title: Intermittent aeration to improve wastewater treatment efficiency in pilot-scale constructed wetland.
abstract: Forced aeration of horizontal subsurface flow constructed wetlands (HSSF CWs) is nowadays a recognized method to improve treatment efficiency, mainly in terms of ammonium removal. While numerous investigations have been reported testing constant aeration, scarce information can be found about the efficiency of intermittent aeration. This study aims at comparing continuous and intermittent aeration, establishing if there is an optimal regime that will increase treatment efficiency of HSSF CWs whilst minimizing the energy requirement. Full and intermittent aeration were tested in a pilot plant of three HSSF CWs (2.64m(2) each) fed with primary treated wastewater. One unit was fully aerated; one intermittently aerated (i.e. by setting a limit of 0.5mg/L dissolved oxygen within the bed) with the remaining unit not aerated as a control. Results indicated that intermittent aeration was the most successful operating method. Indeed, the coexistence of aerobic and anoxic conditions promoted by the intermittent aeration resulted in the highest COD (66%), ammonium (99%) and total nitrogen (79%) removals. On the other hand, continuous aeration promotes ammonium removal (99%), but resulted in nitrate concentrations in the effluent of up to 27mg/L. This study demonstrates the high potential of the intermittent aeration to increase wastewater treatment efficiency of CWs providing an extreme benefit in terms of the energy consumption.
authors.affiliation: GEMMA - Group of Environmental Engineering and Microbiology, Department of Civil and Environmental Engineering, Universitat Politècnica de Catalunya·BarcelonaTech, Barcelona, Spain. Electronic address: enrica.uggetti@upc.edu.
authors.forename: Enrica
authors.initials: E
authors.lastname: Uggetti
authors.affiliation: Nottingham Trent University, Nottingham, United Kingdom.
authors.forename: Theodore
authors.initials: T
authors.lastname: Hughes-Riley
authors.affiliation: Nottingham Trent University, Nottingham, United Kingdom.
authors.forename: Robert H
authors.initials: RH
authors.lastname: Morris
authors.affiliation: Nottingham Trent University, Nottingham, United Kingdom.
authors.forename: Michael I
authors.initials: MI
authors.lastname: Newton
authors.affiliation: Nottingham Trent University, Nottingham, United Kingdom.
authors.forename: Christophe L
authors.initials: CL
authors.lastname: Trabi
authors.affiliation: ARM Ltd, Rydal House, Colton Road, Rugeley, Staffordshire, United Kingdom.
authors.forename: Patrick
authors.initials: P
authors.lastname: Hawes
authors.affiliation: GEMMA - Group of Environmental Engineering and Microbiology, Department of Civil and Environmental Engineering, Universitat Politècnica de Catalunya·BarcelonaTech, Barcelona, Spain.
authors.forename: Jaume
authors.initials: J
authors.lastname: Puigagut
authors.affiliation: GEMMA - Group of Environmental Engineering and Microbiology, Department of Civil and Environmental Engineering, Universitat Politècnica de Catalunya·BarcelonaTech, Barcelona, Spain.
authors.forename: Joan
authors.initials: J
authors.lastname: García
keywords: Ammonium removal; Constructed wetlands; Horizontal sub-surface flow; Intermittent aeration; Nitrification/denitrification