常压供氢体系电场强化硫酸盐还原生物-电化学效应研究

针对氢气作为电子供体的硫酸盐生物还原速率缓慢的问题，设计生物电化学强化系统，采用附加直流电的方式，强化常压条件下供氢体系的硫酸盐还原过程.i≤1.50 mA时，随着电流的增大，硫酸盐还原速率增大，最佳电流强度为1.50 mA，平均还原速率是微生物单独作用的1.7～2.1倍.不同场强条件下电化学与生物学效应不同.当i≤1.50 mA时，电化学对生物过程的强化机制可能是电场/磁场促进硫酸盐还原菌（sulfate reducing bacteria，SRB）增殖、提高酶活性及代谢活性.当i>1.50 mA时，SRB活性受到电场的抑制，硫酸盐的代谢能力下降；当满足电势低于-0.69 V、 H₂分压为1.01×105 Pa时，体系发生以H₂为还原剂的电催化还原过程，但二者共同作用下的硫酸盐还原速率低于i=1.50 mA的情况.因此，基于能耗成本，施加低强度直流电场，利用电化学手段促进微生物的代谢，是强化常压供氢体系硫酸盐还原的重要途径.

Bio-electrochemical Effect on Hydrogenotrophic Sulfate Reduction Stimulated by Electrical Field in the Presence of H2 Under Atmospheric Pressure

Mierobial sulfate reduction rate is limited with H_2 as electron donor. In order to improve hydrogenotrophic sulfate reduction under normal atmospheric H_2 pressure, a bio-electrochemical system with direct current was designed and performed in this study. Results indicates that sulfate reduction rate (SRR) increases with the augment of current intensity under lower current intensity ( I≤1.50 mA) . When optimum current intensity of 1 .50 mA is applied, the SRR is 1.7 to 2.1 times higher than that of the control reactor. The synergistic effect of electrochemistry and microbiology on sulfate reduction varies at different current intensity. Under the condition of /I≤1.50 mA, the most probable mechanism of SRR increase is that electric or magnetic field stimulates the proliferation of sulfate-reducing bacteria (SRB) and the activity of the enzymes. When / is higher than 1.50 mA, the activity of SRB is inhibited, resulting in lower reduction rate compared with that at lower current. If controlling the cathode potential tower than -0.69 V and H_2 partial pressure 1.01 × 10~5 Pa, electro-catalytic sulfate reduction process takes place with H_2 as reductant in this bio-electrochemical system. However, the overall reduction rate is still lower than that when I= 1.50 mA is applied, and additionally the energy consumption is much higher. Therefore, electric field of low intensity can enhance hydrogenotrophic sulfate reduction in the presence of H_2 under atmospheric pressure.