The numerical computer models that simulate municipal solid waste (MSW) bioreactor landfills have mainly two components--a biodegradation process module and a multi-phase flow module. The biodegradation model describes the chemical and microbiological processes of solid waste biodegradation. The models available to date include predefined solid waste biodegradation reactions and participating species. In a bioreactor landfill several processes, such as anaerobic and aerobic biodegradation, nitrogen and sulfate cycling, precipitation and dissolution of metals, and adsorption and gasification of various anthropogenic organic compounds, occur simultaneously. These processes may involve reactions of several species and the available biochemical models for solid waste biodegradation do not provide users with the flexibility to selectively simulate these processes. This research work includes the development of a generalized biochemical process model, BIOKEMOD-3P, which can accommodate a large number of species and process reactions. This model is able to simulate bioreactor landfill processes in a completely mixed condition; when coupled with a multi-phase model it will be able to simulate a full-scale bioreactor landfill. This generalized biochemical model can simulate laboratory and pilot-scale operations which are important to determine biochemical parameters important for simulation of full-scale operations. To illustrate application of BIOKEMOD-3P, two sets of laboratory MSW bioreactors were simulated in this research work. The first demonstrated simulation of data from anaerobic biodegradation of MSW in experimental bioreactors. In another application, simultaneous nitrification and denitrification processes in MSW bioreactors were simulated. The results from these simulations generated information about various modeling parameters that would help implement these processes in a full-scale bioreactor landfill operation.