阴离子对Acidithiobacillus ferrooxidans氧化活性及次生铁矿物形成影响

酸性矿山废水（AMD）具有酸度高并含有大量可溶性Fe、硫酸根及重（类）金属的特点，采用生物矿化方法促使AMD中Fe向羟基硫酸铁次生矿物转变，对AMD后期石灰中和减少氢氧化铁和废石膏的产生，提高中和效率具有实际意义.通过模拟酸性矿山废水，考察了Cl^-、NO₃^-、PO₄^3-3种阴离子对嗜酸性氧化亚铁硫杆菌（A.ferrooxidans）体系中pH值、Fe²⁺氧化率、总Fe沉淀率、次生铁矿物矿相的影响.结果表明，高浓度阴离子对A.ferrooxidans氧化Fe²⁺能力具有抑制作用.A.ferrooxidans对阴离子的耐受性依次为PO₄^3- > NO₃^- > Cl^-.阴离子浓度在A.ferrooxidans耐受范围内时，其对Fe²⁺的生物氧化速率基本没有影响.但高浓度阴离子会通过抑制A.ferrooxidans的氧化活性，从而间接影响Fe³⁺的水解成矿过程，导致培养终点时总Fe沉淀率降低和次生铁矿物产量减少.受Fe³⁺供应速率降低的影响，次生铁矿物的合成途径易向施氏矿物转变.

Effect of anions on the oxidation activity of Acidithiobacillus ferrooxidans and the formation of secondary iron minerals

Acid mine drainage (AMD) is characterized typically by high acidity, soluble Fe, sulfate, and toxic metals. Thus, it is of practical significance to promote the transformation of soluble Fe and sulfate into secondary iron hydroxysulfate minerals by biomineralization of A. ferrooxidans, which is helpful in enhancing subsequent lime neutralization efficiency of AMD due to reducing the production of ferric hydroxide and waste gypsum. In the study, we investigated that the influence of three anions (Cl^-、NO₃^-、PO₄^3-) on the pH value, bio-oxidation rate of Fe²⁺, total Fe deposition efficiency, and phases of secondary iron minerals in simulated AMD containing A. ferrooxidans. The results indicated that a higher concentration of monovalent cations inhibited the biological oxidation of Fe²⁺. The tolerance ability of A. ferrooxidans to the three anions varied significantly (PO₄^3- > NO₃^- > Cl^-). In addition, for anion concentrations lower than those tolerated by A. ferrooxidans, Fe²⁺ oxidation was not affected. However, high concentration of anion can inhibited the hydrolysis and mineralization of Fe³⁺ indirectly by inhibiting the oxidation activity of A. ferrooxidans, resulting in a decrease in the total Fe precipitation rate and a reduction in the secondary iron minerals production. Influenced by the decrease of Fe³⁺ supply rate, the synthetic pathway of secondary iron minerals was biased towards the schwertmannite.