微生物燃料电池降解啤酒废水及同步产电特性

通过构建无媒介双室型微生物燃料电池(MFC),考察其降解啤酒废水的效果及同步产电特性。研究了外接电阻、温度和阴极曝气等条件对MFC产电的影响,监测了电池外电压和电极电势的变化过程,分析了微生物燃料电池的运行机理。通过稳态放电法得到以碳纤维布作为阳极材料的双室型微生物燃料电池的内阻为1 000Ω,最大产电功率密度为375 mW/m2。以啤酒废水为底物的MFC对COD的去除率为84%左右,外电压为0.21 V,库仑效率约为15%;而在以葡萄糖为底物的条件下,MFC的外电压为0.3 V,对COD的去除率为89%,产电性能及除污效率均有所提高。     

无介体微生物燃料电池的研究进展

微生物燃料电池的出现使得降解有机污染物的同时收获电能成为可能，因而受到广泛关注。从产电微生物和电池结构两部分介绍了无介体微生物燃料电池的研究进展，对产电微生物的研究主要从产电微生物的种类、影响微生物产电的因素以及产电机理等方面进行阐述；对微生物燃料电池结构的研究，主要从电池阳极及阳极室、阴极及阴极室、分隔材料、整体结构和运行方式等方面进行了阐述；从提高微生物燃料电池产电能力的角度出发，对微生物和电池结构提出了研究方向，并展望了产电微生物燃料电池的研究前景。     

用于产电纯菌研究的MFC反应器的开发

以纯菌为对象进行产电机理研究是微生物燃料电池(MFC)技术进一步提高输出功率、走向实用的重要基础之一,然而由于产电纯菌研究要求的无菌性、厌氧性较为苛刻,给此类反应器的搭建、运行造成诸多困难。基于此,设计搭建了一种可灭菌的组件式两瓶型MFC,对其各组件进行了比较研究,并考察了接种Geobacter sulfurreducens后MFC的运行情况。研究结果表明,该反应器在运行周期内可保持良好的灭菌状态;使用铁氰化钾可有效地降低阴极极化,并保持阳极室的厌氧状态;该反应器可以较好地满足MFC对纯菌研究的要求。     

表面改性碳纳米管粉体在微生物燃料电池中的应用

微生物燃料电池(MFC)是一种集产电和污水净化为一体的新型水处理技术,但产电性能低限制了MFC的推广应用.为了提高MFC的产电性能,在阳极室投加表面改性的碳纳米管(CNTs)粉体,以加速阳极产电生物膜的形成,同时提高整个生物膜的产电能力.投加经过氨气处理的CNTs粉体后,MFC运行仅4 h其输出电压即升至400 mV;投加经过混酸处理后的CNTs粉体,得到了MFC的最大产电功率密度为(236±5)mW/m<'2>,相对于对照组则提高了约40%.氨基的引入是启动时间缩短的主要原因,而阳极内阻的降低是产电功率密度得以提高的主要原因.     

新型滴滤式生物阴极微生物燃料电池的性能研究

设计了新型滴滤式生物阴极微生物燃料电池(MFC),考察了其产电及污水净化特性。滴滤式MFC阴极的充氧效果良好,稳定产电的电流密度高达39 A/m3,最佳阴极循环流量为120 mL/min,此时最大功率密度为91.2 W/m3。滴滤式MFC可以实现阳极除碳、阴极硝化,对COD和NH4+-N的去除率分别为72.8%和98.7%,且阴极的硝化过程在一定程度上缓解了阴极pH值的升高。滴滤式MFC能够在无机械曝气的条件下维持产电和净化污水效能,其低能耗的特点为MFC的实际应用提供了一种新的解决方案。     

利用藻类和厌氧污泥构建的微生物燃料电池及其产电净水性能研究

针对传统微生物燃料电池产电效率低、处理污水效果差的现状,提出并详细介绍了一种在藻类和厌氧污泥协同作用下的微生物燃料电池装置。该装置利用藻类的光合作用和厌氧污泥净化污水的作用,既能高效产电又能净化城市黑臭水。同时,通过实验研究了该装置的产电性能和COD降解效果。结果显示该装置最大输出功率密度可达到1.83 m W/m~2,COD总降解效率约为64.0%,表明了在藻类和厌氧污泥的协同作用下微生物燃料电池的产电效能和净化黑臭水的效果远大于传统微生物燃料电池,具有良好的应用前景。     

以葡萄糖为底物的微生物燃料电池产电特性研究

以城市污水处理厂的好氧和厌氧污泥作为接种液,通过构建双室微生物燃料电池,考察了以葡萄糖为底物时连续流微生物燃料电池降解有机物及产电的特性.结果表明:以泡沫镍板、石墨板作为阳极时的产电效果较好;在一定温度范围内,提高温度可增大电池的输出电压和开路电压;对阴极室供氧可提高微生物燃料电池的开路电压和输出电压;随着外接电阻值的增大,微生物燃料电池的输出电流变小,符合原电池电极的一般规律.     

微生物燃料电池处理污水并产能的潜力分析

全球性能源危机导致污水处理朝着资源化与能源化的方向发展。欧美倡导的"能源工厂"或"碳中和"运行理念更是激发了从污水中回收能源的国际研发与应用热潮。作为一种能够同时将有机物去除并将其所蕴含的能量直接以电能回收的技术,微生物燃料电池(MFC)技术研发方兴未艾。这就需要首先在科学上系统了解MFC的发展历程、基本原理、研究现状,继而从工程角度分析MFC在污水处理中得以应用的潜力。在总结MFC最新研发进展的基础上,对MFC用于实际污水处理可获得的能量进行了匡算,发现其能源转化效率还不及污水处理剩余污泥厌氧消化产甲烷可获得的能源转化效率。况且,MFC的有限能量转化是以牺牲脱氮除磷所需碳源作为代价。以MFC为基础衍生而来的微生物电解电池(MEC)产氢技术在实际应用时可能亦存在相同问题。面对MFC/MEC目前的应用窘境,对其未来技术研发走向进行了定位。     

人工湿地/微生物燃料电池技术的发展现状

人工湿地技术(CW)和微生物燃料电池(MFC)处理技术都是通过微生物的作用去除污水中的污染物。微生物燃料电池的阳极区为厌氧环境、阴极区则为好氧环境,而氧化还原条件和氧化还原电位梯度在人工湿地填料层中可自然形成。因此,近几年兴起对这两种污水处理技术相结合的研究,由此开发了人工湿地/微生物燃料电池技术(CW/MFC)。虽然国内外对于CW/MFC的研究才刚起步,资料有限,但CW/MFC的雏形已经形成。在综述国内外已有的CW/MFC文献资料的基础上,提出这一环境友好型污水处理和潜能利用技术今后的研究方向及面临的挑战。     

硅烷偶联剂修饰MFC阳极及其电池性能的研究

以碳毡为基础电极材料,使用新型有机材料硅烷偶联剂(KH550、KH580和KH792)修饰MFC的阳极,分析其对MFC产电性能和电极生物膜菌群结构的影响,旨在探讨电极修饰材料、电池性能和电极生物膜三者之间的关系。试验结果表明,带氨基的KH550和KH792能够有效提升MFC的产电性能,其功率密度可分别提高50%和28.5%。而带巯基的KH580不能提升MFC的产电性能,还减缓了启动速度。电极生物膜的群落分析结果表明,阳极生物膜(无论修饰前还是修饰后)的主要微生物群落为变形菌(Proteobacteria)和厚壁菌(Firmicutes)。经过修饰后,电极上的菌群结构发生了变化,其生物多样性高于修饰前,且这种变化主要来自电极材料对微生物吸附效果的差异。此外,硅烷偶联剂的分子结构和电极上微生物菌群结构表明,材料的官能团对于电极生物膜菌群结构的影响大于烷基链。     

A comparative study on treatment of wastewaters with various biodegradability and various pH values using single‐chamber microbial fuel cells

This work assessed the performance of a single‐chamber microbial fuel cell (MFC) with various substrates. Primary settled domestic wastewaters were used to simulate wastewaters of high biodegradability; while phenol‐based wastewaters and benzene‐based wastewaters were used to simulate wastewaters of low biodegradability. Experiments were performed at initial pH values of 6, 7 and 8. The maximum voltage production, power density and removal of substrate were obtained using primary settled domestic wastewater, whereas the lowest values were obtained using phenol‐based wastewater. The maximum chemical oxygen demand removal efficiency, phenol removal efficiency and benzene removal efficiency were 80.8, 63.3 and 77.8%, respectively. The performance of the MFC was enhanced by increasing the influent pH. The lowest coulombic efficiencies were obtained from phenol‐based wastewater and benzene‐based wastewater, which indicated that electrogenic bacteria were not the primary microorganisms responsible for the biodegradation of low biodegradable wastewater.     

Electricity generation from cysteine in a microbial fuel cell

In a microbial fuel cell (MFC), power can be generated from the oxidation of organic matter by bacteria at the anode, with reduction of oxygen at the cathode. Proton exchange membranes used in MFCs are permeable to oxygen, resulting in the diffusion of oxygen into the anode chamber. This could either lower power generation by obligate anaerobes or result in the loss in electron donor from aerobic respiration by facultative or other aerobic bacteria. In order to maintain anaerobic conditions in conventional anaerobic laboratory cultures, chemical oxygen scavengers such as cysteine are commonly used. It is shown here that cysteine can serve as a substrate for electricity generation by bacteria in a MFC. A two-chamber MFC containing a proton exchange membrane was inoculated with an anaerobic marine sediment. Over a period of a few weeks, electricity generation gradually increased to a maximum power density of 19 mW/m(2) (700 or 1000 Omega resistor; 385 mg/L of cysteine). Power output increased to 39 mW/m(2) when cysteine concentrations were increased up to 770 mg/L (493 Omega resistor). The use of a more active cathode with Pt- or Pt-Ru, increased the maximum power from 19 to 33 mW/m(2) demonstrating that cathode efficiency limited power generation. Power was always immediately generated upon addition of fresh medium, but initial power levels consistently increased by ca. 30% during the first 24 h. Electron recovery as electricity was 14% based on complete cysteine oxidation, with an additional 14% (28% total) potentially lost to oxygen diffusion through the proton exchange membrane. 16S rRNA-based analysis of the biofilm on the anode of the MFC indicated that the predominant organisms were Shewanella spp. closely related to Shewanella affinis (37% of 16S rRNA gene sequences recovered in clone libraries).     

Fouling of proton exchange membrane (PEM) deteriorates the performance of microbial fuel cell

The fouling characteristics of proton exchange membrane (PEM) in microbial fuel cell (MFC) and the resulting deterioration of MFC performance were explored in this study. It was observed that the ion exchange capacity, conductivity and diffusion coefficients of cations of PEM were reduced significantly after fouling. Imaging analysis coupled with FTIR analysis indicated that the fouling layer attached on PEM consisted of microorganisms encased in extracellular polymers and inorganic salt precipitations. The results clearly demonstrate that PEM fouling deteriorated the performance of MFCs and led to a decrease in electricity generation. Cation transfer limitation might play an important role in the deterioration of MFC performance because of the membrane fouling. This was attributed to the physical blockage of charge transfer in the MFC resulted from the membrane fouling. With the experimental results, the effect of membrane fouling on the electrical generation of MFCs was evaluated. It was found that the decreased diffusion coefficients of cations and cathodic potential loss after membrane fouling contributed mainly to the deterioration of the MFC performance.     

混合编程在桥梁钻孔桩施工图设计中的应用

以桥梁钻孔桩施工图设计为例,利用MFC与ObjectARX混合编程技术进行CAD二次开发,采用动态链接库的方式,将C＋＋和FORTRAN程序设计语言进行结合,充分发挥MFC强大的功能,编制相关可交互的用户界面,很好的将计算和绘图结合在一起,从而提高桥梁施工图设计效率。     

Biocenosis of BAC(F)s used for groundwater treatment

The studies on the biocenosis of biologically active carbon filters (BAC(F)) used in treatment of Miocene water revealed the presence of protozoa of the group of flagellates and ciliates (Glaucoma sp., Opercularia sp.), saprophytic bacteria, phase I and II nitrifying bacteria, Fe(II) and Mn(II) oxidizing bacteria of the family Siderocapsaceae, Leptothrix ochracea and Pedomicrobium sp., as well as microscopic fungi. The stratification of biofilter colonisation by these microorganisms was found to be similar to that occurring in biofilters applied in sewage treatment. A hypothetical model of microbiological transformations in BAC(F)s, brought about by various physiological groups of microorganisms, is presented. It is shown that ozone pre-treatment of water dosed to the biofilter reduces the number of saprophytic bacteria and moulds in its upper layer, as well as Fe(II) oxidizing bacteria of the family Siderocapsaceae across the full section of the biofilter; it does not, however, influence the abundance of nitrifying phase I and II autotrophic bacteria and Mn(II) oxidizing bacteria of the family Siderocapsaceae. The abundance of microorganisms in the biofilter outflow is increased in comparison with that in untreated water; they do not, however, create a health hazard for human beings.     

Three different phototrophic microbial communities colonizing a single natural shelter containing prehistoric paintings

Three different cases of deterioration were identified in a single natural shelter containing prehistoric paintings. The microbial communities induced by run-off water, a black crust covering a portion of the shelter, and a cryptoendolithic microbial community, were studied. Molecular analyses based both on DNA and RNA were performed to identify the major components of these microbial communities present and metabolically active, respectively, at the studied location. While similar microbial communities were expected due to the proximity of the studied sites, clearly different communities were detected suggesting that specific microorganisms adapt to different micro-environments. Phototrophic microorganisms represented the major portion of total RNA and DNA in the studied microbial communities. Run-off water induced the presence of a large proportion of putative photosynthetic bacteria belonging to Chloroflexi. Different groups of bacteria were associated to phototrophs and were represented by Alpha, Beta, Delta, and Gammaproteobacteria, Acidobacteria, Actinobacteria, Bacteroidetes, and Planctomycetes. The present study confirms a need for careful monitoring of microbial communities associated to distinct cases of deterioration even within a single location, underlining the interest of phototrophic microorganisms as indicators of colonization on cultural heritage at natural shelters.     

Effect of anaerobic conditions on activated sludge filamentous bulking in laboratory systems

The effect of anaerobic conditions on the occurrence of filamentous microorganisms in the biocenosis of activated sludge has been studied in laboratory systems. These systems consisted of an anaerobic completely mixed tank followed by an oxic one. A single oxic completely mixed tank served as a control unit. Synthetic wastewater was used incorporating glucose and ethanol as a carbon source in order to support the growth of filamentous microorganisms in completely mixed tanks. It has been demonstrated that the growth of some filamentous organisms, for instance Type 021N and Sphaerotilus natans, was suppressed under anaerobic conditions as a result of lower rates of polyphosphate depolymerization under anaerobic conditions. However, the positive effect of the anaerobiosis may be eliminated if simultaneous dissimilatory sulphate reduction occurs. In this case filamentous bulking caused by presence of such microorganisms like Thiothrix is possible.     

Electricity generation using membrane and salt bridge microbial fuel cells

Microbial fuel cells (MFCs) can be used to directly generate electricity from the oxidation of dissolved organic matter, but optimization of MFCs will require that we know more about the factors that can increase power output such as the type of proton exchange system which can affect the system internal resistance. Power output in a MFC containing a proton exchange membrane was compared using a pure culture (Geobacter metallireducens) or a mixed culture (wastewater inoculum). Power output with either inoculum was essentially the same, with 40+/-1mW/m2 for G. metallireducens and 38+/-1mW/m2 for the wastewater inoculum. We also examined power output in a MFC with a salt bridge instead of a membrane system. Power output by the salt bridge MFC (inoculated with G. metallireducens) was 2.2mW/m2. The low power output was directly attributed to the higher internal resistance of the salt bridge system (19920+/-50 Ohms) compared to that of the membrane system (1286+/-1Ohms) based on measurements using impedance spectroscopy. In both systems, it was observed that oxygen diffusion from the cathode chamber into the anode chamber was a factor in power generation. Nitrogen gas sparging, L-cysteine (a chemical oxygen scavenger), or suspended cells (biological oxygen scavenger) were used to limit the effects of gas diffusion into the anode chamber. Nitrogen gas sparging, for example, increased overall Coulombic efficiency (47% or 55%) compared to that obtained without gas sparging (19%). These results show that increasing power densities in MFCs will require reducing the internal resistance of the system, and that methods are needed to control the dissolved oxygen flux into the anode chamber in order to increase overall Coulombic efficiency.     

Identification of microorganisms involved in reductive dehalogenation of chlorinated ethenes in an anaerobic microbial community

In this study, we report on phylogenetic and physiological characterization of an anaerobic culture capable of reductive dehalogenation of tetrachloroethene (PCE) obtained from a PCE-contaminated site. The culture was enriched using different combinations of electron donors (hydrogen and acetate) and electron acceptors (PCE, cis-1,2-dichloroethene (cDCE) and controls without chlorinated ethenes). The resulting subcultures were analyzed using three different approaches: chemical analysis to document conversion of chlorinated ethenes; polymerase chain reaction (PCR) of 16S rRNA gene fragments and denaturing gradient gel electrophoresis (DGGE) to compare community compositions; fluorescence in situ hybridization (FISH) to quantify specific groups of microorganisms using oligonucleotide probes previously designed or newly designed based on the sequences retrieved from sequence analysis of specific DGGE bands. Members of two genera which contain bacteria capable of reductive dehalogenation were detected in the culture: Dehalococcoides and Desulfitobacterium. The combined analyses suggested that Dehalococcoides-like bacteria are associated with complete dehalogenation of chlorinated ethenes to ethene with hydrogen as electron donor; and Desulfitobacterium-like bacteria, in contrast, are associated with incomplete PCE dehalogenation to cDCE and appear to be able to use acetate as electron donor. In addition, Sporomusa-like bacteria were identified, which most likely act as homoacetogens. The results demonstrated that combination of culture enrichment with different substrates, DGGE, and FISH allowed a detailed qualitative and quantitative characterization of the dominant microorganisms associated with reductive dehalogenation.