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

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

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。

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 NH＋4 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.