富铁酸性硫酸盐体系施氏矿物附着包裹硫杆菌的Fe^(2+)氧化能力研究

Ferrous ions biooxidation ability of schwertmannite-adsorbed Acidithiobacilus ferrooxidans in iron-rich acidic sulfate environment

探究富铁酸性硫酸盐体系次生铁矿物附着包裹硫杆菌的Fe^(2+)氧化活性,对揭示次生铁矿物调控酸性矿山废水形成过程具有指导意义.本研究首先采用摇瓶实验合成次生铁矿物—施氏矿物,然后将脱水后的0.1、0.2、0.3及0.4 g施氏矿物直接或溶解后加入到pH为2.50的富铁酸性硫酸盐体系(改进型9K液体培养基)中进行Fe^(2+)氧化,分析体系pH、Fe^(2+)氧化率、次生铁矿物产生量等相关指标.研究表明,氧化亚铁硫杆菌在脱水施氏矿物的附着包裹量为2×10~8cells·g^(-1).0.1、0.2、0.3及0.4 g施氏矿物直接加入体系经过108 h培养,pH分别下降至2.28、2.25、2.24及2.22;Fe^(2+)氧化速率随着施氏矿物加入量的增加而增加,且各体系Fe^(2+)氧化率在108 h均达到100%,此时次生铁矿物产生量分别是3.05、3.30、3.61与3.70 g·L^(-1).然而,0.1、0.2、0.3及0.4 g施氏矿物溶解后进入的相应体系经过108 h培养后,pH分别下降至2.19、2.18、2.10及2.02;Fe^(2+)氧化速率随着施氏矿物溶解量的增加而增加,各体系Fe^(2+)氧化率在96 h均达到100%,各体系次生铁矿物在108 h时的产生量分别是6.16、6.44、6.76与7.89 g·L^(-1).可见,施氏矿物对硫杆菌的吸附包裹作用致使体系Fe^(2+)氧化效率降低,次生铁矿物合成量减少,酸化程度减弱.

Exploring the ferrous ions biooxidation ability of schwertmannite-adsorbed Acidithiobacilus ferrooxidans in iron-rich acidic sulfate environment has a certain guiding significance to further reveal the regulation rule of secondary iron minerals formation on the production of acid mine drainage. First,the schwertmannite has been biosynthesized in this study. Then,0.1 g,0.2 g,0.3 g and 0.4 g dewatered bioschwertmannite were added into iron-rich acidic sulfate systems（ modified 9 K liquid medium with pH 2.50） directly or in the form of dissolved state. The pH,ferrous ions oxidation efficiency,and the weight of secondary iron minerals in different treatments have been investigated during Fe（2＋）oxidation. The results showed that the adsorption capacity of Acidithiobacilus ferrooxidans LX5 on dewatered bio-schwertmannite was 2×108 cells·g（-1）. The systems pH were dropped to 2.28,2.25,2.24 and 2.22,respectively when 0.1 g,0.2 g,0.3 g and 0.4 g of dewatered bio-schwertmannite added into systems. The Fe（2＋）oxidation efficiency improved with the bioschwertmannite addition and reached 100% in 108 h in different systems. The secondary iron minerals net increased amount in 0.1 g,0.2 g,0.3 g and 0.4 g bio-schwertmannite-added systems at 108 h were 3.05 g·L（-1）,3.30 g·L（-1）,3.61 g·L（-1）,and 3.70 g·L（-1）. However,the systems pH were decreased to 2.19,2.18,2.10 and 2.02,respectively when 0.1 g,0.2 g,0.3 g and 0.4 g of dewatered bio-schwertmannite added into systems in the form of dissolved state. The Fe（2＋）oxidation efficiency improved with the dissolved bio-schwertmannite addition and reached 100% in 96 h. The secondary iron mineralsamount in 0.1 g,0.2 g,0.3 g and 0.4 g dissolved bio-schwertmannite-added systems at 108 h were 6.16 g·L（-1）,6.44 g·L（-1）,6.76 g·L（-1）,and 7.89 g·L（-1）. It can be seen that the adsorption of Acidithiobacilus ferrooxidans LX5 by bio-schwertmannite in iron-rich acidic sulfate environment can decrease the system Fe（2＋）biooxidation efficiency,decrease the amount of secondary iron minerals,and weaken the system acidification degree.