微生物还原分解硫酸盐矿物和铁氧化物：矿物溶解性的制约
发布时间：2019-03-29 17:38
【摘要】：硫酸盐还原菌(SRB)是地球表生还原环境中重要的功能菌,对元素循环、地球生态及环境治理有重要作用。本文以乳酸钠为碳源,围绕矿物学性质影响硫酸盐还原菌分解矿物的效果开展了如下实验:(1)SRB对不同溶解性硫酸盐矿物(石膏和硬石膏)的分解及针铁矿对分解效果的影响;(2)SRB对铅矾的分解及针铁矿对分解效果的影响;(3)SRB菌作用下磁性铁氧化物的分解。通过监测实验过程中的pH、ORP、蛋白质、硫离子、硫酸根、磁化率等指标和对比反应前后固体相理化性质的差异,分析制约SRB生长和SRB分解矿物的矿物学机制。研究得到如下结果:在SRB-硫酸盐矿物实验体系中,实验结束后S~(2-)上升程度及蛋白浓度均为硫酸钠石膏硬石膏,表明硫酸盐矿物对SRB菌生长代谢的促进作用主要与其溶解速率有关;针铁矿对SRB的生长和硫酸盐矿物的分解均有促进用,主要机制为通过形成铁硫化物的沉淀,减少S~(2-)对SRB的毒害。在SRB-铅矾体系中,实验结束后溶液pH和ORP均有所降低;SO_4~(2-)在SRB生长停滞期上升,随后保持稳定;酸可挥发性S浓度随SRB的生长逐渐升高,并最后保持稳定;实验结束后铅矾大部分转化为白铅矿(PbCO_3)和方铅矿。加入针铁矿后SRB代谢产生的S~(2-)除与Pb反应生成沉淀外,还可与针铁矿反应,还原其中的Fe~(3+)为Fe~(2+),同时自身氧化为多种物相。SRB作用下,铅矾分解转化的机制为:铅矾溶解产生的SO_4~(2-)供SRB生长利用,Pb与CO_3~(2-)反应生成白铅矿(PbCO_3);硫酸盐还原产生的S~(2-)与铅矾和白铅矿分解释放的Pb反应生成方铅矿沉淀;针铁矿促进了铅矾的分解,机制为作为SRB生长的电子受体,提高体系中SRB的生物活性。接种SRB条件下,磁性铁氧化物的磁化率发生有规律变化:磁铁矿先上升后稳定,磁赤铁矿先上升,后下降回初始值。结果表明SRB可直接与磁性铁氧化物作用,促进其还原分解;磁铁矿中的Fe~(2+)会与SRB菌代谢产物反应生成沉淀,覆盖包裹矿物,抑制SRB作用下其自身的还原分解;磁化率可作为表征纳米磁性铁氧化物分解的间接指标。
[Abstract]:Sulfate-reducing bacteria (SRB) are important functional bacteria in the earth's epigenetic reduction environment, and play an important role in element cycle, earth ecology and environmental control. In this paper, sodium lactate is used as carbon source, The effects of mineralogical properties on the decomposition of minerals by sulfate-reducing bacteria were studied as follows: (1) the decomposition of different dissolved sulfate minerals (gypsum and anhydrite) by SRB and the effect of goethite on the decomposition effect; (2) the effect of SRB on the decomposition of lead alum and goethite, (3) the decomposition of magnetic iron oxides under the action of SRB bacteria. By monitoring the indexes of pH,ORP, protein, sulfur ion, sulfate radical and magnetic susceptibility during the experiment and comparing the physical and chemical properties of solid phase before and after the reaction, the mineralogical mechanism of restricting the growth of SRB and the decomposition of SRB minerals was analyzed. The results are as follows: in the experimental system of SRB- sulfate minerals, the increasing degree of S2-and protein concentration are both sodium sulfate gypsum anhydrite at the end of the experiment. The results showed that the promoting effect of sulfate minerals on the growth and metabolism of SRB was mainly related to its dissolution rate. Goethite can promote the growth of SRB and the decomposition of sulfate minerals. The main mechanism of goethite is to reduce the toxicity of S2-to SRB by precipitation of iron sulfides. In the system of SRB- lead alum, both pH and ORP decreased after the experiment, SO_4~ _ (2 -) increased during the growth stagnation period of SRB, then remained stable, and the concentration of acid volatile S increased gradually with the growth of SRB, and remained stable at the end of the experiment. At the end of the experiment, most of the lead alum was converted into PbCO_3 and galena. After addition of goethite, S2-produced by SRB metabolism not only reacts with Pb to form precipitate, but also reacts with goethite, reducing Fe~ (3) to Fe~ (2), at the same time, it oxidizes itself to a variety of phases, under the action of SRB, it can react with goethite and reduce Fe~ (3) to Fe~ (2). The decomposition and transformation mechanism of lead alum is as follows: the SO_4~ (2 -) produced by the dissolution of lead alum is used for the growth and utilization of SRB, and Pb reacts with CO_3~ (2 -) to form bauxite (PbCO_3); The S2-produced by sulfate reduction reacts with lead alum and galena by decomposition and release of Pb to form galena precipitate, and goethite promotes the decomposition of lead alum by acting as an electron acceptor for SRB growth and enhancing the biological activity of SRB in the system. Under the condition of inoculating SRB, the magnetic susceptibility of magnetic iron oxide changes regularly: magnetite rises first and then stabilizes, magnetite rises first, and then decreases back to its initial value. The results show that SRB can react directly with magnetic iron oxide to promote its reduction and decomposition, and the Fe~ (2) in magnetite reacts with the metabolite of SRB bacteria to form precipitate, covering minerals and inhibiting its own reduction and decomposition under the action of SRB. Magnetic susceptibility can be used as an indirect index to characterize the decomposition of nano-magnetic iron oxides.
【学位授予单位】：合肥工业大学
【学位级别】：硕士
【学位授予年份】：2017
【分类号】：X172;X505
[Abstract]:Sulfate-reducing bacteria (SRB) are important functional bacteria in the earth's epigenetic reduction environment, and play an important role in element cycle, earth ecology and environmental control. In this paper, sodium lactate is used as carbon source, The effects of mineralogical properties on the decomposition of minerals by sulfate-reducing bacteria were studied as follows: (1) the decomposition of different dissolved sulfate minerals (gypsum and anhydrite) by SRB and the effect of goethite on the decomposition effect; (2) the effect of SRB on the decomposition of lead alum and goethite, (3) the decomposition of magnetic iron oxides under the action of SRB bacteria. By monitoring the indexes of pH,ORP, protein, sulfur ion, sulfate radical and magnetic susceptibility during the experiment and comparing the physical and chemical properties of solid phase before and after the reaction, the mineralogical mechanism of restricting the growth of SRB and the decomposition of SRB minerals was analyzed. The results are as follows: in the experimental system of SRB- sulfate minerals, the increasing degree of S2-and protein concentration are both sodium sulfate gypsum anhydrite at the end of the experiment. The results showed that the promoting effect of sulfate minerals on the growth and metabolism of SRB was mainly related to its dissolution rate. Goethite can promote the growth of SRB and the decomposition of sulfate minerals. The main mechanism of goethite is to reduce the toxicity of S2-to SRB by precipitation of iron sulfides. In the system of SRB- lead alum, both pH and ORP decreased after the experiment, SO_4~ _ (2 -) increased during the growth stagnation period of SRB, then remained stable, and the concentration of acid volatile S increased gradually with the growth of SRB, and remained stable at the end of the experiment. At the end of the experiment, most of the lead alum was converted into PbCO_3 and galena. After addition of goethite, S2-produced by SRB metabolism not only reacts with Pb to form precipitate, but also reacts with goethite, reducing Fe~ (3) to Fe~ (2), at the same time, it oxidizes itself to a variety of phases, under the action of SRB, it can react with goethite and reduce Fe~ (3) to Fe~ (2). The decomposition and transformation mechanism of lead alum is as follows: the SO_4~ (2 -) produced by the dissolution of lead alum is used for the growth and utilization of SRB, and Pb reacts with CO_3~ (2 -) to form bauxite (PbCO_3); The S2-produced by sulfate reduction reacts with lead alum and galena by decomposition and release of Pb to form galena precipitate, and goethite promotes the decomposition of lead alum by acting as an electron acceptor for SRB growth and enhancing the biological activity of SRB in the system. Under the condition of inoculating SRB, the magnetic susceptibility of magnetic iron oxide changes regularly: magnetite rises first and then stabilizes, magnetite rises first, and then decreases back to its initial value. The results show that SRB can react directly with magnetic iron oxide to promote its reduction and decomposition, and the Fe~ (2) in magnetite reacts with the metabolite of SRB bacteria to form precipitate, covering minerals and inhibiting its own reduction and decomposition under the action of SRB. Magnetic susceptibility can be used as an indirect index to characterize the decomposition of nano-magnetic iron oxides.
【学位授予单位】：合肥工业大学
【学位级别】：硕士
【学位授予年份】：2017
【分类号】：X172;X505
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