Elimination of microplastics in wastewater directly at the source of generation
A team of researchers from the Institut national de la recherche scientifique (INRS) has developed a process for the electrolytic treatment of wastewater that degrades microplastics at their source. The results of this research were published in the journal Environmental Pollution.
Wastewater can carry high concentrations of microplastics into the environment. These small particles of less than 5 mm can come from our clothing, mostly as microfibers. Professor Patrick Drogui, who led the study, points out that there are currently no established degradation methods to treat these contaminants in wastewater treatment. Some techniques already exist, but they often involve physical separation as a means of filtering contaminants. These technologies do not degrade them, which requires additional effort to manage the separated particles.
Therefore, the research team decided to break down the particles through electrolytic oxidation, a process that does not require the addition of chemicals. "We use electrodes to generate hydroxyl radicals (* OH) that attack the microplastics. This process is environmentally friendly because it breaks them down into CO2 and water molecules that are non-toxic to the ecosystem," the researcher explains. While the electrodes used in this process are more expensive than iron or steel electrodes, which degrade over time, they can be reused for several years.
An effective treatment
Professor Drogui envisions the use of this technology at the exit of commercial laundries, a potential source of microplastic release into the environment. "When this commercial laundry water arrives at the treatment plant, it is mixed with large volumes of water, and the pollutants are diluted, making them harder to break down. On the other hand, if you act at the source, i.e. in the laundry, the concentration of microplastics is higher (per liter of water) and therefore more accessible to electrolytic degradation," explains the specialist in electrical engineering and water treatment.
Laboratory tests with water artificially contaminated with polystyrene showed a degradation rate of 89%. The team plans to move on to experiments with 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," says Professor Drogui, scientific director of the Laboratory of Environmental Electrical Technologies and Oxidative Processes (LEEPO).
Once the technology demonstrates its effectiveness on real commercial laundry water, the research group plans to conduct a study to determine the cost of treatment and how to adapt the technology to treat larger volumes of wastewater. Within a few years, the technology could be used in laundries.
Original publication: Environmental Pollution: Kiendregeogo et al. (2021) – Treatment of microplastics in water by anodic oxidation: A case study for polystyrene
Source: Chemie.de – Eliminierung von Mikroplastik im Abwasser direkt an der Entstehungsquelle