Smart bioremediation to clean water, protect wild rice

Lake shore with mirror smooth surface

What does wild rice mean to Minnesotans?

For some, the crop is a food source. Others see it as an economic value to the state, which is among the nation’s leading producers. The crop is also a cultural resource for the state’s tribal communities, and it’s a habitat for the region’s waterfowl.

Despite its important and iconic role in the state, however, wild rice crops are threatened in regions where Minnesota’s water contains too much sulfate from natural sources and from industrial sources like mining, road building, water treatment and agriculture.

A team of University of Minnesota researchers from the Twin Cities and Duluth campuses are now working together to design and develop smart technology that will more efficiently and cost-effectively lower those sulfate concentrations, helping keep the water clear of pollutants and providing a clean, healthy environment for wild rice to grow.  The systems, which will use naturally occurring bacteria and operate on renewable energy, will function year-round to clean Minnesota’s water and protect this critical natural resource even in remote locations.

The project is part of the state-funded MnDRIVE Transdisciplinary Research Program, where researchers from different departments work beyond the limits of their disciplines to address complex challenges.

“This system takes advantage of naturally occurring processes to effectively remove sulfates from the state’s water,” said Michael Sadowsky, Ph.D., director of the U’s BioTechnology Institute and a co-principal investigator in the project. “This unique technology will allow us to expand water treatment in hard-to-reach areas of the state where much of the wild rice is produced.”

Sulfates end up in water from both natural sources and human operations. Sulfur-bearing minerals commonly found on the earth’s surface, for example, can react with oxygen and water to form dissolved sulfates. This process has greater potential to occur, however, when mining operations draw rocks from the ground, giving these minerals the water- and oxygen-rich environment that help spur the chemical reactions.

recent study conducted by the U of M for the Minnesota Pollution Control Agency showed the connection between high sulfate levels and lower growth in wild rice. Following the study, the MPCA plans to adjust the upper limit for sulfate concentration in water, previously at 10 milligrams per liter, to a flexible new standard later this year. Once these regulations are set, industry and utility companies’ operations will need to meet them to continue operating. PolyMet Mining Inc., one company that will need to fall within those regulations, is interested in the U’s sulfate-reduction research and has provided in-kind support for early testing of the technology. Support for the project has also come from the Minnesota Department of Natural Resources, which is responsible for ensuring the state’s mining grounds are reclaimed as safe and pollution-free; from Clearwater Layline LLC, a company that designs smart water treatment systems; and from the Iron Range Resources and Rehabilitation Board, which helped fund an early pilot version of the technology that the MnDRIVE project will expand upon.

The U researchers’ efforts focus on a floating bioreactor — which uses naturally occurring bacteria to break down and remove contaminants from the environment. These bacteria, which are simply drawn from the ecosystem rather than engineered, first break down sulfate into hydrogen sulfide. Then, by adding iron, researchers can trigger a reaction that they predict will form iron sulfide, or “fool’s gold,” a solid compound that sinks to the bottom of a precipitation tank for later removal and will neither harm the ecosystem nor inhibit crop growth. The practice has the potential to be much more cost-effective than the more energy-intensive chemical treatments many companies have used. Researchers are now working to improve the process while also closely monitoring the system to ensure it does not produce any unexpected byproducts, such as methylmercury.

The bioreactor will incorporate communications transmitters, computer modeling, thermometers, flow sensors, pumps and valves to allow researchers to monitor the system remotely using a telephone. Researchers hope to power the final version entirely through renewable energy, using solar panels that charge on-site battery backup systems to allow the “smart” system to operate year-round and even heat itself during the winter. George Hudak, Ph.D., project manager for the effort and director of the Minerals Division at the U’s Natural Resources Research Institute, said the technology aims not only to improve on previous remediation methods, but also to allow it to function in more remote locations.

“There are many well-known treatment technologies out there, including some that use bacteria,” Hudak said. “We’re trying to utilize what we know from those and incorporate an understanding of how these bacteria operate to make the system more cost-effective and bring sulfate levels down. Giving these systems a means for using renewable energy and transmitting data is what will set this system apart.”

Researchers are still working to improve the technology within the system. So far, challenges have included honing in on the optimal mix of nutrients they need to support the bacteria and ensuring the system can run on the solar energy provided. An early, fully-functional prototype of the device is now in the field, but Sadowsky is optimistic that the team can further improve the technology so that it can bring sulfate concentrations below state limits without the aid of other systems.

Collaborating for cleaner water

The research team working on developing and integrating the bioreactor brings together a wide-reaching group of experts from two U of M campuses.

Along with Hudak, other NRRI researchers contributing to the project include David Hendrickson, director of strategic development, and Donald Fosnacht, Ph.D., director of the Center for Applied Research and Technology Development. The NRRI team will work to integrate the smart technologies into remote settings and build long-term cooperative relationships with state regulatory agencies, industry and businesses that may benefit from it.

Other researchers from UMD are also contributing to the effort. Randall Hicks, Ph.D., a professor of environmental microbiology at the U of M Duluth campus, will measure sulfate-reducing bacteria in the bioreactors and help troubleshoot problems, while Thomas Ferguson, adjunct instructor in electrical engineering with UMD, will help refine and advance the bioreactors’ smart system technology to make them more reliable when powered by renewable energy sources. Meanwhile, Monica Haynes, Ph.D., director of the Bureau of Business and Economic Research with UMD’s Labovitz School of Business and Economics, will conduct economic assessments of natural resource businesses and help commercialize the technology once the team has finished developing it.

At the Twin Cities campus, Sadowsky and his team — research associate Chan Lan Chun and postdoctoral associate Daniel Jones — are using genomic tools to determine which microbes are present in the bioreactor, how fast they can remove sulfate from the water, and how to optimize the microbiology of the system.

While the team as a whole is focused on improving the science behind the bioreactor right now, they ultimately plan to commercialize the technology, giving the mining industry, wastewater treatment utilities and state agencies the tools they need to clean water in an efficient and low-cost way that helps preserve Minnesota’s ecosystem.

This project is supported by MnDRIVE, a landmark partnership between the university and the state of Minnesota that aligns areas of university strength with the state’s key and emerging industries to advance new discoveries that address grand challenges.