Researchers separate microplastics from wastewater using sound waves

Most rivers and lakes or from a canal to the Ocean have colorful plastic debris floating along the surface. Less than 5 mm in size and barely noticeable, microplastics can harm aquatic life, plants, and people. Therefore, researchers are developing strategies to eliminate and stop them at the source. Most plastic particles from actual water samples are now removed by a two-stage microfluidic device with steel tubes and pulsating sound waves.

The Conventional Method

Filtration is the most popular method for eliminating microplastic components from water. For instance, washing machine outlet filters can prevent clothing fibers from into wastewater. However, the filters must be cleaned occasionally since they might become clogged, making the process expensive on a wide scale.

The Alternative System 

Researchers are working on another alternative to separate faster and cheaper. The researchers used acoustic or sound waves to concentrate plastic particles in moving water. These forces transmit energy to surrounding particles, causing some to vibrate and move. One can imagine a loudspeaker that shakes the ground. Dirt and dust fly in all directions through sound waves. Scientists have previously been employing these phenomena to separate biological particles from liquids, such as red blood cells from plasma.

Research teams have recently used the sound waves method to separate microplastics from samples generated in the lab using only pure water. But, just modest amounts of water were used for this task.

Scientists built a proof-of-concept system using 8-mm-wide steel tubes coupled to one inlet tube and several output tubes to handle increased water flow rates. They next fastened a transducer to the side of the metal tube. When the transducer was turned on, it sent ultrasonic waves down the metal tube, creating acoustic pressures that made it simpler to trap microplastics as they moved through the system. Because the prototype clogs less quickly than a filter, it is less complicated than conventional filtration techniques.

The researchers found that smaller (6 to 180 micrometer) particles behaved differently than the bigger (180 to 300 micrometer) ones in their experiments with polystyrene, polyethylene, and polymethyl methacrylate microplastics. Particles of both sizes were stacked down the center of the channel and exited through the central outlet as clean water went out of the outlets on either side. But, if fabric softener or laundry detergent were added to the water, the larger particles concentrated towards the sides and left out the side outlets, while the center outlet released clean water.

Conclusion

Based on these findings, the researchers began work on a system that could benefit from the various movements. Two steel tubes were joined together in tandem: Small microplastics of less than 180 micrometers were removed in the first stage. And, the water stream containing the remaining more significant microplastics was cleaned in the second stage.

The next step for the researchers is to make a system with oversized tubes or bundles of numerous tubes and test it on unspiked real-world samples like ocean water and washing machine wastewater. 

Keep Reading

• Microplastics can make other pollutants more harmful
• Microplastics in breast milk and placenta, & can lead to cancer!
• Climate change Warning: Microplastics found in fresh snow in Antarctica
• How much microplastic generated from face masks every year in India?

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