Craft beer grew in popularity over the past decade across Minnesota, but the brewing process has also created a ton of wastewater.

Now, there’s an experiment to make the process carbon neutral. University of Minnesota professor Paige Novak and Fulton Brewing are working on a new, sustainable way to treat wastewater from the brewing process.

She spoke to MPR chief meteorologist Paul Huttner for Climate Cast.

The transcript below has been lightly edited for clarity and length.

Tell us about the craft brewing process and how it contributes to carbon emissions.

When beer is brewed, a whole lot of extra wastewater is produced.

For every pint of beer that’s made, there's usually four to 10 pints of wastewater that’s generated at the same time. This wastewater tends to go to a centralized treatment facility where it’s treated, then cleaned up and discharged to a river.

What happens during that wastewater cleanup process is that a lot of energy is used to pump air into the water, bacteria eat up all the waste, and all that pumping of the air creates a huge energy requirement, and also produces CO2.

It can take up to 15 to 30 percent of a city’s total energy bill to process wastewater, and that can add up to about 2 billion gallons annually. Is that right?

It’s a huge amount of energy that we use to clean our wastewater.

If you look nationally, the amount of electricity that we use nationally just for wastewater is about 2 percent. So you think about everything that we do in terms of driving, heating our homes, lighting things, and 2 percent of that is used for our wastewater. It’s a huge amount.

Tell us about your project with Fulton Brewing.

I work in biological wastewater treatment systems. I look at bacteria that can help clean up pollutants, including wastewater pollutants.

What we’ve done is develop a system where we can put bacteria into little pellets. We can add these pellets to a tank. The bacteria are active, so we can put a lot of bacteria in there and keep them in the tank and they degrade all the wastewater.

And if you do it at the site before the wastewater is diluted, you can treat the wastewater differently and actually generate methane gas, which can be used as an energy source onsite.

In addition to using a lot of water, breweries use energy to heat the material to make the beer — also to heat the brewery in the winter. So you get added energy creation at the brewery, and then you save energy for treatment when you go to the wastewater treatment plant.

Has Fulton Brewing been receptive to your research?

They have been wonderful partners. They’ve been working with us on this process for years now. We did an initial pilot study at their brewery a few years ago, and that was really helpful to see what didn’t work. And then we were able to get additional funding from the Department of Energy to continue to work on this process.

We just finished up a second pilot study at Fulton where we were able to show that the system worked amazingly well.

What else should people know about beer and carbon neutrality?

I think we, just as consumers, need to keep in mind that there’s all this additional work that needs to be done to keep these processes that supply us with the food and beverages going. So think about supporting clean water use, supporting treatment, and supporting research as you go along your day using these products.

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