To overcome the problem that ferrous complexes are easily oxidized by O₂ and then lose NO binding ability in the chemical absorption-biological reduction (CABR) process, cobalt(II)-histidine [Co(II)His] was proposed as an alternative. To evaluate the applicability of Co(II)His, the effects of CoHis absorbent on the aerobic denitrification by Paracoccus versutus LYM were investigated. Results indicated that His significantly promoted nitrite reduction. The inhibition effects of CoHis absorbent could be substantially alleviated by increasing the initial His/Co²⁺ to 4 or higher. CoHis with concentrations of 4, 8, 12, 16 and 20 mM presented no distinct effect on nitrite reduction, but slightly inhibited the reduction of nitrate, resulting in longer lag of nitrate reduction, and obviously promoted the growth of strain LYM. In the presence of 5, 10, 15 and 20 mM CoHis absorbent, the main denitrification product was N₂ (not less than 95.0%). This study is of significance in verifying the applicability of Co(II)His in the CABR process, and provides a referable CoHis absorbent concentration as 20 mM with an initial His/Co²⁺ of 4 for the future experiments.

中文翻译：

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组氨酸钴吸收剂对副球菌LYM的有氧反硝化作用的影响。

为了克服铁络合物在化学吸收-生物还原（CABR）过程中容易被O ₂氧化然后失去NO结合能力的问题，提出了钴（II​​）-组氨酸[Co（II）His]的替代方案。为了评估Co（II）His的适用性，研究了CoHis吸收剂对Paracoccus versutus LYM对好氧反硝化的影响。结果表明，His显着促进了亚硝酸盐的还原。通过增加初始His / Co ²⁺可以大大缓解CoHis吸收剂的抑制作用到4或更高。浓度分别为4、8、12、16和20 mM的CoHis对亚硝酸盐的还原没有明显影响，但对硝酸盐的还原有轻微的抑制作用，导致硝酸盐还原的滞后时间更长，并且明显促进了LYM菌株的生长。在5、10、15和20 mM CoHis吸收剂的存在下，主要反硝化产物为N ₂（不少于95.0％）。这项研究对于验证Co（II）His在CABR工艺中的适用性具有重要意义，并为将来的实验提供了一个可参考的CoHis吸收剂浓度为20 mM，其初始His / Co ²⁺为4。