Microplastics are small pieces of plastic that range in size from 5 mm to 1 nm. Microplastics are created when plastic breaks down into smaller pieces. This can result from many different sources such as weathering or being created this small for products. These polymers are considered harmful for the environment and humans because of the toxic chemicals they release and the connection they are being found to human health issues such as cancer.[1][2]
Microplastics can be removed using physical, chemical, or biological techniques.[4]
Remediation of microplastics in air
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Microplastic are a type of airborne particulates that is found to prevail in air.[5][6][7]
Since microplastics are a type of particulate matter 2.5 found in the air, they can easily be inhaled when breathed in.[8] They enter the atmosphere from many different human induced sources such as transportation and industrial industries. Natural sources can also contribute to the microplastics in the air such as wind that carries them across the globe.[9]
To help reduce the microplastics in the air, it is suggested to constantly dust inside of buildings. There is a greater number of microplastics found indoors compared to outdoors, so it is important to manage the amount inside. Dust can be a big contributor to microplastics, so keeping buildings dust-free will limit the exposure.[10]
Another remediation of microplastics in the air is to use nanofiber membranes as an air filter.[11]
There is a new sensor that uses carbon quantum dots in order to detect microplastics in the atmosphere. This works by exposing the carbon-dot-coated electrodes to microplastics, and it detects the type of microplastics and size.[11]
MXenes is a material that can be used to create microrobots that will remove microplastics from the air. This robot is shaped like an accordion, and attracts the microplastics to them and absorbs them through the silts.[11]
Finally, metal-organic frameworks can be used as air filters to limit the amount of microplastics in the air. These are made from metal ions and organic ligands which make them porous and able to collect and filter the air.[11]
Remediation of microplastics in water
Microplastics have been found in 83% of the world's tap water. They also have been found in fresh snow in Antarctica. This showcases how many microplastics there are worldwide and they are in global water sources, even in remote locations.[12]
One technique used to remove microplastics in water is boiling water. This has shown to effectively remove 80% of microplastics.[12]
The coagulation sediment process (CSP), is one of the most effective and economical ways to remove microplastics from water. This process separates the water and the microplastics from each other. It is most effective with larger pieces of microplastics with a success rate of 90% but with smaller pieces it only has a success rate of about 50%.[12]
Electrocoagulation is another way to remove microplastics from water. This happens when a current is passed through two metallic anodes in a solution which combines with the hydroxide ions. This forms a charged hydrolysis species, which causes the negatively charged microplastics to go to the surface.[12]
Researchers have shown that microplastic remediation in water can also be accomplished by utilizing plant-based polymers from Fenugreek and Okra as flocculants.[14] The most commonly used polysaccharides used as flocculants are cellulose, starch, pectin, and chitosan.[12]
Biochar filtration has been used in wastewater treatment plants.[15] More than 90% of microplastics were effectively removed by biochar filters because the microplastics became "stuck" in the biochar.[16]
Efforts to physically remove microplastics from the Great Pacific Garbage Patch have used nets and collection bags.[17]Although microplastics are almost impossible to remove physically, when the larger pieces of plastics are removed from water, it prevents more microplastics from occurring. This is because the majority of microplastics come from bigger pieces of plastic breaking down into smaller pieces, so when the big pieces are gone, the microplastics cannot be produced.
Remediation of microplastics in soil
Microplastics can be found in soil due to many different things. Firstly, they can be the result of larger pieces of plastic broken down into smaller pieces. This is seen in plastic mulch. Since the mulch is in the soil on the ground, as weathering wears down the plastic, it causes microplastics to be released directly into the soil. Also, microplastics can be caused because of agriculture practices such as crop cultivation, which causes it to go directly into the soil. Finally, because microplastics are prevalent in water, when it rains microplastics are directly put into the soil.[18]
Microplastics have many different effects on soil health. They can directly change the porosity, enzymatic activities, microbial activities, plant growth, photosynthesis, and yield. Since microplastics are made from toxic chemicals, such as polycyclic aromatic hydrocarbons (PAHs), these chemicals can go deep into the soil. When this happens, it can cause ground water to become contaminated and polluted with toxic chemicals.[18]
Bioremediation can help get rid of microplastics in the soil because certain types of microbes have been found to degrade microplastics. Also, phyto-remediation can be used because certain plant roots, such as agronomic crop roots that contain microbes that can get rid of microplastics.[18]
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