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.

Constructed Wetland for Sustainable and Low-Cost Wastewater Treatment: Review Article

“…The reported removal efficiency showed a varied range of treatment across various CW applications. A study of CW to treat landfill leachate by experimental systems showed a significant BOD5 removal efficiency between 91% and 96% of total nitrogen (TN), as reported by Sim et al [6]. Meanwhile, a wetland system in Australia-Townsville achieved a slightly lower range (48-67%) of BOD 5 removal, similar to another project, which consisted of four linear channels where a reduction efficiency of about 46% was reported [37].…”

“…Constructed wetlands (CWs) are fast-growing wastewater treatment technologies designed and constructed to simulate actual physical, chemical and biological processes occurring in natural wetlands [4]. They are manmade wetlands designed to operate and mimic natural wetlands using vegetation, soil and microorganisms, and they may appear as Land 2022, 11, 1388 2 of 17 a more ecologically endowed system for wastewater treatment as either a new or restored habitat for native and migratory wildlife [5,6]. The proven advantages in utilizing the CWs for wastewater treatment as green and sustainable technology was discussed by many researchers and resulted in tremendous increases in both research and applications as a result of the simultaneous rise in the environmental sensitivity [3,7,8].…”

“…CWs are recognized to be effective in treating dissolved organics and suspended solids as well as many other contaminants reported by many researchers [5,11,12]. The recent research has shifted towards examining the applications of constructed wetland technology to treat a wider array of pollutants including metal, dye, organics containing wastewater and heavy metals including iron (Fe), magnesium (Mg), manganese (Mn) and zinc (Zn) [6,13]. Additionally, CW systems were successfully applied to treat phenol compounds and dyes from textile industries, with a considerable level of treatment achieved [13,14].…”

Peat as Substrate for Small-Scale Constructed Wetlands Polishing Secondary Effluents from Municipal Wastewater Treatment Plant

“…Constructed wetlands are considered to be a sustainable passive wastewater treatment technology, and have been used to treat a variety of wastewaters for decades, including domestic or municipal wastewater [1,2], industrial wastewater [3,4], agricultural [5][6][7], acid mine drainage [8], river and lake water [9][10][11], groundwater [12], landfill leachate [13][14][15], highway [16] and airport [17] runoff. They take advantage of many of the same processes that occur in natural wetlands, but do so in a more controlled or engineered system [18].…”

Coexistence of Synechococcus and Microcystis Blooms in a Tropical Urban Reservoir and Their Links with Microbiomes

“… 61 Inland lakes can emit significant amounts of methane from sediment layers, equivalent to 20% of fossil fuel emissions. 73 Our study site, which is next to a historic landfill, 74 could have nutrient-rich sediments releasing methane sources to MOB. The archaeal community in the anoxic sediment layer is believed to be the exclusive source of methane production from lakes.…”