Decolorizing Shewanella (Shewanella decolorationis, S12) can be used as a variety of electron acceptor for anaerobic respiration under anoxic condition, including dissolved nitrates and insoluble iron oxide matrix. Therefore, the aim is to study the interaction mechanism of this interactive response system in iron reduction and nitrate reduction by constructing“S12/iron oxide/nitrate”interactive response system. The results show that there is a significant competitive relationship with the nitrate reduction and ferric reduction in the reaction system. The iron oxides with higher surface area and Fe(Ⅲ) availability take up stronger inhibition of nitrate reduction. The effect of crystalline degree of hematite on the inhibition of nitrate reduction was studied with hematite sintered at different temperature. Results showed that the extent of nitrate reduction inhibition decreased gradually in presence of increasing crystalline degree of hematite. Electrochemical methods were used to investigate the ferrous peak in the presence and absence of nitrate. Results showed that sharp peaks of Fe(Ⅱ) was found in the CV curves, indicating the formation of reactive Fe(Ⅱ), while the presence of nitrate can obviously decrease the reactive Fe(Ⅱ) peaks, indicating the iron reduction was significantly inhibited by the addition of nitrate. In response to the above results, the mainly reasons leading to competition between nitrate reduction and ferric reduction are as follows: (1) Fe (Ⅲ) and NO3– act as the competitive electron acceptor; (b) NO3– reduction by adsorbed Fe(Ⅱ) specials.% 中性厌氧条件下,脱色希瓦氏菌 Shewanella decolorationis(S12)能够使用多种电子受体进行厌氧呼吸,包括溶解态的硝酸盐以及难溶态的氧化铁基质。因此,本文通过构建“脱色希瓦氏菌/铁氧化物/硝态氮”的交互反应体系,研究这一体系中铁还原与硝态氮还原的相互作用过程,并对相互作用机制进行初步探讨。结果表明,交互反应体系中氧化铁还原与硝酸盐还原存在明显的竞争关系；随着氧化铁比表面积、可利用态铁含量的增大,硝酸受抑制作用逐渐增强；通过不同温度煅烧而得到的不同结晶度的赤铁矿对硝态氮的抑制作用也被研究。结果还表明,氧化铁结晶度越高,S12对硝态氮的还原抑制作用越小。循环伏安电化学测试结果发现,加入硝酸条件下,铁氧化峰几乎完全消失,表明硝态氮存在条件下,铁还原受到明显抑制。针对以上结果,初步探讨了铁还原与硝态氮还原竞争的原因,即：(1) Fe(Ⅲ)与NO3–同时作为电子受体,因竞争电子而受到抑制；(2)吸附态Fe(Ⅱ)物种还原NO3–,导致Fe(Ⅱ)累积减少,NO3–还原因产生的Fe(Ⅱ)的低速率而被抑制。
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