A New Paradigm: Carbon Footprint and Sustainability Assessment for Process Selection

In the current age where global climate change is a focal point for implementing any project, greater attention is given towards managing greenhouse gas (GHG) emissions. The most significant sources of greenhouse gas emissions for wastewater treatment are indirect emission of CO2 due to the power (electricity) requirements for aerobic treatment and burning of fossil fuels or biogas for sludge digestion, thermal drying or incineration. Nitrous oxide (N2O) can also be a significant greenhouse gas emission for wastewater treatment plants that provide nitrification. Wastewater treatment factors that effect N2O emissions are starting to be better understood as more research in this area is conducted. Life cycle assessments should be performed when developing a carbon footprint for the purpose of process selection for wastewater treatment. Operational GHG emissions experienced during a 20 to 50 year project life usually far exceed the embodied carbon tied to the construction of the facility.