New Study Outlines Economic and Environmental Benefits To Reducing Nitrogen Pollution

A new study co-authored by Columbia Engineering professor Kartik Chandran and recently published in the journal, Environmental Science & Technology, shows that reducing nitrogen pollution generated by wastewater treatment plants can come with "sizable" economic benefits, as well as the expected benefits for the environment. Chandran was one of five scientists from around the U.S. who worked on the study, along with James Wang of NOAA's Air Resources Laboratory and formerly of Environmental Defense Fund (EDF); Steve Hamburg, Chief Scientist for EDF; Donald Pryor of Brown University; and Glen Daigger of CH2M Hill, a global environmental engineering firm based in Englewood, Colorado.

The study found that adding available technology to the existing infrastructure at a common type of wastewater treatment plant could create a trifecta of reductions in aquatic nitrogen pollution, greenhouse gas pollution, and energy usage. It also found that creating an emissions crediting system for the wastewater treatment sector could make the addition of new technologies much more affordable.

"As wastewater permits on wastewater treatment plants become more and more restrictive, the resultant increased capital and operating costs can pose quite a burden to utilities and municipalities," said Chandran, associate professor of earth and environmental engineering. "Our study shows that, if the reduced emissions associated with well-designed and operated biological nitrogen removal operations can be used to earn CO2 credits, then this could be a big benefit both for the utilities from a cost perspective and for the environment from water quality and air quality perspectives."

The majority of wastewater treatment plants already have systems to reduce ammonia levels in effluent, but pay relatively little attention to overall nitrogen pollution reduction, especially in the form of nitrous oxide (N2O), a potent greenhouse gas. Using emissions credits to address the problem could create an economic incentive of up to $600 million per year for U.S. plants to reduce nitrogen pollution, with the added benefit of up to $100 million per year in electricity savings if they do so.