Green Steel Environmental presented operating results from its first full-scale municipal deployment of Green Steel PSR at WEFTEC 2026 in New Orleans.
The Boulder-based company exhibited at the event from 28 to 30 September. Its presentation focused on a pilot operating at the City of Boulder’s Water Resource Recovery Facility in Colorado since June 2026.
Boulder pilot produces full-scale operating data
Green Steel PSR is a patented treatment additive produced from upcycled steel slag. It is designed to capture phosphorus and sulphur during wastewater treatment and anaerobic digestion while reducing reliance on conventional chemicals such as ferric chloride.
According to Green Steel Environmental, the Boulder deployment had removed approximately 13,000 pounds of phosphate from wastewater by the time of WEFTEC. The company also reported that the system had treated 14 million standard cubic feet of methane and contributed to the treatment of 1.2 billion gallons of wastewater.
Green Steel Environmental said the deployment had displaced the equivalent of 81,000 pounds of conventional treatment chemicals. These figures were reported by the company and represent results from an ongoing pilot rather than an independently published assessment of the full-scale deployment.
The company also reported completing testing covering land application under EPA Part 503 requirements, whole-effluent toxicity and the Toxicity Characteristic Leaching Procedure. These tests assess different aspects of biosolids, effluent and material-management safety but do not constitute blanket regulatory approval for every application.
Steel slag used to capture phosphate and sulphide
The additive used in Boulder is produced using material sourced from a steel mill in Pueblo, Colorado. Steel slag is commonly used as a lower-value aggregate in applications such as road construction.
Green Steel PSR is introduced upstream of the treatment plant’s anaerobic digesters. The company says phosphate and sulphide are captured by the material before it leaves the process with the facility’s biosolids.
Research supporting the underlying approach was published in Water Environment Research. The peer-reviewed study examined basic oxygen furnace slag as a means of sequestering phosphate and sulphide during anaerobic digestion.
The study reported phosphate and hydrogen-sulphide reductions in laboratory and pilot digesters without a significant effect on conventional digester-performance measures at the tested dosage. The Boulder project is intended to evaluate the approach under full-scale municipal operating conditions.
Project responds to phosphorus and chloride constraints
Boulder’s Water Resource Recovery Facility has a treatment capacity of approximately 10 million gallons per day. The company said the plant serves a combined population of more than 200,000 residents and commuter workers.
The facility was seeking additional phosphorus control while managing limits on chloride discharges. Green Steel Environmental said those limits restricted further increases in ferric chloride dosing.
The plant had already invested in biological phosphorus removal, but the company said this process alone could not meet its forthcoming treatment objectives. The Green Steel PSR pilot was introduced as an additional treatment measure.
Wastewater utilities are exploring several alternatives to traditional metal-salt dosing as phosphorus permits become more demanding. H2O Global News has previously examined an industry project assessing electrocoagulation, natural coagulants and reactive media for phosphorus removal.
Other approaches include tertiary filtration. Southern Water has installed modular phosphorus-filtration equipment at its Storrington treatment works after completing an operational trial.
WEFTEC presentation followed earlier product introduction
Green Steel Environmental first introduced Green Steel PSR to the wider wastewater market at WEFTEC 2025. Its return to the exhibition in 2026 allowed the company to present initial results from the Boulder deployment.
Chief executive and co-founder Jon Teaford said the full-scale project had performed in line with the company’s earlier laboratory work.
“Our first full-scale deployment at Boulder’s Water Resource Recovery Facility shows Green Steel PSR performing as the lab data predicted,” Teaford said during the company’s WEFTEC announcement.
Professor Mark Hernandez, Green Steel Environmental’s chief scientific adviser and the technology’s inventor, said the chemistry of steel slag was suited to capturing phosphorus and sulphur in wastewater.
Additional industrial applications under evaluation
Green Steel Environmental is also evaluating the additive for biogas and renewable-natural-gas production. Potential industrial applications include dairy farms, food-processing facilities, pulp and paper mills, breweries and distilleries.
These operations may require phosphorus removal, hydrogen-sulphide control or both. The suitability and required dosage would depend on the characteristics and operating conditions of each process.
The WEFTEC presentation followed a $2.2 million seed-funding round completed by Green Steel Environmental in January 2026. The round included investment from Rockies Venture Club, Central Texas Angel Network, Cowtown Angels and Baylor Angel Network.
Frequently asked questions
What is Green Steel PSR?
Green Steel PSR is a patented wastewater and biogas treatment additive produced from upcycled steel slag. It is designed to capture phosphorus and sulphur while reducing reliance on conventional chemical dosing.
Where is the full-scale pilot operating?
The pilot has been operating at the City of Boulder’s Water Resource Recovery Facility in Colorado since June 2026.
What results has the company reported?
Green Steel Environmental reported removing 13,000 pounds of phosphate, treating 14 million standard cubic feet of methane and contributing to the treatment of 1.2 billion gallons of wastewater.
How much conventional treatment chemical was displaced?
The company reported that the pilot displaced the equivalent of approximately 81,000 pounds of conventional treatment chemicals.
Where were the pilot results presented?
Green Steel Environmental presented the results at WEFTEC 2026, which took place in New Orleans from 28 to 30 September.
