Sensitivity analysis and literature review of parameters controlling local biodegradation processes in municipal solid waste landfills

The local gas production rate in municipal landfills is influenced by a large number of processes, which have been modelled by a local mechanistic reaction model based on Monod kinetics. This type of model, however, requires over 40 input parameters. The aim of this research was to review published values for these input parameters, and to analyse the sensitivity of the model to changes in each of them. Included were rate constants based on Monod kinetics, general rate-controlling variables, and parameters that influence the local pH and temperature of the waste. Mathematical functions that describe the influence of water content, temperature, and pH on biodegradation rates were calibrated on the basis of literature data. The results of the sensitivity analysis suggest that the parameters with the largest impact on model output are the hydrolysis constant kHy, the kinetic constants μmax,Xme,1μmax,Xme,1, bXmebXme, Yac,Xme,1Yac,Xme,1, Ki,ac,Hy, and YCO2,Xme,2YCO2,Xme,2, the water content, temperature, pH, initial concentration of Xme, the enthalpy of formation of the original organic matter, as well as the protein content and buffering capacity of the waste. These parameters, therefore, should be carefully selected when similar modelling studies are performed.