Karri Srilakshmi, Sierra-Alvarez Reyes, Field Jim A
Department of Chemical and Environmental Engineering, University of Arizona, P.O. Box 210011, Tucson, Arizona 85721-0011, USA.
Biotechnol Bioeng. 2005 Dec 30;92(7):810-9. doi: 10.1002/bit.20623.
Zero valent iron (ZVI) is a reactive media commonly utilized in permeable reactive barriers (PRBs). Sulfate reducing bacteria are being considered for the immobilization of heavy metals in PRBs. The purpose of this study was to evaluate the potential of ZVI as an electron donor for sulfate reduction in natural mixed anaerobic cultures. The ability of methanogens to utilize ZVI as an electron-donor was also explored since these microorganisms often compete with sulfate reducers for common substrates. Four grades of ZVI of different particle sizes (1.120, 0.149, 0.044, and 0.010 mm diameter) were compared as electron donor in batch bioassays inoculated with anaerobic bioreactor sludge. Methanogenesis was evaluated in mineral media lacking sulfate. Sulfate reduction was evaluated in mineral media containing sulfate and the specific methanogenic inhibitor, 2-bromoethane sulfonate. ZVI contributed to significant increases in methane production and sulfate reduction-compared to endogenous substrate controls. The rates of methane formation or sulfate reduction were positively correlated with the surface area of ZVI. The highest rates of 0.310 mmol CH4 formed/mol Fe0.day and 0.804 mmol SO4(2-) reduced/mol Fe0.day were obtained with the finest grade of ZVI (0.01 mm). The results demonstrate that ZVI is readily utilized as a slow-release electron donor for methanogenesis and sulfate reduction in anaerobic sludge; and therefore, has a promising potential in bioremediation applications.
零价铁（ZVI）是一种常用于可渗透反应屏障（PRB）的活性介质。硫酸盐还原菌正被考虑用于在PRB中固定重金属。本研究的目的是评估ZVI作为天然混合厌氧培养物中硫酸盐还原电子供体的潜力。由于这些微生物经常与硫酸盐还原菌竞争共同底物，因此还探索了产甲烷菌利用ZVI作为电子供体的能力。在接种厌氧生物反应器污泥的批次生物测定中，比较了四种不同粒径（直径分别为1.120、0.149、0.044和0.010 mm）的ZVI作为电子供体的情况。在缺乏硫酸盐的矿物培养基中评估产甲烷作用。在含有硫酸盐和特定产甲烷抑制剂2-溴乙烷磺酸盐的矿物培养基中评估硫酸盐还原作用。与内源性底物对照相比，ZVI显著促进了甲烷产量和硫酸盐还原的增加。甲烷生成或硫酸盐还原速率与ZVI的表面积呈正相关。使用最细粒度的ZVI（0.01 mm）获得了最高速率，即0.310 mmol CH4形成/mol Fe0·天和0.804 mmol SO4(2-)还原/mol Fe0·天。结果表明，ZVI很容易被用作厌氧污泥中产甲烷作用和硫酸盐还原的缓释电子供体；因此，在生物修复应用中具有广阔的潜力。
