氢自养还原菌同步去除水中Cr(Ⅵ)和NO3-

本实验研究了序批式条件下Cr（Ⅵ）和NO₃^-浓度、pH值和H₂含量对于氢自养还原菌同步去除水中Cr（Ⅵ）和NO₃^-的性能及微生物群落的影响.结果表明：系统中存在氢气时，正常活性的氢自养还原菌可实现Cr（Ⅵ）的还原；Cr（Ⅵ）初始浓度不高于2000 μg/L时，Cr（Ⅵ）和NO₃^-的还原速率及氢自养还原菌的活性不会受到Cr（Ⅵ）初始浓度的影响；作为一种优先电子受体，NO₃^-会与Cr（Ⅵ）争夺电子，降低Cr（Ⅵ）的还原速率；氢自养还原菌同步还原Cr（Ⅵ）和NO₃^-的最佳pH值为7.0左右，酸性或碱性环境都会抑制Cr（Ⅵ）还原，且NO₂^-会随着pH值的升高逐渐积累；作为电子供体，H₂是还原Cr（Ⅵ）和NO₃^-的必要条件，但H₂足量后，过量提供H₂不能提高Cr（Ⅵ）和NO₃^-的还原速率.

Simultaneous removal of Cr(Ⅵ) and NO3- by hydrogen autotrophic reducing bacteria

The effects on the reduction efficiency and microbial community in simultaneous removal of Cr(Ⅵ) and NO₃^- from water by hydrogen autotrophic reducing bacteria (HARB) using sequential batch experiments was investigated under different Cr (Ⅵ) concentration, NO₃^- concentration, pH value and H₂ content conditions. Results showed that Cr(Ⅵ) can be reduced by active HARB. When the influent concentration of Cr(Ⅵ) was less than 2000μg/L, the reduction rates of Cr(Ⅵ) and NO₃^-, and the activity of HARB was not affected by the initial concentration. As a preferred electron acceptor, NO₃^- competed with Cr(Ⅵ), causing a decrease in the reduction rate of Cr(Ⅵ). The optimum pH value for simultaneous reduction of Cr(Ⅵ) and NO₃^- by HARB was about 7.0. Both acidic and alkaline environments can inhibit the reduction of Cr(Ⅵ). NO₂^- accumulated gradually with the increase of pH value. H₂ as an electron donor was a necessary factor for the reduction of Cr(Ⅵ) and NO₃^-, while excess H₂ did not increase the reduction rate of Cr(Ⅵ) and NO₃^-.