Abstract

Chromium (Cr), Nickel (Ni), and zinc (Zn) removal from landfill leachate using mesocosm-scale vertical flow wetlands, the effect of recirculation, and the ability of macrophytes to retain metals were evaluated. Wetlands were filled with coarse sand and light expanded clay aggregates and planted with Typha domingensis or Canna indica. Wetlands were operated using intermittent loading, with and without recirculation. Raw leachate was diluted and spiked with metals to reach the following concentrations: 0.2 mg L⁻¹ Cr , 0.2 mg L⁻¹ Ni, and0.2 mg L⁻¹ Zn and 1.0 mg L⁻¹ Cr, 1.0 mg L⁻¹ Ni, and 1.0 mg L⁻¹ Zn. Wetlands planted with T. domingensis presented higher metal removal than those planted with C. indica. Recirculation enhanced metal removal efficiencies significantly, being for T. domingensis/C. indica: 60/54, 49/47, 61/47% for Cr, Ni, and Zn at 0.2 mg L⁻¹, and 80/71, 76/62, 73/59% for Cr, Ni, and Zn at 1.0 mg L⁻¹, respectively. Metals were efficiently retained by macrophytes. Plant biomass and metal concentrations in roots were significantly higher than in shoots. Scanning electron microscopy and X-ray microanalysis showed that metals were absorbed by internal root tissues. A hybrid wetland planted with T. domingensis may be implemented to improve not only metal but also chemical oxygen demand and total nitrogen removals.

摘要

评估了使用中尺度垂直流湿地从垃圾渗滤液中去除铬 (Cr)、镍 (Ni) 和锌 (Zn)、再循环的效果以及大型植物保留金属的能力。湿地填满粗砂和轻膨胀粘土骨料，种植香蒲或美人蕉。湿地使用间歇装载操作，有和没有再循环。将原始渗滤液稀释并加入金属以达到以下浓度：0.2  mg L ^-1 Cr、0.2  mg L ^-1 Ni、 0.2  mg L ^-1 Zn 和 1.0  mg L ^-1 Cr、1.0  mg L ^-1 Ni , 和 1.0 毫克 L ^-1锌。种植T. domingensis的湿地比种植C. indica的湿地具有更高的金属去除率。再循环显着提高金属去除效率，对于T. domingensis / C. indica：Cr、Ni 和 Zn 在 0.2  mg L ^-1时为 60/54、49/47、61/47%和 80/71、76/在 1.0  mg L ^-1下， Cr、Ni 和 Zn 分别为 62、73/59% 。金属被大型植物有效地保留。根中的植物生物量和金属浓度显着高于枝条。扫描电子显微镜和 X 射线微量分析表明金属被内部根组织吸收。种植了混合湿地可以实施T. domingensis以改善金属以及化学需氧量和总氮去除量。