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
Preliminary tests of our biofilm were performed on a small scale and confirmed the ability of our selected microalgae to retain microplastics. Through this first trial, we were able to develop a protocol for counting and measuring the microplastics retained by the biofilm. Our research team is currently constructing a larger, full-size system to grow and test our biofilm. This system will consist of two ‘raceways’ that our algae can be grown on and tested for factors that will increase algae biomass and microplastic retention. As our larger system is being constructed we are also developing new imaging capabilities. These new imaging methods will help to measure the growth of microalgae on the raceway with minimal disturbance and serve as another method for microplastic quantification. By understanding how to efficiently grow our biofilm, monitor algal growth, and quantify microplastics, we can continue to build an impactful bioremediation solution.