Proposed Dem-Con AD facility inches toward reality

Ramsey/Washington Recycling & Energy and Dem-Con HZI BioEnergy (DCHZI) have agreed on a feedstock supply contract for a proposed regional anaerobic digestion (AD) facility in Scott County, Minnesota. If approved by the county, the project will be the first of its kind in the country. 

The proposed AD facility would be located in Louisville Township and is designed to process up to 75,000 tons of organic waste per year. Food scraps collected from the Twin Cities metropolitan area, including through Ramsey and Washington counties’ Food Scraps Pickup Program, would be processed at the facility. 

At the facility, food scraps and other organic materials would be placed in a digestion unit, a large, airtight tank without oxygen where microbes break the organic materials down. The anaerobic digestion process creates two products: biogas and digestate. The biogas will go through a biogas upgrader to create renewable natural gas (RNG). The digestate would go through a gasification process to make biochar. 

The process of making biochar and the use of biochar in remediation has also shown promise in reducing per- and polyfluoroalkyl substances (PFAS), or “forever chemical,” a class of toxic chemicals that are notoriously difficult to manage. 

This proposed facility would be a vital part of the region’s efforts to reduce waste and combat climate change. Food scraps make up more than 20 percent of residential trash in Ramsey and Washington counties, and this facility would help keep this material out of landfills and incinerators. The Minnesota Pollution Control Agency’s Metropolitan Solid Waste Management Policy Plan requires curbside organics collection to be offered in all metro area cities with a population over 5,000 by 2030. 

“This is a momentous step toward reimagining how we manage waste in the region. This project is integral in helping us reduce waste and fight climate change,” says Ramsey County Commissioner Victoria Reinhardt, who serves as vice chair on the Ramsey/Washington Recycling & Energy Board. 

“Dem-Con, along with our project partners Kanadevia Inova, is excited to be one step closer to bringing an innovative and sustainable solution to manage food waste and organics in Minnesota, helping to meet our state’s sustainability and recycling goals,” says Bill Keegan, president of Dem-Con Cos. 

The project is currently in the local permitting phase with Scott County and Louisville Township. Once permitting is completed, the facility will take two years to construct, after which it will begin producing RNG and biochar.