Since microplastics are becoming an established problem, many have tried to find ways to, at the very least, reduce them while we humans also work to reduce plastic consumption. 

Today, we’re going to talk about two types of technology that scientists have developed to remove the minuscule plastics from water: one using a special magnet, the other using sound. Let’s talk about magnet first. 

Attracting microplastics using a special magnet 

This innovation was developed by researchers at RMIT University, with Professor Nicky Eshtiaghi leading the research.  

Eshtiaghi said that the current methods would take days to remove microplastics from water, while the team’s technology is able to give better results in just one hour, without costing too much and is also sustainable. 

Now, the magnet isn’t like the kind you see every day; it takes form of adsorbents in the form of powder. The research team stated that it’s capable of removing microplastics 1,000 times smaller than those currently detectable by existing wastewater treatment plants. 

The adsorbents have been successfully tested in the lab. According to the team, they plan to further develop their discovery with industry to scale it up and ultimately remove microplastics from waterways. 

“The nano-pillar structure we’ve engineered to remove this pollution, which is impossible to see but very harmful to the environment, is recycled from waste and can be used multiple times. This is a big win for the environment and the circular economy,” Eshtiaghi said. 

Making the adsorbent 

The adsorbent was made from nanomaterials that the researchers can mix into water. That way, they can attract both microplastics and dissolved pollutants. 

According to first author Muhammad Haris, the nanomaterials contained iron. It enabled the team to use magnets to easily separate the microplastics and pollutants from the water. “This whole process takes one hour, compared to other inventions taking days,” Haris said. 

Co-lead researcher Dr Nasir Mahmood added that the nano-pillar structured material was designed to attract microplastics without creating any secondary pollutants or carbon footprints, making it environmentally sustainable. 

Mahmood said, “The adsorbent is prepared with special surface properties so that it can effectively and simultaneously remove both microplastics and dissolved pollutants from water.” 

Eshtiaghi said that it’s not going to be a good long-term solution for microplastics if the devices or technology that remove them now are expensive. Therefore, there should be more cost-effective way to tackle this problem—as the issue may be getting a lot worse. 

“We are looking for industrial collaborators to take our invention to the next steps, where we will be looking at its application in wastewater treatment plants,” the lead researcher said. 

 

 

Power of sound can also capture microplastics in water 

In a similar attempt and effort to get microplastics out of water, Indonesian researchers have also developed a method without the need for expensive filters. 

According to the engineer that developed this, Dhany Arifianto at the Institut Teknologi Sepuluh Nopember (ITS) in Surabaya, Indonesia, this is achievable when contaminated water is passed through a pipe, while underwater speakers make the pipe vibrate like the sound board of a guitar.  

The technology is dubbed the sonic scrubbers. 

Sound is unique and we often take it for granted. To researchers, however, it can be a simple series of pressure waves. So, when microplastics-filled water gets through the pipe, the water, being liquid, simply transmits the tone. On the other hand, microplastic particles, which are solid, feel the pressure differently, and are driven away from it. 

So, when the engineer surrounded contaminated water with the same tone coming from all sides, the only place for the plastics to go is the center of the pipe.  

And when the water goes out of the pipe, the concentrated stream of plastic can then be diverted, while the rest of the water, now cleansed, flows on. “That’s basically the principle of our research, the force created by sound,” Arifianto said. 

What about the efficiency rate? 

Lab tests done by Arifianto’s team was able to filter out nylon fragments to an efficiency of up to 99%, and other microplastics to an efficiency of up to 95%.  

In 2022, the engineer said that those sterling results were for fresh water, which is easier to work with than seawater. It’s not to say that the method doesn’t work in seawater; his team has managed to achieve 58% efficiency so far. 

Now, since the engineer’s primary goal isn’t to filter out water then purify it to become clean, drinking water, that percentage is pretty good. Arifianto’s main goal is actually grander: aiming to help clean up the ocean, starting from the offshores of Indonesia. 

Per his idea and vision, he’d deploy an array of sonic scrubber pipes across the narrow straits between his country’s main islands, through which currents circulating between the Pacific and Indian oceans offer perfect locations in which to intercept a lot of microplastics, especially those originating from Indonesia. 

Arifianto wanted to collect the plastics via pipes which have been spread across the straits, attached to the bottom so they stay in place and powered by solar cells, wave energy, or perhaps even the temperature gradient from the top to the bottom of their cables. 

His ambition was met with skepticism, as to date, nobody has managed to successfully clean big plastics and microplastics from the ocean. Arifianto himself is aware of that. 

“I hope I can spread the message that first, we have to stop dumping plastic on the water, whether it’s fresh water or seawater. Because it’s going to come back to us in a very harmful way,” he said. 

One setback from this method 

This method is quite costly. However, that’s not the major setback from Arifianto’s technology; its noise pollution. “We are generating audible sound, so marine life is going to be affected.” 

It’s currently unknown how bad the noise pollution is, but the sonic level used in lab experiments was around 50–60 decibels. To humans, it’s somewhere between the level of a quiet conversation at home and the buzz of conversation in a busy office—not really a pollution. 

To the marine life, though, the sound may be quite distressing. So, Arifianto has made it a priority to overcome this challenge in future research. 

Meanwhile, the engineer said that cleanup efforts, innovations, and attempts that we see today, both locally or internationally, should still be done so that plastics won’t continue to pollute the environment. 

“I hope [our work] is going to reach more people to be aware of the problem and hopefully participate in this global action to clean up,”Arifianto said. 

 

Sources

https://www.sciencedaily.com/releases/2022/11/221129112729.htm  

https://cosmosmagazine.com/earth/oceans/using-sound-capture-microplastics/