| GHG | Greenhouse gas |
| ECAM | Energy Performance and Carbon Emission Assessment and Monitoring |
| WWTP | Wastewater Treatment Plant |
| CAS | Consumption of Activated Sludge |
| IPCC | Intergovernmental Panel on Climate Change |
| IWA | International Water Association |
| CO2 | Carbon dioxide |
| CH4 | Methane |
| N2O | Nitrous oxide |
| ICEAS | Intermittent Cycle Extended Aeration |