植物微生物燃料电池修复Cr(VI)污染湿地土壤及机理研究

Cr(VI)-contaminated wetland soil remediation by plant microbial fuel cells and its mechanism

本研究通过引入沼生植物香蒲构建植物微生物燃料电池系统(P-MFC)修复Cr(VI)污染湿地土壤,考察了植物、不同初始Cr(VI)浓度对系统产电及去除效率的影响.结果显示,香蒲种植能显著提高P-MFC运行性能,系统最大功率密度与Cr(VI)去除率分别提高至23.83 mW·m^(-2)、33.01%,随着Cr(VI)暴露浓度的升高,系统运行性能降低.利用P-MFC修复Cr(VI)污染土壤过程中,电化学还原作用是Cr(VI)去除的主要机制,近90%的Cr(VI)通过电化学还原去除,系统中0.3%～1.86%的Cr(VI)被香蒲吸收富集,3.5%～9.5%的Cr(VI)被微生物与还原性有机物直接还原.通过高通量测序技术分析发现,香蒲种植与低浓度Cr(VI)暴露下阳极微生物群落多样性较大,优势门类Proteobacteria相对丰度最高为63.9%,较未种植香蒲与高浓度Cr(VI)暴露条件下提高了3.4%～19.0%,电化学活性微生物Geobacter相对丰度最高为12.4%,较未种植香蒲与高浓度Cr(VI)暴露条件下提高了4.4%～6.8%.系统中对Cr(VI)具有较强耐受性与还原能力的Acinetobacter、Bacillus占有较大比例,且相对丰度随暴露浓度升高而增大,最高分别为19.0%、14.4%,进一步说明微生物群落在Cr(VI)去除上发挥了一定作用.上述结果表明,P-MFC在去除湿地土壤Cr(VI)污染方面具有良好的潜力.

Cr(VI)-contaminated wetland soil was treated using Typha latifolia L. plant microbial fuel cells (P-MFC). The effect of Typha latifolia L. and initial Cr(VI) concentrations (200, 400, 600, 800 mg·kg-1 ) on the electricity production and Cr(VI) removal efficiency was investigated. Results demonstrated that the existence of Typha latifolia L. could significantly enhance P-MFC performance, maximum power density and Cr(VI) removal efficiency increased to 23. 83 mW·m-2 and 33. 01%, respectively. The performance decreased with increasing of Cr(VI) exposure concentration. Bioelectrochemical reduction was the main mechanism in Cr(VI) removal in P-MFC, approximately 90% Cr(VI) is removed by electrochemical reduction, 0.3%~1.86% of total Cr was uptake by Typha latifolia L., and 3.5%~9.5% was directly reduced by microorganisms and reducing organics. High-throughput sequencing analysis showed that the diversity of anodic microbial communities was relatively high with Typha latifolia L. planting and low Cr(VI) exposure, the relative abundance of dominant species Proteobacteria was up to 63.9%, increased by 3.4%~19.0% and the relative abundance of the exoelectrogenic bacteria Geobacter was 12.4%, increased by 4.4%~6.8%. A relatively large proportion of Acinetobacter, Bacillus with strong resistance to Cr(VI) was found in the system, indicating that microorganisms played a role in the removal of Cr(VI). In a word, P-MFC has good potential for removing Cr(VI) in wetland soil.