title: Pollutant removal from municipal wastewater employing baffled subsurface flow and integrated surface flow-floating treatment wetlands.
abstract: This article reports pollutant removal performances of baffled subsurface flow, and integrated surface flow-floating treatment wetland units, when arranged in series for the treatment of municipal wastewater in Bangladesh. The wetland units (of the hybrid system) included organic, inorganic media, and were planted with nineteen types of macrophytes. The wetland train was operated under hydraulic loading fluctuation and seasonal variation. The performance analyses (across the wetland units) illustrated simultaneous denitrification and organics removal rates in the first stage vertical flow wetland, due to organic carbon leaching from the employed organic media. Higher mean organics removal rates (656.0 g COD/(m(2)·day)) did not completely inhibit nitrification in the first stage vertical flow system; such pattern could be linked to effective utilization of the trapped oxygen, as the flow was directed throughout the media by the baffle walls. Second stage horizontal flow wetland showed enhanced biodegradable organics removal, which depleted organic carbon availability for denitrification. The final stage integrated wetland system allowed further nitrogen removal from wastewater, via nutrient uptake by plant roots (along with nitrification), and generation of organic carbon (by the dead macrophytes) to support denitrification. The system achieved higher E. coli mortality through protozoa predation, E. coli oxidation, and destruction by UV radiation. In general, enhanced pollutant removal efficiencies as demonstrated by the structurally modified hybrid wetland system signify the necessity of such modification, when operated under adverse conditions such as: substantial input organics loading, hydraulic loading fluctuation, and seasonal variation.
authors: Department of Civil Engineering, Ahsanullah University of Science and Technology, Dhaka 1208, Bangladesh. Electronic address: tanveer@alumni.ait.asia.
authors: Tanveer
authors: T
authors: Saeed
authors: Department of Civil Engineering, Ahsanullah University of Science and Technology, Dhaka 1208, Bangladesh.
authors: Abdullah
authors: A
authors: Al-Muyeed
authors: Department of Civil Engineering, Ahsanullah University of Science and Technology, Dhaka 1208, Bangladesh.
authors: Rumana
authors: R
authors: Afrin
authors: Department of Civil Engineering, Bangladesh University of Engineering and Technology, Dhaka 1000, Bangladesh.
authors: Habibur
authors: H
authors: Rahman
authors: School of Engineering and Physical Sciences, James Cook University, Townsville, QLD 4811, Australia.
authors: Guangzhi
authors: G
authors: Sun
mesh_terms: D004926:Escherichia coli / Q000302:isolation & purification; D009584:Nitrogen / Q000302:isolation & purification; D009930:Organic Chemicals / Q000302:isolation & purification; D014872:Water Movements; D014873:Water Pollutants / Q000302:isolation & purification*; D018508:Water Purification; D053833:Wetlands
chemical_list: D009930:Organic Chemicals; D014873:Water Pollutants; D009584:Nitrogen
keywords: constructed wetlands; loading fluctuation; media; nitrogen; organics; seasonal variation