Faculty of Life Applied Sciences, Niigata University of Pharmacy and Applied Life Sciences, 265-1 Higashijima, Akiha-ku, Niigata 956-8603, Japan.
Chemosphere. 2008 Nov;73(9):1428-35. doi: 10.1016/j.chemosphere.2008.08.021. Epub 2008 Oct 7.
This pilot-scale study evaluated the use of intermediate cover soil barriers for removing heavy metals in leachate generated from test cells for co-disposed fly ash from municipal solid waste incinerators, ash melting plants, and shredder residue. Cover soil barriers were mixtures of Andisol (volcanic ash soil), waste iron powder, (grinder dust waste from iron foundries), and slag fragments. The cover soil barriers were installed in the test cells' bottom layer. Sorption/desorption is an important process in cover soil bottom barrier for removal of heavy metals in landfill leachate. Salt concentrations such as those of Na, K, and Ca in leachate were extremely high (often greater than 30 gL(-1)) because of high salt content in fly ash from ash melting plants. Concentrations of all heavy metals (nickel, manganese, copper, zinc, lead, and cadmium) in test cell leachates with a cover soil barrier were lower than those of the test cell without a cover soil barrier and were mostly below the discharge limit, probably because of dilution caused by the amount of leachate and heavy metal removal by the cover soil barrier. The cover soil barriers' heavy metal removal efficiency was calculated. About 50% of copper, nickel, and manganese were removed. About 20% of the zinc and boron were removed, but lead and cadmium were removed only slightly. Based on results of calculation of the Langelier saturation index and analyses of core samples, the reactivity of the cover soil barrier apparently decreases because of calcium carbonate precipitation on the cover soil barriers' surfaces.
本中试研究评估了中间覆盖土壤屏障在去除来自城市固体废物焚烧炉、灰熔融厂和粉碎机残渣共处置飞灰的测试单元产生的渗滤液中的重金属的应用。覆盖土壤屏障是安山土（火山灰土壤）、废铁粉、（来自铸造厂的磨粉机粉尘废物）和炉渣碎片的混合物。覆盖土壤屏障被安装在测试单元的底层。吸附/解吸是覆盖土壤底层屏障去除垃圾渗滤液中重金属的重要过程。由于灰熔融厂飞灰中的盐分含量很高，渗滤液中的盐浓度（如 Na、K 和 Ca 等）非常高（通常大于 30 gL(-1)）。在有覆盖土壤屏障的测试单元的渗滤液中，所有重金属（镍、锰、铜、锌、铅和镉）的浓度都低于没有覆盖土壤屏障的测试单元，并且大部分都低于排放标准，这可能是由于渗滤液的数量和覆盖土壤屏障对重金属的去除造成的稀释所致。计算了覆盖土壤屏障的重金属去除效率。大约 50%的铜、镍和锰被去除。大约 20%的锌和硼被去除，但铅和镉只被轻微去除。根据朗格利尔饱和度指数的计算结果和芯样分析，由于碳酸钙在覆盖土壤屏障表面的沉淀，覆盖土壤屏障的反应性显然降低。
