Investigation of the leaching characteristics of landfilled waste material

• Main Author: Wong, Julius Kok Zee
• Other Authors: Lim Teik Thye
• Format: Final Year Project
• Language: English
• Published: Nanyang Technological University 2023
• Subjects: Engineering::Environmental engineering::Waste management
• Online Access: https://hdl.handle.net/10356/167127
• Institution: Nanyang Technological University

Semakau Landfill is currently Singapore’s only operating landfill. The landfill is currently expected to support the country’s waste disposal needs till 2035. As part of the Zero Waste Masterplan, a circular economy approach has been adopted to prolong the lifespan of the landfill and to close the waste loop. One of the key methods to adopted is to recycle the mixed landfilled material, by excavating the material out and reusing it as a construction material. However, as the mixed landfilled material composes of incineration bottom ash, incineration fly ash and non-incinerable waste, determining the leaching characteristics of the landfilled material is highly important as the landfilled material could contain highly pollutive contaminants. The focus of this project is to study the leaching characteristics of the mixed landfilled material. A batch leaching test was conducted to determine the leachable metals, anions and organic compounds within the landfill and as well as to determine the variation of leachate concentration according to the depth of the landfill. The severity of the contamination and pollution impacts of reusing the mixed landfilled material was studied using the Geo-accumulation index, Contamination factor and Pollution Load index. The results from the study have shown that the mixed landfilled material contains high levels of contaminants and exhibits a significant pollution level. Treatment of the mixed landfilled material will be required before the excavated landfilled material is to be reused as a construction material and reintroduced back into the environment. The treatment methods should be designed according to the leaching characteristics identified.