Wastewater Treatment and Climate Change

Kartik Chandran Laboratory

Earth and Environmental Engineering

CLIMATE CHANGE RESEARCH

Wastewater Treatment and Climate Change Program

Waste discharge and wastewater treatment are sources of greenhouse gas emissions. Although carbon dioxide (CO₂) and methane (CH₄) have been the main focus in climate change calculations and discussions, the potential impact of nitrous oxide (N₂O), which is also generated from wastewater treatment plants (WWTPs) is now gaining increased prominence. N₂O is one of the radiatively important gases considered by the Intergovernmental Panel on Climate Change (IPCC) for its greenhouse gas emission scenarios. This is understandable given that the greenhouse impact of N₂O is about three hundred times that of CO₂.

The following are three outstanding and related issues that we address as part of our research program

Inventory, triggers and mechanisms of N-GHG release from WWTPs

Despite the acknowledgment of N₂O release from WWTPs, a standardized protocol for its emission did not even exist.

We have developed a protocol, which after review by the USEPA is being implemented at WWTPs nationwide to capture the net inventory of N-GHG fluxes from WWTPs. Using such plant-wide N-GHG measurements in conjunction with lab-scale research, we are also identifying the triggers and mechanisms of N-GHG release.

Global climate impact of wastewater treatment operations

(Global Temperature map courtesy, Dr. Linda Sohl, NASA GISS)

Notwithstanding the recognized impact of N2O and the acknowledged role of wastewater treatment in its generation, there are few studies that attempt to explicitly determine the impact of global wastewater treatment strategies on actual climate change indicators.

Working in conjunction with NASA Goddard Institute for Space Studies, we are feeding the inventory of N₂O fluxes from WWTPs worldwide (both in developed and developing nations) to determine the global climate change impact of waste treatment operations.

Process optimization for minimizing N-GHG release from WWTPs

Based on full-scale and lab-scale studies, we have developed computational models that describe N₂O release from biological processes, ranging from the process scale to the metabolic scale.

We are integrating these models with full-scale and lab-scale reactor performance measures to develop operating strategies that meet both water quality and air quality limits.