They found that electrolytic treatment of wastewater can literally eliminate microplastics – other methods simply separate microplastics from water, creating the problem of unwanted leftovers
While the issue of microplastics in water bottles has been thoroughly discussed, other microplastics continue to quietly enter the environment.
Why is this a problem?
Microplastics are often defined as plastic particles smaller than 5 mm in length, with a subset smaller than 1 µm in length often referred to as nanoplastics. However, the term microplastics represent a diverse group of materials, that are composed of different substances, with different physical-chemical properties, shapes and sizes. This adds complexity to their assessment, including the assessment of health risks.
Jennifer De France, from the WHO, explains: “Over the past few years, several studies have reported the presence of microplastics in tap water and bottled water, raising questions about whether microplastics in drinking-water might have any effect on human health and whether regulators should require water suppliers to conduct routine monitoring of microplastics in drinking-water.”
When these tiny elements get in the human body, they present a problem for your immune system. Often, they break down within – releasing toxic chemicals into the bloodstream.
So, what about microfibers that are plastic?
Wastewater can carry high concentrations of microplastics into the environment. These small particles of less than 5 mm can come from our clothes, usually as microfibers. Professor Patrick Drogui, who led the study at the Institut national de la recherche scientifique (INRS), highlights that there are currently no established degradation methods to handle this contaminant during wastewater treatment.
Some techniques already exist, but they often involve physical separation as a means of filtering pollutants. While this method works to get rid of the fibres, those fibres have now become somebody else’s problem.
Additional time and resources have to go into dealing with the leftover microplastics.
So, what if scientists could destroy microplastics in the first place?
After identifying the problem of leftovers, the team decided to try destroying the particles via electrolytic oxidation. This is a process that doesn’t need the addition of chemicals, which could then create more pollutant elements.
Professor Patrick Drogui explains that: “Using electrodes, we generate hydroxyl radicals (* OH) to attack microplastics. This process is environmentally friendly because it breaks them down into CO2 and water molecules, which are non-toxic to the ecosystem.”
The electrodes used in this process are more expensive than iron or steel electrodes, which degrade over time. However, this is a process that can be reused for several years.
Where would this tech be most helpful?
Professor Drogui dreams of the technology at the exit of commercial laundries, which is a common and mass-scale source of microplastic release into the world. He commented: “When this commercial laundry water arrives at the wastewater treatment plant, it is mixed with large quantities of water, the pollutants are diluted and therefore more difficult to degrade.
“Conversely, by acting at the source, i.e., at the laundry, the concentration of microplastics is higher (per litre of water), thus more accessible for electrolytic degradation.”
Laboratory tests conducted on water artificially contaminated with polystyrene showed a degradation efficiency of 89%.
If tests go well with real contaminated water, after the next few years, this tech could become a common sight at any laundry.
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