In this article, we present a literature review of CH₄, H₂S and N₂O emissions in sewers. Moreover, CH₄, H₂S and N₂O emissions were quantified in 2 medium-sized Spanish cities with different climate (Betanzos and Calafell). The results shown that wet wells were the sources with the highest concentrations (321 μg L⁻¹ of CH₄ and 6.8 μg L⁻¹ of N₂O). This allows us to calculate that CH₄ and N₂O emissions contribute up to 4 to 30% of the sewer life cycle carbon footprint depending on the calculation method employed.

This article was made in the framework of the Aquaenvec project (LIFE10/ENV/ES/520) “Assessment and improvement of the urban water cycle eco-efficiency using LCA and LCC”. The authors are members of SOSTENIPRA, CETAQUA and GENOCOV.