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Pinto Awarded $330K NSF Grant

Research led by Civil and Environmental Engineering Assistant Professor Ameet Pinto will seek to advance understanding of effective nitrogen pollution management under a three-year, $330,000 National Science Foundation grant.

“Managing nitrogen pollution is extremely important because discharges from wastewater treatment plants can have a huge impact on ecosystem health,” says Pinto. “This has resulted in increasingly stringent requirements to remove a large portion of nitrogen coming into wastewater treatment plants.”

Nitrogen removal traditionally relied on two types of bacteria, one that oxidizes ammonia to nitrite and one that oxidizes nitrite to nitrate. “Converting ammonia all the way to nitrate is an energy-intensive process,” says Pinto, “in some cases, requiring nearly 30 percent of electricity consumption at wastewater plants.”

Over the past 20 years, the focus on achieving greater energy efficiency in nitrogen removal resulted in the development of new technologies based on a third type of a new bacteria or other iterations that partially oxidize ammonia to nitrite, and then get rid of nitrite and ammonia without being converted to nitrate. This approach saves energy as it requires less oxygen.

According to Pinto, everything changed two years ago when he and other research groups in Europe discovered a single bacterium – a complete oxidizing bacteria known as “comammox” – that oxidizes ammonia all the way to nitrate. As a result of this discovery, researchers must now consider “how this single bacterium will impact our aspirations to limit oxidation only to nitrite,” says Pinto. “That’s where our project comes in.”

A more sustainable nitrogen removal process

Pinto’s research will focus on understanding both the “process-relevant ecology” of these new bacteria in the presence of other well-known nitrifiers and the impact of ammonia concentration on which organisms thrive.

The implications are significant. “If we understand these two things better,” says Pinto, “then we can design our systems more effectively to limit the proliferation of comammox. Alternatively, if these bacteria are present and are oxidizing ammonia, we can determine if there is any relationship between their presence and the effectiveness of the wastewater system’s performance.” Pinto notes that it “might not be a bad thing that they are present in these systems” as having better control over the nitrogen removal process is a potential benefit, making the process more reliable and robust.

Pinto’s team includes one PhD student along with student specialists from the Woods Hole Oceanographic Institution – recipient of a sub-award from the NSF – under the direction of Dr. Julie Huber.

As part of his educational outreach, Pinto plans to integrate the latest developments in comammox research into coursework on the wastewater treatment process and use project data as a learning tool for students to do hands-on analysis. In addition, K-12 participants in Northeastern’s College of Engineering Center for STEM Education will have an opportunity to tour local wastewater treatment plants to learn more about current efforts to maximize pollutant removal.

“Being able to manage nitrogen pollution is one of the Grand Challenges identified by the National Academy of Engineering,” says Pinto. “Getting a fundamental understanding of the nitrogen removal process will help us better manage nitrogen pollution. Ultimately our goal is to remove more nitrogen using less energy and at lower cost.”


CEE Assistant Professor Ameet Pinto was awarded a $330K NSF grant for "Deciphering the role of comammox bacteria in nitrogen removal systems". Dr. Pinto, whose research interests include microbial ecology and physiology, drinking water treatment and distribution, wastewater treatment and more, is revolutionizing the way water is treated for nitrogen. His research team promotes a “fundamental understanding of [the bacterium] ecology, physiology, and engineering relevance” by applying molecular, bioinformatics, and statistical methods along with experiments in the laboratory and field in order to examine the “ecology, physiology, and engineering relevance of the comammox bacterium in four key nitrogen removal process configurations.” Ultimately, their goal is to advance the method of nitrogen removal from water with the application of the comammox bacteria, making the process more energy-efficient.

Abstract Source: NSF

Nitrification is a chemical reaction process that plays an important role in the removal of organic nitrogen from municipal wastewater. Nitrification is also an energy intensive process. The recent discovery of a single organism (the comammox bacterium: COMplete AMMonia OXidiser) that can perform nitrification, has led to research into whether this bacterium may be useful for creating a less energy intensive process for nitrogen removal from wastewater. The ability to manage comammox impact on nitrogen removal is critically dependent on a fundamental understanding of its ecology, physiology, and engineering relevance. This research project advances our understanding of the comammox bacterium by developing novel, scalable, and quantitative methods for its characterization. The project goals are being accomplished by coupling state-of-the-art molecular, bioinformatics, and statistical methods with laboratory and field experiments. This project is yielding fundamental insights into comammox bacterial importance, ecology, and physiology and informing process strategies to exploit this novel organism for sustainable nitrogen removal in wastewater treatment plants. The research plan is integrated with a comprehensive suite of educational outreach activities involving undergraduate, graduate, and K-12 students. The activities include a blend of bioinformatics training for undergraduate and graduate students, mentoring of researchers from underrepresented minority groups, and modules for K-12 students on wastewater treatment.

Ensuring the effectiveness and sustainability of nitrogen removal from wastewater requires a detailed understanding of its biotransformation pathways. The recent discovery of comammox bacterium represents a paradigm shift in the understanding of aerobic nitrification, the first key step in nitrogen removal. The research team is investigating the ecology, physiology, and engineering relevance of the comammox bacterium in four key nitrogen removal process configurations. A primary objective of the project is to develop novel methods to characterize the abundance, diversity, and activity of comammox bacteria in complex microbial communities. A deeper understanding of the impact of process and environmental conditions on comammox bacteria will lead to improved strategies to manage and manipulate their contribution in nitrogen removal. Results of this project are advancing our understanding of the role and relevance of novel comammox bacteria within complex nitrifying communities.

Related Faculty: Ameet Pinto

Related Departments:Civil & Environmental Engineering