Edinburgh Napier University

  Municipal solid waste (MSW) is biodegradable in landfills under anaerobic conditions. The evolution of the hydro-biochemical-mechanical (HBM) processes during degradation is investigated first through experiments and subsequently via modelling. Three well-characterized MSW specimens with significantly different waste composition ranging from "waste-rich" to "soil-rich" were degraded in large-scale experimental setups that enabled simultaneous characterization of the processes with time. The closely-monitored processes are subsequently modelled using a two-stage anaerobic degradation model which is incorporated in the HBM model. This allows an assessment of model performance as a function of waste composition and derivation of waste composition-dependent model parameters. The model performed fairly well in capturing the biochemical and physical behaviour. An increase in biodegradable material in waste specimen corresponds to increase in anaerobic activity (volatile fatty acids and methanogenic biomass accumulation), higher rate of organic fraction depletion, increase in settlement and increase in methane production. However, the model is found to significantly over-predict methane production for all the specimens.