Wastewater Miners

The toxic chemical soup generated from garbage in landfills is one of the most common liquids contaminating water supplies worldwide. This so-called landfill leachate is created as rain, melting snow, or the liquid waste itself seeps through garbage. Treatment of landfill leachate is one of the most costly and environmentally problematic challenges of modern wastewater treatment.

Graduate students Steve White and Hossein Tabatabaie in OSU’s Department of Biological and Ecological Engineering have designed a way to treat landfill leachate to remove many of its pollutants and to reclaim resources such as metals and ammonia. Their design “mines” valuable metals from leachate, generates energy for local use, and cleans large volumes of water for irrigation. In that way, the students’ innovation turns the waste treatment process from an expense to a revenue stream.

[caption caption="OSU ecological engineers Steve White and Hossein Tabatabaie show the before-and-after results of their design to clean water and recover solids from landfill leachate. (Photo by Juan Barraza, Portland State University.)"] [/caption]

Most landfill leachate makes its way to municipal water treatment plants that are not designed to handle the toxic organic compounds it contains. These pollutants remain in the treatment plant effluent and are often dispersed on farm fields, where their impact on human health and the environment is poorly understood.

“The variety of compounds found in the leachate makes this problem go beyond a solely biological approach,” says White. “We must look at the chemistry behind each of those compounds.”

Their model is designed to sequentially precipitate, dry, and recover metals from the waste stream, while generating large volumes of water for agricultural applications. Ammonia is converted into ammonium sulfate crystals for fertilizer; and energy is generated from organic material through incineration.

White and Tabatabaie, semifinalists in the 2016 Portland State Cleantech Challenge, built a prototype of their model and presented it in September at the Oregon BEST FEST, a showcase of clean technology innovation. The students’ presentation prompted meetings with venture capitalists from Wells Fargo, Dow Chemical, and a group from Saudi Arabia

“It’s a slick process,” says Karl Mundorff, Director of OSU Advantage Accelerator/RAIN Corvallis, an organization that focuses on high-growth innovative start-ups. “These guys are using proven science in an innovative way to improve a system that currently is not working. In the end, they will save solid waste landfills a lot of money, create value-added products from the waste stream, and protect the environment.”