Microbial Fuel Cells

Das Ziel dieser Arbeit war, das Anwendungspotential der Wasserstofftechnologien auf Kläranlagen aufzuzeigen. Wie bereits in der Einleitung dieser Arbeit erwähnt, ist zum Schutze des Klimas eine massive Minderung der von uns Menschen erzeugten CO2-Emissionen erforderlich. Das heisst, dass die derzeitigen primären, fossilen und auch endlichen Energieträger durch nachhaltige, erneuerbare Energieträger, wie z.B. Windkraft, Photovoltaik, etc., ersetzt werden müssen. Der Ausbau der erneuerbaren Energien und die Reduzierung der Treibhausgase um 80 % bis zum Jahr 2050, sind klare Ziele der deutschen Bundesregierung. Der Ausbau der erneuerbaren Energien hat zur Folge, dass grosse Kapazitäten an elektrischer Energie als Überschussenergie vorhanden sein werden. Diese Überschussenergie gilt es für nachhaltige Prozesspfade sinnvoll einzusetzen. Einer dieser Pfade stellt die Umwandlung der Überschussenergie in „Power-to-X“ mittels diverser Wasserstofftechnologien dar. Wasserstoff wird im Rahmen der Dekarbonisierung wieder als idealer sekundärer Energieträger für eine schadstofffreie Energieversorgung gehandelt. Kläranlagen sind grosse Energieverbraucher, aber auch potentielle Energieerzeuger. Der Standort Kläranlage bietet sich, aufgrund seiner bestehenden Infrastruktur, hervorragend für die Implementierung der Wasserstofftechnologie an. Zur Herstellung von Wasserstoff gibt es viele verschiedene Verfahren. Auf Kläranlagen hat sich bisher gezeigt, dass die Wasserdampfreformierung und die Wasserelektrolyse für die Herstellung von Wasserstoff Stand der Technik sind. Der Unterschied zwischen beiden Verfahren ist, dass für die Wasserdampfreformierung eine ausreichend grosse Faulgasmenge zum kontinuierlichen Betrieb der Dampfreformierung notwendig ist. Bei der Wasserelektrolyse gibt es mit der alkalischen - und der PEM-Elektrolyse zwei kommerzielle Typen von Elektrolyseuren, welche sich auf Kläranlangen in kommerziellen Projekten bewiesen haben. Abhängig vom Leistungsbereich, von den Investitionskosten und vom Platzangebot auf der Kläranlage, ergeben sich für den Einsatz von Elektrolyseuren kläranlagenspezifische Entscheidungen. Die hier angegebenen Systemwirkungsgrade der Elektrolyseure liegen in Wirklichkeit viel höher, da zum einen ihre Abwärme auf der Kläranlage, z.B. für den Faulbehälter, verwendet werden könnte und zum anderen können sie bei Überschussenergieaufnahme eine Abschaltung der Windkraft- und Photovoltaikanlagen verhindern. Mit beiden Elektrolyseurtypen wird neben dem Wasserstoff auch Sauerstoff erzeugt. Der Sauerstoff kann stofflich im Belebungsbecken oder in der Beseitigung von Spurenstoffen mit Ozon eingesetzt werden. In beiden Fällen hätte der eingesetzte Sauerstoff eine Energieeinsparung zur Folge, weil zum einen die herkömmliche energieintensive Druckbelüftung wegfallen könnte und zum anderen für die Ozonierung der Sauerstoff nicht zusätzlich produziert oder über externe Lieferanten bereitgestellt werden müsste. Für den Einsatz von Sauerstoff auf Kläranlagen gibt es in der Literatur noch keine ausreichend praxistauglichen und belastbaren Zahlen, jedoch wird derzeit dieses Thema in verschiedenen Projekten untersucht. Der auf Kläranlagen erzeugte Wasserstoff kann zwischengespeichert und je nach Bedarf zu einem späteren Zeitpunkt rückverstromt werden. Die Rückverstromung kann über ein Wasserstoff- oder über ein Brennstoffzellen-BHKW stattfinden. Dabei kann die entstehende Abwärme für Wärmesenken, wie z.B. den Faulbehälter, die Betriebsgebäudeheizung oder die Beheizung des Belebungsbeckens im Winter, verwendet werden. Falls ein lokales Erdgasnetz vorhanden ist, besteht die
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Möglichkeit, den entstandenen Wasserstoff bis zu 2 Vol. % direkt einzuspeisen. Neben der Wasserstofferzeugung wurden auch die technischen Möglichkeiten der Speicherung von Produkten der Wasserstofftechnologie untersucht. Im Rahmen des Konzeptes „Power-to-X“ ergeben sich mehrere Möglichkeiten den Überschussstrom aus den erneuerbaren Energien zwischen zu speichern. Eine Möglichkeit besteht im Konzept „Power-to-Hydrogen“. Dabei wird der erzeugte Wasserstoff direkt, entweder in Druckbehältertanks, in Metallhydridspeichern oder über Verflüssigungsverfahren in Flüssigtanks, bis zu seiner bedarfsabhängigen Nutzung, z.B. der Rückverstromung, zwischengelagert. Da jede Speichereinheit ihre Vor- und Nachteile hat, ist die Wahl des richtigen und wirtschaftlichsten Speichers kläranlagenspezifisch zu prüfen. Eine weitere Möglichkeit besteht im Konzept „Power-to-Methan“. Dabei wird der Wasserstoff zusammen mit dem ebenfalls auf Kläranlagen vorhandenen Kohlendioxid, entweder einem katalytischen- oder einem biologischen Methanisierungsreaktor zugeführt, um dadurch ein hochwertiges Methan als Synthesegas zu erhalten. Bei diesem Prozess entsteht Abwärme die abgeführt und im Sinne einer hohen Anlageneffizienz in Wärmesenken der Kläranlage verwendet werden muss. Das entstandene Synthesegas Methan kann in Erdgastanks zwischengespeichert, in Gasmotoren- und Brennstoffzellen-BHKWs rückverstromt oder in ein lokales Erdgasnetz eingespeist werden. Eine dritte Möglichkeit besteht im Konzept „Power-to-Liquid“. Dabei wird auf der Kläranlage das Faulgas aufbereitet und zusammen mit Elektrolyse-Wasserstoff dem Methanolsynthesereaktor zugeführt. Methanol ist einfacher zu handhaben als Wasserstoff und kann einfach in Flüssigtanks bis zu seiner späteren Verwendung zwischengelagert werden. Zudem kann Methanol in Methanol-BHKWs, in Direktmethanolbrennstoffzellen rückverstromt oder Kraftstoffen beigemischt werden. Allerdings existieren bis heute weder ausgereifte Methanol-BHKWs, noch entsprechend grosse und leistungsstarke Direktmethanolbrennstoffzellen. Des Weiteren ist in Deutschland und Europa auch noch keine nennenswerte Methanol-Infrastruktur vorhanden. Für die energetischen Nutzungen der Wasserstofftechnologie gibt es sieben verschiedene Brennstoffzellentypen. Beim Einsatz von Brennstoffzellen auf Kläranlagen haben sich bisher die Festoxidbrennstoffzelle (SOFC), die Schmelzkarbonatbrennstoffzelle (MCFC) und die Phosphorsäurebrennstoffzelle (PAFC), in verschiedenen Pilotprojekten, erfolgreich bewährt. Diese drei Brennstoffzellentypen sind brennstoffflexibel und können mit aufbereitetem Faulgas betrieben werden. Die MCFC und die SOFC haben, mit durchschnittlichen 65 %, die höchsten elektrischen Wirkungsgrade und ihre entstehende Prozessabwärme kann für eine interne oder externe Reformierung verwendet werden. Die Reinigungsstufe des Faulgases stellt die grösste Herausforderung bei der Brennstoffzellentechnik auf Kläranlagen dar. Da die Zusammensetzung des Faulgases variiert und somit kläranlagenspezifisch ist, muss für die Implementierung der Brennstoffzellentechnik, im Vorfeld die Zusammensetzung des Faulgasstroms für jede einzelne Kläranlage über Zeitreihen analysiert werden. Die Mikrobielle Brennstoffzelle (MFC) stellt, unter den in dieser Arbeit beschriebenen Brennstoffzellen, einen Spezialfall dar, da in ihre Brennkammer keine Gase, sondern Abwasser einströmt, dessen Energiegehalt über den chemischen Sauerstoffbedarf (CSB) ermittelt wird. Mit der Verwendung der MFC im Abwasserbereich könnte, neben der Stromproduktion, auch die organischen Kohlenstoffverbindungen reduziert werden. Für die MFC besteht ein grosses zukünftiges Potential zur relevanten Stromproduktion auf Kläranlagen, allerdings ist dafür noch viel Forschungsarbeit notwendig. Wasserstoff kann weiterhin energetisch in Wasserstoff-BHKWs verbrannt werden. Der Wirkungsgrad der Wasserstoff-BHKWs ist
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gegenüber den Brennstoffzellen zwar geringer und durch den Carnot-Kreisprozess begrenzt, dafür ist die Technik ausgereifter und auch massiv günstiger. Der produzierte Wasserstoff kann ausserdem für die betriebseigene Fahrzeugflotte verwendet werden. Dabei können kommerzielle Brennstoffzellenfahrzeuge und Fahrzeuge mit Wasserstoffverbrennungsmotor eingesetzt werden. Im Fall der Methanisierung bietet sich auch die Nutzung des erzeugten Methans in Erdgasfahrzeugen an. Für die mobile Nutzung durch Betriebsfahrzeuge ist allerdings eine kostenintensive Implementierung von Wasserstoff- oder Erdgastankstellen notwendig. Ähnlich den erneuerbaren Energien, wird sich auch bei der Wasserstofftechnologie auf Kläranlagen, nicht nur eine einzelne spezifische Technologie durchsetzen, sondern es wird ein Zusammenspiel aus mehreren hier beschriebener Wassertechnologien stattfinden. Mit den in dieser Arbeit beschriebenen Wasserstofftechnologien ist es grundsätzlich auf Kläranlagen möglich, den Überschussstrom aus erneuerbaren Energien, in die sekundären Energieträger Wasserstoff, Biomethan und Methanol umzuwandeln. Diese Energieträger können zwischengespeichert und bedarfsgesteuert zu einem späteren Zeitpunkt wieder rückverstromt werden. Mit den hier beschriebenen Wasserstofftechnologien können Kläranlagen als Energieproduzenten, sowie als Kurz- und Langzeitspeicher fungieren. Dennoch sind diese hier beschriebenen Wasserstofftechnologien derzeit noch von finanziellen Förderungen abhängig, da ohne sie kein wirtschaftlicher Betrieb möglich wäre. Aber nicht nur Förderprogramme spielen zur Implementierung der Wasserstofftechnologie eine Rolle, sondern auch die Energierechtlichen Angelegenheiten, wie beispielsweise die Regelung im Umgang mit Nutzungsentgelten, mit der Stromsteuer und mit der EEG-Umlage.

Wood-based biochars were used as microbial fuel cell electrodes to significantly reduce cost and carbon
footprint. The biochar was made using forestry residue (BCc) and compressed milling residue (BCp). Sideby-
side comparison show the specific area of BCp (469.9 m2 g1) and BCc (428.6 cm2 g1) is lower than
granular activated carbon (GAC) (1247.8 m2 g1) but higher than graphite granule (GG) (0.44 m2 g1).
Both biochars showed power outputs of 532 ± 18 mWm2 (BCp) and 457 ± 20 mWm2 (BCc), comparable
with GAC (674 ± 10 mWm2) and GG (566 ± 5mW m2). However, lower material expenses made
their power output cost 17–35 US$W1, 90% cheaper than GAC (402 US$W1) or GG (392 US$W1).
Biochar from waste also reduced the energy and carbon footprint associated with electrode manufacturing
and the disposal of which could have additional agronomic benefits.

Sediment microbial fuel cell (SMFC) is a bioelectrochemical device which produces the pollution-free
energy. SMFC generates low voltage with fluctuation between
0.982 V to 1.16 V of 60 days of the experiment. This voltage is
not suitable to power the electronic device. So an ultra-low
voltage DC-DC boost converter is proposed to regulated and
step up the output voltage of SMFC. Performance of the boost
converter is verified through simulation and experimental
results. Single SMFC discharges in 30 sec by connecting the
boost converter and gain maximum voltage in 210 sec after
disconnecting the boost converter. Further, a scheme proposed
for continuous energy harvesting from sediment microbial fuel
cell in which eight parallel connected SMFCs provide an input
voltage to boost converter one by one. It is noticed that the
energy harvester DC-DC boost converter provides a
continuous 2.56 V with the efficiency of 85.46%. The boost
converter works well up to the voltage of 20 mV so this
converter is appropriate for the SMFC energy harvesting. The
proposed scheme is able to produce a suitable voltage for a
small electronic device which needs a continuous power supply.

Thermal properties of bio-materials are properties which depict the reaction of the materials as a result of change in temperature. This study determined the effects of moisture variation on some thermal properties of Mucuna Pruriens and Veracruz seeds grown in Nigeria under different moisture contents range of 6.04 to 15.82% (db) employing standard experimental equipments and procedures. From the analysis of the results the thermal properties of both species were observed to increase as the moisture content increases but varied slightly between both species. Their values were found to range from 102.86 to 196.46KJ/kgK; 17.53 to 32.82W/m and 2.46 x10-7 to 8.39 x 10-7 ms-1 for specific heat, thermal conductivity and thermal diffusivity respectively. From the result and analysis of this study, it can be stated that knowledge of engineering properties of crops are very vital for design of processing equipment and post harvest handling. It is expected that the information obtained will be put to use by researchers who wish to work further on this legume species.

The present study aims at designing a promising Microbial Fuel Cell (MFC) to utilize wastewater in order to generate electricity. Two types of salt bridge have been used in MFC (KCl and NaCl). The maximum electricity generation with 1M KCl and NaCl has been 823 and 713 mV, respectively. Varied salt concentrations (0.5M, 1M, 2M, and 3M) of salt bridge in MFC have been analyzed with different factors like temperature, type of electrode, configuration, and surface area of electrode being studied. The optimum temperature is found to be 32Co, with the optimum type of electrode being graphite rod, while the optimum configuration and surface area of electrode is graphite plate with surface area of 183.6 cm2. Artificial Neural Network (ANN) has been employed to predict voltage production of MFC and compare it with the experimental voltage. Multiple   correlation methodology has optimized the voltage production with the correlation coefficient (R2) being 0.999.

This study focused on the use of spinel manganese–cobalt (Mn–Co) oxide, prepared by a solid state reaction,
as a cathode catalyst to replace platinum in microbial fuel cells (MFCs) applications. Spinel Mn–Co
oxides, with an Mn/Co atomic ratios of 0.5, 1, and 2, were prepared and examined in an air cathode MFCs
which was fed with a molasses-laden synthetic wastewater and operated in batch mode. Among the
three Mn–Co oxide cathodes and after 300 h of operation, the Mn–Co oxide catalyst with Mn/Co atomic
ratio of 2 (MnCo-2) exhibited the highest power generation 113 mW/m2 at cell potential of 279 mV,
which were lower than those for the Pt catalyst (148 mW/m2 and 325 mV, respectively). This study indicated
that using spinel Mn–Co oxide to replace platinum as a cathodic catalyst enhances power generation,
increases contaminant removal, and substantially reduces the cost of MFCs.

Oсобливості утворення біогазу із жировмісної сировини в поєднанні з курячим послідом характерно тим, що на етапі ацитогенезу в процесі утворення молекул метил-СоМ участь беруть не тільки проміжні сполуки перетворення ацетату та метанолу, а й метиламіни, диметиламіни та триметиламіни, які є продуктами розпаду курячого посліду. При такому поєднанні компонентів, маємо більший вихід біогазу, але меншу калорійність по його якісному складу.
The peculiarities of the formation of biogas from fatty raw materials in combination with chicken manure are characterized by the fact that, during the generation of methyl-SOC molecules during the stage of acitogenesis, not only intermediates convert acetate and methanol but also methylamines, dimethylamines and trimethylamines, which are products of the decay of chicken manure, take part. With such a combination of components, we have a higher yield of biogas, but less caloric in its qualitative composition.

Microbial fuel cell (MFC) merupakan salah satu teknologi sel bahan bakar alternatif yang dapat diperbarui. MFC memanfaatkan proses oksidasi senyawa kimia oleh biokatalis untuk menghasilkan energi listrik daya rendah. Tujuan dari penelitian ini adalah mengetahui kinerja MFC dengan dan tanpa mediator elektron metilen biru (MB) menggunakan biokatalis Acetobacter aceti dan substrat glukosa agar diperoleh energi listrik. Metode yang dilakukan adalah peremajaan kultur A. aceti, persiapan inokulum, persiapan reaktor MFC, persiapan media MFC dengan substrat glukosa 2% dengan dan tanpa mediator MB, pencuplikan secara periodik, penentuan kurva pertumbuhan, arus, potensial, kerapatan daya, energi, kadar glukosa dan tingkat keasaman (pH). Hasil penelitian menunjukkan bahwa MFC dengan mediator menghasilkan kuat arus sebesar 0,040 mA, potensial 878 mV, kerapatan daya 0,395 mW/cm2, energi maksimum 3,685 kJ, pemanfaatan glukosa 93,02% dan pH akhir 3,33, sedangkan MFC tanpa mediator menghasilkan kuat arus 0,035 mA, potensial 773 mV, kerapatan daya 0,290 mW/cm2, energi maksimum 2,434 kJ, pemanfaatan glukosa 90,16% dan pH akhir 3,24. Perolehan kerapatan daya pada kedua jenis MFC masih tergolong kecil dan tidak berbeda secara signifikan. Dari hasil penelitian dapat disimpulkan bahwa penggunaan mediator MB hanya berpengaruh terhadap perolehan potensial pada MFC dengan kondisi perlakuan yang diterapkan dalam penelitian ini.

Death, decay, and transcendence are transformed if interpreted from a microbial perspective. This paper constructs a non-anthropocentric approach on a microbial scale through the concept of microbiopolitics, an expanded notion of biopolitics with the inclusion of ​zoe​, a postanthropocentric interpretation of ecological relations, focused on the life of microorganisms and introducing an ecological thought for the microbial planet. This research explores, in particular, the work of Latin American artists Ana Laura Cantera and Gilberto Esparza as a form of material speculation that opens up alternatives of thought grounded on the accountability of biological and technological matter, its limits and possibilities.

Resumen
El objetivo de la presente investigación fue generar bioelectricidad en celdas de combustible microbiana con depuración simultánea de agua residual de la industria alimenticia. Se construyeron dos tipos de celdas, de una y doble cámara, con 5 réplicas cada una, con el fin de comparar la eficiencia en ambos tipos. Los parámetros de control a monitorear fueron turbidez y sólidos totales como indicadores de contaminación del agua residual y voltaje para la generación de bioelectricidad. Las celdas fueron construidas utilizando envases plásticos con un volumen de 500 mL (una cámara) y 400 mL (doble cámara), como electrodos se escogió trabajar con una malla de acero inoxidable recubierto de carbón activado granular previamente triturado, 30 mL de cultivo bacteriano fueron agregados en cada celda, con el propósito de mejorar la generación de energía. Como resultado, se obtuvieron porcentajes de remoción de turbidez del 75% y 48%, en celdas de una y doble cámara respectivamente. Por otro lado, en cuanto a producción de bioelectricidad se alcanzaron niveles de voltaje máximos de 222 mV en celdas de una cámara y 88 mV en celdas de doble cámara. En conclusión, las celdas de una sola cámara probaron ser mas eficientes, tanto en remoción de contaminantes, como en generación de bioelectricidad.
    Palabras clave: agua residual, acero inoxidable, bioelectricidad, carbón activado, celdas de combustible microbiano.

E.coli yang telah diisolasi dari kotoran atau feses ayam dapat menghasilkan energi listrik. E.coli mengkonsumsi substrat seperti gula dalam kondisi anerobik untuk menghasilkan karbon dioksida (CO2), proton dan elektron. Elektron yang dihasilkan dapat dimanfaatkan sebagai sumber listrik. Koversi listrik berdasarkan hasil analisis dan perhitungan sebesar 17,520 kwh/hari untuk 1.000 ekor ayam dewasa (usaha peternakan kecil-menengah) sehingga mampu menghemat biaya operasional usaha peternakan ayam sebesar 507.729/bulan. Melalui pemanfaatan feses ayam dengan sistem MFC selain meminimalisir limbah namun juga memberikan nilai ekonomi yang lebih yakni sebagai sumber energi listrik dan mengurangi biaya operasional bagi usaha peternakan ayam.

Microbial fuel cells (MFCs) have been demonstrated as a challenging and promising technology towards management of various environmental problems. Bioremediation has been accepted widely as viable option utilizing the naturally inhabited microorganisms, but sometimes the severe low efficiency of the microorganisms and poor controllability limits its application. In this context, MFC technology can be used as a potential means to stimulate bioremediation for effective removal of various pollutants. The special features including energy saving, less sludge and energy production make MFCs as outstanding technology compared to conventional technologies. This article is mainly focused on application of MFCs towards removal of various environmental pollutants viz. antibiotics, synthetic dyes, phenolic compounds, nitrogen based compounds, ethyl acetate, toluene, polycyclic aromatic hydrocarbons, perchlorate, pesticide, sulphur, emerging contaminants, trace organic compounds etc. from aqueous environment. Although the current applications of MFC technology is still at laboratory level, it will definitely prove a great potential towards commercial applications in near future.

The current fossil fuel-based generation of energy has led to large-scale industrial development. However, the reliance on fossil fuels leads to the significant depletion of natural resources of buried combustible geologic deposits and to negative effects on the global climate with emissions of greenhouse gases. Accordingly, enormous efforts are directed to transition from fossil fuels to nonpolluting and renewable energy sources. One potential alternative is biohydrogen (H2), a clean energy carrier with high-energy yields; upon the combustion of H2, H2O is the only major by-product. In recent decades, the attractive and renewable characteristics of H2 led us to develop a variety of biological routes for the production of H2. Based on the mode of H2 generation, the biological routes for H2 production are categorized into four groups: photobiological fermentation, anaerobic fermentation, enzymatic and microbial electrolysis, and a combination of these processes. Thus, this review primarily focuses on the evaluation of the biological routes for the production of H2. In particular, we assess the efficiency and feasibility of these bioprocesses with respect to the factors that affect operations, and we delineate the limitations. Additionally, alternative options such as bioaugmentation, multiple process integration, and microbial electrolysis to improve process efficiency are discussed to address industrial-level applications.

Application of the Fenton process for textile wastewater treatment is limited due to high treatment cost, substantially contributed by the un-availability of cheap hydrogen peroxide. Therefore, alternative methods for hydrogen peroxide production
are in demand. One such option is in situ hydrogen peroxide production using a wastewater based microbial fuel cell (WBMFC).
However, not much have been published regarding in situ production of hydrogen peroxide for textile wastewater treatment in
a WBMFC. Therefore, in this work the concept, advantages, challenges and prospects of using WBMFC to treat textile wastewater by simultaneously producing hydrogen peroxide (hence in situ hydrogen peroxide) and power are reviewed. The concept
of WBMFC is the reduction of oxygen in the presence of electrons and protons from the anode chamber to produce hydrogen
peroxide with simultaneous power production. This review confirms that use of dual chambers, proton exchange membrane,
domestic or municipal wastewater/Geobacter Sulfurreducens or Shewanella species, pure graphite cathode, ammonia and heat
treated carbon-based anode can treat most textile wastewaters. However, single chamber WBMFCs can be used as a low power
source for an electro-Fenton reactor. Power produced can be used to provide energy for aeration required in the WBMFC, thus
providing an integrated and sustainable solution for textile wastewater treatment.

— A low cost Sediment Microbial fuel cell designed to provide an opportunity to produce renewable energy from sediment. The power produced by the MFC by microbes present in sediment. In this paper maximum energy extraction is investigated with copper anode and zinc cathode and compare with previous work. Here maximum generated voltage and current of sediment MFC was 1.160V and 0.301mA.Maximum power in sediment MFC with copper anode was 3.491mW for steady state operating condition. Sediment Microbial fuel cell is gifted for sustainable cheap-cost green electricity produce, stable power generation and the long-term operation of MFCs. Sediment microbial fuel cells can be used as a renewable power source for remote environmental monitoring.

Microbial fuel cells have received increased attention as a means to produce "green" electricity from natural substances such as carbohydrates, agricultural wastes or dairy waste. A microbial fuel cell is a biological system in which bacteria do not directly transfer their produced electrons to their electron acceptor, rather transported over an anode, conducting wire and a cathode. It is divided into two halves: aerobic and anaerobic. The aerobic half has a positively charged electrode and is bubbled with oxygen. The anaerobic half does not have oxygen, allowing a negatively charged electrode to act as the electron receptor for the algal processes. The cathode chamber was sterilized and then refilled with basal medium with Chlorella vulgaris as inoculom to provide electron that transferred from cathode to anode for electricity production. The electricity producing bacteria are known as electrogens. Proton conductive materials in an MFC should ideally be able to inhibit the transfer of other materials such as the fuel (substrate) or the electron acceptor (oxygen) while conducting protons to the cathode at high efficiency. Thus bacterial energy is directly converted into electrical energy. The potential between the respiratory system and electron acceptor generates the current and voltage needed to make electricity. The electrons and protons react with oxygen molecules in the cathode chamber to form water. In nutshell, the novel reactor design and idea of using photosynthetic algae for oxygen supply to cathodic reaction green are also helpful in CO 2 sequestration.

In this study, a microbial fuel cell (MFC) was developed to treat waste, produce electricity and to grow
microalgae simultaneously. Dead microalgae biomass (a potential pollution vector in streams) was used
as a substrate at anode. CO2 generated at anode was used to grow freshwater microalgae at cathode. The
performance of microalgae-fed MFC was compared with acetate-fed MFC. The maximum power density
of 1926 ± 21.4 mW/m2 (8.67 ± 0.10 W/m3, at Rext = 100 X) and Coulombic efficiency (CE) of 6.3 ± 0.2%
were obtained at 2500 mg COD/L of microalgae powder (0.5 g/L). Microalgae captured CO2 (5–14%, v/v)
to produce a biomass concentration of 1247 ± 52 mg/L. However, microalgae could not grow in acetate-
fed (0.5 g/L) MFC (acetate-control) and without anodic CO2 supplying MFC (CO2-control).

Microorganisms naturally form biofilms on solid surfaces for their mutual benefits including protection from environmental stresses caused by contaminants, nutritional depletion or imbalances. The biofilms are normally dangerous to human health due to their inherited robustness. On the other hand, a recent study suggested that electrochemically active biofilms (EABs) generated by electrically active microorganisms have properties that can be used to catalyze or control the electrochemical reactions in a range of fields, such as bioenergy production, bioremediation, chemical/biological synthesis, bio-corrosion mitigation and biosensor development. EABs have attracted considerable attraction in bioelectrochemical systems (BESs), such as microbial fuel cells and microbial electrolysis cells, where they act as living bioanode or biocathode catalysts. Recently, it was reported that EABs can be used to synthesize metal nanoparticles and metal nanocomposites. The EAB-mediated synthesis of metal and metal-semiconductor nanocomposites is expected to provide a new avenue for the greener synthesis of nanomaterials with high efficiency and speed than other synthetic methods. This review covers the general introduction of EABs, as well as the applications of EABs in BESs, and the production of bio-hydrogen, high value chemicals and bio-inspired nanomaterials.

Microbial fuel cells (MFCs) produce electricity as a result of the microbial metabolism of organic substrates, hence they represent
a sustainable approach for energy production andwaste treatment. If the technology is to be implemented in industry, lowcost
and sustainable bioelectrodes must be developed to increase power output, increase waste treatment capacity, and improve
service intervals. Although the current application of abiotic electrode catalysts, such as platinum and electrode binders such
as Nafion leads to greater MFC performance, their use is cost prohibitive. Novel bioelectrodes which use cost effective and
sustainable materials are being developed. These electrodes are developed with the intention to reduce start-up time, reduce
costs, extend life-span and improve coreMFC performancemetrics (i.e.power density, current density, chemical oxygen demand
(COD) reduction and Coulombic efficiency (CE)). Comparison of differentMFC systems is not an easy task. This is due to variations
in MFC design, construction, operation, and different inocula (in the case of mixed-culture MFCs). This high intra-system
variability should be considered when assessing MFC data, operation and performance. This review article examines themajor
issues surrounding bioanode and biocathode improvement in differentMFC systems, with the ultimate goal of streamlining and
standardising improvement processes.

The potential enzyme evaluation of the acidophilic, chemolitotrophic and heterotrophic bacteria specific to the mining biotope is of high interest in the solubilization, recovery and / or removal of platinum metals from industrial waste car tires. The obtained data show that the formation of extracellular polymeric substances plays an important role in the attachment of the chemolithotrophic bacteria on the surface of minerals, as well as sulphur. In this sense, a direct interaction between the bacterial cells and the solid surface is mandatory for an efficient mobilization of platinum metals from waste car tires. These occur at two levels: (a) physical sorption due to electrostatic forces with low pH in the leaching media; (b) chemical sorption is carried out only in the type of chemical bonds between the bacterial cell disulphide bond and minerals. The optimization of the technological process such as solubilization and the recovery of platinum metal ions contained in ferrous and non-ferrous industrial waste was materialized through a series of laboratory experiments based mainly on the affinity of bacterial cells for certain organic and / or inorganic surfaces. It is based on the results of the physical-chemical characterization of the liquid samples taken. This study deals with the optimization of the solubilization process of metal ions contained in such samples.

In present study, different blend compositions of polybenzimidazole (PBI) and polyvinylpyrrolidone (PVP) have been analyzed as polymer electrolyte membrane in single chambered MFCs. Four membranes namely, pure PBI, PBI/PVP 70:30, 50:50, and 30:70 blend ratios with increasing PVP content were casted, where the hygroscopic properties of the membranes were found enhanced with increasing PVP content. The membranes were characterized at room temperature (22 + 2 • C) with different ion exchange (IEC) and proton conductive capacities, where an IEC of 0.06 meq g −1 , 0.15 meq g −1 , 0.24 meq g −1 and 0.36 meq g −1 and proton conductivity of 2.5 × 10 −4 , 4.8 × 10 −4 , 9.36 × 10 −4 and 1.2 × 10 −3 S cm −1 were observed from pure PBI, PBI/PVP 70:30, 50:50, and 30:70 membranes respectively. As membrane electrode assemblies (MEA), the casted membranes were sandwiched in-between carbon cloths, where a maximum power and current density of 231.38 ± 12 mW m −2 and 1242 ± 62 mA m −2 were observed from 30:70 PBI/PVP fitted MFC, using mixed firmicutes as biocatalysts. A gross 84.36% COD removal from 30:70 PBI/PVP membrane indicated the added effect of PVP in blend composition with approximately 81% higher power over pure PBI membrane. The results indicate the potential efficacy of PBI/PVP blends as seperators in microbial fuel cell, for bio-energy conversion over pure PBI membrane.

Microbial fuel cells (MFCs) and membrane photobioreactors are two emerging technologies for simultaneous wastewater treatment and bioenergy production. In this study, those two technologies were coupled to form an integrated treatment system, whose performance was examined under different operating conditions. The coupled system could achieve 92–97 % removal of soluble chemical oxygen demand (SCOD) and nearly 100 % removal of ammonia. Extending the hydraulic retention time (HRT) of the membrane photobioreactor to 3.0 days improved the production of algal biomass from 44.4 ± 23.8 to 133.7 ± 12.9 mg L-1 (based on the volume of the treated water). When the MFCs were operated in a loop mode, their effluent (which was the influent to the algal reactor) contained nitrate and had a high pH, leading to the decreased algal production in the membrane photobiore-actor. Energy analysis showed that the energy consumption was mainly due to the recirculation of the anolyte and the catholyte in the MFCs and that decreasing the recirculation rates could significantly reduce energy consumption. The energy production was dominated by indirect electricity generation from algal biomass. The highest energy production of 0.205 kWh m-3 was obtained with the highest algal biomass production, resulting in a theoretically positive energy balance of 0.033 kWh m-3. Those results have demonstrated that the coupled system could be an alternative approach for energy-efficient wastewater treatment and using wastewater effluent for algal production.

A membrane bioelectrochemical reactor (MBER) is a system integrating membrane filtration into microbial fuel cells. To control membrane fouling, fluidized granular activated carbon (GAC) was applied to the cathodic compartment of an MBER, which was examined for contaminant removal and electricity generation with low or medium strength synthetic wastewater. The MBER was operated for more than 160 days and achieved nearly 100% removal of organic compounds, regardless of presence/absence of GAC. However, fluidized GAC alleviated the membrane fouling issue and maintained transmembrane pressure (TMP) between 10 and 15 kPa with 24 g of GAC. The presence of GAC also enhanced current generation from 200.3 to 256.0 A m À3 , because some GAC might have functioned as a part of the cathodic electrode through physical contact with the electrode during fluidization. A higher aeration intensity could benefit both membrane fouling control (via scouring effect) and electricity generation (via oxygen supply), but required a higher energy demand. The energy consumption of the MBER including pumping and aeration was estimated to be 0.38 kWh m À3 or 0.25 kWh kgCOD À1 , lower than that of conventional membrane bioreactors (MBRs). Those results encourage further investigation and development of the MBER technology to treat wastewater in an energy efficient way.