A new case study from Quebec’s Institut national de la recherche scientifique (INRS) has shown some success in degrading microplastic particles through electrolytic oxidation until they become carbon dioxide and water molecules.
Laboratory tests conducted on water artificially contaminated with polystyrene showed a degradation efficiency of 89%, researchers found. They used a synthetic solution prepared with distilled water and a commercial polystyrene solution containing a surfactant, but say they will test in real water conditions soon.
Microplastics are often small particles of less than 5 mm and can come from a variety of sources including clothes, usually as microfibres.
Professor Patrick Drogui specializes in electrotechnologies and water treatment at INRS and led the case study published in the Environmental Pollution journal. He says there are currently no established degradation methods to handle microplastics during wastewater treatment, and while some techniques do exist, they often involve physical separation as a means of filtering pollutants.
“Using electrodes, we generate hydroxyl radicals to attack microplastics,” Drogui explained in an announcement about the case study. “This process is environmentally friendly because it breaks them down into CO2 and water molecules, which are non-toxic to the ecosystem,” he added.
Drogui said the technology could be particularly useful at the exit of commercial laundry facilities, often a source of microplastics released into the environment.
“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,” said Drogui. “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.”
Although they began the case study with artificial contamination, researchers say they plan to move on to experiments involving real 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.
Drogui is also scientific director of the Laboratory of Environmental Electrotechnologies and Oxidative Processes.
Recently, Ottawa’s Global Water Institute received a $230,000, 18-month grant for research to develop solutions for the detection and removal of microplastics and microfibres from freshwater and wastewater systems.