Colloids are known to be the often neglected phase for the transport of pollutants in aquatic ecosystems. The book covers the basics of abiotic colloid characterization, of biocolloids and biofilms, the resulting transport phenomena and their engineering aspects. The subject is presented from an international group of leading specialists devoted to colloidal sciences. The contributions include theoretical considerations, results from model experiments as well as field studies. The information given will serve students and scientists interested in the analytical, chemical, microbiological, geological and hydrological aspects of material transport in aquatic systems and soils.