Mechanical Biological Treatment as a Solution for Mitigating Greenhouse Gas Emissions from Landfills in Thailand
Open dumping and landfilling are the two predominant waste disposal methods in Thailand. In 2009, only 23% of Municipal Solid Waste (MSW) was separated for recycling. As far as on land disposal is concerned, it has been estimated that 47% of collected waste is being landfilled and 53% is being openly dumped. These simple MSW management methods are causing negative socio-economic impacts, environmental pollution, and contributing to climate change; their many drawbacks are becoming increasingly recognised. Moving toward biological treatment methods is by many regarded by many as an appropriate strategy for reducing the Greenhouse gas (GHG) emissions from the waste sector. Therefore, in this study, the GHG mitigation potential of Mechanical Biological Treatment (MBT) is assessed in comparison with the two most common disposal practices from a life cycle perspective.
In Phitsanulok Municipality, 78 tonnes/day of MSW is treated by MBT instead of landfilling or open dumping. The MBT process consists of several steps such as unloading, homogenisation, piling, aeration, sieving and separation of compost-like materials and high-energy fractions prior to final disposal. In order to calculate life cycle GHG emissions, data was collected and analysed considering all the phases of the life cycle of the existing MSW management system, including energy and raw materials production, MSW collection and transportation, MBT process and final disposal. Intergovernmental Panel on Climate Change (IPCC) 2006 guidelines were followed to estimate GHG emissions from both MBT and base scenarios (open dumping and sanitary landfilling without gas recovery).
According to our calculations, GHG emissions from the MBT amounted to 161 kg CO2-eq/tonne of waste received at the facility. In contrast, GHG emissions from open dumping and sanitary landfilling (without gas recovery) would be 448kg CO2-eq/tonne and 925 kg of CO2-eq/tonne respectively. The results indicate that by adopting MBT, Phitsanulok Municipality can significantly cut down GHG emissions, by 287 kg of CO2-eq and 764 kg CO2-eq per tonne of waste as compared to open dumping and sanitary landfilling respectively. On an annual basis the GHG emissions reduction potential from the system in Phitsanulok amounts to 21,758 tCO2-eq as compared to sanitary landfilling. We conclude that the current waste management model in Phitsanulok has very significant climate benefits and that a widespread adoption of similar systems could contribute substantially to the national GHG mitigation program and improve the overall sustainability of the waste management sector.