Parameters for image-map-2:{}
University of New Haven logo
Parameters for article:{}

Clean Air or Clean Water? Biological Nitrogen Removal Strategies

Release Date:
11/14/2011 11:15 AM

University of New Haven: Kartik Chandran, events, Alvine Lecture Series Kartik Chandran


The University of New Haven (UNH) Tagliatela College of Engineering will host a free public lecture, “Clean Air or Clean Water? Biogenic Nitrous Oxide Production During Engineered Nitrogen Removal,” by Dr. Kartik Chandran, Associate Professor, Columbia University. Chandran’s lecture is part of the UNH Fall 2011 Alvine Engineering Professional Effectiveness and Enrichment Program.


Wednesday, November 16, 12:15 p.m. - 1:30 p.m.


Schumann Auditorium in the Tagliatela College of Engineering, room B120


Biological Nitrogen Removal (BNR) strategies could be a significant contributor to atmospheric N2O and NO depending upon the reactor configurations and operating conditions. In the future, as BNR is implemented at wastewater treatment plants around the nation, the flux of these gases to the atmosphere could significantly increase. The contribution of nitrification to nitrous oxide (N2O) emissions from engineered wastewater treatment plants has been largely ignored in greenhouse gas inventories thereof. We are leading the first nationwide study on the quantification of the N2O and NO emissions inventory at several wastewater treatment facilities. Under the purview of this project, we have developed and implemented as a first crucial step, a detailed protocol for determining the N2O and NO emissions fluxes from activated sludge reactors. Field-scale measurements have revealed that nitrification related N2O emissions could be far higher than emissions related to heterotrophic denitrification.

Additionally, we have developed a molecular level elucidation of specific triggers and pathways for biogenic N2O and NO production by nitrifying bacteria. Under specific conditions, including transitions from anoxia to oxic conditions, excessive ammonia loading, ammonia oxidizing bacteria are also documented to produce gaseous nitric oxide and nitrous oxide. A specific directionality, wherein the recovery from rather than imposition of anoxic conditions, in nitrous oxide production has been further demonstrated and linked to changes at the transcript levels of select genes in redox Ncycling. When considered in conjunction, the field and lab-scale results suggest that water quality and air quality are not in conflict. Rather, engineering designs that achieve low aqueous nitrogen concentrations also minimize gaseous nitrogen emissions.

Speaker Bio

Dr. Kartik Chandran is Associate Professor and Director of the CUBES Program at Columbia University. The main focus of Dr. Chandran’s work is on biological nitrogen transformations. Dr. Chandran leads the multiagency supported Wastewater Treatment and Climate Change program at Columbia University. Dr. Chandran also serves on the Board of Trustees of the Water Environment Federation and is vice-chair of the Research Subcommittee of the Program Committee of the Water Environment Federation.

For more information contact:  Program Director: Dr. Ismail Orabi at or 203 932 7144.