Detroit's wastewater plant - the nation's largest - gets a $474K phosphorus problem

Every summer, satellite images of western Lake Erie show the same troubling pattern: vast green blooms of toxic algae spreading across the water. The fuel for those blooms is phosphorus, and a significant share of it flows through the Great Lakes Water Authority's Water Resource Recovery Facility in Detroit - the largest single-site wastewater treatment plant in the United States.

The facility serves 77 communities across a nearly 1,000-square-mile sewer shed. Now, a three-year, $473,566 grant from the GLWA will fund a Wayne State University-led research effort to figure out how to pull more phosphorus out of that water before it reaches the Rouge River and, ultimately, Lake Erie.

Tracking phosphorus through the plant

The project, led by Shawn McElmurry, chair of Wayne State's Department of Civil and Environmental Engineering, will take a methodical approach to a complicated chemical problem. Phosphorus enters wastewater treatment plants in multiple chemical forms - dissolved, particulate, organic, inorganic - and each behaves differently during treatment. The team plans to use advanced chemical analyses to identify and quantify the specific phosphorus species moving through the facility.

Understanding what forms of phosphorus are present at each stage of treatment is essential for optimizing removal. A process that captures dissolved orthophosphate efficiently may do nothing for phosphorus bound to organic particles, and vice versa.

The researchers will then build bench-scale treatment systems - small, controlled replicas that allow side-by-side testing of biological and chemical phosphorus removal processes. This setup lets them compare approaches under identical conditions without disrupting the full-scale facility's operations.

Real-time optimization

The third component is perhaps the most forward-looking: developing predictive models that would allow plant operators to optimize phosphorus removal in real time. Wastewater composition varies with weather, season, and upstream activity. A model that can anticipate these changes and adjust treatment parameters accordingly could significantly improve removal efficiency without requiring new infrastructure.

"Phosphorus enters our water systems through various ways like agricultural and urban runoff, sewage and waste," McElmurry said. "When the amount entering the environment is too large, it can cause significant problems like algal blooms."

Tightening regulations, aging infrastructure

The research comes at a time when environmental regulations on phosphorus discharge are becoming increasingly stringent. The Great Lakes states and the U.S. Environmental Protection Agency have been pushing for tighter limits on nutrient loading into the Great Lakes basin, driven by the recurring algal bloom crises that have at times threatened drinking water supplies for millions of people.

Meeting those tighter limits at a facility as large as the GLWA's WRRF - which handles flows from nearly a thousand square miles of urban and suburban landscape - is a different challenge than optimizing a small municipal plant. The scale, variability of influent, and age of the infrastructure all add complexity.

The project will also train Wayne State graduate students in wastewater treatment and environmental protection - a practical benefit given the aging workforce in the water treatment sector. John Norton, GLWA's director of energy, research and innovation, described it as a partnership that would "enhance our treatment capabilities" while helping to develop the next generation of water professionals.

The research is part of Wayne State's Grand Challenges initiative, which targets complex real-world problems with direct community impact. For the communities downstream of the WRRF - and for the millions of people who depend on Lake Erie for drinking water, fishing, and recreation - the question of how much phosphorus leaves this facility is not academic. It is a public health issue measured in toxic algal blooms and beach closures.