Center for Algal Innovations: Microplastic Project

The Problem

Bioaccumulation of Microplastics
Figure 1: Showing the process of bioaccumulation within the food-chain, courtesy of The Ocean CleanUp
The accumulation of microplastics in marine and freshwater environments is a growing threat to environmental, animal, and human health. Microplastics are small bits of plastic classified as being less than 5 millimeters in diameter, about the size of a pencil eraser. Microplastics can be intentionally produced for things like microbeads in facial cleansers, or they break off from larger plastic items, such as water bottles, tea bags, tires, and other larger products made of plastic.

In recent years, more attention has been given to microplastics as a source of pollution, however, it is still a relatively new field of research with many unknowns. For example, one of the major concerns linked with microplastics is their bioaccumulation in food chains (Figure 1). Small organisms, such as zooplankton, sometimes ingest microplastics they mistake for food. As progressively larger fish consume zooplankton, the microplastics within them are also ingested by the fish and retained in their bodies. Humans can then ingest these microplastics that have bioaccumulated through seafood such as fish, shellfish, shrimp, and lobster. With the ingestion of microplastics, there is a potential for them to act as a carrier to toxins and pollutants which can cause humans and other organisms to get sick.

The Challenge

images of extremely small microplastics
Figure 2: Microplastics around 30 micrometers in diameter, imaged via FlowCam, Center for Algal Innovation
The good news is the majority of microplastics in wastewater can be filtered out by wastewater treatment plants. These treatment facilities have high efficiency for filtering out bigger microplastics and can do so on a large scale. However, the current filtration system in wastewater treatment facilities is not able to remove microplastics that are smaller than 100 micrometers, about the thickness of a sheet of paper. While this may seem like a small portion of microplastics not being filtered, due to the amount of water that goes through wastewater treatment plants, this is a substantial amount of microplastics re-entering the environment.

The Solution

The Center for Algal Innovation (CAI) seeks to provide a solution to this problem through the cultivation of microalgae. Certain strains of microalgae produce a substance we believe could retain microplastics smaller than 100 micrometers that are not filtered out at wastewater treatment plants. This project will combine engineering knowledge from the CAI Fabrication Lab and algae growing techniques from the NCMA to produce a biological microalgae filter that will remove microplastics from circulation.

Current Progress

images of microalgae throough a microscope
Figure 3: Potential microalgae to be used in the CAI microplastics project
Currently, we are in the early stages of this project. Our research team is working on increasing the growth of our potential algal strain and learning which conditions make it thrive. To support this process, the CAI research team is testing different conditions such as light intensity, temperature, gas supplementation, nitrogen source, and type of growth media. All these variables play a role in the algae’s growth, ‘stickiness’, and success. Another branch of this project involves understanding how our microalgae can retain microplastics. Our preliminary experiments have shown that the algae will hold onto small microplastics but within the coming months, we are working to understand this interaction on a chemical, physical and biological level. By understanding these intricacies, we will be able to better predict the limitations, as well as the full potential of our biological filter.