To the editor,

Per the Spotlight at the River Falls’ School District meeting last month highlighting a partnership with Vanguard Renewables for disposal of their food waste in a local biogas co-digester – it seems there has been some lopsided marketing in Vanguard’s report to make this sound like it’s just “Tator tots and tomatoes.”

What we don’t see mentioned from Vanguard is language from their DNR permit allowing the biogas digester to accept industrial food processors’ waste, sludge, and biosolids and the testing needed for PFAS, heavy metals, and concentrated nutrients (phosphorus and nitrogen) from these highly processed wastes.  This is not simply “composting” as their presentation stated. Certified compost demands higher temperatures (>130 degrees) to eliminate pathogens and prohibits the use of biosolids, sewage sludge, hazardous waste, carcasses, rendering waste, etc. Co-digesters operate at much lower temperatures (<105 degrees) to generate more methane, then by-product (digestate) is spread on fields near homes and schools in River Falls. The anaerobic digester makes nitrates and phosphorus more water-soluble and prone to runoff, which contaminates surface and groundwater (drinking) waters. Spreading fields for this digestate are in the Kinnickinnic and St. Croix River Watersheds.

Research from Europe (which has been using this technology longer with much better guardrails) titled “Industrial Waste is Quietly Poisoning the World’s Most Productive Farmland” states, “A field can be agronomically excellent and toxicologically compromised at the same time, and no farmer, consumer or policymaker will know without testing.”  Thus, these contaminants (including microplastics) can make their way onto our dinner plates.

Nor was it mentioned that USDA now has a pause on funding any new co-digesters because many have not been able to produce enough quality gas to sell and pay their creditors.  The delinquency rate of these facilities is nearly 30%. 

Before this pilot project goes further – we advise local officials to take a deeper look into the whole story.

Kim Dupre
Co-Vice President
St. Croix CURES (Citizens Uniting for Responsible Environmental Stewardship)
Hudson