Microbial Fuel Cells: Electricity Generation from Organic. Wastes by Microbes. Kun Guo a., Daniel J. Hassett b., and Tingyue Gu c a. National Key Laboratory of. Energies , 3, ; doi/en energies. ISSN cafein.pro Review. Microbial Fuel Cells. Microbial Fuel Cells. Principles, Development and. Applications. Chalmers Energy Conference. January 27th , Göteborg, Sweden. Industrial Biotechnology.
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𝗣𝗗𝗙 | Microbial fuel cells (MFCs) are bioelectrochemical devices that convert the chemical energy present in organic or inorganic compounds. Microbial fuel cells (MFCs) are devices that use bacteria as the catalysts to oxidize organic and inorganic matter and generate current (). MFCs can be the next generation of fuel cell and thus play an important role in energy There are different aspects of Microbial fuel Cells as well as different.
Pure copper crystals were observed as the main products formed on the cathode surface and no CuO or Cu 2 O was detected. In this case, the nitrate is reduced to nitrogen gas by the denitrification process in the cathode compartment. In a MFC operated using acetate and perchlorate, 0. A comparison of air and hydrogen peroxide oxygenated microbial fuel cell reactors. While uranium removal can be done by adsorption, biological reduction or membrane filtration, cathodic U VI reduction seems also to be a promising method. Apart from nitrate, some heavy metals such as copper Tao et al.
Not only do MFCs clean wastewater, but they also convert organics in these wastewaters into usable energy. Given the world's limited supply of fossil fuels and fossil fuels' impact on climate change, MFC technology's ability to create renewable, carbon-neutral energy has generated tremendous interest around the world. This timely book is the first dedicated to MFCs. It not only serves as an introduction to the theory underlying the development and functioning of MFCs, it also serves as a manual for ongoing research.
In addition, author Bruce Logan, a leading pioneer in MFC research and development, provides practical guidance for the effective design and operation of MFCs based on his own firsthand experience.
This reference covers everything you need to fully understand MFCs, including: Author Bios Bruce E. Free Access. Summary PDF Request permissions. PDF Request permissions. Tools Get online access For authors. Email or Customer ID. Forgot password?
Old Password. New Password. Your password has been changed. Persulfate is used in many applications such as clarifying swimming pools, hair bleaching, micro-etching of copper printed circuit boards, total organic carbon analysis and destructing soil and groundwater contaminants.
It is considered to be hazardous waste because it is an oxidizing agent Li J. Applicability of persulfate in MFCs is possible with its standard oxidation reduction potential of 2. Because of the above properties, persulfate was used as electron acceptor. This case was explained by the faster electron reduction kinetics of ferricyanide solution on the surface of the carbon electrode Li J.
Under both acidic and alkaline conditions, permanganate is reduced to manganese dioxide by receiving three electrons as shown in the Equations 8, 9. This property of permanganate makes it a potential electron acceptor. In acidic conditions, permanganate is expected to show higher power output since its oxidation potential is higher than it is in alkaline conditions. Therefore, studies in different pH values were done to investigate the performance of permanganate in MFCs You et al.
In a previous study, a power density of Moreover, in the same study, a bushing MFC using permanganate as the electron acceptor achieved the maximum power density of Therefore, it is worth pointing out that permanganate can be an efficient cathodic electron acceptor in MFCs You et al.
However, there are also some drawbacks existing in this application. For example, like other soluble electron acceptors, depletion of permanganate during electricity generation requires continuous liquid replacements.
Moreover, since the cathode potential is mainly dependent on the solution pH, pH control is required for stable power output, which may only be applied to small-scale power supplies as suggested by the authors. On the other hand, the advantage of this system is that it does not require catalysis You et al.
In a more recent study, the best permanganate concentration was studied in terms of electricity production. The maximum power density with mM of potassium permanganate and the current density at this power density were found to be Studies have reported that manganese dioxide is a good cathode material and catalysis for battery and alkalinine fuel cells Li et al.
Rather than direct utilization of oxygen, the use of electron mediators between cathode and oxygen is more efficient because of the difficulties in the direct utilization of oxygen i. The possibility of biomineralized manganese oxides was investigated by Rhoads et al. The reaction begins with the accumulation of manganese dioxide on the cathode surface and subsequent reduction with electrons from the anode.
The reaction results in the release of manganese ions which are subsequently reoxidized to manganese dioxide by manganese-oxidizing bacteria Lepthothrix discophora SP-6 , and the cycle continues Equations 10— Maximum power density of Manganese dioxide can be used not only in the electron mediator mechanism but also as an alternative cathode catalyst to platinum due to its low cost Liew et al. It could be, therefore, noted that using MnO 2 instead of Pt could serve as a suitable option for real applications due to its low cost Zhang L.
By using mercury in MFC, its removal from the aquatic environment can be achieved simultaneously with electricity production. Iron can be used as an electron mediator to enhance the performance in the cathode compartment. Ferric iron can be reduced to ferrous iron in the cathode chamber according to Equation This reversible electron transfer reaction provides several advantages such as fast reaction, high standard potentials, biological degradability Heijne et al.
In a study where this redox was coupled together with a bipolar membrane and graphite electrode combination, the maximum power density of 0. To achieve this, Heijne et al. Besides being an electron mediator, iron can also be used as an electron acceptor. Phosphorus is an essential element for both agricultural and industrial production. This important element, however, is assumed to be depleted within 50— years Cordell et al.
Since it is also one of the primary causes of eutrophication, it is essential to consider the recovery of phosphate rather than its disposal Usharani and Lakshmanaperumalsamy, CEMs are not suitable for pH adjustment in the cathode chamber since they carry other cations together with protons.
Therefore, either a bipolar membrane or acid addition is required when ferric iron is used Heijne et al.
The main advantage of this process is that the phosphate is obtained in pure form. Thus, phosphate can be separated from iron and other toxic materials such as As, Pb, Cr. However, low pH is required to keep ferric iron soluble since ferric iron is tent to be precipitated as ferric iron hydroxides at pH values higher than 2. These precipitates are reported to be harmful to membrane use. While iron was used as an electron acceptor, up-to-date studies show that it can also be used to prepare efficient catalysts Nguyen et al.
Copper is one of the widespread heavy metals in the soil and aquatic environment, which are mainly emitted from mining and metallurgical industries. Therefore, the removal of copper is of great importance. Simultaneous copper recovery and energy production in a two-compartment MFC were investigated Heijne et al.
The copper reduction in its basic form is shown in Equation Copper recovery in MFC was done by Heijne et al. The maximum power density was 0. Pure copper crystals were observed as the main products formed on the cathode surface and no CuO or Cu 2 O was detected. As noted in the previous work of the authors, the bipolar membrane provided low pH in the cathode compartment.
Tao et al. The maximum power density at the initial copper concentration of In order to further lower the construction cost for this process, Tao et al.
Copper is an attractive electron receiver that can compete with oxygen Tao et al. For this reason, the cathodic copper reduction has broadened the field of MFC applications.
Copper reduction and electricity generation may vary depending on the architectural structure and operational parameters of the reactors. In an up-to-date study, electricity production was investigated by multiple batch cycle operations with different cathode materials Wu D.
For the copper removal, a carbon rod, a titanium sheet, and stainless steel woven mesh materials were tested as cathode material. Stainless steel woven mesh was found as the most effective and cheap cathode material.
When copper reduction is desired in MFC, the deposition of copper on the cathode has a great effect on power density and copper removal.
However, this technology is still in an early stage of development, more developments such as cost-effective reactor design and study of the catalytic behavior of copper for oxygen reduction at the cathode are required.
Studies on copper removal in MFC indicate that the power density can be up to The use of chromium as an electron acceptor has been demonstrated in several studies Li et al. Real and synthetic wastewaters containing chromium were treated in MFCs and chromium reduction and electricity production were accomplished simultaneously.
This reduction reaction is thermodynamically feasible with a redox potential of 1. In another study, Li et al. In this study, Cr VI removal was found to be influenced by the electrode material.
Graphite paper and graphite plates were used as cathode material in chrome removal and graphite paper gave better results than graphite plate power density: The maximum potential generated under light irradiation and dark controls were 0.
The authors used rutile coated cathode for waste treatment and solar energy conversion in a single unit of MFC. These synergies between a biocatalyzed anode and a rutile coated cathode promoted the power output and Cr IV reduction Li Y.
In an up-to-date study, the microbial concentration was increased to improve chromium reduction performance in the cathode chamber. For this, the exoelectrogenic biofilm was enriched in the anode compartment and the system was subsequently established using the anode as biocathode. This new method has increased Cr VI reduction efficiency by 2.
Other recent studies on Cr VI reduction were focused on self-assembled graphene biocathode applications Song et al. Current studies are usually focused on the cathode material for chromium removal. In another study with abiotic cathode, a power density of There are some advantages of using this redox couple in the cathode.
It also demonstrates the feasibility of using carbonaceous materials as the cathode. Triiodide is stable at both acidic and alkaline conditions. The feasibility of this redox couple as the electron acceptor or mediator was first demonstrated using a two-chambered MFC Li J. Schematic view of the MFC using aqueous iodide ion solution as the catholyte Li et al. The present investigations are mainly carried out with H type MFCs, more efficient reactor design for high power generation is still required.
Therefore, this negative effect should be taken into consideration when designing a new configuration for better performance Li J. Because of its strong oxidizing properties, H 2 O 2 is used as an electron acceptor and its mechanism is presented in the following equation.
The oxygen concentration used in the cathode section can also be added to hydrogen peroxide. The use of hydrogen peroxide has been reported to provide stability in long-run operations in MFC Tartakovsky and Guiot, In a comparison of air with hydrogen peroxide, the power density in the air-operated MFC was 7.
Liquid hydrogen peroxide provides high levels of oxygen. This ensures high performance in long-run operation Tartakovsky and Guiot, While H 2 O 2 is used to remove contaminants with hydroxyl radicals formed as a result of reaction with fenton, the remaining H 2 O 2 must be removed. For this purpose, Zhang et al. In the MEC mode, methylene blue was removed with H 2 O 2 , while the residual H 2 O 2 was removed in the cathode as an electron acceptor.
With the study, H 2 O 2 was effectively controlled and contaminant removal was ensured Zhang Y. Thermodynamically, CO 2 reduction has a very low redox potential and its use in the cathode compartment produces a very low voltage. However, the cathode potential must be higher than the anode potential in order to generate electricity.
For this reason, external energy must be supplied in order to provide CO 2 reduction Cao et al. Cao et al. Electrons could be received by the carbon dioxide, according to the following equation Equation 23 , where CH 2 O represents the biomass. In this way, CO2 reduction is provided together with biomass production. This bio-reaction allows the CO 2 sequestration.
Another application of CO 2 in the cathodic chambers is to reduce carbon dioxide to methane Equation 24; Villano et al. Since both electrons and CO 2 are released during the oxidation of organic matter, these substances may participate in the production of methane.
Villano et al. This process has some advantages. Firstly, the methanogens are protected from possible inhibitors present in the wastewater by separating the oxidation part of the organic matter from the methane production. Secondly, this process consumes less energy because there is no need to heat the cathode section to maintain the temperature.
In addition, this process leads the operation of anaerobic digestion and methane producing steps in the series. Therefore, the system is also effective at low substrate concentrations Villano et al. In recent years, reduction of CO 2 to biofuels or commodity chemicals in the cathode with the help of microbes and externally supplied electricity has gained tremendous attention.
Researches in this area have opened a new door for biofuel or chemical production by overcoming the limitation in natural photosynthesis processes and corresponding processes have been commonly named as microbial electrosynthesis or recently as artificial photosynthesis.
Via these processes, multicarbon compounds such as acetate Patil et al. Perchlorate is a drinking water contamination of interest due to its high mobility and inhibitory effect on thyroid functions Cetin et al. Among the treatment alternatives, biological reduction is a cost effective method Ucar et al.
Butler et al. In a MFC operated using acetate and perchlorate, 0. With this method, it is possible to purify perchlorate, which can be found in ground waters. Nitrate is the most common pollutant found in groundwater. Thus, perchlorate and nitrate removal can be considered together in MFC. In a recent study conducted for this purpose, nitrate and perchlorate removal were investigated in the autotrophic denitrification biocathode. In acetate-fed MFC, Acetate has been reported as the most suitable electron source for perchlorate and nitrate reductions Lian et al.
Reduction of nitrate and perchlorate with acetate can be carried out at high efficiency, but in the case of nitrates in drinking water, the use of organic electron sources such as acetate is likely to lead to unused acetate in the effluent.
In such cases, the use of inorganic electron sources such as sulfur may be more appropriate. Inorganic electron donors also have their own disadvantages, for example, when sulfur is used, sulfate and acidity can occur in the effluent.
However, in recent studies, the use of the advantages of both systems in the removal of nitrate and perchlorate from drinking and underground waters and the elimination of disadvantages are becoming increasingly widespread Ucar et al. Another example of the use of MFC in pollutant removal is vanadium removal. Vanadium is usually found in wastewaters of vanadium mines and pentoxide processing activities Carpentier et al. At the vanadium reduction, both organic and inorganic compounds can be used as electron donors Zhang et al.
Zhang B. The authors demonstrated the removal of sulfide and vanadium in the anode and cathode chambers of MFC respectively Equations 26— Sulfur and vanadium removal rates were Zhang et al. It has been reported that the initial sulfur concentration has an effect on microbial activity Zhang et al. As the initial sulfide concentration increased, microbes in the anode compartment became less effective, which resulted in a long lag time and decreased sulfide removal efficiency from Anodic electrolyte conductivity is another factor affecting vanadium V removal and electricity production Zhang et al.
Increased anode electrolyte conductivity considerably raised the sulfur and vanadium reduction rates. This can be explained by the increased electron transfer rate at enhanced conductivity. Increasing anode electrolyte conductivity to The initial concentration of Vanadium V is also the factor affecting the system performance.
In addition, Vanadium V removal rate increased with the decrease of pH. Acidic conditions were necessary to compensate for the slower proton transport rate through the membrane. Under optimized conditions, average removal rates of sulfide and V V were Similar power densities were found in more recent studies. Hao et al. In another study, V was simultaneously reduced in both anode and cathode compartments. The total vanadium removal rate was reported as Leachate in uranium processing areas have low but stable uranium concentrations and can contaminate water resources, groundwater and sediment Williams et al.
To solve this problem in situ, metal reducing bacteria are usually used together with the acetate feed Vrionis et al. While uranium removal can be done by adsorption, biological reduction or membrane filtration, cathodic U VI reduction seems also to be a promising method. Williams et al. The removal pathway of U IV , however, is still uncertain. The removal mechanism of the uranium may be explained as reductive immobilization of U IV by non-acetate oxidizing sulfate reducers N'Guessan et al.
Chlorinated aliphatic hydrocarbons CAHs , which are widely used as solvents and degreasing agents, could become a huge risk due to their toxic and carcinogenic properties. These pollutants can be removed by some anaerobic bacteria which remove chlorines from CAHs by degrading them with the electrons obtained from an external electron donor or externally supplied voltage Holliger and Schraa, An alternative version of this approach is to use insoluble electrodes to provide electrons to dechlorinating communities.
Studies with two different communities mixed culture of dechlorinating bacteria and pure culture of Geobacter lovleyi showed that in a mixed culture, dechlorination of TCE was successfully achieved under acetate fed conditions Aulenta et al. The formed dechlorination products were cis-DCE It has been proved that polarized carbon paper electrode can be used as the sole electron donor for the complete dechlorination of TCE with a mixed culture Aulenta et al.
Supplying external electron donors to the contamination zone may result in some unwanted processes and accumulate byproducts. In that case MFC with a solid electrode has a great advantage since bacterial oxidation happens in the anode and no external organic matter is added to the site Aulenta et al.
As reported in the case of chloroethens, using solid electrode as the sole electron donor is more advantageous than using soluble electron donors directly Aulenta et al. Application of electrodes to support necessary electrons for pollutant reduction, could be used for bioremediation of chlorinated contaminants and metals Strycharz et al.
Geobacter is one of the typical species used for this purpose. Strycharz et al.
More recently, dechlorination of 2-chlorophenol has also been examined by Akbulut et al. One hundred fifty micro molar 2-chlorophenol was removed with a crude laccase enzyme under optimum dechlorination conditions Akbulut et al. There are several advantages to use solid electrodes as an electron donor for chloroethens reduction Strycharz et al.
Firstly, electrons can be effectively transferred to microorganisms for reducing the pollutant. Secondly, the electrode as electron donor can be easily applied to the site. Thirdly, if contaminants are reacted directly with electrode, unwanted reaction can be eliminated. Lastly, contaminant metals can be extracted from the electrode surface where they precipitated.
This review summarizes the various cathodic electron acceptors that have been used in MFCs Some of these electron acceptors are also pollutants in aquatic systems. Therefore, a treatment process is also possible with MFC. Yet, the list is by no means exhaustive as newer electron acceptors may emerge accompanying the development of cathodic catalysts, electrode materials and solution chemistry.
In the early applications of MFC, oxygen was commonly used as a terminal electron acceptor in the cathode chamber. However, in recent years, researchers are exploring more unconventional cathodic electron acceptors with an aim of improving MFC voltage potential on one hand and treating special wastewater or recovering valuable chemical on the other hand.
The production of electricity with the reduction of specific electron acceptors in the cathode has promising potential in terms of bioenergy production as well as reducing the cost of special pollutant treatment e. MFC could be more efficient by using specific electron acceptors. Ferricyanide or hydrogen peroxide may be used for high power output or iron could be used to release of some valuable compounds such as phosphate from wastewaters. Cathodic electron acceptors being used in MFCs have grown in diversity.
The aim of alternative electron acceptors exploration shifted from initial high voltage output to both energy production and recalcitrant pollutant treatment or valuable chemical recovery. Similar application of MFC configuration in the contaminated site remediation is to apply electrodes into the land and providing the voltage externally to transfer electrons to microorganisms as mentioned in Section Chloroethenes and 2-Chlorophenol.
This application could provide the effective delivery of electrons.
By this way, electrodes can also place to site according to the remediation requirements. On the other hand, reduced metals and other pollutants can be effectively removed from the site by precipitating on the electrode surface. Electricity current is an indication of the microbial activity in MFC. Thus, biosensors can be developed on the basis of MFC to detect substances which may directly affect the microbial activity i. This process is related to activity in the anode compartment, and MFCs can also be developed as cathodic biosensors for monitoring specific pollutants in the cathode compartment according to varied redox potentials.
Substantial contributions to the conception or design of the work; or the acquisition, analysis, or interpretation of data for the work; IA: Drafting the work or revising it critically for important intellectual content; DU and YZ: Agreement to be accountable for all aspects of the work in ensuring that questions related to the accuracy or integrity of any part of the work are appropriately investigated and resolved; YZ: Critical revision; IA: Final approval of the version to be published.
The authors declare that the research was conducted in the absence of any commercial or financial relationships that could be construed as a potential conflict of interest. National Center for Biotechnology Information , U. Journal List Front Microbiol v. Front Microbiol. Published online Apr Author information Article notes Copyright and License information Disclaimer. Reviewed by: Deniz Ucar moc. Yifeng Zhang kd. This article was submitted to Microbiotechnology, Ecotoxicology and Bioremediation, a section of the journal Frontiers in Microbiology.
Received Dec 14; Accepted Mar The use, distribution or reproduction in other forums is permitted, provided the original author s or licensor are credited and that the original publication in this journal is cited, in accordance with accepted academic practice. No use, distribution or reproduction is permitted which does not comply with these terms. This article has been cited by other articles in PMC. Abstract Microbial fuel cells MFC have recently received increasing attention due to their promising potential in sustainable wastewater treatment and contaminant removal.
Introduction A microbial fuel cell MFC is a bioelectrochemical device that can generate electricity by the use of electrons obtained from the anaerobic oxidation of substrates. Open in a separate window. Figure 1. Schematic representation of a two-chambered MFC. Alternative electron acceptors Ferriciyanide Besides oxygen, ferricyanide is another common electron donor used in MFC studies since its concentration is not limited to solubility like in the case of oxygen Rhoads et al.
Nitrogen species Nitrate is one of the common types of nitrogen that is widely found in waters, and causes a variety of serious environmental and health problems that threaten human and animal health Demirel et al. Persulfate Persulfate is used in many applications such as clarifying swimming pools, hair bleaching, micro-etching of copper printed circuit boards, total organic carbon analysis and destructing soil and groundwater contaminants. Permanganate Under both acidic and alkaline conditions, permanganate is reduced to manganese dioxide by receiving three electrons as shown in the Equations 8, 9.
Manganese dioxide Studies have reported that manganese dioxide is a good cathode material and catalysis for battery and alkalinine fuel cells Li et al. Iron Fe Iron can be used as an electron mediator to enhance the performance in the cathode compartment.
Figure 2. Table 1 Cathodic electron acceptors and the maximum power densities. Copper Copper is one of the widespread heavy metals in the soil and aquatic environment, which are mainly emitted from mining and metallurgical industries.