ABSTRACT
This chapter discusses the role of mass transfer limitations in landfills and discusses possible consequences. It argues that under certain circumstances mass transfer is the rate controlling step in landfill stabilization and that detailed knowledge of metabolic pathways for the microorganisms may not be always necessary for predictive purposes. The work is part of a larger study on landfill dynamics at Tufts University, Center for Environmental Management to develop first-round systems model for landfill behavior. Long time scales for landfill stabilization stand in marked contrast to the fairly short time scales for decomposition demonstrated by the myriad of published papers on biomass conversion and the extracellular enzymatic hydrolysis of cellulosic materials in the laboratory. Three important reasons that landfills decompose so slowly are: lack of sufficient moisture for optimal enzyme activity; imbalance between the production of organic acids by acid-forming bacteria and the conversion of these acids into methane by methanogenic bacteria; and mass transfer limitations in the landfill environment.
