Sorption properties of biofilms

The distribution and fate of pollutants in biological wastewater treatment is highly influenced by sorption processes. Biofilms can provide a sink for dissolved matter with extracelluar polymeric substances (EPS), cell walls, cell membranes, and cytoplasm serving as sorption sites. These sites display different sorption properties, preferences, and capacities. The distribution of organic pollutants such as BTX or heavy metals such as cadmium and zinc in biofilms could be investigated by fractionating the biomass. Therefore. an EPS extraction method with a crown ether was used which allowed the detection of organic and inorganic substances in the different fractions. After extraction, more than 60% of BTX could be localized in the EPS In contrast to organic substances, more than 80% of the total content of cadmium and zinc was found in the cellular fraction. (C) 1998 IAWQ. Published by Elsevier Science Ltd.