Landfill gas generation and emission at danish waste disposal sites receiving waste with a low organic waste content

The landfill gas (LFG) generation from four Danish landfills was estimated using three first-order-decay (FOD) models; the LandGEM model (developed by the US EPA), the IPCC (developed by the Intergovernmental Panel on Climate Change) and the Afvalzorg model (developed by a Dutch company). The last two models are multi-phase models, which defines waste fractions into traditional MSW and low-organic waste categories, respectively. Both the LandGEM and the IPCC model estimated significantly larger methane (CH4) generation in comparison to the Afvalzorg model. The Afvalzorg model could better show the influence of not only the total disposed waste amount, but also various waste categories, and was found more suitable to estimate LFG generation from landfills receiving low-organic waste. Four major waste categories currently being disposed at Danish landfills (mixed bulky, shredder, dewatered sludge and street cleansing waste) and temporarily stored combustible waste were sampled and characterized in terms of TS, VS, TC, TOC, and biochemical methane potential (BMP). Decay rates (k values), were determined by conducting anaerobic degradation experiments and applying FOD equations to the experimental results. The LFG generation from four Danish landfills was estimated by the Afvalzorg model using the experimentally based BMP and k values and compared to whole landfill emission rates measured by applying a tracer gas dispersion method. The results showed that the revised modelled LFG generation rates were in good agreement with field emission measurements, indicating that the revised model with site-specific data could provide a practical and accurate estimation of LFG emissions.