Abstract Naturally occurring manganese (Mn) oxide, biogenic birnessite ((Na, Ca, K)0.5 MnIII, IV2O4·1.5 H2O), is involved in the geochemical cycling of variety of metals including arsenic (As). This natural reaction was exploited in this study to develop a sustainable oxidation treatment process of As(III) to the less soluble (and less toxic) As(V). It is known that the birnessite surface becomes passivated during As(III) oxidation, which quickly decreases its reactivity. The cycle batch test and the following XANES (X-ray absorption near-edge structure) analysis in this study confirmed that combining chemical As(III) oxidation by birnessite with simultaneous birnessite regeneration by Mn-oxidizing microorganisms (Pseudomonas sp. SK3) can avoid passivation of MnIII-precipitates and enables continuous As(III) oxidation while increasing the AOS (average oxidation state) of birnessite. This chemical/microbiological synergism was observed for the As(III) concentration range of 0.2–0.5 mM with 0.1% birnessite, wherein no net Mn loss from birnessite was noticed for complete As(III) oxidation. The continuous column test was run for 40 days at a HRT (hydraulic retention time) of 3 h by feeding a 0.2 mM As(III) solution. The As(III) oxidation efficiency of >98% was consistently achieved while strictly controlling the Mn2+ dissolution throughout the test period. This study concluded that by taking advantage of a robust microbial Mn-oxidizing activity, the use of “bioactive” birnessite realizes self-sustainable oxidation of As(III), without necessitating additional feed of oxidant birnessite, Mn2+ ions or organics.

中文翻译：

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自再生生物活性水钠锰矿在连续流动柱式反应器中氧化亚砷酸盐

摘要 天然存在的氧化锰 (Mn)、生物水钠锰矿 ((Na, Ca, K)0.5 MnIII, IV2O4·1.5 H2O) 参与包括砷 (As) 在内的多种金属的地球化学循环。本研究利用这种自然反应开发了一种可持续的 As(III) 氧化处理工艺，将其氧化为溶解度较低（且毒性较低）的 As(V)。众所周知，水钠锰矿表面在 As(III) 氧化过程中变得钝化，这会迅速降低其反应性。本研究中的循环批次测试和以下 XANES（X 射线吸收近边缘结构）分析证实，将水钠锰矿的化学 As(III)氧化与锰氧化微生物（假单胞菌属）的水钠锰矿同时再生相结合。SK3) 可以避免 MnIII 沉淀物的钝化，并使 As(III) 连续氧化，同时提高水钠锰矿的 AOS（平均氧化态）。在 0.2-0.5 mM 的 As(III) 浓度范围内观察到这种化学/微生物协同作用，其中含有 0.1% 的水钠锰矿，其中对于完全的 As(III) 氧化没有注意到水钠锰矿的净锰损失。通过加入 0.2 mM As(III) 溶液，以 3 小时的 HRT（水力保留时间）运行连续柱测试 40 天。在整个测试期间严格控制 Mn2+ 溶解的同时，始终实现 >98% 的 As(III) 氧化效率。该研究得出的结论是，通过利用强大的微生物 Mn 氧化活性，使用“生物活性”水钠锰矿实现了 As(III) 的自我持续氧化，