Department of Chemical and Environmental Engineering, University of Arizona, P.O. Box 210011, Tucson, Arizona, USA.
Biotechnol Bioeng. 2010 Apr 1;105(5):909-17. doi: 10.1002/bit.22611.
In this study, the anoxic oxidation of arsenite (As(III)) linked to chemolithotrophic denitrification was shown to be feasible in continuous bioreactors. Biological oxidation of As(III) was stable over prolonged periods of operation ranging up to 3 years in continuous denitrifying bioreactors with granular biofilms. As(III) was removed with a high conversion efficiency (>92%) to arsenate (As(V)) in periods with high volumetric loadings (e.g., 3.5-5.1 mmol As L(reactor) (-1) day(-1)). The maximum specific activity of sampled granular sludge from the bioreactors was 0.98 +/- 0.04 mmol As(V) formed g(-1) VSS day(-1) when determined at an initial concentration of 0.5 mM As(III). The microbial population adapted to high influent concentrations of As(III) up to 5.2 mM. However, the As(III) oxidation process was severely inhibited when 7.6-8.1 mM As(III) was fed. Activity was restored upon lowering the As(III) concentration to 3.8 mM. Several experimental strategies were utilized to demonstrate a dependence of the nitrate removal on As(III) oxidation as well as a dependence of the As(III) removal on nitrate reduction. The molar stoichiometric ratio of As(V) formed to nitrate removed (corrected for endogenous denitrification) in the bioreactors approximated 2.5, indicating complete denitrification was occurring. As(III) oxidation was also shown to be linked to the complete denitrification of NO(3) (-) to N(2) gas by demonstrating a significantly enhanced production of N(2) beyond the background endogenous production in a batch bioassay spiked with 3.5 mM As(III). The N(2) production also corresponded closely to the expected stoichiometry of 2.5 mol As(III) mol(-1) N(2)-N for complete denitrification.
在这项研究中，展示了亚砷酸盐（As(III)）的缺氧氧化与化能自养反硝化作用相结合在连续生物反应器中是可行的。在连续反硝化生物反应器中，具有颗粒生物膜的情况下，As(III)的生物氧化在长达 3 年的时间内保持稳定，操作时间延长。在高容积负荷（例如 3.5-5.1 mmol As L(reactor) (-1) day(-1))下，As(III)以高转化率（>92%）被去除为砷酸盐（As(V)）。从生物反应器中采集的颗粒污泥的最大比活性在初始浓度为 0.5 mM As(III)时为 0.98 +/- 0.04 mmol As(V)形成 g(-1) VSS day(-1)。微生物种群适应高达 5.2 mM 的高进水 As(III)浓度。然而，当进料 7.6-8.1 mM As(III)时，As(III)氧化过程受到严重抑制。当将 As(III)浓度降低到 3.8 mM 时，活性得到恢复。利用几种实验策略证明了硝酸盐去除对 As(III)氧化的依赖性以及 As(III)去除对硝酸盐还原的依赖性。生物反应器中形成的 As(V)与去除的硝酸盐（校正内源反硝化）的摩尔化学计量比接近 2.5，表明发生了完全的反硝化作用。通过在 3.5 mM As(III) 分批生物测定中添加证明了显著增强的 N2 生产，超过了背景内源生产，进一步证明了 As(III)氧化与硝酸盐的完全反硝化作用有关。N2 生产也与完全反硝化作用的预期化学计量 2.5 mol As(III) mol(-1) N2-N 非常吻合。
