Characteristics of colloids in landfill leachate

Colloidal materials in aquatic environments are receiving increased attention because they can enhance contaminant transport and affect treatment processes. The objective of this thesis was to describe the characteristics of colloidal materials in municipal landfill leachate and evaluate their potential to sorb and transport specific contaminants.; Landfill leachate samples were collected from a municipal landfill and treated by microfiltration and ultrafiltration to separate their colloidal materials into specific size fractions. Each of these size fractions was then analyzed to quantify and characterize the colloidal materials and identify any associated contaminants. Samples were collected from different locations and at different times to assess the spatial and temporal variations of the colloidal concentration and properties.; The major component of the colloids isolated was organic matter. The inorganic component of the colloids was predominantly carbonate and phosphate precipitates. The organic matter probably coats the surface of the colloids and keeps them in a stable suspension. All the colloids were found to be extremely stable and those smaller than 1 {dollar}mu{dollar}m could be mobile in sandy aquifers.; Significant fractions of heavy metals were associated with the colloids, however, major parts were also complexed with dissolved organic ligands. Hydrophobic organic pollutants were found to be strongly associated with colloids larger than 0.1 {dollar}mu{dollar}m.; Treatment processes of landfill leachate are likely to be affected by the colloidal content of the leachate due to significant associations found between leachate pollutants and colloids. It is unlikely, however, that those associations can contribute significantly to the movement of pollutants in contaminated aquifers.