Application of the BioClog model for landfill leachate clogging of gravel-packed columns

Abstract

A numerical, multiple-species, reactive chemical transport model (BioClog) developed to predict clogging in landfill leachate collection systems is used to interpret results from experiments conducted with gravel-packed columns permeated with landfill leachate. The model predicts changes to the microbial community and leachate chemistry, including the concentrations of volatile fatty acids, suspended biomass, dissolved calcium, and suspended inorganic solids. The calculated quantity and composition of the clog matter (biomass and mineral), along with the associated decrease in porosity, are compared to the measured values. The modelled clogging is in reasonable agreement with that observed in the gravel column experiments. By identifying and quantitatively linking many microbiological, chemical, and transport mechanisms, the model helps elucidate the phenomena controlling the rate and extent of clogging.Key words: clogging, landfills, leachate collection systems, biofilms, mineral precipitation.