含硫酸亚铁废溶液的生物氧化过程中氮源对溶解性Fe（Ⅲ）生成量的影响

利用嗜酸性氧化亚铁硫杆菌将含硫酸亚铁废溶液中的Fe²⁺氧化成Fe³⁺后用于脱除H₂S，同时实现了含硫酸亚铁废溶液的循环利用和H₂S的脱除。而溶解性Fe³⁺较高的生成量是保证该处理系统连续高效运行的关键因素。但在充足氮源和K⁺条件下大量Fe³⁺以黄铁矾沉淀形式存在。因此，本文通过控制氮源种类及投加浓度，减少沉淀生成，增大溶解性Fe³⁺生成量，以期提高H₂S的去除效率。结果表明（NH₄）₂HPO₄可替代以往研究中的（NH₄）₂SO₄作为氮源，确定适宜菌体生长的氮源浓度范围为0.33～1 g·L^-1。在1 g·L^-1 （NH₄）₂HPO₄条件下细菌生长无明显停滞期、Fe²⁺平均氧化速率为0.221～0.229 g·（L·h） ^-1，Fe³⁺生成量为7.62～7.72 g·L^-1，沉淀量为1.17 g·L^-1，因此确定（NH₄）₂HPO₄为1 g·L^-1时最能保证H₂S的脱除效率。为降低工艺成本，最低可采用0.33 g·L^-1为运行浓度。该优化方案不仅保证了菌体的Fe²⁺氧化活性，而且有效地减少了菌体培养过程中沉淀的产生，获得了较高的Fe³⁺生成量和增速，为使用含硫酸亚铁废溶液处理H₂S的工艺条件优化提供了依据。

Effect of different nitrogen sources on producing dissolved ferric ions in biological oxidation process of ferrisulfas liquor

Acidithiobacillus ferroxidans was used to oxidize Fe²⁺ into Fe³⁺ in the ferrisulfas liquor, and then dissolved Fe³⁺ was reduced by H₂S, achieving both reclamation of the liquor and removal of H₂S. The key factor for the removal efficiency of this treatment system was high concentration of dissolved Fe³⁺. However, when NH₄⁺ and K⁺ were excessive, most portions of dissolved Fe³⁺ would be transferred into Jarosite. The nitrogen source was optimized to obtain high concentration of Fe³⁺ by controlling its ingredients and concentrations. It showed that (NH₄)₂HPO₄ could replace (NH₄)₂SO₄ to be the nitrogen source and its concentration in 0.33-1 g·L^-1 was a suitable range for cell growth of Acidithiobacillus ferroxidans. At 1 g·L^-1, the bacterial growth did not exhibit obvious lag period; average oxidation rate of Fe²⁺ was 0.221-0.229 g·(L·h)^-1, dissolved Fe³⁺ increased to 7.62-7.72 g·L^-1, and precipitation was 1.17 g·L^-1. Therefore, the optimal concentration of (NH₄)₂HPO₄ was 1 g·L^-1. In order to reduce cost, the concentration was lowered 0.33 g·L^-1. This technique not only maintained the Fe²⁺ oxidative activity of Acidithiobacillus ferroxidans but also effectively increased dissolved Fe³⁺ produced during bacterial culture process, providing scientific optimization basis for removal of H₂S by the ferrisulfas liquor.