Prediction of Wastewater Treatment Greenhouse Gas Emissions Using a Real-time Model

David Hume (Mott MacDonald)

Kenny Williamson (Watercare Services Ltd.)

Kevan Brian (Watercare Services Ltd.)

Nick Dempsey (Mott MacDonald)

Nitrous oxide (N2O) is the major contributor to greenhouse gas (GHG) emissions from activated sludge plants, with a global warming potential 298 times that of carbon dioxide (CO2). The underlying biological mechanisms leading to its production are complex and not fully understood. At present, fixed emission factors are typically used to estimate N2O emissions. However, these factors do not reflect the high level of uncertainty around how emissions are affected by a number of influences, including wastewater characteristics, the type of treatment process, and how the process is operated and controlled. Whilst mechanistic models have been developed for predicting GHG emissions, these are not yet well proven, or widely adopted by water utilities for predicting and reporting emissions. Additionally, these models typically represent a fixed point in time, and don’t benefit from real-time data inputs and control opportunities. Further emissions monitoring data is required to support the development of such models.