotspot. Waste incineration bottom ash incineration ash accounted for about 80% of the total weight, a considerable part of the accumulation of heavy metals in bottom ash. So in landfill, bottom ash is affected by factors such as geochemistry, morphology and migration heavy metal will change, so the study of migration of heavy metals in bottom ash and transformation mechanism is necessary. In this paper, on the basis of fresh bottom ash physicochemical properties were analyzed, including the bottom ash physical composition, water content, total porosity, morphology and mineral content of heavy metals. The experimental data show that the bottom ash belongs to the porous medium that is strongly alkaline, the main minerals of quartz and calcite. Under laboratory conditions of MSWI bottom ash simulated landfill test for 64 weeks, and the character of leachate were analyzed. The simulation test Test including anoxic aerobic column column, P H, leachate two columns were determined by ORP, TP, TN, COD and TOC were analyzed. According to the test results, the leachate properties were found to increase with time and the number of simulated rainfall changes, of which p H continued to decline. While ORP is gradually increased and then decreased; COD, TOC, TN and TP can be divided into the rapid rise, rapid decline, slow decline and stable four stages. From the entire test process, P H remained in strong alkaline at the end of the experiment. At the end of the experiment two experiment of leachate generated P H, TOC and COD three indexes of water quality exceeded < plant pollutant discharge standard of urban sewage treatment (> GB18918-2002) level A emission standard. The fresh bottom ash and bottom ash during the test from the sampling port acquisition test, find the fresh bottom ash of Cu, Zn and Cd content is beyond the standard value the hypoxia The conditions and aerobic conditions in bottom ash of Cu, Zn and Cr content change trend is not obvious; the content of Pb under hypoxic conditions increased, while under aerobic conditions Pb content fluctuation; under hypoxic conditions A sampling port Ni content increased, B sampling port decreased, under aerobic conditions A bottom ash B sampling port was decreased; the content of As under aerobic conditions decreased with time under hypoxic conditions, obvious changes. The initial stage of experiment, the leachate containing Cd, Pb, Zn, Cr, Ni and Cu and other heavy metal ions, which is lower than that of Cd "integrated wastewater discharge standard" (GB8978-2002) leaching and Pb, Zn, Cr, Ni, Cu were higher than that of leaching. Bottom ash is higher, but the content of exudation and the total quantity difference of different heavy metals. The heavy metals mainly larger volume of exudate from high to low: CuCrNiZnPb, the same element in different conditions but different exudation exudation rate differences Small leakage rate from high to low: NiCuCrPbZn, Ni leakage rate at around 20%, Cu and Cr between 3%~8%, Pb and Zn leakage rate below the 0.12%. to test the bottom ash in the form of Zn and fitting analysis by Ifeffit software using XAFS technology, found in Zn2Si O4 in fresh ash deposit Zn, Fe2O4, O and Zn compound Zn SO4 four Zn.

【学位授予单位】：河北工程大学
【学位级别】：硕士
【学位授予年份】：2015
【分类号】：X705

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