A research team from the Institut National de la Recherche Scientifique (INRS) in Canada developed the electrolytic treatment.
Wastewater can carry high concentrations of microplastics into the environment. These small particles of less than 5mm can come from our clothes, usually as microfibres.
Professor Patrick Drogui, who led the study, pointed out that there are currently no established degradation methods to handle the contaminant during wastewater treatment. Some techniques already exist, but they often involve physical separation to filter out pollutants. These technologies do not degrade the particles, which requires additional work.
Instead, the team decided to degrade the particles by electrolytic oxidation, which does not require the addition of chemicals.
“Using electrodes, we generate hydroxyl radicals 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,” said Drogui. The electrodes used in this process are reportedly more expensive than iron or steel electrodes, which degrade over time, but could be reused for several years.
The researchers envision the use of this technology at the exit of commercial laundries.
“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, ie. at the laundry, the concentration of microplastics is higher per litre of water, thus more accessible for electrolytic degradation,” said Drogui, a specialist in electrotechnology and water treatment.
Laboratory tests on water artificially contaminated with polystyrene showed a degradation efficiency of 89%. The team plans to move on to experiments on real-world water.
“Real water contains other materials that can affect the degradation process, such as carbonates and phosphates, which can trap radicals and reduce the performance of the oxidation process,” said Drogui.
If the technology demonstrates its effectiveness on real commercial laundry water, the research group intends to study the cost of treatment and the adaptation of the technology to treat larger quantities of wastewater. They said the technology could be implemented in laundries within "a few years".
The research was published in Environmental Pollution.
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