Interdisciplinary greenhouse gas assessment – nitrous oxide emissions from marine wastewater disposal

ARC Discovery (2010–2013): Interdisciplinary international collaboration with Associate Professor Bill Peirson, Associate Professor Greg Peters (Chalmers University of Technology, Sweden) and Professor Nicholas Ashbolt (US EPA).

Project funding: $330,000

Some 300 times more powerful per kilogram than carbon dioxide, nitrous oxide (N2O) is an important greenhouse gas that plays a significant role in several aspects of atmospheric chemistry and climate. Human activities have steadily increased atmospheric N2O concentrations over the past decades; this rising appears likely to continue in the coming decades and is the subject of international concern.

N2O generation occurs during advanced wastewater treatment by way of both microbial nitrification and denitrification of nitrogenous compounds. In oceanic waters, N2O is also emitted as a by-product of nitrification and as chemical intermediate during denitrification. Existing wastewater management practices internationally result in the disposal of large volumes of untreated or primary-treated effluent to the coastal marine environment. Currently, however, there is little international data available to estimate the magnitude of N2O emissions linked to this practice. For the urban water sector, this ‘unknown’ represents a potentially significant un-costed liability in the emerging business environment of carbon pricing and trading.

Through a combination of field surveys, controlled laboratory experiments, hydrodynamic modelling and the application of life cycle assessment methods, this Project seeks to address key knowledge gaps in our current understanding of full cycle N2O emissions from wastewater management. Improving the current characterisation of this emission source will enable more accurate assessments of the international water sector’s carbon footprint and will ultimately facilitate more sustainable management of the water sector internationally.

Research Staff: Dr Michael Short.