7 ms·
Sound waves used to separate microplastics from laundry wastewater
- aiphex 7y agoVery cool idea. Probably wouldn't want to do it where there is marine life though.
- chrisweekly 7y agoAgreed, so cool! And good point. Here's to finding a way to keep micro-plastics out of the ocean altogether, for the sake of marine life, humanity and the planet.
- krallja 7y agoGenerally, there is not marine life in the drain line of a washing machine.
- r00fus 7y agoAmusing but I think aiphex was considering the possible reuse of this tech against the pacific gyre.
- chongli 7y agoIf we cut off the microplastics at the source then the gyre will eventually take care of itself. The problem right now is that we’re continually adding more and more pollution.
- dwiel 7y agoWhat do you mean "take care of itself"?
- chongli 7y agoIt'll make its way through the food chain and gradually clear up. Yes, it's going to harm a lot of ocean life in the mean time, but there's not much we can do about that. It's like trying to get red wine out of the white carpet and back into the bottle. We should stop spilling the wine or at the very least drink it somewhere safer.
- hanniabu 7y agoOr we can attack the issue at the source and the gyre...
- 4ntonius8lock 7y agoWhere in the FA does it talk about using it in the ocean?
- noninoy 7y agowashing machine waste water goes to rivers, rivers go to oceans
- 4ntonius8lock 7y agoEven cooler idea; reading articles before commenting. Where in the FA does it talk about using this in the ocean?
- jpearson 7y agoThe first sentence of the article mentions that the key problem is the microplastics that have reached the ocean. Cutting off one source is valuable, but that will still leave lots of microplastics in the ocean. I don't think aiphex is wrong to comment on the technology's limitations. Why do you think that the inability to solve a related problem (microplastics in laundry wastewater vs in the ocean) with the same technique is too far off topic?
- dang 7y agoPlease don't be a jerk on HN, no matter how right you are about an article. https://news.ycombinator.com/newsguidelines.html https://news.ycombinator.com/newsguidelines.html
- nashashmi 7y agoWhat is it about Soundwaves that allow plastics to move in a direction?
- newfocogi 7y agoResonant waves in a liquid can cause particles of different sizes to move toward the nodes or anti-nodes of a standing wave. A secondary effect is the particles can conglomerate and fall out depending on density.
- DoingIsLearning 7y agoI am more familiar with resonance in an electrical domain more so than a mechanical one. How do they determine at what frequency to actuate the piezos in order to match the resonant frequency of these plastic particles? Is it just 'guestimated' or is there a more systematic way?
- newfocogi 7y agoMy guess would be that they choose the frequency based on the speed of sound in the liquid such that the nodes in the standing wave occur at a designed location in the chamber where the separation occurs.
- peter_d_sherman 7y agoNote To Future Self: There's an interesting Physics question posed here, which looks something like this: If resonant waves, in this case of sound, can cause particles of different sizes to move towards the nodes or anti-nodes of standing waves, then if we consider a completely different area of physics, that is, the case of electroplating metals with electricity, that is, we have an electrode of metal A (for example, Copper), and an electrode of metal B (for example, Gold), in some electrolyte, for example, salt water, then does the electroplating procedure (via electricity) mimic what's happening to the microplastics in water, via sound waves, but just at a smaller wave scale? In other words, maybe electricity does the same thing as what happens to the sound/microplastics -- but the electricity is a wave which is much faster in frequency, and much smaller? Now, there's another aspect of all of this too. See, if we can get conglomeration or dissipation of microplastics via the use of sound, then perhaps this mimics the creation or destruction of matter (well, let's say 'particles' at this point, "smaller pieces of matter"), that is, the "clumps" of less rarified/more dense substances inside of more rarified/less dense substances... Anyway, the principle at work here might be the starting point for Star Trek's food replicator... maybe this is Star Trek's Food Replicator version 0.000000001 (just applied to plastic particles in water, not food/matter particles from air, obviously... <g>) Note: I don't claim any correctness in the ideas presented above; merely that more experimentation/research might need to be done... see the "Note To Future" self part...<g>
- jnwatson 7y agoI use a Cora Ball [1] in my laundry for the same purpose. Studies say it is only 26% effective, better than nothing. 1: https://coraball.com/ https://coraball.com/
- 4ntonius8lock 7y agoThanks for sharing that. I use a lot of polyester garments for sports and feel kinda crumby knowing it really hurts the environment. Hopefully these sound wave systems can be adapted to municipal water systems so as to remove the consumer as the point of failure. Really cool to see the technology that creates Chladni figures being applied to something so useful. Reminds me of how things start off as entertainment many times, and eventually make a way into an industrial application.
- maxwell 7y ago> Reminds me of how things start off as entertainment many times, and eventually make a way into an industrial application. I was just thinking about this phenomenon, in terms of how it runs counter to the criticism of "solutions in search of problems" and projects derided as "toys". This is a good response to those condemnations: often great ideas work in entertainment first, then industry. The canonical example from antiquity is Heron of Alexandria's automata. Nowadays, roller coasters seem like a technology that future historians will puzzle over non-utilization beyond entertainment. (The cause of course is zoning, which halted housing and transportation innovation a hundred years ago.)
- chockablock 7y agoThe full text of the study that Cora Ball cites is available at the lead author's website: https://rochmanlab.files.wordpress.com/2019/01/mcilwraith-et-al.-2019.pdf https://rochmanlab.files.wordpress.com/2019/01/mcilwraith-et... From the paper: > We observed no significant reduction of microfibers by weight with the Cora Ball compared to the control. Check out figures 2, 3 and 4. It turns out that the cited 26% number is only for the number of fibers removed. Oddly, in the same experiments, there was no significant decrease in the mass of microfibers, or the length of the remaining fibers when using the Cora ball (but there was a > 80% decrease in both number and mass of fibers when using a product that actually filters lint out of the wastewater. My read of this study is the the 26% number may not be reliable. The reported p-value was near 0.05, which means it would not be too surprising if the difference between Cora Ball and control was due to expected experimental variation.
- makerofspoons 7y agoOr we could stop making clothes out of materials that shed microplastics. And while we're at it, cotton too for the vast amounts of water it uses. Industrial hemp and linen are far more sustainable options. Tencel looks like a great replacement for cotton and uses wood cellulose.
- skyyler 7y agoCotton is softer than hemp and it's lighter than hemp. And unlike either of them, cotton is slightly elastic. If you've ever had linen sheets you know that they get softer and looser over time. There are companies that specialise in making clothing out of flax, but a quick look at their designs showcase just how bad linen is for clothing. The only linen garments that resemble the cut / silhouette of their standard counterparts are blouses and dresses. I'd love to see a comparison of water required to make a square yard of cotton textile vs rayon (tencel is a form of rayon)
- manicdee 7y agoI don’t care about technical qualities, for me I find hemp cloth to be far more comfortable to wear. Softer on the skin, longer wearing, easier to wash and iron. I go out of my way to get hemp clothing, especially when the options are cotton/plastic blends.
- spodek 7y agoOr we could stop making plastic. Or at least the 90% of it making junk. Even if we separate it, it still exists, as does basically all the plastic we've ever produced. Even separated, at the rate we're producing it, wherever we put it will overflow.
- nitrogen 7y agowherever we put it will overflow. The scarcity of landfill space is a myth sparked by the infamous "garbage barge", which nobody accepted because it came from the NY mafia and was getting too much attention, not because there was no room for it. https://en.wikipedia.org/wiki/Mobro_4000 https://en.wikipedia.org/wiki/Mobro_4000 This Planet Money episode is a good listen: https://www.npr.org/2019/07/09/739893511/episode-925-a-mob-boss-a-garbage-boat-and-why-we-recycle https://www.npr.org/2019/07/09/739893511/episode-925-a-mob-b...
- mrfusion 7y agoWhat other applications for this could there be?
- jcims 7y agoFiltering beer?
- newfocogi 7y agoI worked on a project using a similar concept for concentrating micro-algae in the water solution it is grown in. The previous method of extracting micro-algae was filtration or centrifuges. Filters get full too quickly and need regular attention, and centrifuges take too much energy since the density of the particles were very close to the density of water and didn't spin out easily. We tried using standing acoustic waves to organize and "conclomerate" the micro-algae in the flow and siphon off water quite similarly to the image in the article. It "sort of" worked but only when the flow rate was really, really low because these forces are totally dominated by drag forces and even the smallest levels of turbulence remixes the solution. What else could this be used for? Think of something that doesn't play nicely with filters or centrifuges and doesn't need to be processed at really high flow rates. Applications in the medical industry come to mind.
- seriesf 7y agoI've never owned a polyester garment that could be washed in water. Aren't they all dry-clean only? Blends (like denim) I can see but in general it seems like people just wash their clothes too often and use the machine too much instead of hand-washing.
- 14 7y agoNo I just checked and many clothes like jackets, swim shorts and blue jeans the first 2 on the list made from 100% polyester are supposed to be machine washed. Save yourself some money and throw that clothing in the wash machine on delicate and you should be fine.
- deleted 7y ago[deleted]
- brianpan 7y agoI'm no expert but it seems highly likely to me that you have owned polyester. Do you own socks? Jeans or shirts? A jacket? A throw blanket? So many things are poly blends or have polyester components. Unless you are explicitly checking every label, if you are just buying clothes, you are buying polyester.
- aSplash0fDerp 7y agoIf this works like non-newtonian fluids, I imagine "finding the right shape" or series of tones/patterns works well in bulk. https://m.youtube.com/watch?v=SYMvOxIsES4 https://m.youtube.com/watch?v=SYMvOxIsES4 I don't have any hard numbers, but it almost seems like we could easily spend a trillion dollars fixing a problem caused by a 100 billion dollar industries by-products. What would a carbon credit scheme look like if it were for microplastics?
- soulofmischief 7y agoThe effect you're thinking of isn't relegated to just non-Newtonian fluids. https://en.wikipedia.org/wiki/Cymatics https://en.wikipedia.org/wiki/Cymatics
- aSplash0fDerp 7y agoCool! I was thinking of granular convection using vibrations, but cymatics and -nf's have much more entertaining videos to visualize sound. https://m.youtube.com/watch?v=mmPpUztcqB8 https://m.youtube.com/watch?v=mmPpUztcqB8 > What would a carbon credit scheme look like for microplastics? A payment plan for a ransom...(insert punchline rimshot here)
- nudgeee 7y agoBack in 2006 I was contracted to design a power amplifier prototype for the civil engineering department of a university. We built an adjustable 500W h-bridge based amplifier (operating between 50kHz to 300kHz+) which was used to drive transducers to create standing waves for waste water treatment, and it seemed to work alright in a bunch of our tests, but at fairly low flow rates. We passed the prototype on to the client (I think it was for a joint project between Monash University and Melbourne Water), not sure where it ended up. Great to see the technique being applied in consumer applications :)
- kazinator 7y agoSay this has been productized and I now have a seven-year-old washing machine equipped with this. How do I know that the acoustic standing wave is still activating, and separating the microplastics?
- sml156 7y agoAfter month's or year's you would have bucket of micro plastic.