Simulation of municipal solid waste reactors using Moduelo

The biodegradation and settlement of two consolidating municipal solid waste (MSW) anaerobic reactors operated at Southampton University, UK, were modelled with the Moduelo landfill simulation tool. This paper presents the fundamental concepts of the model, the difficulties found in its application to the studied case and the simulation results obtained. The significant difference found between the rates of anaerobic processes that took place in the field in relation to those in the laboratory required the reduction of the default simulation time step of the model and the introduction of a new parameter to represent the delay in the onset of methanogenesis so that it became predominant after rapid hydrolysis was experienced. Once calibrated by fitting the evolution of the organic content of the leachate during the start-up period (the first 77 days), the model was used to predict leachate concentration, gas generation and composition and settlement of the waste mass throughout the experimental period (919 days). The predicted results will be compared with actual data and discussed in another paper. The exercise here constitutes a basis for reflection on the model's structure and applicability, and serves as a reminder of the difficulty of representing field (landfill) conditions in a laboratory.