r/Showerthoughts • u/Conscious-Ball8373 • 13d ago
Casual Thought A septic tank is one big bacterial battle for species supremacy. You can tell who is winning by the smell.
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u/tcpukl 13d ago
It's just another ecosystem. Another common one is a gardeners compost bin.
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u/freakytapir 13d ago edited 13d ago
Fun fact, a large enough compost heap for gardening actually gets really hot. (Visited a garden waste facility once as part of my education and the insides were at least steaming Then again, we're talking about 10*50 foot piles of wood cuttings) 140°F/ 71°C
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u/Sufficient_Result558 13d ago
Hay bales and hay piles spontaneous catch fire if you are not careful with the moisture levels.
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u/writingthefuture 13d ago
Funny enough, adding water can make compost piles combust
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u/ExcaliburClarent 12d ago
Wait how?
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u/Tropadol 12d ago
Increases bacterial growth which increases internal temperature
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u/freakytapir 12d ago
That's why at that facility they moved the wood trimmings around regularly with heavy machinery. Release trapped heat. You can't control the rain.
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u/Gnonthgol 12d ago
A lot of the bacteria hibernate because it is too dry, by adding water you wake them up and they start producing heat. Adding to this a lot of bacteria can still survive without oxygen, they just produce combustibles like alcohol, methane, ammonia, etc. And when these get heated enough you get convection through the pile bringing inn oxygen and you end up with all the sides of the fire triangle.
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u/knows_knothing 12d ago
I wonder how bacteria has evolved to survive spontaneous combustions? Presumably the fire would kill off the bacteria.
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u/Sufficient_Result558 12d ago
It does not need to survive in fire and surviving in fire serves no purpose. The bacteria left on ash and char would just starve since the food source is gone. Bacteria multiply extreme rapidly, the parts that got too hot but left a food source are just quickly repopulated again, just like they did at the start.
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u/Liamlah 12d ago
Its not a common enough part of their life to have mattered. Similar to asking how humans have evolved to survive volcanoes.
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u/Sufficient_Result558 10d ago
Except that bacteria have no need for survival of individuals, they multiply extreme rapidly. One single bacterium can multiply into more than 1 million cells in just 7 hours, and over 2 million in 8 hours. Kill them all in area and the population is back the next day.
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u/knows_knothing 12d ago
Did a quick deepdive, bacteria can turn into endospores which can widthstand the heat, or the hay/compost pile is big enough and wet enough for the center to continue to be livable for the bacteria.
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u/Sufficient_Result558 10d ago
Your deep dive should have told you it doesn't matter if they die. One single bacterium can multiply into more than 1 million cells in just 7 hours, and over 2 million in 8 hours. Kill them all in area and the population is back the next day.
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u/solidsausage900 11d ago
Imagine being invited to an orgy and the building catching on fore from everyone doing the sex too much
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u/Sufficient_Result558 11d ago
Bacteria don’t have sex, nor is the heat from reproduction. The heat is from metabolic energy as they digest.
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u/Conscious-Ball8373 12d ago
There's a guy on youtube who built a hot tub with woodchip-decomposition heating. Just built a ten-foot-diameter round wire cage and filled it with woodchips, with a coil of pipe every few inches. He reckons it'll keep the hot tub hot for about eighteen months before he has to renew the woodchips.
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u/freakytapir 12d ago
At the facility I visited they just let it dissipate as they moved the heaps. They had no need for the hot water and it was in the middle of nowhere so no reasonable way to get it somewhere else where it would be useful. It was the county (Well we would call it a province) yard trimmings compost centre, so enormous heaps row after row of the stuff.
Big industrial machinery.
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u/Maple-Mayhem 13d ago edited 13d ago
Could you use this for a heating system I wonder? Like geothermal heating but pipes in a compost pile.
Edited to add: Lots of interesting answers to my question, thanks everyone!
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u/TheWalrus_15 13d ago
I have seen a garden greenhouse that grows things in the dead of snowy winter using compost piles to heat the room.
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u/West-Gur4598 13d ago edited 13d ago
Plenty of farmers makeup a pile every year. Hydronic with a pump typically. Pipe or hose running into a greenhouse. or shed.
It takes a large volume and done correctly as well as understanding it isnt a 100k btu furnace. It is a steady supply of surprisingly warm water
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u/freakytapir 13d ago
As part of my work for another company, we were actually trying to use grass cuttings to produce methane (burnable gas), but it kept getting infected with other bacteria so we only got carbon dioxide after a while.
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u/namemcuser 13d ago
I’m pretty sure there was someone over on r/composting a couple years ago who tried this with limited success. Keeping a small greenhouse above freezing in the winter though is feasible in a milder climate.
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u/iwouldhugwonderwoman 10d ago
I go smaller and simpler and I keep my bananas and citrus trees warm over winter by building a wire fence and loading it down hay, grass clippings and shredded cardboard. My real compost piles get much hotter but little bit of microbial fun is enough to keep those trees warm enough to make it through the winter.
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u/freakytapir 13d ago
I mean, the real question is if this is more energy efficient than just burning the wood clippings.
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u/zekromNLR 11d ago
You don't get as much of the chemical energy that is in the wood out, because there's still plenty of organic carbon in the compost. On the other hand, you do not have to spend any energy on drying the material, which you have to do when you burn it.
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u/vowelqueue 12d ago
Not sure about capturing the heat directly but dumps can capture the methane that is produced by decomposing trash and burn it for energy.
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u/reb678 12d ago
There was an orchard behind my house. The owner converted it to a solar farm. He had someone come in and shred all the trees and they were left in several large piles.
One of the piles self ignited because it got so hot inside. The firefighters were there for several days along with a bulldozer to spread out the pile and spray water on them.
I think it took 4-5 days for the smoke to clear.
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u/freakytapir 12d ago
They do the same at a County yard trimming compost plant visited. Bulldozered about regularly.
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u/Fract_L 12d ago
Tbf, you don’t need a huge pile - you need a pile that has plenty of nutrients left in the center. A single person’s compost, especially if only for a garden, will grow so slowly that it will be more noticeably bereft of nutrients under the top layer so it won’t be as active in the most insulated parts of the pile.
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u/zekromNLR 11d ago
Fun fact: Per unit volume, a good compost heap puts out more heat than the sun's core
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u/Wonderful_Ninja 8d ago
71c ! That’s pretty darn hot ! I wonder if temps can get even hotter that the stuff just bursts into flames lol
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u/freakytapir 8d ago
It can but not your average garden pile. Or it would be rare.
Visited a county facility for mulching wood trimmings once and there it lay in heaps meters long and tall
Some of the piles they were turning over were already getting smokey/steamy on the inside.
That's why they mix them through from time to time with bulldozers and earth movers. To release the trapped heat.
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u/Gnomio1 9d ago
Your average home compost bin has a greater energy density than the sun.
I’m not making that up. The sun makes a lot of energy. But it’s also absolutely enormous. It’s not very energy dense. Fusion, at stellar temperatures, is slow.
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u/tcpukl 9d ago
That is nonsense. The centre of the Sun is very very dense.
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u/Gnomio1 7d ago
Note that I said “energy density”, which is the amount of energy produced per volume.
The sun produces about 275 watts per cubic meter. This is about the same as a compost heap.
This is a quirk of nuclear fusion at stellar temperatures. It’s incredibly slow, there’s just an enormous amount of sun so it all adds up.
It may read like nonsense, but it is correct.
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u/Able_Transition_5049 12d ago
It’s kinda cool how much life is happening in things we normally just see as waste.
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u/Bool3636 13d ago
Being born as a poop eating bacteria in a septic tank is probably the most blissful life ever to be had
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u/holyfire001202 13d ago
Until some fucker can't find his plunger, but accidentally ordered way too much lye, so decides to try to use a bunch of it to unclog the toilet.
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u/Fausto2002 12d ago
Nah
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u/GarethBaus 12d ago
You are literally surrounded by food in a space optimized to have you flourish and protected from most hazards while being too dumb to realize or care that your reality is literally shit. There aren't very many forms of existence better than that.
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u/Doveda 12d ago
I mean, you have to deal with being crowded out or killed by your competition for the food space. The bacteria don't all get along peacefully with different kinds
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u/holyfire001202 12d ago
I'm stuck on that "surrounded by food" part. Obviously there's more to consider, but last year I watched a deer just laying around in a bunch of dandelions, going between napping and just snacking on the bed of food she was laying on. I dunno, that stuck with me. Being able to just lay in a field of salad, basking in the sun. That's bliss right there.
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u/JennyFromDaHood 12d ago
Laying on grass and plants sounds so itchy. Then there’s also the fact a tick can latch on to your back and you can’t do anything about it. Eventually they start making babies and your got multiple ticks all over your body.
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u/Masterpiece-Haunting 12d ago
Correction, NaOH, some guy is probably bombing his septic tank with lye right now.
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u/freakytapir 13d ago
You don't have to tell me, did my thesis on Water treatment plant sludge... Smells like rancid butter? Butyrate producing ones are winning. Vinegar smell? Propionate or acetate producers are winning...
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u/AlephBaker 13d ago
I assume the vinegar smell is the one you "want", inasmuch as you would want any sewer smells. Or is either smell indicative or a problem?
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u/freakytapir 13d ago edited 13d ago
Uh, well as I was studying methane production
If I smelled the butyrate it meant something had gone wrong in the chain and a certain group of bacteria wasn't doing its job.
Both propionate or acetate can be converted into methane (you know, actual usable gas)
But if it was stuck at the butyrate stage it meant none of that was happening.
So you want to smell the acetate. (Vinegar acid) Acetoclastic methanogenesis.
Propionate either get broken down to acetate or follows the hydrogenotrophic pathway which also produces acetate as a middle step.
TLDR: Lot of science babble but the smell was a sign the production line had a blockage.
That said, my first few weeks of doing my Thesis involved a lot of "running outside before I retch" moments.
Concentrated Activated sludge is no joke in the smell department (and I needed multiple vaccines before even being allowed near it )
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u/-Redstoneboi- 13d ago
did you at least have a reusable artificial nose device? like a bunch of sensors on a chip, or a washable litmus paper-like object for scent instead of ph, or did you just rawdog the smell?
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u/freakytapir 13d ago edited 13d ago
I had gloves, safety goggles and a labcoat. But the moment you open that micro reactor you know what's up.
But yeah, Ph, HPLC, and we planned a MALDI-TOF to analyse the proteome but couldn’t get the samples clean enough.
As well as a Cation and Anion analysis.
But I did get vaccinations against Hep A and B and a booster shot for Tetanus before starting my master's thesis.
Oh, and off course Gas chromatography on the gaseous contents of the reactor. Seeing if the CO2/CH4/H2 changed as I Tried to murder the reactors with salt.
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u/Conscious-Ball8373 12d ago
Isn't there a reasonable chance it would produce dangerous levels of H2S?
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u/freakytapir 12d ago edited 12d ago
For commercial use (like they do in some water sanitation plants), yes, the H2S has to be scrubbed, but my reactors were 1L filled to about 800 ml. (so 200 ml headspace).
So me opening them might get a rotten egg smell, but among all the other smells in there ... It stayed several orders of magnitude below a dangerous dose.
But I did have to manually take samples, refeed them with fresh sludge.
This was my set-up (not me in the video but my thesis tutor). Some other student is now probably using it right now
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u/Frietmetstoofvlees 7d ago
Didn't expect you to be Belgian as well! Very interesting read/watch as my uncle and nephew work in Aquafin Deurne where they have bioreactors as well
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u/freakytapir 7d ago edited 7d ago
Just found that video by coincidence. Hope they scrubbed the ceiling since one of my reactors overpressure-ised. Unscrewed the top and wound up as a Dalmatian and the ceiling as a Rorschach test
But Yes, I am Belgian
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u/Frietmetstoofvlees 7d ago
Oof, that sounds like quite the unpleasant occurence. I remember I visited the Deurne plant once and it did take some getting used to the smell the first couple of minutes lol
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u/GlowingJewel 12d ago
May I ask what your thesis is about? My slight autism has displayed an insolent affinity with sludge, water facilities and all related matters and I’m finding it fascinating. Specially captivated by how algae is being used to treat mining rundown + catching rare earth minerals while doing so…
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u/freakytapir 12d ago
Originally It was going to be about using MALDI-TOF to detect a change in a (usable) methane producing water treatment plant before Methane production dropped off.
Never got the samples clean enough for a MALDI-TOF to work.
So we switched to adaptation of the microbial culture under Sodium+ stress.
Sodium+ (as part of a salt, not pure sodium) we used because it was easy to measure, easy to dose and safe to work with (Just half of Table Salt Sodium Chloride.)
So I was adding salt to the reactors until they started to fail, and measured both the Volume produced and the gas ratios (CO2/CH4/H2/H2S).
Over 4 months we had our 4 control reactors, our 3 gradual slope reactors (bit more salt every time) and 3 our (jump) reactors who got sudden jumps in salt concentration. (If you're wondering why 4/3/3, it's because we expected one to fail to "boot" so then we'd have 3/3/3)
Then we checked if they adapted to the stress and what the limit was.
Then over the next 4 months we removed the salt bit by bit. (10 % Old sludge, out new sludge in same as in the salting stage.) Seeing if they recovered.
My set up looked like this. (Not me in the video but same room and he was my Mentor)
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u/priya-6370 13h ago
Did the smell give you an early warning before the methane yield changed, or did it only confirm what the gas readings already showed?
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u/freakytapir 5h ago edited 5h ago
I trusted the GC (gas chromatograph), but yeah, you couldn't smell the methane above the smell of activated concentrated sewage. The consistency and colour of a blended elephant, the smell of death.
But butyrate does smell very specific. (Basically rancid butter)
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u/Sabz5150 13d ago
So for another species in the galaxy, the "smells like victory" could be an actual thing.
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u/bluehands 13d ago
I certainly know the smell of da feet
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u/Arokthis 12d ago
Heh. You just reminded me of how I evacuated a 15-passenger van by taking off my shoes.
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u/ragnarok635 12d ago
Did you not shower for a year or something?
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u/Arokthis 12d ago
I was 17. I had spent all day walking. They were winter sneakers, designed to keep heat in and to keep water/snow/slush out. You do the math.
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u/demunted 13d ago
For those wondering if is usually a battle of methane, hydrogen, CO2, h2s and some other gasses. Depending on what bacteria are winning depends on the concentration.
Fun fact, our guts operate similarly with bacteria and archaea breaking things down and outputting different products. Those with SIBO have an overactive concentration of one family and can have hydrogen or methane dominant output which can mess things up.
The smell part is accurate.
Another fun fact is that companies harness this power for anaerobic digestion, breaking down food waste to make methane gas as renewable energy (it's going into the atmosphere otherwise!).
ADHD guy signing off!
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u/Conscious-Ball8373 12d ago
There's a guy whose name I forget for the minute (Tim someone?) but he pushes the idea that health is heavily linked to gut biome variety and so the key to good health is to eat as wide a range of plants as possible because each one feeds a different type of bacteria. Interesting idea.
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u/Ilovejooce 12d ago
Renewable methane energy is not cost effective at all right now but it is getting more popular with federal grants paying for them. I've seen a system that captures mathane from cow manure at a feed lot, and another one that uses all organic material from the whole farm process like husks from corn farming mixed in with manure. The cogeneration process gets even more efficient when they capture the heat from the generators burning the methane fuel, the heat is routed to be reused in the composting process or to simply heat buildings.
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u/LogicalByte 13d ago
i'm convinced it's just geopolitical warfare down there. when it rains, the pressure changes and some faction gets pushed back to the secondary lines... then the temp drops overnight and boom, sudden counter-offensive that smells like old gym socks. it's not just 'winning', it's tactical retreats and flanking maneuvers happening in real time while i'm trying to shower. absolute chaos. rough out there.
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u/danath34 11d ago
Change the word bacterial for microbial and you've also described any fermentation process: beer, wine, cheese, sauerkraut, kombucha, etc
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u/ShowerSentinel 13d ago
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