title: Management and treatment of landfill leachate by a system of constructed wetlands and ponds in Singapore.
abstract: Lorong Halus, Singapore's first landfill leachate treatment system, consists of a pre-treatment system (8,000 m(2)), five constructed reed beds (38,000 m(2)), five polishing ponds (13,000 m(2)), an education centre and a learning trail for visitors. Eight species of wetland plants (total 160,000 plants) were selected for their ability to uptake nutrients, tolerance to low phosphorus concentrations and resistance to pest infestations. The wetland was launched in March 2011 and water quality monitoring started in April 2011. The removal efficiencies of the pre-treatment system from April 2011 to August 2012 are biochemical oxygen demand (BOD5) 57.4%; chemical oxygen demand (COD) 23.6%; total suspended solids (TSS) 55.1%; ammoniacal nitrogen (NH4-N) 76.8%; total phosphorus (TP) 33.3% and total nitrogen (TN) 60.2%. Removal efficiencies of the reed beds are BOD5 47.0%; COD 42.2%; TSS 57.0%; NH4-N 82.5%; TP 29.3% and TN 83.9%. Plant growth is generally satisfactory, but the lower than designed volume of leachate has adversely affected some sections of plants and resulted in uneven flow distribution in reed beds. The plant management programme includes improving plant regrowth by harvesting of alternate strips of plants and replanting. The treated effluent meets water quality limits for discharge to the public sewer and is subsequently treated by the NEWater treatment system, which recycles water for industrial and indirect potable use.
authors.affiliation: PUB, National Water Agency, 40 Scotts Road #15-01 Environment Building, Singapore 228231 E-mail: michelle_sim@pub.gov.sg.
authors.forename: C H
authors.initials: CH
authors.lastname: Sim
authors.forename: B S
authors.initials: BS
authors.lastname: Quek
authors.forename: R B E
authors.initials: RB
authors.lastname: Shutes
authors.forename: K H
authors.initials: KH
authors.lastname: Goh
mesh_terms: D057919:Biological Oxygen Demand Analysis; D009584:Nitrogen / Q000737:chemistry; D061005:Ponds; D012846:Singapore; D014874:Water Pollutants, Chemical / Q000737:chemistry; D018508:Water Purification / Q000379:methods*; D053833:Wetlands
chemical_list: D014874:Water Pollutants, Chemical; D009584:Nitrogen