三价铁离子对微生物燃料电池产电性能的影响机制

发布时间：2018-02-16 05:48

  本文关键词： 微生物燃料电池(MFC) 污泥 Fe(Ⅲ) 静磁场 细胞色素c　出处：《江南大学》2017年博士论文　论文类型：学位论文

【摘要】：沉积型微生物燃料电池(SMFC)是一种将阳极电极埋覆于厌氧沉积物中,利用电极表面及沉淀物中微生物的代谢,去除污染物并回收电能的新兴处理技术。微量金属元素在SMFC运行过程中具有重要的作用,缺乏必要的微量金属元素会导致微生物的活力下降,进而影响整个系统运行的稳定性和有机物的去除效果。在SMFC电子传递过程中,产电微生物内的细胞色素c起到关键作用。细胞色素c的活性中心为铁,铁的加入会引起细胞色素c的变化,但铁与细胞色素c含量及活性的关系仍有待探讨。本研究以三价铁离子为主要研究对象,探讨SMFC系统中外加三价铁离子对其运行特性的影响,同时,研究外加静磁场复合三价铁离子添加进一步提高MFC系统的产电特性的可行性。主要研究内容如下:(1)考察了三价铁离子对SMFC系统产电性能的影响。三价铁离子的加入有助于提高剩余污泥SMFC的产电性能。铁离子浓度在500 mg/L以下时,SMFC系统的产电性能随着三价铁离子浓度的增加而提升。当外加铁离子浓度为500 mg/L时,SMFC系统取得了最佳的产电性能,电极表面的电化学活性最强、内阻最低。该条件下,电池最大输出功率密度、最高输出电压、库伦效率和系统表观内阻分别为597.2 mW/m2、509.7mV、37.7%和101.1Ω。(2)研究了三价铁离子对阳极剩余污泥性质的影响。阳极污泥的VSS和TSS的去除率呈随铁离子浓度增加先提高后降低的变化趋势。当外加铁离子浓度为500 mg/L时,VSS和TSS去除率最高,分别为37.2%和26.4%。在SMFC系统运行过程中,污泥上清液中的SCOD、溶解性多糖和蛋白质均呈现先上升后下降的变化规律。随外加铁离子浓度的增加,阳极污泥的脱氢酶活性呈现先升高后降低的变化,而产甲烷活性则持续降低。当外加铁离子浓度为500 mg/L时,脱氢酶活性最高为2569.4μgTF/gVSS。铁离子加入到SMFC系统中后会与剩余污泥中的物质结合降低加入的铁的生物有效性。铁离子加入后形成的不易被微生物利用的碳酸盐结合态、有机结合态和硫酸盐结合态铁的含量在运行前后基本没有变化,可交换态和吸附态这两种形态的铁多被被微生物利用转化为剩余态铁。500 mg/L铁离子浓度可满足微生物生长需求,该浓度下初始具有生物有效性的铁浓度为100 mg/L。(3)研究了铁对SMFC阳极生物膜的影响机制及铁与细胞色素c间的关系。铁离子浓度为500 mg/L时,SMFC系统阳极生物膜的生物量较未添加铁离子的对照组增加了约30%,但胞外聚合物含量下降了14%。铁的加入会提高阳极生物膜上变形菌门的丰度,铁离子浓度为500 mg/L时,阳极生物膜上变形菌门的丰度从不添加铁的47%增加到80%。铁的加入不会改变阳极生物膜电活性物质的种类,但会提高其电化学活性。加入500 mg/L铁离子后,阳极生物膜上单位质量微生物的细胞色素c合成量提高了2.4倍,单位质量生物膜的电子传递效率提高了1.1倍,但由于底物不足,单位质量细胞色素c传递电子数有所下降。通过从阳极生物膜上纯化出的细胞色素c分析可知1 mol细胞色素c含有5 mol铁。铁在阳极除了会影响阳极生物膜的构成外还会在阳极附近形成Fe(II)/Fe(Ⅲ)作为电子中介体提高电子传递效率;铁在阴极会形成Fe(II)/Fe(Ⅲ)临时电容降低阴极极化内阻,进而提高阴极性能,且阴极添加铁离子的最佳浓度为500 mg/L。(4)探究了外加静磁场复合三价铁离子添加对系统产电性能进一步提升的可行性。研究了外加静磁场条件下系统的产电性能、阳极生物膜变化和细胞色素c的含量及活性的变化。外加静磁场可以进一步提高系统产电性能,缩短系统启动时间。低强度的静磁场(≤220 mT)条件下,MFC系统的运行特性随着磁场强度的增强而增强,高强度磁场(≥370 m T)条件下会对系统造成不可逆损伤,电池性能急剧下降。外加静磁场为220 m T时,MFC系统运行性能最优,电池输出峰电压、最高功率密度、电池表观内阻和阳极内阻分别为756.1 mV、1.5 W/m2、66.5Ω和49.8Ω。低强度的静磁场条件下,阳极生物膜上的生物量、胞外聚合物含量和生物膜中的脱氢酶活性随着外加静磁场强度的增加而增加。外加静磁场为220 mT时,MFC系统阳极生物量、胞外聚合物含量和生物膜中的脱氢酶活性最高分别为60.31μgP/cm3、0.81μg/μgP和2.45μgTF/(μgP·h)。低强度的静磁场可以提高细胞色素c将电子传递到阳极的效率。在220 mT强度条件下,细胞色素c的含量和电子传递效率较不外加磁场的对照组分别提高了36%和47%。(5)为了进一步解析外加静磁场对MFC电池性能的提升机理,论文对不同外加磁场强度条件下系统内碳氮元素流向进行了分析,并且建立了可以用于描述MFC运行过程的数学模型。结果表明:在低磁场强度下,MFC系统有机物、氨氮和总氮的去除率及库伦效率随着磁场强度的增加而上升。外加静磁场强度为220 mT时,系统COD去除率、氨氮去除率、总氮去除率和库伦效率最高,分别达到67.4%、63.6%、13.6%和60.5%。且通过氮平衡分析发现系统中有2%左右的氨氮是通过挥发去除的,剩余的是通过生化作用去除。外加静磁场作用下,MFC系统中更多的氨氮转化为硝态氮,系统的硝化作用更加彻底。通过碳平衡分析,可以发现在磁场作用下产甲烷过程会受到抑制,更多的碳元素会流向产电过程。通过建立的数学模型计算分析得到,MFC系统中产甲烷菌浓度随着磁场强度的增加而降低、产电微生物浓度随着磁场强度的增加呈现先上升后下降,磁场强度变化对硫酸盐还原菌浓度几乎没有影响;阳极极化电势损失、底物利用率及细胞膜厚度随着磁场强度的增加先上升后下降,而活化电势损失变化趋势相反,呈现随磁场强度增加先下降后上升。
[Abstract]:Sediment microbial fuel cell (SMFC) is a kind of anode electrode buried in anaerobic sediments, using microbial electrode surface and sediment metabolism, new processing technology pollutant removal and energy recovery. Trace elements play an important role in the process of the SMFC, the lack of trace elements necessary to cause microorganism the activity decreased, the removal effect and thus affect the stability of the operation of the whole system and the organic matter. In the process of electron transfer in SMFC, electricigens in cytochrome C plays a key role. The active center of cytochrome C for iron, iron addition will cause changes of cytochrome c, but the relationship between the content and activity of C iron and cytochrome remains to be explored. In this study, ferric ion as the main research object, to explore the influence of SMFC system, adding ferric ion to its operating characteristics at the same time, study abroad Static magnetic field composite ferric ion to further improve the feasibility of producing the electrical characteristics of the MFC system. The main contents are as follows: (1) the effects of ferric ion on the SMFC system of power generation performance. Adding ferric ion is helpful to improve the electricity production performance of sludge SMFC iron ion concentration at 500 mg/L. When the electricity production performance of SMFC system and enhance with the increase of concentration of ferric ion. When the iron ion concentration is 500 mg/L, the SMFC system has achieved the best performance of electricity production, electrochemical activity of the electrode surface resistance minimum. Under this condition, the maximum output power density of the battery, the maximum output voltage meter the concept of resistance was 597.2 mW/m2509.7mV in Kulun and the system efficiency, 37.7% and 101.1. (2) studied the effect of ferric ion on anode sludge properties. Anode sludge VSS and the removal rate of TSS was with iron ion concentration The increasing trend of first increase and then decrease. When the iron ion concentration is 500 mg/L, VSS and TSS, the highest removal rate, respectively 37.2% and 26.4%. SMFC in the process of system operation, SCOD in the supernatant of sludge, soluble polysaccharide and protein showed a variation of first increase and then decrease. With the increase of applied iron the ion concentration, the dehydrogenase activity of anode sludge firstly increased and then decreased, and the methanogenic activity was decreased. When the iron ion concentration is 500 mg/L, the highest dehydrogenase activity was 2569.4 u gTF/gVSS. iron ion is added to the SMFC system will be combined with the excess sludge material decreased bioavailability of added the formation of iron. Iron ions added is not easy to be use of Microbial Carbonates, organic and sulfate content of iron did not change in before and after the operation, exchangeable and adsorption State that the two forms of iron were used by microbes into the residual iron.500 mg/L iron ion concentration can meet the demand of microbial growth, concentration of iron concentration with initial bioavailability was 100 mg/L. (3) to study the relationship between the iron on the SMFC anode biofilm and influence mechanism of iron and cytochrome c the iron ion concentration is 500 mg/L, the control group biomass SMFC system of anode biofilm was added iron ions increased by about 30%, but the content of extracellular polymers decreased by 14%. addition of iron bacteria will improve door deformation on the anode biofilm abundance, iron ion concentration is 500 mg/L, the abundance of never bacterial deformation on the anode biofilm to add iron increased to 47% 80%. iron addition does not change the types of the anode biofilm electro active material, but will improve its electrochemical activity. Adding 500 mg/L iron ion, unit mass on the anode biofilm microorganisms The cytochrome C synthesis was increased by 2.4 times, the electron transfer efficiency of biological membrane unit mass was increased by 1.1 times, but due to lack of substrate, per unit mass of cytochrome C electron transfer number decreased. The purified from the anode biofilm on the cytochrome c analysis showed that the 1 mol cytochrome c containing 5 mol iron. Iron in the anode will affect the anode biofilm structure will be formed in the vicinity of the anode of Fe (II) /Fe (III) is used to improve the electron transfer efficiency of electronic intermediary; iron formed at the cathode of Fe (II) /Fe (III) temporary capacitor to decrease the cathodic polarization resistance, and improve the performance of the cathode, and the cathode is added the optimal concentration of iron ions was 500 mg/L. (4) to explore the external static magnetic composite ferric ion added to further enhance the feasibility of electricity generation system. To study the electrical properties of the system under the condition of static magnetic field applied, the anode biofilm changes and fine Changes in the content and activity of cytochrome c. The applied static magnetic field can further improve the electrical performance of the production system, shorten the starting time of the system. The static magnetic field of low intensity (mT = 220) conditions, the running characteristics of MFC system increases with the increase of magnetic intensity, high intensity magnetic field (370 m T) under the condition of cause irreversible damage to the system, the battery performance dramatically. The applied static magnetic field of 220 m T, the operation performance of the optimal MFC system, the battery output peak voltage, high power density, apparent battery internal resistance and anodic internal resistance were 756.1 mV, 1.5 W/m2,66.5 and 49.8 ohms. The static magnetic field strength under the condition of low, biological the amount of the anode biofilm on the dehydrogenase activity of extracellular polymer content and the biofilm increased with increasing intensity of static magnetic field. The applied static magnetic field is 220 mT, the MFC system of anode biomass, extracellular polymer content and biofilm removal The highest catalase activity were 60.31 mu gP/cm3,0.81 mu g/ gP and 2.45 gTF/ (gP - H). The static magnetic field of low intensity can improve the cytochrome C electron transfer to the anode efficiency. In 220 mT conditions, the content of cytochrome c and the electron transfer efficiency is not an external magnetic field on control group were increased by 36% and 47%. (5) in order to further improve the mechanism analysis of the applied static magnetic field on the performance of MFC battery, the paper analyzes the different magnetic field strength under the condition of carbon and nitrogen flow within the system, and the establishment of the mathematical model can be used to describe the MFC process. The results showed that: in the low magnetic field intensity MFC, organic matter, ammonia nitrogen and total nitrogen removal rate and Kulun efficiency increases with the increase of magnetic field strength. The applied static magnetic field strength is 220 mT, COD removal rate, the removal rate of ammonia nitrogen and total nitrogen removal rate and the high efficiency of Kulun, respectively. 67.4%, 63.6%, 13.6% and 60.5%. and the nitrogen balance analysis showed that the system has about 2% of the ammonia by volatilization is removed, the remaining is removed by biochemical effects. The applied static magnetic field, more ammonia nitrogen converted into nitrate nitrogen in MFC system, the nitrification system more completely. The carbon balance the analysis can be found, can be suppressed in methane production process under the action of magnetic field, the carbon flow will be more electricity production process. Through the establishment of mathematical model calculation and analysis, the MFC system of methanogenicbacteria concentration decreases with the increase of magnetic field intensity, the electricigens concentration with increasing magnetic field strength increased first and then decreased, magnetic field the intensity change has little effect on sulfate reducing bacteria concentration; anodic polarization potential loss, substrate utilization rate and membrane thickness with increasing magnetic field strength increases first and then decreases, and the activation potential The change trend of the loss is opposite, and it decreases and then rises with the increase of magnetic field strength.

【学位授予单位】：江南大学
【学位级别】：博士
【学位授予年份】：2017
【分类号】：TM911.45

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