title: Release of hydrogen sulfide in a sewer system under intermittent flow conditions: the Eiceira case study, in Portugal.
abstract: The presence and fate of hydrogen sulfide in wastewater systems were studied in two stretches of an intercepting sewer system located in a coastal village, in Portugal. A range of hydraulic parameters were obtained and liquid and gas phase measurements were carried out, both continuously and through intensive sampling campaigns. Upstream, where flow rates were relatively low, dissolved sulfide concentrations around 12 mg S L-1and hydrogen sulfide gas concentrations above 250 ppm were observed, along with limited corrosion damage. It is believed this is due to the low relative humidity detected along the atmosphere of the studied sewer system. Downstream, gas concentrations were always below 40 ppm. Despite that, high signs of corrosion were detected, particularly in manholes with drop structures. It is thought that condensation of spray produced by the fall is the main cause of the phenomenon. Another relevant observation was the rapid decline in dissolved sulfide contents along gravity trunk sewers following the discharge of rising mains, with loss rates as high as 40 mg S L-1h-1. Air-flow velocities corresponded to 15-50% of wastewater flows, an observation which agrees with other authors' publications addressing relatively small pipes and moderate water flows.
authors.affiliation: Department of Civil Engineering, Architecture and Georesources (DECivil) & Civil Engineering Research and Innovation for Sustainability (CERIS), Instituto Superior Técnico (IST), University of Lisbon, Avenida Rovisco Pais, Lisbon 1049-001, Portugal E-mail: natercia.matias@ist.utl.pt.
authors.forename: Natércia
authors.initials: N
authors.lastname: Matias
authors.affiliation: Department of Civil Engineering, Architecture and Georesources (DECivil) & Civil Engineering Research and Innovation for Sustainability (CERIS), Instituto Superior Técnico (IST), University of Lisbon, Avenida Rovisco Pais, Lisbon 1049-001, Portugal E-mail: natercia.matias@ist.utl.pt.
authors.forename: Rita Ventura
authors.initials: RV
authors.lastname: Matos
authors.affiliation: Department of Civil Engineering, Architecture and Georesources (DECivil) & Civil Engineering Research and Innovation for Sustainability (CERIS), Instituto Superior Técnico (IST), University of Lisbon, Avenida Rovisco Pais, Lisbon 1049-001, Portugal E-mail: natercia.matias@ist.utl.pt.
authors.forename: Filipa
authors.initials: F
authors.lastname: Ferreira
authors.affiliation: Department of Civil Engineering, Aalborg University, Sofiendalsvej 11, Aalborg SV DK-9200, Denmark.
authors.forename: Jes
authors.initials: J
authors.lastname: Vollertsen
authors.affiliation: Department of Civil Engineering, Architecture and Georesources (DECivil) & Civil Engineering Research and Innovation for Sustainability (CERIS), Instituto Superior Técnico (IST), University of Lisbon, Avenida Rovisco Pais, Lisbon 1049-001, Portugal E-mail: natercia.matias@ist.utl.pt.
authors.forename: José Saldanha
authors.initials: JS
authors.lastname: Matos
mesh_terms: D003343:Corrosion; D006112:Gravitation; D006813:Humidity; D006862:Hydrogen Sulfide / Q000737:chemistry*; D011174:Portugal; D012722:Sewage / Q000737:chemistry*; D062065:Wastewater / Q000737:chemistry
chemical_list: D006862:Hydrogen Sulfide; D012722:Sewage; D062065:Wastewater