Sorption equilibria for trichloroethene on algae

Abstract

The sorption of chlorinated solvents by algae can remove the solvents from natural waters and wastewaters treated in stabilization lagoons and other phototrophically active treatment processes. The equilibrium sorption of 14C-labeled trichloroethene (TCE) to three species of algae— Chlorella vulgaris, Scenedesmus quadricauda and Selenastrum capricornutum—was studied in batch reactors in which no biotransformations occurred. The sorption density was nonlinear with respect to equilibrium TCE concentration. The Freundlich isotherm, Q = KC n , successfully described the sorption equilibria, and n was greater than 1 for all three species. Thus, the apparent bioconcentration factor (BCF) increased with increasing TCE concentrations. Empirical correlations that predict the BCF as a function of the compound's octanol-water partition coefficient gave BCF values about one order of magnitude lower than shown by these experiments with algae. The content and distribution of lipids within the algae appear to cause substantially greater sorption by algae than by other forms of organic solids.