title: Effect of water depth on the removal of organic matter in horizontal subsurface flow constructed wetlands.
abstract: The objective of this article is to evaluate the effect of water depth on organic matter removal efficiency in horizontal subsurface flow constructed wetlands (SSFs). Experiments were carried out in a pilot plant comprising eight parallel SSF of almost equal surface area (54-56 m2 each) and treating urban wastewater. Each SSF differs from the others in the aspect ratio or the size of the granular medium or the water depth. During a period of two years, the shallow SSFs (0.27 m water depth) removed more chemical oxygen demand (COD) (72-81%), biochemical oxygen demand (BOD)5 (72-85%), ammonia (35-56%), and dissolved reactive phosphorus (DRP) (8-23%) than deep SSFs (0.5 m water depth) (59-64% for COD; 51-57% for BOD5; 18-29% for ammonia; and 0-7% for DRP). Experiments carried out during the summer indicated that sulphate reduction accounted for a clearly higher organic matter removal in the deep SSFs than in the shallow ones. Denitrification seemed to be a significant mechanism for organic matter removal to occur in shallow SSFs. The results suggest that the relative contribution of different metabolic pathways varies with depth.
authors.affiliation: Enviromental Engineering Division, Department of Hydraulics, Maritime and Environmental Engineering, Technical University of Catalonia, Barcelona, Spain.
authors.forename: Paula
authors.initials: P
authors.lastname: Aguirre
authors.forename: Esther
authors.initials: E
authors.lastname: Ojeda
authors.forename: Joan
authors.initials: J
authors.lastname: García
authors.forename: Jesús
authors.initials: J
authors.lastname: Barragán
authors.forename: Rafael
authors.initials: R
authors.lastname: Mujeriego
mesh_terms: D017753:Ecosystem; D009584:Nitrogen / Q000378:metabolism*; D009930:Organic Chemicals; D010100:Oxygen / Q000378:metabolism; D010758:Phosphorus / Q000032:analysis / Q000737:chemistry; D010944:Plants; D012621:Seasons; D014865:Waste Disposal, Fluid / Q000379:methods*; D014872:Water Movements
chemical_list: D009930:Organic Chemicals; D010758:Phosphorus; D009584:Nitrogen; D010100:Oxygen