title: Recirculation or artificial aeration in vertical flow constructed wetlands: a comparative study for treating high load wastewater.
abstract: Vertical subsurface-flow constructed wetlands at pilot-scale have been applied to treat high hydraulic and organic loads by implementing the following configurations: (1) intermittent recirculation of the treated wastewater from the bottom to the top of the bed, (2) intermittent artificial aeration supplied at the bottom of the bed and (3) the combination of both. These configurations were operated with a saturated bottom layer for a 6h-treatment phase, followed by a free drainage phase prior to a new feeding. COD removal efficiency was 85-90% in all the configurations and removed loads were 54-70 gCOD m(-2)d(-1). The aerated and recirculated wetland resulted in a higher total nitrogen removal (8.6 gN m(-2)d(-1)) due to simultaneous nitrification/denitrification, even in the presence of intermittent aeration (6.8 Nm(3)m(-2)d(-1)). The extra investment needed for implementing aeration/recirculation would be compensated for by a reduction of the surface area per population equivalent, which decreased to 1.5m(2)/PE.
authors.affiliation: Department of Civil, Environmental and Mechanical Engineering, University of Trento, via Mesiano, 77, 38123 Trento, Italy. Electronic address: paola.foladori@ing.unitn.it.
authors.forename: Paola
authors.initials: P
authors.lastname: Foladori
authors.forename: Jenny
authors.initials: J
authors.lastname: Ruaben
authors.forename: Angela R C
authors.initials: AR
authors.lastname: Ortigara
mesh_terms: D000332:Aerobiosis; D064751:Ammonium Compounds / Q000032:analysis; D057919:Biological Oxygen Demand Analysis; D009566:Nitrates / Q000032:analysis; D010865:Pilot Projects; D012212:Rheology; D013997:Time Factors; D014865:Waste Disposal, Fluid; D062065:Wastewater / Q000737:chemistry*; D018508:Water Purification / Q000379:methods*; D053833:Wetlands
chemical_list: D064751:Ammonium Compounds; D009566:Nitrates; D062065:Wastewater
keywords: Constructed wetlands; Intermittent aeration; Recirculation; Simultaneous nitrification–denitrification; Vertical subsurface flow constructed wetlands