Biosorption of Hazardous Organic Pollutants

Abstract

<p>A study of the sorption of hazardous organic pollutants by live and dead microbial biomass (biosorption) has been made. Biosorption of lindane, pentachlorophenol, diazinon, 2-chlorobiphenyl, and malathion by Rhizopus arrhizus and activated sludge were investigated. Malathion was found to be removed by a chemical decomposition process when contacted with dead biomass. The other compounds were observed to be sorbed by the biomuss, and the sorption process was found to be reversible. The biosorption isotherms could be represented by the Freundlich equation and were found to be nearly linear over the range of concentrations examined. The biosorptive uptake is positively correlated with the octanol/water partition coefficient for the compounds. Heats of sorption were estimated and indicate that the biosorption process involves a physicaI rather than a chemical mechanism. The biosorption phenomenon appears to involve both surface adsorption and absorption into the cell interior. Biosorptive uptake generally appears not to be strongly affected by competition from other sorbing compounds. The kinetics of biosorption of lindane are characterized by a rapid initial uptake followed by a slower accumulation process. In general, live and dead biomass were found to exhibit a different level of biosorptive uptake, however no generalizations could be made concerning the direction or magnitude of the differences. The order of magnitude of removal of non-biodegradable hazardous compounds in biological treatment plants can be predicted from the biosorption isotherms.</p>