Marquette University professor at forefront in defending clean water

In the history of slogans, one of the least appealing is probably the phrase “from toilet to tap.” 

But Brooke Mayer, an engineering professor at Marquette University who is one of the lead researchers for the In Defense of Water project, says that water reuse needs to happen in our modern world. 

“People think about water reuse as hooking a pipe to a toilet. That’s not exactly what it is, but the terminology of ‘toilet to tap’ kind of gave a bad ring to it,” Mayer recently told WPR’s “Wisconsin Today.”

“Pretty much all of the water in all of the world is reused, to some extent, because it’s just a cycle,” Mayer added. “So it goes from our human systems out into Lake Michigan and then back into human systems. It’s all part of reuse. We just look at advanced processes to accelerate it so that we have a ready supply of water when you need it.”

Mayer will be honored by STEM Forward as Engineer of the Year on Feb. 6, in part for her work on the In Defense of Water project, which the U.S. Department of Defense recently awarded a third-phase grant of $4.2 million. 

She spoke to “Wisconsin Today” about the various aspects of the project and the developing technologies to protect clean water. 

The following was edited for brevity and clarity. 

Kate Archer Kent: There’s a new phase of this project that will further develop sensors that can alert people when water has been polluted. Describe how this will work.

Brooke Mayer: As we look at regulations evolving in the U.S., especially with things like PFAS, being able to detect concentrations of these compounds at extraordinarily low levels has been challenging. But the development of sensors allows us to look at levels that are equivalent to having a drop of a contaminant in an Olympic-sized swimming pool. So, very, very tiny. We need new technologies that can sense those [contaminants] … so we know if we have to take some sort of action to make sure that water is safe for human consumption. 

KAK: The PFAS problem is so vast, with over 12,000 substances. What progress can be made on treating PFAS in drinking water?

BM: These are referred to as “forever chemicals,” so they don’t like to break down. They just like to hang around in water systems. There’s a lot of people working on strategies that can target those so they aren’t forever. It’s a really active research area.

Some of the things that we’ve been working on are using electrochemical treatment processes and biodegradation, and we see a lot of promise in being able to: one, physically separate those compounds, so take them out of water; or two, to be able to actually chemically break them down. And so looking at full breakdown paths that make them not harmful to humans.

KAK: So many communities around the country are dealing with severe drought conditions. Cities are treating and reusing water to varying degrees. What do you see as the potential for that here in Wisconsin?

BM: We’re a state that’s tremendously blessed with amazing water resources. A lot of times, I think people might not have water reuse at the top of their minds, but I would argue that it’s our responsibility to be good stewards of those resources.

So if you think about energy or even high tech manufacturing, there’s a lot of water that’s used, but it can be cleaned up and reused on site to reduce natural resources that we’re pulling from.

KAK: You’re involved in another project, Science and Technologies for Phosphorus Sustainability, looking to reduce mining of phosphorus, recycling it from wastewater. Can you talk about the problems with the way that we’re using phosphorus now?

BM: Phosphorus is an incredible element. We mine it to use as fertilizer. All global food supplies rely on being able to access sustainable supplies of fertilizer. We apply it onto fields and then some of that runs off and isn’t used by the plants. And that downstream phosphorus that’s released into the environment, if it’s too high of a level, creates negative environmental conditions where we see things like algae blooms that happen essentially every summer here in Wisconsin and across the United States. These algae blooms can be so bad in a couple of cases that they might actually [monopolize] the oxygen and suffocate organisms that are in the water. So you could have dead zones like in the Gulf of Mexico, or they could produce toxins that are harmful for animals and for people. 

On one hand, we try to remove phosphorus from waste before they go into the environment to prevent that degradation. But on the other hand, these supplies of phosphorus that we mine, they’re finite. It’s essentially a nonrenewable resource, just like fossil fuels. The big challenge there is that it’s not replaceable. With fossil fuels, we might be thinking of clean energy technology. But phosphorus is the only thing that can be used to sustain cells to grow food. And so we focus on whether we can get that waste and then put it back in a reusable resource that can be used to support food development.