Can algae help pull microplastics out of our water supply?

KATHLEEN DAVIS: Hey, it’s Science Friday producer Kathleen Davis. And you’re listening to Science Friday.

Microplastics and nanoplastics have been in the news a lot. These are teeny tiny pieces of plastic fragments that are found pretty much everywhere. They’ve been found in the soil, in the water, in our bodies, even on the top of Mount Everest. And it all feels overwhelming and existential.

But there’s some good news, too. Just this week, the EPA announced it’s taking the first step to regulate microplastics in drinking water. And lots of scientists are looking for solutions for our microplastic malaise. And here to fill us in on some research happening in the Midwest is Kate Grumke, senior environmental reporter for St. Louis Public Radio. Hey, Kate. Thanks for being here.

KATE GRUMKE: Hi, Kathleen. Thanks for having me.

KATHLEEN DAVIS: So, Kate, as an environmental reporter, what’s your level of personal concern on microplastics? Where do they rank on your list of topics that are big and scary that you cover?

KATE GRUMKE: Oh, man. Well, we have a lot of scary weather events here, so I would say that those can be maybe bigger or more urgent feeling than microplastics. But the thing about microplastics is you can end up thinking about them quite a lot, because there’s so much plastic in our daily life. So I feel like I have just constant reminders of this issue because there’s so much plastic around us.

KATHLEEN DAVIS: Right. So as I said, microplastics are everywhere. Has there been anything in your neck of the woods that has made you be like, OK, this is actually very freaky.

KATE GRUMKE: Oh, definitely. So one story I wrote about was about a group of scientists at St. Louis University. They recently found microplastics in a cave around here that had been closed to the public for 30 years.

KATHLEEN DAVIS: Whoa!

KATE GRUMKE: So there’s a population of endangered bats in this cave. So people are generally not allowed to go in there. And they found a lot of microplastics. And they found it in both the water and in sediment in the cave. And one thing that was really interesting, they published a paper about this, that they found it even more during flooding. So the caves around St. Louis are generally connected to the outside world. And so during flooding events, more of that outside world and the plastic inside of it is being washed into that cave.

KATHLEEN DAVIS: So let’s talk about a story that you did recently. You reported on a lab in Missouri that’s doing some pretty innovative stuff with algae. Tell me about this.

KATE GRUMKE: Yeah. So there is a professor at the University of Missouri who is working with engineered algae. And she recently worked with a team to see what this would do with microplastics. So this algae is essentially really hydrophobic. So it repels water. And microplastics are also hydrophobic. So they basically found that these algae clump onto the microplastics, and then bring them down to the bottom of water. And they’re really good at cleaning the microplastics out of the water.

So they laid out this process in a new paper in Nature Communications, where they can clean up microplastics this way, and then maybe even recycle that sludge of algae and microplastics into a new product.

KATHLEEN DAVIS: OK. So you said it’s effective. How effective is it?

KATE GRUMKE: They found that it removed more than 90% of microplastics in the water that they were testing in a solution.

KATHLEEN DAVIS: Wow.

KATE GRUMKE: So very, very good. And it’s especially good at removing super, super tiny pieces of plastic. So sometimes it’s easier to filter things that are bigger out, but they are really targeting those super extra small pieces of plastic with this process.

KATHLEEN DAVIS: And we’ll talk to the lead researcher on that study in a little bit here. But let’s talk a little bit about other local efforts that you’ve reported on to tackle this microplastics problem. Does anything spring to mind?

KATE GRUMKE: Yeah, there have been a few other projects in St. Louis that are really interesting. One, I was especially interested in at, St. Louis University. So there’s a researcher there who is looking at creating something that kind of acts like whale baleen. So this is sort of like the fibrous, not teeth, but teeth-like structure in a whale’s mouth.

And so this professor realized that plankton are kind of a similar size to microplastics. And if whales are really good at sucking up plankton, maybe they could also use baleen to suck up microplastics. So I thought that was a really interesting test case.

And then at Washington University, they actually have a research center now that’s working on creating plastic alternatives that are also kind of brewed and a natural process. So I think that is pretty interesting as well. They’re targeting fibers, which is a big problem, from our clothes, from plastic in the clothing. And so yeah, there’s a lot of people around here who are trying to find a solution to this problem.

KATHLEEN DAVIS: I mean, as a reporter who covers this, how does it make you feel to have some promising things to talk about when it comes to microplastics?

KATE GRUMKE: This is one of those issues where I talk to the scientists, and they’re really hopeful. They’re really excited about what they’re working on. They feel like they’re finding solutions to a big problem in our lives. So I really think that this is a great area to look at if you’re looking for some hope in an otherwise kind of stressful environment.

KATHLEEN DAVIS: Well, thanks so much, Kate.

KATE GRUMKE: Thanks, Kathleen.

KATHLEEN DAVIS: Kate Grumke, senior environmental reporter for St. Louis Public Radio. We have to take a break, but don’t go away. When we come back, talking to the researcher behind this algae breakthrough. Stay with us.

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KATHLEEN DAVIS: Now, we’re going to dive into some more detail on this bioengineered algae. We’ve learned that it can clump onto microplastics and make them easier to remove. But how could it actually work out in the world? Joining me now is Dr. Susie Dai, professor of chemical and biological engineering at the University of Missouri. Thanks so much for being here.

SUSIE DAI: Oh, it’s my great pleasure.

KATHLEEN DAVIS: So this is a really exciting idea, right? And I know that you’ve gotten a lot of attention for this, but is it scalable? How can we imagine this actually working effectively in the future?

SUSIE DAI: Yeah. And it’s more than a $1 million question, right? So we have to remember we’re dealing with multiple things here. Number one, we need to grow a stable culture in a container that’s large enough for the treatment of our target of the water. And number two– and this is really a genetically modified organism. And many times people are concerned about genetically modified organisms.

Then in my vision, we will not freely release that back into the environment. So this will be done in a confined environment. So once you design a bioreactor, you can have this algae grow in a controlled manner, such as you can control the temperature, you can control the pH, you can control many things. So in this case, then we can cultivate at the optimized condition in the future in large containers that we can put in the field potentially, or in a plant, or in a facility that’s supposed to be used together for other water treatment purposes.

KATHLEEN DAVIS: So we’re talking about keeping this in wastewater plants?

SUSIE DAI: Yes. And so a wastewater plant is one viable venue to operate this. But together, we can think of, if you have other water body that the algae can grow, so that we can also use those water bodies, potentially, with other source of contamination.

And then we can also integrate this reactor for other purposes, because algae can use CO2, carbon dioxide, as its carbon source. So basically, you can grow it in the place once you have sunlight. And then you can grow it with water that comes in with extra of the nutrient that you want to remove. So definitely, wastewater plant is one destination that we can implement this platform. But there are other places maybe in the culture that we can do that, too.

KATHLEEN DAVIS: So microplastics are everywhere. I think this is something that most people are aware of at this point. I mean, in the grand scale of this issue, how impactful would it be to be able to get microplastics out of wastewater? How much of a dent do you think that could make on this overall problem?

SUSIE DAI: Yeah. And that’s actually a question that needs a multi-level analysis. So I think right now people know we have the presence of microplastics. And then we don’t really what’s the final impact in our ecosystem in, let’s say, in the urban area. I think we know better in the sea and in those waters. But how much do we know those microplastics are getting into our life, into our food system, into our drinking system?

So together with treatment of those microplastics, I think another benefit we need to remember is this algae can also remove the extra nutrients from the wastewater. Currently, most of the wastewater facilities are designed to deal with the organic carbon and oxygen level. But most of the current infrastructure for wastewater treatment is not dealing with extra nitrogen and phosphorous.

So that’s what I hope this platform is not only bringing one benefit, but one stone for multiple birds. Then when we can manage microplastics, which is an emerging contaminant still with a lot of research needs going on, we can also do at the same time remove those extra nutrients that are also not very good for our environment.

KATHLEEN DAVIS: Before I let you go, I want to ask you, because I hear you did not necessarily originally intend to make an algae that could absorb microplastics. What was your original goal?

SUSIE DAI: Yes, that’s a very good question. So I think this builds on years of research when we were trying to work on algae in the very beginning. At that time, we didn’t have this beautiful imagination we can apply the algae for this purpose. At that time, we were looking into using algae as a feedstock to produce high value products.

So if you look at the structure, the chemical property of this compound coming from the algae, this is a wonderful compound. You can think of parallel to all those aviation fuel you can pump into the plane. And this compound has a higher energy density than ethanol. Nowadays everybody pump about 10% of bioethanol into our fuel tank for the car. And then, because the energy density for this molecule is higher than ethanol, it made that more ideal for the aviation fuel. And that’s the original purpose.

KATHLEEN DAVIS: I mean, aviation fuel is so different from microplastic cleanup. How did you get from point A to point B?

SUSIE DAI: In parallel to that study process, we’re looking to other means to remove contaminants from the water, such as using the fungus biomass to remove those microplastics. So because those two research lines are going on with each other in parallel, and when we saw that algae can self-precipitate, then simultaneously we’re thinking, oh, what can we do with it? So how about we apply that to the microplastics? And then can we observe the same phenomena? And bingo, it happened.

KATHLEEN DAVIS: I mean, this, to me, is such a perfect example of how random and unexpected scientific discovery can be sometimes.

SUSIE DAI: Yes. That’s why I think as a scientist, we should not limit ourselves for the only goal at that time for that one research project. I think very interesting about research is you have open mind, then that you talk with people, then you collaborate, and then different minds come together. I think it creates a much better project than the one by their self in the very beginning.

KATHLEEN DAVIS: Well, thank you so much, Susie. This was such a great conversation. I really appreciate the chance to talk to you about this.

SUSIE DAI: Yeah. Thank you for your time. And it’s my great pleasure talking to you.

KATHLEEN DAVIS: Dr. Susie Dai is a professor of chemical and biological engineering at the University of Missouri. This episode was produced by me, Kathleen Davis. And if there’s another good news story about a big environmental problem that you want us to talk about, give us a ring, 877-4-SCIFRI. That’s 877-4-SCIFRI. We’ll catch you next time. I’m Kathleen Davis.

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