How do we deal with microplastics ?

What Are Microplastics?

To properly understand this issue, we first need to understand microplastics themselves. Microplastics are defined as small pieces of plastic less than 5mm in length; there is a further subclass of microplastics called nanoplastics, which are defined as being less than 1μm in size . That’s 10,000 times smaller than a centimetre!

Microplastics is a topic that regularly makes the headlines, especially with the increasing awareness around the impacts of plastic pollution. These tiny pieces of plastic have been found almost everywhere on our planet: in the ocean, in freshwater ecosystems such as lakes, ponds, and rivers, at the summit of Mount Everest, and even closer to home - in drinking water! A 2017 study of drinking water, which spanned five continents, found that over 80% of the samples analysed contained microplastics!

The World Health Organization (WHO) have identified three forms of potential hazards from microplastics in drinking water: the physical hazard caused by particles, chemicals from the plastics leaching into the water, and microorganisms that attach to and colonise microplastics in structures known as biofilms. The physical particles may be absorbed into the human body, which could pose a threat due to the possible toxicity of chemicals that leach from the microplastics. Research has also shown that heavy metals, such as chromium, could be transported into the body through microplastics. Microplastics can adsorb heavy metals, and when consumed, may act as a vector for carrying these heavy metals into the human digestive system. Risks from both the physical particles and the chemicals present in microplastics are poorly understood, just like the field in general. The concern around biofilms is mainly based on the potential for pathogens, such as Legionella, to spread through the biofilms on the surface of the microplastics. Legionella causes Legionnaires’ disease, a form of pneumonia which, while treatable, can be very dangerous. Typically, the disease is spread through the inhalation of droplets of water containing the bacteria, however, it can be spread through drinking water if droplets enter the lungs while drinking.

Microplastic Filtration: Methods and Its Importance

There are several ways we can filter out microplastics, and there are many companies that sell products to do so. However, their vested interest in product sales means that some of these companies over-exaggerate the need for filtering microplastics. Let’s consider the facts. Firstly, the levels of microplastics in water depends on where you live - in the United States, 94% of water samples tested had microplastics present. In comparison, Europe had lower levels of about 72% of water samples having microplastics present . If you live in an area where there are generally lower amounts of microplastics in drinking water, having a personal water filter is probably not going to be a priority for you. Secondly, the WHO states that available data shows that water treatments are very effective - more than 90% of microplastics are removed by wastewater treatments. This is a fact that many water filter companies fail to tell us while trying to convince us to buy their products.

Granular Activated Carbon Filters

One method of filtering microplastics is with a granular activated carbon filter. Granular activated carbon filters can filter out contaminants as small as 5μm, which means that some microplastics will be filtered out. They work by adsorption, where organic compounds (contaminants) are held to the surface of the carbon by Van der Waals forces.? Van der Waals forces are intermolecular forces of attraction that pull molecules together, and in this case, they pull the contaminants to the carbon. This results in the contaminants being removed from the water, as they are held to the surface of the carbon while the water flows past. Although this method of filtration is efficient for particles larger than 5μm, there is a clear limitation in that it does not remove the smallest microplastics, such as nanoparticles.

Reverse Osmosis Systems

The word osmosis might sound familiar, as it is a commonly taught concept in biology classes. Osmosis is the process of solvent molecules moving from a region of low solute concentration to an area of high solute concentration across a semipermeable membrane. Semipermeable membranes let some solutes through, but not all. Reverse osmosis systems use semipermeable membranes as well as pressure to remove contaminants from water . Contaminated water is forced through the semipermeable membrane using pressure. The contaminant molecules do not fit through the membrane, and therefore the water on the other side of the membrane is free from contaminants, such as microplastics. This is the reverse of osmosis, as the contaminated water moves from an area of lower concentration of water to an area of higher concentration of water. Reverse osmosis systems are incredibly effective and can filter out particles that are as small as 0.001μm, so nearly all microplastics can be removed from the water, as well as a lot of nanoplastics.

To truly deal with the issue of microplastic, we need to address the wider and significantly larger issue of plastic pollution. Plastic production has been constantly rising since 2008, with 381 million tonnes of plastic being produced in 2015 . As secondary microplastics are formed from the breakdown of larger plastics, decreasing the consumption of plastic would decrease the number of secondary microplastics. This is a huge issue to tackle, but by taking small steps in our personal lives, such as trying to avoid the use of plastics where possible, we can be part of a much bigger impact. Some countries, including the USA, UK, Italy, and Korea, have gone as far as to ban microbeads, a move that will certainly decrease the amount of microplastics in general. As for industry, a large responsibility lies with them.? Moving towards circular economies, where processes are designed to keep out pollution and waste and keep materials in circulation, would make a substantive difference in reducing the amount of microplastics in our world and water systems, as well as reducing the overall amount of waste produced. We need to be aware of the facts and not be scared by companies trying to sell us substandard filtration products. High performance Filters for microplastics may become more necessary in the future, as the scale of plastic pollution changes alongside our understanding of the health implications of consuming microplastics.

M19 labs assist industries, startups & researchers in evaluating the performances and retention capacities RO membranes, and various types of filter media across different separation stages. For more information visit us at https://m19.io/Product/advanced%20filtration.php

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