| Summary: | Semakau Landfill is Singapore’s one and only landfill to fulfil all of Singapore’s waste disposal needs. Semakau Landfill’s current expected fill date is in 2035. It is imperative that a solution to the extension of the lifespan of Semakau Landfill is found. Proper treatment of mixed waste (MM) samples before reutilization is crucial to minimize potential harmful effects on the environment and human health. Treatment methods may vary depending on the properties and compositions of the mixed wastes in the landfill, and physical and chemical characterization tests can provide useful information for determining the best methods of treatment and reutilization for the mixed waste material from Semakau Landfill.
In this study, physical and chemical characterization of more than 100 mixed waste materials (MM) samples from Cell 9 of Semakau Landfill were carried out. Batch leaching tests were carried out to determine the basic leaching indexes (pH, Oxidative Reduction Potential, Electrical Conductivity), leachable metals anions, and organics content, which could help to understand the leaching behaviours and the leachable contaminants in the MM samples. Solid sample characterization tests such as moisture content test, loss on ignition (LOI) test, and acid digestion test were also conducted to investigate the water, organics, and total element contents in the solid sample. Furthermore, the MM samples from 3 sampling boreholes were selected out for further analysis to access the contamination levels of the MM samples.
In general, the MM samples from Cell 9 of Semakau Landfill exhibit high contamination properties that exceeded regulative values for the reutilization of incineration bottom ash set by NEA. Further treatment methods should be developed based on the characterization results of the MM samples to meet the requirements of different reuse applications.
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