Emission of greenhouse gases from wastewater treatment processes

Abstract Biological wastewater treatment processes are a source of emission of the greenhouse gases CO 2 , CH 4 and N 2 O into the atmosphere. Studies were carried out to quantify the emissions of these gases from the municipal wastewater treatment plants in The Netherlands, which in 1987 handle a total waste load of 17,049,000 population equivalents. On the basis of detailed calculations for the different treatment methods and assumptions for the formation of N 2 O the following emissions were calculated: CO 2 -880 million kg/yr (0.5% of the total CO 2 -emission in The Netherlands), CH 4 -12.5 million kg/yr (1% of the total CH 4 -emission) and N 2 O-829,000 kg N per year (0.9% of the total N 2 O-emission). Measurements of N 2 O-emissions from 2 low load activated sludge plants were carried out. First results indicated that the N 2 O formation and emission amount to 0.1% of the total N-load with the influent to the wastewater treatment plants.