氧化亚铁硫杆菌密度与营养供给对硫铁矿生物氧化的影响

探究硫铁矿生物氧化过程的影响因素有利于揭示酸性矿山废水形成规律.本研究采用摇瓶试验,探究了氧化亚铁硫杆菌Acidithiobacillus ferrooxidans LX5(A.ferrooxidans LX5)密度对硫铁矿生物氧化的影响.同时,在菌密度为1.40×107cells·m L-1的环境中,研究了微生物营养(无铁改进型9K液体培养基)供给对硫铁矿生物氧化的影响.结果表明,A.ferrooxidans LX5及其营养成分的引入显著加速了硫铁矿生物氧化体系H+的释放,0.70×107~2.10×107cells·m L-1A.ferrooxidans LX5的引入,可使得H+释放量较无菌对照提高1.51~3.31倍.半量浓度和全量浓度无铁改进型9K液体培养基的加入,可使菌密度为1.40×107cells·m L-1硫铁矿氧化体系的H+释放量提高3.24与2.75倍.相对于A.ferrooxidans LX5密度为0.70×107cells·m L-1的体系,1.40×107cells·m L-1或2.10×107cells·m L-1A.ferrooxidans LX5的引入明显提高硫铁矿氧化体系总Fe离子与SO2-4的释放效率,且71.9%~88.3%的总Fe离子主要以Fe2+存在.微生物营养供给使得总Fe离子与SO2-4的释放效率加速显著,而总Fe离子几乎全部以Fe3+存在.当菌密度大于1.40×107cells·m L-1时,体系生物氧化后所得硫铁矿表面存在明显的侵蚀坑.相对于半量浓度改进型9K培养基养分供给,全量改进型9K液体培养基的引入由于体系次生铁矿物覆盖硫铁矿明显而抑制了总Fe离子与SO2-4的释放.硫铁矿氧化所得酸性废水经Ca O中和至pH约为7.00,总Fe近乎全部去除,而SO2-4去除率相对较低(26.7%~73.9%).本研究所得结果对明晰酸性矿山废水形成规律具有一定的指导意义.

Effect of density and nutrition supply of Acidithiobacillus ferrooxidans on biological oxidation of pyrite

Exploring the influence factors of pyrite biological oxidation process could help to reveal the formation of acid mine drainage. The effect of Acidithiobacillus ferrooxidans LX5(A. ferrooxidans LX5) density on pyrite biooxidation process has been investigated. In addition, the effect of microbial nutrient (iron-free modified 9K liquid medium) on the bio-oxidation of pyrite was explored in the A. ferrooxidans LX5 cell density of 1.40×10⁷ cells·mL^-1. The results show that the introduction of A. ferrooxidans LX5 and its nutrient components significantly accelerated the release of H⁺ in pyrite oxidation system. A. ferrooxidans LX5 of 0.70×10⁷~2.10×10⁷ cells·mL^-1 can increase the release of H⁺ by 1.51~3.31 fold. The addition of iron-free 9K liquid medium with half or total concentration can increase the release rate of H⁺ by 3.24 and 2.75 times in the pyrite oxidation system with 1.40×10⁷ cells·mL^-1 of A. ferrooxidans LX5. Compared with A. ferrooxidans LX5 density of 0.70×10⁷ cells·mL^-1 system, the release efficiency of total Fe and SO₄^2- was improved because of introduction of A. ferrooxidans LX5 of 1.40×10⁷ or 2.10×10⁷ cells·mL^-1 with 71.9%~88.3% of total Fe ions mainly exists as Fe²⁺. The release efficiency of total Fe ions and SO₄^2- was obvious accelerated by microbial nutrition supply, and the total Fe mainly exists as Fe³⁺. There are obvious erosion pit on the pyrite surface after the biological oxidation when the density of A. ferrooxidans LX5 was more than 1.40×10⁷ cells·mL^-1. Compared with the half concentration, the total iron-free modified 9K liquid medium introduction was apparently suppress the release of total Fe ions and SO₄^2- because of the secondary iron minerals covers the pyrite during pyrite biooxidation process. After pyrite oxidation, the acid waste water was neutralized to pH~7 with calcium oxide, and the total Fe ions was almost completely removed, while the SO₄^2- removal rate was relatively low with 26.7%~73.9%. The outcomes of this study will provide scientific significance to clarify the formation rule of acid mine drainage.