Fugitive greenhouse gas emissions from wastewater systems

Current Australian Greenhouse Office (AGO) methodologies for wastewater treatment focus mainly on emissions associated with energy use (e.g. electricity and fuel consumption). Quantifying fugitive emissions from wastewater systems is an area of uncertainty for the industry, with less developed and less reliable methodologies. This level of uncertainty in the wastewater industry’s “carbon profile” is unacceptable in the emerging business environment of carbon pricing, and managerial commitments to “carbon neutrality”. Methane and nitrous oxide emissions have much higher global warming potentials than carbon dioxide. This study reviews existing knowledge on their production in wastewater systems and defines their relative importance compared to emissions from energy usage in both wastewater systems and other economic sectors. Further areas of research were identified, to provide sound guidance to water authorities. An interim draft methodology for fugitive greenhouse gas emissions from Australian wastewater systems was proposed for consideration by the AGO.