Microbial Fuel Cell - Science topic

Dear Pedro Braun,

I am working in same project like MFC with different principle. We can collaborate to gather.

With regards.

Probably the solution is not homogeneous. Use centrifuge and then prepare the samples

A mass flow controller automatically controls the flow rate of a gas according to a set flow rate sent as an electric signal, without being affected by use conditions or changes in gas pressure. Mass Flow Meter operating on the "Coriolis principle" contains a vibrating tube in which a fluid flow causes changes in frequency, phase shift or amplitude. The sensor signal is fed into the integrally mounted pc-board. The resulting output signal is strictly proportional to the real mass flow rate, whereas thermal mass flow meters are dependent of the physical properties of the fluid. The mass flow meter depends upon density ,the ammonia density varies with temperature. Please calibrate your MFC according to standard.

Thanks for your query, I might be helping you if you are interested, please contact with me in my e-mail address.

In microbial fuel cells (MFCs), different electrodes and membranes are used. Carbonaceous materials like graphene and metals are common for the anode, where organic material is oxidized. Cathodes can be air or aqueous, and biocathodes with microorganisms are also used. Ion exchange membranes separate compartments while allowing ion transport. Organic materials in wastewater, such as dyes, serve as fuel for the anode bacteria. Glucose and acetate from food waste or sewage can also be used.

Thank you for your interest Dr. Somil Thakur .

I've just emailed you our key AD+™ bioenergy references and messaged you on LinkedIn as well.

Bruno

The appropriate design for the above subject matter is the Experimental Research Design

The microbial fuel cell in its entirety might be called the test apparatus. The consortium of bacteria should just be called "the consortium of bacteria." There should be one or more objective, numerical measurements of performance of the apparatus and its bacterial contents. There is no need for a survey.

I can suggest some questions for your pre-test and post-test experiments. However, the specific questions may vary depending on the exact nature of your experiment. Here are some general questions you might consider:

Remember, these are just suggestions. It would be best if you tailored your questions to suit the specific learning objectives of your experiment.

1 to 3 g/L

Hi Dr., I like your question, and I would love to answer and support you on your research, but I would appreciate it if you could click RECOMMEND for my 6 research papers under my AUTHORSHIP below is my short answer to your question. Click the RECOMMEND word under each of my research papers and follow me. In return for your kind support, I provide you with the answer to your question :

Specifically regarding bacterial replication kinetics under optimum conditions, published experimental data consistently report doubling periods of just a few hours for many electrochemically-active microbial species.

Extrapolating such exponential growth trajectories mathematically illustrates how initial inocula on the scale of hundreds of cells could plausibly yield populations in the millions after only a few days' operation, even at modest chemical reaction rates.

This has considerable implications for long-term reactor design and management. Without sufficient operating volume or efflux mechanisms to accommodate such prolific biomass accumulation, rapid chamber occlusion and attendant perturbations to fluid flow would seem inevitable.

However, with well-designed hydrodynamics to forestall mass transfer limitations, the inherent advantages of microbial fuel cell processes are amplified. Sustained exponential population expansion serves to maximize catalytic surface area and reaction throughput over time, theoretically scaling power output in a highly favorable manner.

In view of wastewater treatment applications, the self-replicative abilities of exoelectrogenic bacteria may confer additional benefits. As organic loading is converted to electrical current, carbon conversion efficiency increases while pathogenic contaminants are simultaneously biodegraded.

In summary, while unchecked bacterial overgrowth poses technical challenges, harnessing the intrinsic population kinetics of electrochemically-active microbes appears key to optimizing microbial fuel cell performance at both the laboratory and industrial scales

Thank you Ms. Negin Naghibi for your answer. I shall ensure the efficiency of the PEM and electrodes, as well as their pretreatment methods.

In microbial fuel cells (MFCs), the Coulombic efficiency and Chemical Oxygen Demand (COD) removal are two important performance indicators that reflect the efficiency of the system in converting organic matter into electricity.

CE = (Total electrons transferred as current) / (Total electrons theoretically available from COD)

A Coulombic efficiency of 100% indicates that all the electrons released during microbial metabolism are successfully harvested as electricity in the MFC. However, in practical systems, the Coulombic efficiency is usually less than 100% due to factors such as electron losses to side reactions (e.g., microbial biomass formation) and inefficiencies in electron transfer.

COD Removal (%) = [(Initial COD - Final COD) / Initial COD] x 100

A higher COD removal indicates a more effective treatment of organic pollutants in the wastewater.

Relationship between Coulombic Efficiency and COD Removal: The relationship between Coulombic efficiency and COD removal in MFCs can vary depending on the operating conditions and the nature of the organic matter present in the wastewater.

In some cases, a higher COD removal may be associated with a higher Coulombic efficiency. This is because a more efficient microbial degradation of organic matter can lead to increased electron generation, which can then be harvested as electricity, resulting in a higher Coulombic efficiency.

However, there may be instances where a trade-off exists between COD removal and Coulombic efficiency. For example, certain operating conditions or microbial communities might favor the complete degradation of organic matter to carbon dioxide, resulting in a high COD removal but lower Coulombic efficiency as fewer electrons are available for electricity generation.

In summary, while there can be a positive correlation between Coulombic efficiency and COD removal in MFCs, it is not a straightforward relationship and can be influenced by various factors. The optimization of MFC performance involves finding a balance between maximizing organic matter removal and electricity generation.

To calculate the coulombic efficiency in microbial fuel cells (MFCs), you need to measure the total charge (Q) produced by the MFC during a specific time period and determine the total chemical oxygen demand (COD) of the substrate used. Then, calculate the theoretical maximum charge (Q_theoretical) that could be generated from the complete oxidation of the COD. Coulombic efficiency can be calculated using the formula: Coulombic Efficiency = (Q / Q_theoretical) x 100%. This provides the percentage of electrons effectively converted into electrical current during MFC operation.

NHD files is the North Star Harizon Hard Disk I mage is the popular type of NHD- FILE WE KNOW OF 2 different uses of the NHD file extension Different information on this page provides instruction on how to save unsupported files to different formats to allow them to be unloaded info.

Where M is the molecule weight of oxygen (32), F Faradays constant (9.64870x10 Coloumbs\ Faraday), b=4 indicates the number of electrons exchanged per mole of oxygen, van is the volume of liquid in the anode compartment (250 ml) and COD (COD in =250, COD out =20 mg \ litre) ia the change in the COD overtime "t''

The OCP means that there is no change in the potential by injecting feed into the MFC, so the system is stable. This could be evaluated when two consecutive peaks (potential) appear.

You can also take a look at this paper for more illustration (Fig. 2):

Fuel Cell & Electrolyzer Module could be used.

4 Examples of Fuel Cell Modeling in COMSOL Multiphysics® | COMSOL Blog

Dear Safina Ali

SEM and XRD are the best techniques for morphological and structural characterization, requiring a sample size of around a pea-size powder volume.

Thanks

Dear Aref Tehranian,

MFC operation was conducted for 30 days to ensure that steady voltage is achieved for at least three consecutive cycles before output measurements. At this time, the biofilm at the anode is complete. You should also consider the most stable times in a feeding cycle. Because if it is too early, it is not the maximum time, but too late, the substrate is exhausted and does not give maximum capacity.

The current (I), unit: ampere (A) was calculated using Ohm's law, I = U/R, where U represents the voltage output, unit: volts (V) and R is the external load resistance, unit: Ohm (Ω). Power (P), unit: watts (W) was calculated by charging the voltage and amperage: P = U × I. The power density was calculated by the surface of the electrode; PD = P/Aanode, where Aanode is the total surface area of the anode electrode in square meters (m2).

Phil Geis Alex Ignatov

Thanks for giving your suggestion. Phil Geis, you are right I am suffering from general fungal contamination. In general, labs around the department, use fluconazole. So, I decided to give it a try at low concentration.

The best way would be to look in an internet search engine. You can choose the articles that interest you the most.

Regards

Vit

@ Anshika, you may try with vacuum degassing, applying a partial vacuum to the water to remove dissolved oxygen from a sample.

When the output voltage is stable. At that time, the biofilm on the anode was completed.

Hello, dear Najah Putri

The important things in choosing the right multimeter for MFC are:

1. High accuracy in current measurement

2. Ability to record data in applicable formats

3. It has reading ranges from very low (micro) to high

4. Using high-quality clip wires

I wish you success.

Hello. You should wait until your open circuit voltage reaches a relatively stable state before loading the external resistor.

Respect R. Sagayaraj,

Thank you for the valuable information.

Open-circuit voltage (abbreviated as OCV or VOC) is the difference of electrical potential between two terminals of an electronic device when disconnected from any circuit. There is no external load connected. No external electric current flows between the terminals.Hence in an open circuit, the current flowing through the circuit is zero, and voltage is present (non-zero). , and the current is equal to zero. Hence power is also equal to zero, and no power dissipates from an open circuit.

Hi,

The most followed pretreatment is

1. Boiling Nafion membrane in 3% hydrogen peroxide solution at 80 degree C for 1 hour(hot plate), then rinsing several times with Distelled water....

2. Boiling again with Distilled water at 80C for 2 hrs, then rinsing several times

3. Finally, Boiling in 4-5% H2SO4 solution at 80C for 1- 1.5 hrs, and rinsing again with DW.

Hope it will help you, All the best.

If another methods you come across, please share here.

Both exist, although the classical literature focuses on anaerobic "exo-electrogenic" microbes. Put in simple words:

1) Instead of adding oxygen, they oxidize organic matter by removing electrons and protons, that is: hydrogen.

2) The removed electron is transferred to an anode (by different biochemical mechanisms), while the proton is simply ejected to the growth medium.

3) The electron is led to the cathode by an external circuit, the proton diffuses to this same cathode in the media, through a proton exchange membrane (so that it cannot swim back). At the cathode, they unite with oxygen to form water.

Please carefully investigate other factors as well such as nature of electrolytes, inoculation source. Also double check the potnetistate whether is it working properly. Hopefully you will able to get something. Reevised it carefully and carefully see each step.

Yes, current density = Measured Current/ Wire Cross section area. The multimeter should be of standard company with good accuracy….

Hydrogen can be generated in the cathode of an MFC if you keep the cathode anaerobic. However, the system then becomes thermodynamically unfavourable and so a small voltage is often supplemented to the system and when this is done it is called a microbial electrolysis cell (MEC). There are advantages of using a system like that compared to pure anaerobic processes (involving acidogenesis) e.g. the hydrogen produced is nearly 100% pure whereas in purely anaerobic processes you get a sizable amount of carbon dioxide which would subsequently need removing. I wrote a paper about MEC for hydrogen production some years ago - see https://www.sciencedirect.com/science/article/pii/S0360319910009717. Dark/photofermentation for hydrogen production have been studied for a while. If you could integrate MECs with dark/photofermentation, you might get somewhere - read about electrofermentation. Hope that helps.

if you looking for electrical power generation using microorganisms in MFC, of course in this case the accumulation of electrons is loaded in the anode chamber. Thus the electron travels through the external circuit to the cathode chamber. Therefore the anode is an important chamber as the biofilm is found there. Besides that O2 is found in the cathode just called an electron acceptor.

yeah i will.

First - NFC are too small to be accurately observed with SEM. You need to use AFM for those fibers. The coating depth required is not insignificant and will obscure any details that you may have with larger diameter NFC fibers. As cellulose fibers are hygroscopic, it is very unlikely that you will have a completely dry sample for SEM. The technique that I've found works is to allow the sample to dry in an oven at 50C, then store it in a nitrogen atmosphere until ready to coat. Once coated you should have no issues obtaining good scans of your fibers. I coat approximately 4 nm depth and obtain good resolution images.

Yes, somebody suggested me to use a PTFE paper between the press and the MEA like Press/PTFE/Nafion/GDE/PTFE/Press. I just ordered it online and it's supposed to arrive tomorrow. I will keep you updated :D Maira Anam

I'm not growing MoS₂ but other stuff, however your questions are general enough so I can answer:

1. Turning off the vacuum pump is in the worst case bad for your surface finish, so I wouldn't recommend it. Apart from that, depending on your process pressure, the shutdown might actually be bad for the pump.

2. Unless the MFC is broken, 0sccm should mean 0sccm and a full shutdown should not be necessary. A control drop (and a shutdown is that) is rarely a good idea.

Thank you for your answer Kyeongmin Kim. I am working on an upflow vertical Constructed Wetland- Microbial Fuel Cell and the anode is completely inserted in the soil (bottom layer) while the cathode is half placed in the soil and half open to the atmosphere (top layer).

After researching this topic, it seems that Nafion 117 indeed binds cationic dyes that can effect the MFC performance. I recommend reading Biofuel Research Journal 1 (2014) 7-15 for an excellent review on this topic. https://www.biofueljournal.com/pdf_4746_7b633aba2b133dd3a48839b34170a021.html

Of course, you should wait. Different microorganisms involved in microbial fuel production or study present different start-up times. It is a function of their differences in electron generation and capture.

You can get details in paper

Harnisch, F., & Freguia, S. (2012). A basic tutorial on cyclic voltammetry for the investigation of electroactive microbial biofilms. Chemistry–An Asian Journal, 7(3), 466-475.

Even I can help you out for CV measurement & analysis -MFC

Thank you so much for your suggestion.I tried ANSYS help and found guidelines related to piezoelectric materials only . This program does not work properly for MFC because MFC actuator has different configuration.

Gunda Mohanakrishna

USB TC-08 (Pico® Technology Ltd., St Neots, UK) -https://www.mdpi.com/2227-9717/9/8/1330/htm

Keithley instrument for voltage and current measurement (recommended by RG community)

Mukesh Sharma Hie, Pls check out these links,

It may help,

Regards

Gautam

Dear Karan Singh Maan ,

If the open circuit voltage is relatively high and the the the harvested electric power is too low, it means that the short circuit current is too low. The fill factor may be also too low.

If you display you your dark and illuminated I-v curve one can diagnose your cell.

This book chapter may help you interpret your results:

Also this paper may help you:

Best wishes

I've made a single-chamber MFC made of plexiglass.

you can order your reactor dimension to the plexiglass store, then attach pieces together.

you have to design anode and cathode places.

I've made anode and cathode too.

Indeed the external resistance should be comparable to the internal resistance. However, during the starting stage, the internal resistance is supposed to gradually decrease due to the development of functional microbial film on electrodes. So there is no rule, and you may yield different MFCs when apply different resistors.

There are some advices: The internal resistance depends on the surface area of the electrodes and the distances between the electrodes. If the area is huge and the distance is close, choose a resistor less than 1 k ohm, If not, choose more than 1k ohm. If you have no idea, just use any resistor and monitor the CCV for several days. For a conventional MFC, the OCV varies from 0.5 to 0.8. The CCV will decrease dramatically when loaded and slowly recover. If not recover, use bigger resistor; if no significant decrease, use smaller resistor.

Also depends on the purpose. If you want to obtain the maximum power output, the external resistance should be similar to the internal resistance. If the objective is the maximum exolectrogenic biomass growth, the external resistance should be lower to avoid current limitations. Exoelectrogenic activity is proportional to the current intensity; if your intensity is low (higher external resistance), exoelectrogens growth will be limited. When the cell is working at OCV (infinite resistance), intensity is zero and no exoelectrogenic activity is possible.

So you could benefit from these two valuable articles:

First....

"Microbial Fuel Cells: Influence of External Resistors on Power, Current and Power Density".

By: Kamau JM, Mbui DN, Mwaniki JM, Mwaura FB and Kamau GN.

Abstract:

The effect of external resistance on voltage, current, power, power density and current density is investigated in a microbial fuel cells using cowdung is investigated. This involves use of varying resistance resistors. The fuel cells

were operated under anaerobic condition for 9 days. PVC pipe was used to make a salt bridge using lamp wicks and potassium chloride. The obtained results indicated that the maximum voltage was on day 7 with 0.153 V across 33 kΩ resistor. The power was in the range of 0.000001 to 0.01 mW, current density was in the 0.1 to 23.29 mA/m2 range while the power density was in 7.5 × 10-7 to 3.1036 mW/m2 range.

And this is the second article:

"The Influence of External Load on the Performance of Microbial Fuel Cells"

By: Szymon Potrykus , Luis Fernando León-Fernández , Janusz Niezna ´nski

, Dariusz Karkosi ´nski.and Francisco Jesus Fernandez-Morales.

Abstract:

In this work, the effect of the external load on the current and power generation, as well as on the pollutant removal by microbial fuel cells (MFCs), has been studied by step-wise modifying the

external load. The load changes included a direct scan, in which the external resistance was increased from 120 Ω to 3300 Ω, and a subsequent reverse scan, in which the external resistance was decreased back to 120 Ω. The reduction in the current, experienced when increasing the external resistance, was maintained even in the reverse scan when the external resistance was step-wise decreased.

Regarding the power exerted, when the external resistance was increased below the value of the internal resistance, an enhancement in the power exerted was observed. However, when operating

near the value of the internal resistance, a stable power exerted of about 1.6 µW was reached. These current and power responses can be explained by the change in population distribution, which shifts to a more fermentative than electrogenic culture, as was confirmed by the population analyses.

Regarding the pollutant removal, the effluent chemical oxygen demand (COD) decreased when the external resistance increased up to the internal resistance value. However, the effluent COD increased

when the external resistance was higher than the internal resistance. This behavior was maintained in the reverse scan, which confirmed the modification in the microbial population of the MFC.

I have attached the pdf files ....

I hope it will be helpful...

You can sampling an measure the bicarbonate amount by IC (ion chromatography). Check the pdf file attached for more details

Regards,

K

Technique for accurate biomass estimation in biofilm is not yet properly developed in an easy quantitative format. Besides, there are several approaches and the best choice depends on what are your specific objectives. The simplest way is to remove the biofilm from the anode using sonication or just simple gloves finger rubbing in sterile water. Then shake well your suspension and measure OD at 600 nm. Finally, convert OD to dry masa using a preliminary found conversion factor for your bacteria. If cell mass is enough for direct dry weight - that would be the best. Before drying take aliquots of suspension for the phase-contrast, microscopy to characterize the heterogeneity of population: how many single and aggregated cells, morphological diversity, the normal and the 'ghosts' (empty dead cells). If you have a fluorescent microscope, buy the live/dead kit and determine the fraction of viable cells. From the dry mass, you can calculate the wet mass (roughly multiply by 10) and then the volume assuming the average density of wet cells 1.08 g/cc. Good luck!

Cornel Radu Thank you for your answer, but everything is connected as it should be, unfortunately, the voltage is reversed.

@jeetendra Prasad okay, but is the problem when I use different volume in anoda and cathode?

I meant that you do not add any bacteria. If current happens then it is from soil microorganisms. If you repeat this several times with one sample of soil - then you will get an enrichment culture of electrogenic bacteria.

in my case, I was trying with some single MFC cells, inoculated with wastewater sludge, and I noticed that the voltage take some times to increase and continue to increase over time and stay stable for a period and after that start to decrease when the voltage decrease drasticly I add a source of carbon like acetate and I start a new cycle (increase .... stable.... decrease).

Yes Sigme,

I agree with others many scientific hearts are exactly beating for this right now, it is a kind of gold fever starting now, I would say! But if you are successful with this topic, please do not start to fertilize our lakes and oceans further ;-). Of course there are many constructed wetlands around often appearing as heavy algae soups :- ))!

Indeed it would be worthy to translate these biogeochemical processes into energy yield, should be not a too heavy task if you are familiar with thermodynamics, I guess??!

Good luck also from my side!

Dominik

Did you let your system in OCV for sometimes and connect an external resistor?

Biogas is a mixture of gases (mainly methane) produced by the breakdown of organic matter in absence of oxygen under controlled environment (pH, temp, volatile acids, HRT, OLR....).

Volatile fatty acids are the intermediate in the methane formation pathway of anaerobic digestion. We need to maintain a balance between the volatile acid produced and consumed inside the digester. If there is accumulation of volatile fatty acid then the digester pH will drop along with the COD, BOD reduction and biogas production.

So, if your digester pH is becoming acidic means there is accumulation of VFA (also reducing the alkalinity / buffering capacity) and need to find the reason by reducing the feed rate (intake of COD or BOD). The reason may be overloading, high / low temperature in the digester, dead culture (inoculum) etc...

Hakim S. sultan Aljibori & Manish Kumar Thakur Thank you for your reply!

FuMa-Tech and Asahi Kasei likely have some non-fluorinated options for this application. My company, Ionomr, has a non-fluorinated / fully hydrocarbon material we call Pemion that is designed to replace Nafion in hydrogen fuel cells and PEM electrolyzers that may work depending on requirements.

Normally, there is a proportional relationship between humidity and voltage generation with a P-MFC. Moqsud et al. (2015), reported that the humidity factor influences the generation of electricity with P-MFCs. When the plants are under water stress, the performance of the voltage is reduced (Apollon et al. (2020) https://authors.elsevier.com/a/1bh-l15eiez%7EsH .

Following

Yes, especially now if you see the whole COVID-19 situation, it is a perfect example of: If we keep producing food, the way we do, we are going to get sick with something medicine cannot fix. Same applies for the fossil energy at large with climate change, and the ever increasing landscape of alternate energy is likely to prosper.

This paper might be useful:

They designed a special energy harvester for MFCs, which required minimum input power of 2.09 μW for charging a supercapacitor to 3.3 V.

These following links are useful for your question.

https://link.springer.com/article/10.1007/s00114-004-0516-x,

Arduino plus HX711 module should do the job. Components are dirt cheap from Aliexpress. Total cost will maybe $10 if you use a smartphone or laptop to power the system and log the data. HX711 is mainly used as an amplifier for loadcells, But it really just measures voltage across terminals. Here's a circuit and some code for a scale. https://www.botshop.co.za/product/hx711-load-cell-amplifier/ There are many similar ones available online. Your main challenge will be to calibrate the system.

To upload the data, you need to add a Wifi module like https://www.aliexpress.com/item/4000505567851.html

Dear Kartik,

The power density curve should be obtained, and the internal resistance is equal to external resistance at maximum power density.

Also, you can read this article for further information:

Kind Regards,

If it is for PEMFC, DI water would be fine within a week. But if you worry about the contamination, you could boil it before using.

Dear Nedan,

The drop in voltage during the OCV evolution is due to the fact that the substrate is depleting. The substrate, such as organic compounds, has been utilized by the microbes to generate electricity in MFCs. Hence, if you are using a bioelectrochemical system in a batch mode, I strongly recommend you to perform feed (substrate) injection until two sequential equal peaks in voltage are obtained. Depending on the experiment, It is impossible to say the exact time for achieving two consecutive equal peaks in voltage (It may take several days to several months).

Variable external resistances are suggested to obtain polarization and power density curves.

For more information, I suggest the following article.

Best Regards,

Yes we have measured the conductivity on the cage, on the shields and all the other parts accesible.

I send you an application note on active surface of platinum determination by CV.

You can also use PEIS technique to perform impedance measurement. Most people use a polarization technique at first analysis on fuel cells.

Go through the following documents, please:

Got it!

Thank you for your brief explanation.

as you know adhesion is the key step of biofilm formation , if the anode (in the case of bio anode) or the cathode (in the case of biocathode) have some caracteristics that boost adhesion (rooghness, hydrophobicity, biocompatibility, surface charge, electrostatic interaction, internal rsistance,....) you will have the formation of biofilm in a fastest way, and also the presense of nutrients and the absense of inhibitors splay a crucial role in this process.

Dear Bala Ganesh,

You can use the technique of pyrolysing coal-tar pitch mixed with fine sulfur. See e.g.:

Clausse, V., Bastien, T., Hoppe, S., Marêché, J. F., Fierro, V., & Celzard, A. (2009). Investigation of pitch–sulphur mixtures used as binder in the preparation of black ceramics. Materials Chemistry and Physics, 116(2-3), 619-630.

Make sure that you use the suitable scan rate for your experiments

Thomas Cuff,

I did simulate a comparator with positive feedback but the MOSFETs used in the simulation were B_SIM modules.

However, the problem with IRF540 is that it has a minimum threshold voltage of 2V. The output of my microbial fuel cell (MFC) is less than 0.5V. Connecting the cells series to get 1V is one way to solve the problem. However, I was thinking of another way to solve the problem without stacking MFCs to prevent voltage reversal.