A Bio-Friendly Extraction of Microplastics from Water

By Rowan Ross and William Li
Intermediate Category
Experiment | Environment

Nearly half a century ago, microplastics were not yet discovered. Only 50 years later, microplastics are now one of the world’s most prevalent and forthcoming problems. Microplastics are fragments of plastic that are 5mm or smaller. They are formed from the degradation of larger pieces of plastic. Microplastics in the oceans and great lakes are a devastating problem. Microplastics move through the marine food web as they are ingested by animals and will inevitably reach humans. The health concerns from the ingestion of microplastics are still unknown and to this date are being studied. Although research has now begun to explore the subject of microplastics and their respectful extraction, there still remains a lack of solutions to remove microplastics, especially microplastics in the ocean.

A successful solution for the extraction of microplastics from the ocean must be both feasible and bio-friendly. In a search to meet those goals, we explored the potential utility of filter feeders to extract microplastics from the ocean. We investigated the ability of solitary filter-feeders, specifically Ascidians, to remove microplastics from ocean water, as a potential bio-filter to reduce ocean pollution.

We hypothesized that Ascidians will filter microplastics from water. Specifically, if Ascidians are exposed to microplastics in a body of water, then the concentration of microplastics would decrease after the Ascidians filtered the water.

Microplastics were added to three tanks of saltwater that contained living Ascidians. A similar quantity of microplastics was added to three negative control tanks that did not contain Ascidians. To simulate the microplastics found in the ocean, 10μm diameter microbeads were added to each tank.

The concentration of microplastics in the tanks housing the Ascidians demonstrated a rapid 24.7% decrease within 1 day. By day 4, the concentration of microplastics had decreased by 94.7%. In contrast, there was no change in the microplastic concentration in the control group.

Ascidians efficiently filtered microplastics from water through their natural feeding and respiratory process. Our research demonstrates that this method of bio-filtration is a potentially effective and viable option for the extraction of microplastics in the ocean. These findings could lay the path for future research in safe microplastic extraction from the ocean using live organisms. Based on our results, we can extrapolate that a 5m x 5m x 5m cage of Ascidians would filter out almost 50kg of microplastics every day. This newfound knowledge can lead to many practical applications in the field of ocean pollution, such as commercially farming Ascidians for the purpose of microplastic extraction.

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