Improved Wastewater Treatment Technologies Hold Promise For Cost Savings, Energy Production

Improved wastewater treatment methods that lead to cost savings and energy production are part of Oregon State University’s new Clean and Sustainable Water Technology Initiative.

A $3.28M gift to the OSU College of Engineering from Jon and Stephanie DeVaan enabled OSU to launch the initiative.

“The College of Engineering is grateful to Jon and Stephanie for their visionary gift, an investment that could make a difference for millions of people around the world,” said Scott Ashford, Kearney professor and dean of the OSU College of Engineering. “The initiative will build a collaborative community of faculty, graduate students, undergraduate students – all working together on providing access to clean water throughout the globe, one of the 14 Grand Challenges for Engineering in the 21st century.”

The initiative will include the work of Tyler Radniecki, assistant professor of environmental engineering, who studies the chemical and biological processes that allow for the decontamination of wastewater and stormwater runoff.

Radniecki is co-director of the OSU-Benton County Green Stormwater Infrastructure Research Facility, an Oregon BEST-funded field laboratory for testing green stormwater infrastructure, also known as low-impact development technologies.

His research focus includes a pair of emerging technologies in microbial resource management:

• Anammox – anaerobic ammonia oxidation – gets nitrogen gas out of wastewater much less expensively than conventional “bubbling” techniques.
• FOG – fats, oils and grease – codigestion purifies wastewater while increasing the production of methane that can be converted into electricity to power treatment plants, in some cases resulting in electricity being sold back to the grid.

“Nitrogen is a contaminant that is coming under ever-increasing scrutiny due to its primary role in causing eutrophication of rivers and lakes,” Radniecki said.

Eutrophication refers to what happens when excess nutrients end up in a body of water, causing a biomass load imbalance that depletes oxygen.

“Anammox uses a recently discovered class of bacteria collectively known as anammox bacteria that can use nitrite to oxidize ammonia to form dinitrogen gas, which then bubbles out of the water and into the atmosphere,” Radniecki said. “This process can reduce the electricity consumption required for traditional nitrogen removal in a wastewater treatment plant by 60 percent and methanol addition by 100 percent.”

The problem is that so far an anammox setup calls for unit operation systems that require “immense technical expertise, monitoring and infrastructure.”

“That puts the process out of reach of most small to midsized treatment plants,” Radniecki said. “We are trying to revolutionize this technology by taking it out of these demanding, highly technical systems and putting it into low-impact constructed wetlands, a more suitable technology for treatment plants that aren’t huge.”

Adding restaurant waste – the aforementioned FOG – to anaerobic digesters to increase methane production is another option available to plants of varying sizes. But for FOG co-digestion to reach its full potential, greater understanding of the digesters’ microbial communities is needed.

“The treatment plant in Gresham, Oregon, has used this technology to become net energy positive – it’s energy independent and actually sells electricity back to the grid,” Radniecki said. “While this is a very exciting development, the technology can be better by improving its reliability under high FOG loading rates as well as when the FOG switches from one food source to another.”

There is also the potential for FOG codigestion to produce other resources besides methane, including hydrogen gas and bioplastic precursors, he said.

“However, we need to know a lot more about how the microbial communities within the anaerobic digester responds to operational parameters – loading rates, for example,” Radniecki said. “We are taking both top-down and bottom-up approaches to gain greater understanding of how to shape these microbial communities to maximize their potential.”

Top-down approaches, he explained, include gene sequencing those communities as they experience operational changes, providing insight into how the communities respond and how that affects digester performance.

An example of a bottom-up approach is genome-enabled modeling of representative anaerobic digester microorganisms.

“GEMs are complex models that, based on the genome sequence of a microorganism, can model every metabolic reaction that can occur in that microorganism,” Radniecki said. “GEMs give us a tool that allows us to probe the metabolic potential of any given microorganism under any given environmental condition. It may be possible for anaerobic digesters to produce additional economically viable products and not just methane.”

About The OSU College of Engineering:
The OSU College of Engineering is among the nation's largest and most productive engineering programs. Since 1999, the college has more than tripled its research expenditures to $37.2M by emphasizing highly collaborative research that solves global problems. It is a leader in signature research areas, including precision health, clean energy, resilient infrastructure and advanced manufacturing; and targeted strategic areas, including robotics, materials research and clean water.