title: Microcosm wetlands for wastewater treatment with different hydraulic loading rates and macrophytes.
abstract: Constructed wetlands (CW) usually require large land areas for treating wastewater. This study evaluated the feasibility of applying CW with less land requirement by operating a group of microcosm wetlands at a hydraulic retention time (HRT) of less than 4 d in southern Taiwan. An artificial wastewater, simulating municipal wastewater containing 200 mg L(-1) of chemical oxygen demand (COD), 20 mg L(-1) of NH4+-N (AN), and 20 mg L(-1) of PO4(3-)-P (OP), was the inflow source. Three emergent plants [reed, Phragmites australis (Cav.) Trin. ex Steud.; water primrose, Ludwigia octovalvis (Jacq.) P.H. Raven; and dayflower, Commelina communis L.] and two floating plants [water spinach, Ipomoea aquatica Forssk.; and water lettuce, Pistia stratiotes L.] plants were tested. The planted systems showed more nutrient removal than unplanted systems; however, the type of macrophytes in CW did not make a major difference in treatment. At the HRTs of 2 to 4 d, the planted system maintained greater than 72,80, and 46% removal for COD, AN, and OP, respectively. For AN and OP removal, the highest efficiencies occurred at the HRT of 3 d, whereas maximum removal rates for AN and OP occurred at the HRT of 2 d. Both removal rates and efficiencies were reduced drastically at the HRT of 1 d. Removals of COD, OP, and AN followed first-order reactions within the HRTs of 1 to 4 d. The efficient removals of these constituents obtained with HRT between 2 and 4 d indicated the possibility of using a CW system for wastewater treatment with less land requirement.
authors.affiliation: Department of Environmental Engineering and Health, Chia-Nan University of Pharmacy and Science, Tainan, Taiwan. jingsr@-mail.chna.edu.tw
authors.forename: Shuh-Ren
authors.initials: SR
authors.lastname: Jing
authors.forename: Ying-Feng
authors.initials: YF
authors.lastname: Lin
authors.forename: Tze-Wen
authors.initials: TW
authors.lastname: Wang
authors.forename: Der-Yuan
authors.initials: DY
authors.lastname: Lee
mesh_terms: D017753:Ecosystem; D008962:Models, Theoretical; D009584:Nitrogen / Q000032:analysis; D010758:Phosphorus / Q000032:analysis; D010944:Plants; D014865:Waste Disposal, Fluid / Q000379:methods*; D014872:Water Movements
chemical_list: D010758:Phosphorus; D009584:Nitrogen