About microbial fuel cells and wastewater

[CatEmperorTime]

I wanted to do one of those microbial fuel cell projects and the kit linked to it was this https://www.homesciencetools.com/produc ... t/?aff=SB1
The original purpose of this kit was for mud but i was wondering if they can also be used with wastewater?

Many thanks.

[SciB]

The microbes that power the fuel cell are living only in mud as far as I know. I think that they would probably die in wastewater, although that would depend on what contaminants were in the water. The sludge from a water treatment plant might contain the sort of bacteria that can be used in a MFC, however.

Here are some references that talk about these soil microbes so you will get a better idea what you are dealing with:

1. https://www.ncbi.nlm.nih.gov/pmc/articles/PMC5099896/ - quite technical, but useful nonetheless

2. https://en.wikipedia.org/wiki/Microbial_fuel_cell

3. http://www.bioelectrogenesis.com/docs/A ... dia_04.pdf

4. https://www.youtube.com/watch?v=e6u765X1Ml4 - this video mentions using wastewater microbes to extract enough electricity to power a wastewater treatment station, so I guess the water itself CAN be a source of these bacteria. You will have to do some experiments to see how to adapt the fuel cell to use water instead of mud.

Good luck and do post again to let us know how you are making out with this type of MFC.

Sybee

[CatEmperorTime]

From what I've gathered online, I assume that it is possible that microbial fuel cells to use wastewater. I suppose I didn't make it clear (and I apologize for that) but what I'm asking is if that specific microbial fuel cell I linked can use wastewater. It would be a waste of money if I were to buy one for my project then it turns out that model isn't what I was looking for.

Cheers

[SciB]

I understand what you are asking and I do not have an answer from my own experience. My guess based on what I know about how a fuel cell works would be that the MFC that you buy as a kit will generate power using waste water.

My other suggestion would be to simply set up a mud-based fuel cell, get it working and then add waste water and see if the power output increases. I can imagine a commercial MFC in which the bacteria are attached to some non-conducting matrix, maybe plastic, and the wastewater is pumped over them. The bacteria will generate electricity and keep doing it as long as fresh wastewater flows over them.

You could, of course, try to use wastewater as the source of MFC bacteria. These microbes might be better at using wastewater as a source of nutrients since they were living there.

I'm sure you will have more questions, so post again.

Sybee

[CatEmperorTime]

Ah, I see. That is certainly interesting; I'll try it once the next school year comes. The actual experimentation for our project is next year and I just wanted to have a jump start, haha.

Anyways, I think I'll just be creating a microbial fuel cell myself. I've seen many articles online that are about DIY MFC's. I'll be posting updates if you are interested.

Cheers

[SciB]

Yes, please post your results and observations from time to time. I get a lot of questions about this MFC and the more feedback I get the better. Making it work better and keeping it working are challenges.

Check the published literature on MFCs. There are companies looking to commercialize the technology and they are worth reading about because they have to overcome the problems of scale-up from small MFCs to huge ones.

Photovoltaic solar panels get most of the news coverage, but other sources of power like bacteria need to be researched because they work when the sun is not shining.

I'm glad you are interested in this field and willing to do some work outside the required time. That's the mark of a real scientist. Discovering new things and making them work is great fun and so satisfying--and with the web as your source of all info--you can do anything! Especially with us to guide you!

Good luck,

Sybee

[CatEmperorTime]

Hey there! It's been a while. Here's a sort of update.

My teacher told me this earlier (keep in mind I'm paraphrasing) :

"Since every sample has different bacterial content, which would in turn would change the amount of exoelectrogenic bacteria, then that would mean that the findings in your research would not be conclusive because the energy output might change on other trials."

This stumped me. Do you have any ideas how to resolve this?

Cheers

[SciB]

Hi CET,
Technically correct, but us scientists always have ways around niggling critics.

In my humble opinion, the goal is to find the BEST bacteria to create electricity and feed them their fave yummies so they work hard to charge our phones and tablets for us.

Sure if you sample 10 different muds they will have different bacterial species and numbers, but that's not the point. Which species works best and under what conditions? You might find a species that does really well in wastewater but hates mud. I'm sure the companies that are interested in turning MFCs into profitable energy sources are trying hard to find the best bacteria to do the job with the source of food that is easiest of access.

Maybe the humble backyard septic tank could one day be turned into an electric generator. Hook it up to a lithium ion battery and you could store enough power for phones, laptops and maybe even a TV.

Did I answer your question? Do some more reading and find out which bacterial species are the best for MFCs and why. Now that we have CRISPR genetic engineering tools, we could modify the bacteria so that they produced even more electricity and grew better under the desired conditions.

Let me know what you find out. You may have a career in bacterial power supplies!

Sybee