Superworms for bioremediation of polystyrene: ideas for extending the (re)processing?

Composting styrofoam using superworms/mealworms has been discussed before here:

https://permies.com/t/72035/critters/Styrofoam-Composting-Mealworms

And here is the scientific study:

https://pubs.acs.org/doi/abs/10.1021/acs.est.5b02661

I am going to experiment with this, and have some superworms on the way.

My understanding is that the polystyrene is partially converted into CO2 during digestion, but that part of it passes through still as polystyrene, albeit shorter hydrocarbon chains. My understanding of this process is not super firm, however.

Questions:

Presumably, if the worms eat and redigest their waste multiple times, the HC chains will get shorter and shorter and eventually become harmless/not really plastic anymore, although I don’t know how to determine when this has happened. Suggestions?

I know my red wigglers, if not fed new stuff, will reprocess their castings into finer and finer material and live for quite a while without the bin becoming nasty. Will mealworms/superworms do the same, or will they die/become really gross?

I have heard that oyster mushrooms can break down plastics. I have never grown mushrooms of any kind. Would it be feasible to use the superworm waste and potentially their carcasses as a mushroom substrate somehow, or do the oysters only grow on specific stuff and you can’t just stick them on dead worm goo?

Any other suggestions for additional fauna/flora or other methods of cycling the polystyrene so that it actually gets digested instead of just disintegrating into microplastics?

Thanks!

The worms are here! I dumped them in a plastic container from my dad’s bottomless pit of a garage, along with the bedding included when they shipped and a plastic take-out container. Weirdly enough, after a couple minutes in the bin, I could actually hear them start chomping on the styrofoam!

They can be kept in any plastic container of sufficient size, and allegedly they don’t climb, so it can be lidless. I have a lid with holes poked in for ventilation, however.

Superworms, unlike mealworms, are a tropical species and need to be kept warm. I live in a subtropical climate, but those wanting to vermicompost styrofoam in colder climates might want to stick with the smaller and more cold-hardy mealworms.

That's fascinating. I wonder how much time it would take a similar number of these to eat a piece of polystyrene insulation board? Also, what do you do with the waste? Just let them keep re-processing it until they can't anymore, like you suggest? Or is it just finely ground styrofoam?

Here is a picture of the progress they made overnight on a piece of the take-out container. You can see where they have begun to gnaw away the edges. These are allegedly 1,000 worms. I also put a few of them in a glass overnight with some chunks of styrofoam to isolate the waste product. It looks like white and brown dust, essentially. From what I have read, they do actually have the ability to truly digest the styrofoam via their gut bacteria, not merely chew it up. However, they don’t get it all on the first round, so some of the waste is basically ground up styrofoam still. I am going to try to let them reprocess repeatedly, but I will say that they have a less pleasant smell than my red wiggler bin, although not terrible, and that may get worse if they are left to reprocess their own waste repeatedly. I am also considering using oyster mushrooms to try to add another cycle of styrofoam breakdown, but not clear on how that could work yet.

This is fantastic! Please keep us updated on your results. I don't quite understand one thing, though.... assuming that all of the plastic gets broken down eventually to a non-toxic level, will the resulting material be useful in any way, or will it simply be non-toxic? Which is pretty fantastic in it's own right! And can the worms be used safely as fodder?

Thanks!

Kelly

Please keep us posted on this one. I find it as exciting as mycoremediation.

Are you planning on having the worm feces and carcasses tested afterwards to see if there is any styrofoam present? That is my only caveat, as this is great if it's being broken down by the worms' gut bacteria, but terrible if they're just a biological shredder. I have read and am hopeful about the indications that it is actually digested, not just broken into smaller pieces, but I would need confirmation of this before, say, growing my food with it.

At worst, though, I suppose fuel and fibre crops could be grown with it even if it weren't a perfect solution.

-CK

Kelly,

I am not sure if the waste would be especially beneficial, but according to the study I read, if I remember correctly, the researchers considered it safe to add to agricultural soils. Then again, scientists consider all kinds of things safe to add to soils which I don’t agree with! In my personal opinion, I probably would not add it to garden soil at this point, although I’d probably feel okay throwing it into a compost pile and putting the result under fruit trees. I likewise probably wouldn’t feed the worms to animals I intended to eat; I doubt they’d hurt the animal, but I don’t want to eat any leftover microplastics. I would like to get some testing done on the waste or mealworm corpses, etc to have better answers to some of these questions, but not really sure how to go about doing it at this point. So at this point it’s more about just degrading the styrofoam, but I think with enough cycling it could probably be safe and beneficial to incorporate in food systems.

Chris,

I would love to get them tested. Most of the equipment and methodology listed in the abstract of the journal article is beyond my ken. Ideally I would like to test the waste, the worm carcasses, the carcasses of second generation worms, the product of adding the waste to bacterially and fungally dominated compost piles, the result of processing it secondarily through oyster mushrooms, red wigglers, chickens, etc...but I need to look into logistics and costs first

The worms had a close call when my dad shut off the part of the house the worms were in while I was out of town, causing them to go comatose from the cold. I thought they were dead, but revived when placed in front of the butane heater for emergency resuscitation.

I have found some thicker blocks of styrofoam for them, which they seem to vastly prefer to the thinner cups and takeout containers. They make tons of burrows and hang out inside/underneath the large blocks.

I have observed that they cannibalize their fallen brethren (sistren?), and, in one case, I saw one worm eat another alive verrrrry slowly as the poor unfortunate writhed ineffectually for hours. High drama. I provided some old carrots for moisture, and they gobbled them up. Today I tried a piece of moldy bread, and they’ve eaten a hole in it, so that seems promising. I also added a green onion and a chunk of celery; not sure if they will eat those or not. It does seem that they have some potential for composting food scraps (similar to red wigglers) as well as styrofoam.

Apparently the cannibalism I observed can indicate that the worms are getting too little moisture, so I spritzed their bin with water.

hau Jennifer, very nice experiment you have going there.

You might want to add some substrate to hold the moisture the super meal worms need to thrive (think like they are red wigglers that don't need as moist an environment as worms but almost).
Shredded paper will do great and you can, as you discovered, add some small amounts of food stuffs to keep them healthy too.
If you can break up the Styrofoam some, that helps them process it faster.
Once the SMW (super meal worms) have gone through the Styrofoam twice you can take that material and simply add it to a working compost heap (most compost heaps will have fungi living there and those will work on processing the material further).
If you are not sure your compost heap has thriving fungi hyphae strands, just make up a mushroom slurry, dilute it by 10 and pour all over and down into the heap for a kick start addition.
Once you can't see the white color present in the SMW bin, you do have the option of taking that and using it in a garden bed, but as you have indicated, it is better to run it through a compost heap at that point to make sure it is completely broken down.

Keep posting your findings here, they are awesome help and very informative.

Redhawk

I would try to cycle the worm poop through fungi and then through BSF larvae and/or red wigglers and then tested by a chemist.

Running it back and forth between these small helpful animals and fungi a bunch of times "should" render it harmless eventually.

Will these superworms reproduce in captivity for you?  If they do, can I buy some from you?

superworms for sale

Those folks have a really good price Tyler

and this is their blurb about them

"Superworms are 1.75 to 2" in length and ¼ inch in diameter!

Reptiles, birds, fish, and even chickens just love them.

They are very lively and fast moving.  They have a long shelf life and are easily digestible.

They don't need refrigeration (it will actually harm them).  Keep them at warm room temperatures (75° to 85°).  

For storing larger numbers of Superworms, add a few slices of potato for their water source to keep them alive.  They will also need a grain such as wheat bran as their food.

The worms will not pupate as long as you keep them with many other larvae.  If they receive constant bodily contact, they stay in the larvae stage."

Ordered!  Thanks Dr!

Bryant Redhawk,

Thank you, that is very helpful info! I spent some of the morning ripping up waste paper and breaking up the styrofoam into smaller pieces for their bin, and then misted the whole thing. I feel better for them now that they are not just wiggling around in bare plastic and their own waste.

I was reading another of your threads about adding soil to compost as a way to bind carbon and keep CO2 from escaping into the atmosphere. Since the worms turn some of the polystyrene into CO2, do you think it would be a good idea to mix some soil into the shredded paper substrate in their bin? I could go get some of the good stuff from the oak woods by the creek, which might get a head start on the fungal action, too. What do you think?

Tyler,

Unfortunately they do not just automatically reproduce in their bin as do my eisenia fetida, but I do intend to try breeding them at some point and will post the results here.

I had considered cycling the waste through my red wiggler bin. To my knowledge, the wigglers don’t possess the ability to break down the polystyrene, but I figure it can only help. Don’t have BSF but may get some in future.

I would like to try growing oyster mushrooms on the superworm waste, then feed the mushrooms to the wigglers, and then their castings composted in a working pile. I know some people grow oysters on coffee ground substrate. But it seemingly has to be sterilized. Maybe I could mix the superworm fecula with my mom’s coffee grounds and somehow sterilize it (with heat?) and try that? I am a mushroom novice. I will do more research.

So, I found research indicating that mealworms can also digest polyethylene, in addition to polystyrene!

https://pubs.acs.org/doi/10.1021/acs.est.8b02301

I tried to induce my superworms to eat some polyethylene, first by tying them up in a plastic grocery bag for a few hours to see if they’d eat their way out, and then by isolating a few in a separate, empty bin with a carrot wrapped in the grocery bag (on the theory that they might be motivated to chew through the bag to get the carrot), and then by leaving them in the empty bin with a six-pack ring overnight. Total failure on all fronts. They didn’t touch any of it, so I put them back in the styrofoam bin this morning with their buddies.

Maybe it’s because they’re superworms and not mealworms, or maybe I need to feed it to them in some other form/manner. Would be very interested to hear if anyone else has success with getting superworms or normal mealworms to eat polyethylene.

This is currently one of my favorite threads on permies!  Very excited about these experiments.  :)

Got my Superworms and set them up in a bin with some polystyrene.  I will also give them some fruit and vegetable scraps.

Tyler,

I am very excited to have you trying this out as well! Let me know how it goes!

hau Jennifer, I think that adding a small amount of soil would be a grand idea, go slow with it though, I'm not sure how the larvae will do, they are normally found in detritus on forest floors.
To breed these you will first need to let them pupate and become adults, this means you would take a few and place them in a separate bin since in groups they tend to remain in the larval stage.
The beetles will most likely need a cover to contain them for breeding and hatching the eggs.

polyethylene is, as you have discovered better handled by regular meal worms.

Redhawk

Bryant Redhawk,

Thank you for the info! I will try a small amount of soil and see how they do. I am tempted to get some normal mealworms too, to work on polyethylene, since the nearest recycling center (which I already have to drive 30 minutes to reach) does not accept #4 plastic, low density polyethylene. Hmmm...

Great work, everyone! Here's an article about someone doing this in a long term, controlled way, involving woodlouse, arthropods, and mushrooms, resulting after months in black, rich, soil. Personally feel that dirt oughta be quarantined and broken down Indefinitely (sure, grow fibers with it, just minimize anything else eating it). Soil is shifted by all manner of forces animal wind rain and more, any slight leakage of plastic from this process remains a huge problem if we scale that up to seriously tackle our Earthly epidemic.

Article
https://www.surfer.com/features/can-worms-eat-old-surfboards/

Eddy's Site
http://livingearthsystems.com/

I couldn't find if he had the soil tested for toxins.

Wen Magnus wrote:Soil is shifted by all manner of forces animal wind rain and more, any slight leakage of plastic from this process remains a huge problem if we scale that up to seriously tackle our Earthly epidemic.

I'm genuinely curious. What "huge problem" do you see exactly? Is this in some way more harmful than other form of pollution in the soil? I'm thinking about all the pollution from exhausts of cars that washes into the soil with the rain - and back in the bad old days that included lead. We don't quarantine soil against pollution in general, and certainly not indefinitely unless there is a very real and immediate risk of harm.

Personally I see the tiny tiny fragments referred to here as relatively benign, especially when buried in soil where it will continue to break down under biological action.

I agree that there are huge problems with plastics in the environment, especially when they wash into the oceans and end up in marine food chains. But we should be careful not to conflate that into all plastics in any circumstances are inherently bad. When we do that we both fear-monger over things that are essentially benign, and also by contrast end up downplaying the harms of those things which are genuinely very harmful. Perspective is important for making reasonable decisions in a complex world.

Before calling the worm poop/soil "clean" I would want it tested for styrene, which can be toxic.  I would not expect it to be detectable in a sample but I would still want to know for sure.

"Styrene is rapidly degraded in most soils when incubated under aerobic conditions, but it persists when
soil conditions are anaerobic (e.g., waterlogged). Styrene was rapidly degraded when added to either a
low organic-matter content landfill soil or a high organic-matter content loamy soil. When added at
2 g/kg, >87% of the styrene was degraded in the landfill soil, and >95% was degraded in the loamy soil
(measured over a period of 16 weeks; Sielicki et al. 1978). When styrene was added to the soils at higher
concentrations (5 g/kg), degradation was slower and less was degraded, with ~60% degraded in both soils
after a 16-week incubation. Fu and Alexander (1992) showed that styrene was biodegraded in loamy soil
(when added at 2 mg/kg soil), with >50% degradation occurring over a 30-day incubation period, and the
same soil in a later study showed similar amounts of degradation (40% degradation in 50 days; Fu et al.
1994). In contrast to the findings in aerobic soils, this research group showed that styrene persisted when
soil conditions were waterlogged and anaerobic (Fu and Alexander 1996). Other researchers, however,
have been able to demonstrate degradation of styrene under anaerobic conditions by consortia of
microbial cultures (Grbic-Galic et al. 1990). The relevance of these consortia studies to actual
environmental samples is unknown.
Several bacterial and fungal species have been isolated from soils that are capable of using styrene as a
sole-carbon source (Braun-Lüllemann et al. 1997; Burback and Perry 1993; Hartmans 1995; Sielicki et al.
1978; Warhurst and Fewson 1994), and these organisms degrade styrene by either side chain oxidation or
aromatic ring attack. Initial biodegradation products included styrene oxide, 1-phenylethanol,
2-phenylethanol, and then phenylacetaldehyde, acetophenone, and phenylethanediol, and then
phenylacetic acid, with degradation proceeding towards normal metabolic intermediates such as
acetaldehyde and pyruvate (Warhurst and Fewson 1994). "

https://www.atsdr.cdc.gov/toxprofiles/tp53-c6.pdf

Michael Cox wrote:

Wen Magnus wrote:Soil is shifted by all manner of forces animal wind rain and more, any slight leakage of plastic from this process remains a huge problem if we scale that up to seriously tackle our Earthly epidemic.

I'm genuinely curious. What "huge problem" do you see exactly? Is this in some way more harmful than other form of pollution in the soil? I'm thinking about all the pollution from exhausts of cars that washes into the soil with the rain - and back in the bad old days that included lead. We don't quarantine soil against pollution in general, and certainly not indefinitely unless there is a very real and immediate risk of harm.

Personally I see the tiny tiny fragments referred to here as relatively benign, especially when buried in soil where it will continue to break down under biological action.

I agree that there are huge problems with plastics in the environment, especially when they wash into the oceans and end up in marine food chains. But we should be careful not to conflate that into all plastics in any circumstances are inherently bad. When we do that we both fear-monger over things that are essentially benign, and also by contrast end up downplaying the harms of those things which are genuinely very harmful. Perspective is important for making reasonable decisions in a complex world.

Hi! Yes, referring to the epidemic of plastic garbage. Recognize that there are situations in which it's utterly benign (this thread is about conditions to make plastics benign), and that there are other serious contaminants - who's downplaying? But let us address the reality. Here is an article citing but a single compound, Benzopyrene, present in some(?) plastics, which can cause mutations in some(?) organisms. There is a vast variety of plastic materials. I'm personally a fan of bioplastics, but in certain conditions even these can pose a threat. You don't want to eat plastics, you don't want to eat things grown in soil it's recently broken down in, you don't want to inhale particles of it, certainly not those of its smoke, animals choke on it, it's bizarrely long breakdown interferes with biomes, do you seek further painting of scene we're all in? The mentality of 'once it's in a soil biome its usually fine' is massively downplaying. IMO

Wen Magnus wrote: The mentality of 'once it's in a soil biome its usually fine' is massively downplaying. IMO

I think the idea is to get it to a state in which it is no longer plastic.  If it is no longer plastic but instead benign compounds, it will actually be fine.  I'm not sure we've gotten to that point yet because I haven't seen where anyone has tested the final product to see if it is chemically benign.

Tyler Ludens wrote:

Wen Magnus wrote: The mentality of 'once it's in a soil biome its usually fine' is massively downplaying. IMO

I think the idea is to get it to a state in which it is no longer plastic.  If it is no longer plastic but instead benign compounds, it will actually be fine.  I'm not sure we've gotten to that point yet because I haven't seen where anyone has tested the final product to see if it is chemically benign.

Exactly. That's very breakout science that we ought to undertake with great care, and treat mixtures / masses dissolving plastic (such as soil) as though they're still contaminated, for a long time. Maybe it will be our ancestors who are sure that it's properly broken down.

Wen Magnus wrote: treat mixtures / masses dissolving plastic (such as soil) as though they're still contaminated, for a long time.

I think we have the knowledge to test for substances which would not be present in "natural" soil.  Testing for toxic substances in soil is a common practice.

Interestingly, styrene occurs naturally in some plants.  Of course, that something occurs naturally does not mean it is benign to humans. Cyanide occurs naturally in many plants, and can be deadly to humans.

Tyler Ludens wrote:

Wen Magnus wrote: treat mixtures / masses dissolving plastic (such as soil) as though they're still contaminated, for a long time.

I think we have the knowledge to test for substances which would not be present in "natural" soil.  Testing for toxic substances in soil is a common practice.

Interestingly, styrene occurs naturally in some plants.  Of course, that something occurs naturally does not mean it is benign to humans. Cyanide occurs naturally in many plants, and can be deadly to humans.

It's a fine line, considering the seemingly infinite puzzle we've created for ourselves! Sometimes it's important to let go of that desire to control and perfect, it's true. Just extra cautious in recognition of the world's fragility and potency of our influence. Let us be in service to Earth's resilience (yes, honoring the Earth as a being with that apostrophe)

My little guys have eaten most of a small meat tray, so I gave them a restaurant takeout box.  I also gave them some leaves and soil to play in, plus an apple core.

hau Wen, good points.

Right now there are three studies going that are working on how to best decompose seven of the widest spread plastic compounds on the planet.
In all three, things are looking very good for being able to achieve acceptable break down within a two to five year period.
All three studies are using multiple methods in differing configurations which makes me confident of success.

There is light at the end of tunnel and much of the work being done should shorten the distance to the end of that tunnel.

I like that you seem to realize that our earth mother is a being just as we are beings.

Redhawk

Tyler, I saw in the bioremediation thread that you were contacting TAMU for info on lab testing for the worms/waste. I would very much appreciate hearing what you find out. Thanks!

I may start my own little bioremediation experiment and then use some sort of crowdfunding campaign to fund the chemical analysis necessary to really understand the result.  Would anyone be interested if I did do this? My inner academic writer is just abuzz with possibilities. Now I want to do different groups with different conditions and see if that affects the rate of consumption...

Tyler, about how fast do your worms consume the polystyrene? I wonder how many worms would be necessary to process large amounts of the stuff within a decent amount of time.

Mine have not been kept at optimum temperature, so they are working slowly.  I think if they were kept in a heated space they would work faster. 1000 Superworms ate about half of a small styrofoam meat tray in a week.  I should have weighed everything at the beginning but I'm not a scientifically-oriented person, so this experiment is less useful to others than it might have been if I were a better record-keeper.

So far I'm not impressed with these Superworms.  I had a big die off (low temperatures?) and the bin became infested with small flies.  I had to move it outside, so it may soon become colonized by Black Soldier Flies.
Seems like after a decent start the Superworms have stopped eating the styrofoam and are now mostly eating their fallen comrades.  I've added some Red Wigglers to the bin to see if they can clean it up some.

Still have not found a lab to test for styrene residue.

Tyler, that’s a shame! Mine are still doing well, chomping away. Haven’t found anything either re: testing.

Has anyone tried multi-species worm bins? I was thinking of combining superworms and regular mealworms, in case they process the styrofoam in slightly different ways, which might lead to better overall breakdown.

And/or combining them with red wigglers so that more food scraps could be processed through the same bin.

Waxworms are another option which may degrade styrofoam.

Thoughts?

I put Red Wigglers in with my (dying) Superworms last week.  I'll find out tomorrow if anyone survived....