微生物還原分解硫酸鹽礦物和鐵氧化物：礦物溶解性的制約
發(fā)布時間：2019-03-29 17:38
【摘要】：硫酸鹽還原菌(SRB)是地球表生還原環(huán)境中重要的功能菌,對元素循環(huán)、地球生態(tài)及環(huán)境治理有重要作用。本文以乳酸鈉為碳源,圍繞礦物學(xué)性質(zhì)影響硫酸鹽還原菌分解礦物的效果開展了如下實驗:(1)SRB對不同溶解性硫酸鹽礦物(石膏和硬石膏)的分解及針鐵礦對分解效果的影響;(2)SRB對鉛礬的分解及針鐵礦對分解效果的影響;(3)SRB菌作用下磁性鐵氧化物的分解。通過監(jiān)測實驗過程中的pH、ORP、蛋白質(zhì)、硫離子、硫酸根、磁化率等指標和對比反應(yīng)前后固體相理化性質(zhì)的差異,分析制約SRB生長和SRB分解礦物的礦物學(xué)機制。研究得到如下結(jié)果:在SRB-硫酸鹽礦物實驗體系中,實驗結(jié)束后S~(2-)上升程度及蛋白濃度均為硫酸鈉石膏硬石膏,表明硫酸鹽礦物對SRB菌生長代謝的促進作用主要與其溶解速率有關(guān);針鐵礦對SRB的生長和硫酸鹽礦物的分解均有促進用,主要機制為通過形成鐵硫化物的沉淀,減少S~(2-)對SRB的毒害。在SRB-鉛礬體系中,實驗結(jié)束后溶液pH和ORP均有所降低;SO_4~(2-)在SRB生長停滯期上升,隨后保持穩(wěn)定;酸可揮發(fā)性S濃度隨SRB的生長逐漸升高,并最后保持穩(wěn)定;實驗結(jié)束后鉛礬大部分轉(zhuǎn)化為白鉛礦(PbCO_3)和方鉛礦。加入針鐵礦后SRB代謝產(chǎn)生的S~(2-)除與Pb反應(yīng)生成沉淀外,還可與針鐵礦反應(yīng),還原其中的Fe~(3+)為Fe~(2+),同時自身氧化為多種物相。SRB作用下,鉛礬分解轉(zhuǎn)化的機制為:鉛礬溶解產(chǎn)生的SO_4~(2-)供SRB生長利用,Pb與CO_3~(2-)反應(yīng)生成白鉛礦(PbCO_3);硫酸鹽還原產(chǎn)生的S~(2-)與鉛礬和白鉛礦分解釋放的Pb反應(yīng)生成方鉛礦沉淀;針鐵礦促進了鉛礬的分解,機制為作為SRB生長的電子受體,提高體系中SRB的生物活性。接種SRB條件下,磁性鐵氧化物的磁化率發(fā)生有規(guī)律變化:磁鐵礦先上升后穩(wěn)定,磁赤鐵礦先上升,后下降回初始值。結(jié)果表明SRB可直接與磁性鐵氧化物作用,促進其還原分解;磁鐵礦中的Fe~(2+)會與SRB菌代謝產(chǎn)物反應(yīng)生成沉淀,覆蓋包裹礦物,抑制SRB作用下其自身的還原分解;磁化率可作為表征納米磁性鐵氧化物分解的間接指標。
[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.
【學(xué)位授予單位】：合肥工業(yè)大學(xué)
【學(xué)位級別】：碩士
【學(xué)位授予年份】：2017
【分類號】：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.
【學(xué)位授予單位】：合肥工業(yè)大學(xué)
【學(xué)位級別】：碩士
【學(xué)位授予年份】：2017
【分類號】：X172;X505
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