Bacteria generate electricity from wastewater | Hacker News Reader

Bacteria generate electricity from wastewater

actu.epfl.ch

119 pointsgeox35 comments

I think researching in the opposite direction has more potential. Let me explain:

what we want isn't to generate electricity through bacteria that digests wastewater -- what we want is to feed electricity to the bacteria that digests wastewater, just to enable that bacteria to do it better, faster, and "wider".

Let's imagine I have a septic tank behind the house. I don't need to find out how I can run a LED light from the bacteria in the tank. What I want is to plug that biosystem to electrical power, so that the septic tank biorection is 100x speeded up, in a 10x smaller tank. Even if it uses up a few Watts of power.

And, once we do that, think of the possibilities that open up: once you feed power into the biosystem, it becomes energetically possible to drive bioreactions in the opposite direction from the energy gradient, basically driving the reaction "up the hill" with electrical power. Now that's something!

You could check the idea by throwing sugar into the septic tank.

Yes, and that might help the reaction. Also heating the tank to the optimum temperature (for the particular bacteria) helps, optimum pH, etc. helps. But the point is to provide the "help" with electricity directly.

What the sugar and electricity have in common that the pH and temperature don't is the possibility of setting up an ecosystem that crowds out the original one for nutrients but doesn't process the waste, due to having another more effective energy source.

You can do this to some degree with a septic tank aerator pump.

One important version of this idea is using electricity to drive photosynthesis. If this manages to be even 10% efficient it could massively increase the amount of calories available without much increase in land usage (or ecosystem damage). Of course I suspect this wouldn't produce particularly good food, so it would probably be something of last resort.

> using electricity to drive photosynthesis

Like using electric lights in a shady warehouse?

Or blasting UV light in perfectly legitimate warehouses.

https://www.ncbi.nlm.nih.gov/pmc/articles/PMC9551646/

We actually do this as the basins populated with bacteria that process our waste are heated to improve their metabolic activity and speed up the process.

edit: in regular waste processing plants

We have e. coli as part of our gut biome right? Curious how dangerous, if at all, it would be to get this modified version in there. I have a hard time beliving it is very efficent so doubt it would somehow electrocute you from the inside, but could cause other issues.

I wonder how it compares to something like methane digesters in production and ease to maintain. Seems like it would produce less energy and not make nearly as good fertilizer, but be much less finicky and not require an anaerobic environment or careful temperature control.

One helpful way to think of it is that having a wide variety of bacteria is what matters for a healthy gut biome.

If one species like e. coli flares up, maybe from food poisoning, it can overwhelm the immune system. The other type of food poisoning (like with botulism I think?) is where the bacteria have already contaminated food with their waste and it overwhelms the organs so the toxin reaches the body. But with so many variations of e. coli already in existence, I would expect the risk from an engineered version to be low.

That said, I lost my gut health in late 2018 due to a number of factors including work stress, too many beers/cocktails and ignoring my body's response when I ate stuff like almond butter which I didn't know I was sensitive to. That punched holes through my intestines and gave me leaky gut. Which allowed gluten, lectins and lactose to pass the gut lining and trigger my immune system. Now I'm sensitive to foods containing those compounds, and they are in almost everything and especially processed foods. It took me at least 3 years to recover and I must largely avoid wheat and fast food now, which is.. annoying to say the least.

Gluten sensitivity has reached such levels that many people can only drink hard seltzer now, not beer. And having to offer gluten-free options has become a burden on restaurants. What most people don't realize is that gluten sensitivity can occur at any age unexpectedly. I look at it now like smoking: every time we eat grains, we run a small risk of becoming sensitized. IMHO that's mostly due to the increased use of wheat and gluten in processed foods, incentivized by the lowered cost of GMO crops:

https://www.researchgate.net/figure/Correlation-between-incr...

This was all predicted by a small minority of scientists in the 1990s and armchair activists like me who warned that GMOs would have unintended consequences. TANSTAAFL except with GMO foods.. right.

I'd choose GMOs for industry over messing with our food supply any day.

Engineered microbes are almost always far less fit than wild-type. They will survive best in a monoculture, and if they are forced to compete with less hobbled strains they will usually find a way to get rid of the engineered modifications in order to grow faster.

> Engineered microbes are almost always far less fit than wild-type. They will survive best in a monoculture

True

But the article did not address this, it should have.

It will be the big question before deployment

I've always wondered how quickly this effect would ruin the monoculture.

Suppose you're treating the engineered microbes like sourdough starter: Add them to nutrient solution, wait for desired effect, take a small sample, add to next batch.

You'd expect a selective pressure away from the engineered outcome, such that after X batches, your samples are overrun by wild-ish type mutants. But is that a merely academic concern, something that might happen after 500 batches, or are you out of luck by batch three?

From the "supplemental information" [1] part of the actual paper [2], the levels of current are measured in μA and tenths of volts (ie. in the order of μW of power).

What is fully unclear to me is how (or whether) that power can be harvested and put to any electrical use. Or perhaps it is only of chemical interest?

[1] https://www.cell.com/cms/10.1016/j.joule.2023.08.006/attachm... [2] https://www.cell.com/joule/fulltext/S2542-4351(23)00352-5?_r...

From the video it looks like they are just using a few mils of liquid volume. My question would be how well does this method scale up? Maybe waste water treatment plants could offset their carbon footprint a significant amount or even become a power plant if this technology gets better.

Most waste water treatment plants are already 'carbon negative' - since they're getting fossil-fuel-free turds and normally turn it into methane for energy generation.

On official charts, it shows as 'biogas' - although usually in statistics the biogas from waste water treatment processes isn't separated from the biogas generated from municipal landfills.

I was skeptical about your claim but I turns out that you are right! I knew about agricultural biogas production but never though about the potential of methane production from waste water treatment.

Even more surprising is that the generated biogas is used in the municipital gas supply in my town[1]. So I literally cook with fecal products.

[1] https://www.stadt-zuerich.ch/energie/de/index/heizen-kuehlen...

You eat what you ate!

I'll have to finish the read, but my first thoughts were the number of organisms we are bioengineering to do specific things, and how they might crossover with other naturally occurring or bioengineered microbes. I remember the plastic-eating microbes found in colder climates[1]. There are other plastic-eating microbes, but they need hotter temps ~86F. These work in cold climates. Visions of the blob with lightning and plastic-eating powers ;)

[1] https://www.cbsnews.com/news/plastic-eating-microbes-from-on...

How exactly do you 'wire up' E. coli bacteria? Is the idea here that we could somehow string a bunch of them together into a tiny battery? Or is it more like using them as the electrolyte in a battery?

They turn hydrogen+carbon and oxygen into protons, electrons, and CO₂.

The protons and electrons serve the same role as hydrogen in a fuel cell.

It's more like using them as an electrolyte, but it acts like a battery (you charge by adding waste, discharge by extracting electrons), I guess? You run the bioreactor with some special electrodes that bacteria like to touch, and then directly harvest electrons from the medium as the little ones grow.

Mohammed and Melania (the lead researchers on the paper) are both super talented scientists. I had the pleasure of meeting them both in SF last year when they were on the west coast for a conference.

Bill Gates will drink the results.

https://en.wikipedia.org/wiki/Omni_Processor

Hi everyone, this is Mohammed from the article. Thanks for taking an interest and discussing our study here!

If you have any question just reply to this comment.

Science magic saving us from climate change

I can be a bit of an over-optimistic person, but I've always been of the opinion that mass extinction events are always going to occur without intervention and while humans certainly seem to have contributed towards speeding up the timeline heading towards the next extinction event, we're more importantly the only species with potential to mitigate these extinction events all-together.

Without humans extinction events will occur (at least history suggests this is the case). With humans, they might not. For all of our flaws, I think humans are the most beautiful species to come into existence. We have seemingly boundless potential.

Depends a lot on the timeline and extinction event.

In the case of human caused global warming, human harvesting of forests and top soil, endocrine interfering plastics, or global thermonuclear extinction where there is a causal link, those specific events would not happen without human industrialization (and exponential reproduction).

The Sun will one day consume the earth, the possibility of an asteroid (that humans can't destroy) is still there, the magma/volcanic cycle of heating and cooling is there.

I'm curious what extinction events you're so sure humans are capable of preventing that haven't been directly caused by humans (whales, eagles, buffalo, cfcs). And I don't think bacteria or viruses we've experienced qualify to have been extinction level events.

I'm not sure of anything but our potential. It's only been roughly 150 years since the first internal combustion engine. Today a 50lbs machine mows my lawn by itself by communicating invisibly with hunks of metal in outer space traveling at 17,000mph around earth to determine its position on the face of the planet within roughly a few centimeters. This machine cost me roughly a week of labor.

I think the much more interesting question is what sorts of extinction events do you think we will be incapable of preventing in 1,000 years?

> I'm curious what extinction events you're so sure humans are capable of preventing that haven't been directly caused by humans

It's hard to say, but we may be able to pull off redirecting an asteroid and geoengineering might help offset the worst of some future crisis. Being able to do something from a technical standpoint and being able to actually do it when necessary are very different things though. We're already in the middle of a mass extinction event of our own making and I doubt we'll be able to repair all the harm we've done. Expecting humanity to solve the next one might be asking too much.

> Science magic saving us from climate change

I hope you are joking

Something to "save" us is not what we need

We have all we need and if we can adjust are economic and social relationships we do not need saving, we can look after ourselves

A big if.

One step closer to AI robots that can subsist by eating. :)

It's about time they did something useful!

> Our work is ...pushing the boundaries in more and more real-world applications

Is this how we end up in the matrix?

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