纳滤膜浓缩液淋滤焚烧飞灰过程中氯盐溶出及重金属的迁移特性

为解决生活垃圾填埋场的纳滤膜浓缩液和生活垃圾焚烧飞灰协同处置中淋滤条件对氯盐和重金属溶出效果的问题，采用北京市某生活垃圾填埋场的纳滤膜浓缩液在不同液固比和酸碱条件下淋滤北京市某生活垃圾焚烧厂的焚烧飞灰，探讨氯离子溶出及重金属的迁移特性. 结果表明:在液固比为12∶1、8∶1和4∶1条件下，焚烧飞灰中氯离子的总溶出率分别为81%、76%和61%，液固比越大，导致填料高度越低，氯离子溶出越充分；在液固比为4∶1条件下，纳滤膜浓缩液pH分别为3.20和10.70时，氯离子可与含氧阴离子竞争吸附位置，导致氯离子的总溶出率较未调节pH时大幅提升，增幅分别为81%和83%；不同液固比和酸碱条件下，采用XRD对淋滤灰渣分析发现，淋滤灰渣中均未检测到NaCl和KCl的矿物相. 改变纳滤膜浓缩液的pH为3.20和10.70后，淋滤灰渣中重金属Pb、Zn、Cu、Cr、Cd和Hg的浸出浓度均满足《危险废物鉴别标准 浸出毒性鉴别》(GB 5085.3—2007)和《生活垃圾填埋场污染控制标准》(GB 16889—2008)标准限值要求. 研究显示，纳滤膜浓缩液淋滤飞灰可脱除焚烧飞灰中的氯盐及部分重金属，淋滤灰渣经热处理后可焚毁截留纳滤膜浓缩液的有机物，热处理后灰渣有望实现安全资源利用. 

Characteristics of Chloride Salt Dissolution and Heavy Metal Migration during Leaching of Municipal Solid Waste Incineration Fly Ash with Membrane Concentrate

In order to solve the leaching problem of chloride salts and heavy metals in co-disposal of membrane concentrate and incineration fly ash in domestic waste landfills, the nanofitration membrane solution from a municipal solid waste landfill in Beijing was used to leach incineration fly ash from a domestic waste incineration plant in Beijing under different liquid-solid ratios and acid-alkaline conditions, and the leaching characteristics of Cl and heavy metal migration were investigated. The results showed that the total chloride dissolution rate in incineration fly ash was 81%, 76% and 61% under the liquid-solid ratios of 12∶1, 8∶1 and 4∶1, respectively. The higher the liquid-solid ratio, the lower the packing height, and the more sufficient chloride ion dissolution. The total chloride dissolution rate significantly increased at the nanofiltration membrane concentrate pH of 3.20 and 10.70 when the adsorption of chloride ions was competitive with that of oxygen-containing anions under the liquid-solid ratio of 4∶1 compared with the unadjusted pH, which was 81% and 83% under different liquid-solid ratio and acid-base conditions. Analysis of the leached ash using XRD showed that no mineral phases of NaCl and KCl were not detected in the leached ash. The leaching concentrations of heavy metals Pb, Zn, Cu, Cr, Cd and Hg in the leachate met the requirements of the Standard for Identification of Hazardous Wastes: Leaching Toxicity Identification (GB 5085.3-2007) and the Standard for Pollution Control of Domestic Waste Landfills (GB 16889-2008) after changing the pH of the nanofiltration membrane concentrate to 3.20 and 10.70. The study showed that the membrane concentrate leaching of fly ash can remove chloride salts and some heavy metals from incineration fly ash, and the leached ash residue can be burned after thermal treatment to remove the organic matter in the nanofiltration membrane concentrate, and the ash residue is expected to achieve safe resource utilization after thermal treatment.