title: Potential for CSO treatment with horizontal flow constructed wetlands: influence of hydraulic load, plant presence and loading frequency.
abstract: This study aimed at analysing the performance of horizontal subsurface flow constructed wetlands (CWs) to treat combined sewer overflow (CSO). Four horizontal subsurface flow CWs, organized in two groups (A and B) each with a planted (Phragmites australis) and a non-planted bed, were loaded with simulated CSO, with group B receiving twice the hydraulic load of group A. Beds were monitored for pH, dissolved oxygen, conductivity, redox potential, chemical oxygen demand (COD), total suspended solids (TSS) and enterococci. Porosity variations were also estimated. Monitoring was conducted during spring and wintertime, with regular and irregular loading frequencies. Results showed an average treatment efficiency of 90-100 % for TSS, 60-90 % for COD and 2-6 log for enterococci. Removal rates were especially relevant in the first 24 h for COD and TSS. TSS and enterococci removal did not exhibit the influence of macrophytes or the applied hydraulic load while COD's removal efficiency was lower in the higher load group and in planted beds.
authors.affiliation: CERIS, Instituto Superior Técnico, Universidade de Lisboa, Av. Rovisco Pais, 1049-001, Lisbon, Portugal.
authors.forename: J
authors.initials: J
authors.lastname: Pisoeiro
authors.affiliation: CERIS, Instituto Superior Técnico, Universidade de Lisboa, Av. Rovisco Pais, 1049-001, Lisbon, Portugal. ana.galvao@tecnico.ulisboa.pt.
authors.forename: A
authors.identifier: http://orcid.org/0000-0003-1513-4522
authors.initials: A
authors.lastname: Galvão
authors.affiliation: CERIS, Instituto Superior Técnico, Universidade de Lisboa, Av. Rovisco Pais, 1049-001, Lisbon, Portugal.
authors.forename: F
authors.initials: F
authors.lastname: Ferreira
authors.affiliation: CERIS, Instituto Superior Técnico, Universidade de Lisboa, Av. Rovisco Pais, 1049-001, Lisbon, Portugal.
authors.forename: J
authors.initials: J
authors.lastname: Matos
mesh_terms: D057919:Biological Oxygen Demand Analysis; D016983:Enterococcus / Q000302:isolation & purification; D062070:Hydrology; D015999:Multivariate Analysis; D006109:Poaceae / Q000254:growth & development*; D011174:Portugal; D012621:Seasons; D012722:Sewage / Q000737:chemistry / Q000382:microbiology; D014865:Waste Disposal, Fluid / Q000379:methods*; D053833:Wetlands
chemical_list: D012722:Sewage
keywords: CSO treatment; Constructed wetlands; Microbial contaminants; k − C* model