Greenhouse gas emission quantification from wastewater treatment plants, using a tracer gas dispersion method

摘要

Plant-integrated methane (CH_4) and nitrous oxide (N_20) emission quantifications were performed at five Scandinavian wastewater treatment plants, using a ground-based remote sensing approach that combines a controlled release of tracer gas from the plant with downwind concentration measurements. CH_4 emission factors were between 1 and 21% of CH_4 production, and between 02 and 3.2% of COD influent The main CH4 emitting sources at the five plants were sludge treatment and energy production units. The lowest CH_4 emission factors were obtained at plants with enclosed sludge treatment and storage units. N_2O emission factors ranged from <0.1 to 52% of TN influent and from <0.1 to 5.9% of TN removed. In general, measurement-based, site-specific CH4 and N_20 emission factors for the five studied plants were in the upper range of the literature values and default emission factors applied in international guidelines. This study showed that measured CH_4 and N_20 emission rates from wastewater treatment plants were plant-specific and that emission rates estimated using models in current guidelines, mainly meant for reporting emissions on the country scale, were unsuitable for Scandinavian plant-specific emission reporting.