Lyon Co. hears treatment proposal for landfill runoff

Reverse osmosis option being studied

MARSHALL -- Lyon County is still studying its options when it comes to dealing with "forever chemicals" like PFAS in its landfill runoff.

Last week, county commissioners learned about using reverse osmosis systems to filter contaminants out from runoff at the landfill.

Lyon County Environmental Administrator Roger Schroeder said commissioners could expect to hear a report comparing reverse osmosis to evaporation systems early next year.

Commissioners heard a presentation on a possible reverse osmosis treatment system from Greg Ackerson, president and CEO of Apex Water Solutions.

Lyon County has been studying ways to possibly cut down on the amount of PFAS in landfill leachate, a liquid made from decomposing garbage mixed with precipitation like rainwater. PFAS, short for per- and polyfluoroalkyl substances, are a group of manmade chemicals used in a variety of products. The chemicals don't break down easily, and can end up in groundwater and drinking water.

"This is part of our PFAS treatment grant that we got from the Minnesota Pollution Control Agency where we evaluated two different types of potential on-site treatment" for leachate, Schroeder said. "One was an evaporation system, and this one that Greg is going to talk about uses their WARP (Wastewater Alternate Remediation Process) system, based on reverse osmosis technology."

The Lyon County landfill currently trucks leachate to the Marshall wastewater treatment plant. However, Ackerson said, "More and more wastewater treatment plants are not accepting landfill leachate anymore. Marshall is one of them, and that's largely because landfill leachate contains PFAS, as well as a lot of other contaminants of concern."

Having fewer options for treatment means transporting leachate further distances at a greater cost, Ackerson said.

"This is one of the drivers for the county to obtain that MPCA grant to test the viability of some PFAS leachate treatment systems," he said.

Ackerson said there is research being done on sequestering contaminants like PFAS in landfills, instead of treating leachate and letting that treated wastewater be discharged into the environment. It would also eliminate the need to truck leachate to an external site for treatment.

Ackerson said Apex Water Solutions' technology would use a reverse osmosis treatment system at the landfill to take leachate and separate contaminants like PFAS out from it.

"So it's clean water that goes out, but all of the rest of the bad stuff stays in a concentrate," he said.

The water would be released into a stormwater pond, and the concentrate would be dumped back into the landfill, where it would be sequestered, he said.

Apex Water Solutions installed a landfill leachate treatment system in Kandiyohi County, said Commissioner Todd Draper.

"What changes have happened since that trial was put in, on that system? Have there been a lot of changes in the system design and the cost of the filters and maintenance?" Draper said.

"Yes and no," Ackerson said. The core of Apex's system hasn't changed, but the system that was installed Kandiyohi County in 2016 had some space constraints that weren't optimal, he said.

"So the mechanical design has changed a lot, and we've standardized on different pumps, and things like that," he said.

Ackerson said the changes have improved reliability and made servicing the systems easier and cheaper.

"As a general rule, right now, once the system is installed, it costs about a penny and a half to operate it per gallon, and that includes the cost of the filters, the membranes, the maintenance, calibrations," Ackerson said.

Commissioner Rick Anderson said he had some reservations about the reverse-osmosis system.

"I don't like just sending it back into the landfill to be sequestered, because you're not getting rid of it," Anderson said.

Ackerson said Apex can leave space in its designs to incorporate PFAS destruction technologies in the future. However, "Right now the destruction technologies that exist are not economically feasible," he said. Ackerson said the carbon filter of a landfill would be a safe repository for PFAS.

Apex is currently in the process of designing a potential reverse osmosis system for the Lyon County landfill, as well as cost and savings information, Ackerson said. Apex would come back before commissioners in a few months, he said.

Schroeder said the goal of the county's grant for researching PFAS treatment will be to do a cost comparison of evaporation and reverse osmosis, and to look at possible recommendations. The grant report has to be done by the middle of December, and the county could discuss the results early in 2027, he said.

"If we were to select an on-site leachate treatment facility of any kind, the board discussion would be whether or not they want to try to fund it themselves," or to go for grant funding, Schroeder said.