Last week, this column asked a basic question about the proposed anaerobic digestion facility near Green Forest in Carroll County: What exactly is being built? Documents submitted to ADEQ during the project’s early environmental review, and obtained through the Arkansas Freedom of Information Act, provide a clearer picture of how the facility is intended to operate.
That raises the next question: After the methane leaves the site, what happens to everything else? Knowing the answer matters because the facility is positioned as an entrant into the renewable natural gas (RNG) market, with the conversion of its industrial-scale waste stream as a secondary function. For our watersheds, the question is whether that transition produces a measurable reduction in nutrient burden.
In Northwest Arkansas, nutrient generation exceeds agronomic demand. Unless nutrients, particularly phosphorus, are meaningfully removed from the RNG facility and managed in a way that reduces regional surpluses, the process risks becoming a profitable way to create a new energy market rather than a meaningful solution to the nutrient problem. In our region, which is already designated a Nutrient Surplus Area, understanding how phosphorus will ultimately be managed remains an important public question.
The facility would accept poultry litter together with dissolved air flotation (DAF) sludge—a concentrated mixture of fats, proteins, blood, and other organic material removed from poultry-processing wastewater. Through anaerobic digestion, those materials would be converted into pipeline-quality renewable natural gas, liquid food-grade carbon dioxide, fertilizer products, and recycled process water. Digestate would be separated into liquid and solid fractions; the liquid would pass through an ammonia recovery system to produce liquid nitrogen fertilizer, while the solid fraction would be dried and marketed to the fertilizer industry.
The process flow diagram identifies a dedicated nitrogen recovery system but does not identify a comparable phosphorus recovery process. Instead, digestate solids leave the facility as fertilizer products.
The Environmental Permit Questionnaire estimates annual production of approximately 41,000 short tons of NPK fertilizer products and 13,000 short tons of nitrogen fertilizer products—a combined 54,000 tons. Set against the scale of the proposed poultry litter intake, those figures raise an obvious question: What happens to everything that does not leave the facility in those products?
The facility’s February 2026 Registration Air Permit Application identifies a 350-ton-per-day chicken-litter feedstock throughput in its emissions calculations. At a 365-day operating rate, that equates to approximately 127,750 tons of chicken litter annually, before accounting for additional poultry-processing residuals such as DAF sludge. As a back-of-the-envelope estimate, that baseline would represent roughly 14 to 18 truckloads of poultry litter arriving every day, depending on truck capacity. That figure reflects the project’s February 2026 submission; the FOI records reviewed did not include updated information.
Capturing methane changes the form of the waste stream, but it does not eliminate the need to account for the nutrients that remain. The nutrient disposition cannot be determined simply by comparing tonnage entering the facility with tonnage of fertilizer products leaving it. Anaerobic digestion involves gas production, separation of liquids and solids, water recycling, drying, and other transfers among process streams. The nutrients therefore need to be tracked through the facility: how much nitrogen and phosphorus enters, how much leaves in marketable products or other streams, and where does the remainder go?
If nutrient recovery is presented as a public benefit supporting permits, tax incentives, renewable energy credits, or other forms of public support, that claim should be supported by transparent, independently verifiable data.
But facility-level accounting is only half the picture. The larger question is what happens to those nutrients once they leave as fertilizer products—and whether their ultimate disposition reduces or simply relocates the nutrient burden affecting Northwest Arkansas’s watersheds.
Northwest Arkansas’s nutrient challenges did not develop overnight. Decades of poultry production and repeated land application have left many of our watersheds carrying legacy phosphorus that continues to influence water quality today. The Illinois River Watershed litigation demonstrated that nutrient management decisions can have environmental consequences lasting for decades.
Renewable natural gas, fertilizer products, and the environmental attributes associated with their production can become revenue streams. If public support helps make that market possible, the public has a right to ask who benefits from that arrangement, and whether environmental accounting keeps pace with financial accounting.
That is not an unreasonable request. It is basic accountability.
Dane Schumacher