共存离子对地浸废水中铀生物沉淀过程的影响

采用硫酸盐还原菌生物(还原)沉淀法消除地浸废水中的放射性铀污染,研究了共污染离子Cu(II)、Zn(II)、Fe(III)和SO42-分别对铀生物沉淀过程的影响。序批式实验结果表明,初始Cu(II)浓度低于10mg/L或Zn(II)浓度低于20mg/L时对铀生物沉淀过程影响不大,当Cu(II)浓度超过15mg/L或Zn(II)浓度超过25mg/L时,该过程会因重金属的生物毒性作用受到完全抑制。在含有Fe(III)的氧化环境中,铀生物沉淀过程与Fe(III)还原过程同时进行,但铀沉淀速度相对减慢。初始SO42-浓度低于4000mg/L时对铀生物沉淀过程影响很小,超过5000mg/L时会产生明显的抑制作用,且抑制作用随着SO42-浓度的上升而加强。

Influence of Coexistent Ions on Microbial Reduction and Precipitation of Wastewater from in situ Leach Uranium Mining

Microbial reduction and precipitation technology by sulphate reducing bacteria (SRB) was employed to treat wastewater from in situ leach uranium mining. Influences of coexistent ions including Zn(II), Cu(II), Fe(III) and sulphate on bioprecipitation of U(VI) were studied. Batch testing results showed that no significant effect on U(VI) bioprecipitation was observed when Zn(II) concentration was less than 20mg/L or Cu(II) less than 10mg/L. It was utterly inhibited at 25mg/L Zn(II) or 15mg/L Cu(II) due to the bio-toxicity. Under Fe(III)-bearing oxidizing conditions, U(VI) bioprecipitation was concurrent with Fe(III) reduction and the coexistent Fe(III) made this process slower. Inhibition of U(VI) reduction was not found with initial concentration of sulfate less than 4000mg/L, and anion levels above 5000mg/L slowed U(VI) biopre-cipitation and the inhibitory effect was enhanced with increasing sulfate concentration.