There is no life without water. We drink it, we bathe in it, we use it to build and grow. We cannot survive without it.
According to the United Nations, in 2022, two billion people worldwide did not have access to safe drinking water, and only 0.5 percent of water on the planet was usable freshwater. To help combat this water insecurity, we use desalination, a process implemented globally to increase the amount of fresh water available by removing salt and other pollutants from seawater and brackish water. Desalination, while an effective method of producing freshwater, is not without its challenges. Brine is the unavoidable byproduct of desalination and disposing of it causes problems on land and in the ocean.
What is Brine?
The US produces 2 million gallons of brine every single day. This amount of brine would fill roughly three olympic sized swimming pools. Most of this ends up back in the environment.
What if, instead, brine could be used to help make the sidewalks we walk on, the toothpaste we brush our teeth with, or the paper we print?
Elizabeth North, Ph.D., a scientist and professor at the University of Maryland Center for Environmental Science, and her team of researchers are currently developing a biomanufacturing process designed to produce calcium carbonate, a chemical compound prominent in various industries such as construction, cosmetics, dentistry, etc.
The process, fondly dubbed SequestSTAR, mimics naturally occurring “whiting events,” a biological phenomenon involving the natural production of calcium carbonate (a combination of calcium ions and carbonate ions) in bodies of water due to photosynthesized micro-organisms, such as algae.
What makes a "Whiting Event?"
“We're looking to the Earth and how the Earth sequesters carbon dioxide to create the biomanufacturing process,” says North, the lead researcher on the SequestSTAR project, in an interview with Planet Forward.
North and her team have cultivated their own “superstar microalgae,” which interacts with the brine from desalination plants, not only producing calcium carbonate, but effectively diluting the brine by drawing calcium ions from it, allowing for the reuse of the previously inundated liquid. This, in addition to trapping CO2 from the atmosphere, creates a “circular water economy” where water can be reused and resources can be conserved.
The microalgae are tiny, single-celled plants, and though they be but little, they are fierce. If SequestSTAR’s algae are grown with the right nutrients, they are capable of altering the pH levels of the water they’re in, making it basic rather than acidic.
PH values range from 0 to 14, with 0 being the most acidic, and 14 being the most basic. When the microalgae make the water basic, it creates the potential to precipitate substances from the solution, specifically the calcium carbonate. According to North, the ideal pH value for this reaction to occur is anything above 11.
“At these levels, dissolved carbon dioxide takes the form of carbonate ions,” North explained in an email exchange. “One of our bioreactors at Horn Point Lab reached a pH of 11.4,” she said, punctuated with a smiley face.
Currently, the SequestSTAR process exists only in North’s lab, but she and her team are looking to get the “superstar” microalgae in desalination plants across the U.S.
The work being done by North and her team is a positive step towards climate conscious manufacturing. “Currently calcium carbonate is produced in a carbon emitting way,” North said. “We're trying to come up with a way to make calcium carbonate that actually pulls carbon out of the atmosphere instead of putting carbon into it.”
One challenge North and her team are facing is ensuring that the algae remain alive and growing well. Temperature is a major factor for the little superstars, as they “shut down and stop growing when the temperature gets too high.”
Another challenge is figuring out the ideal ratio of brine to algae to produce the most calcium carbonate.
If the team is successful in addressing these challenges, and can prove that SequestSTAR is both financially viable and capable of operating on a large scale, the process could drastically reduce the amount of carbon emitted by major industries, such as the construction industry, which is responsible for one-third of global greenhouse gas emissions, primarily carbon dioxide.
“We need this process now. Because of global climate change. We need many different biomanufacturing processes that will pull carbon dioxide out. And this is one of the ones that we hope to bring to the market,” North said.
Finding hope through the brine
North approaches her work with excitement and determination, even as she faces challenges from temperature maintenance to global pandemics.
“I remember driving on a dark empty highway when [Maryland] went into lockdown mode during COVID,” she recounted to me. “It was eerie being the only car on the highway for miles. The lab building was empty, silent, and lonely too, but the algae cultures in my lab were bright and green and hummed with bubbles and pumps. These little tiny plants filled me with hope.”
“What can we all do to combat global climate change?”
“First is the belief that we can do something.”
Mykal Bailey is a rising junior at Howard University. She is studying film and political science, and is a passionate advocate for environmental justice and climate solutions.