Removal of Hazardous Organic Pollutants by Adsorption on Microbial Biomass

Removal of five toxic organic compounds from water by adsorption on microbial biomass was investigated. Lindane, diazinon, malathion, pentachlorophenol, and the PCB 2-chlorobiphenyl were adsorbed onto two types of inactive microbial biomass (a pure strain of Rhizopusarrhizus, and a mixed culture of activated sludge). Desorption and the thermodynamics of the adsorption process were also investigated. With the exception of malathion, the adsorptive uptake data fit the Freundlich equation and were well correlated with the octanol/water partition coefficient, but not as well correlated with water solubility of the compounds. Except for malathion the adsorption was reversible. Malathion showed unusually high apparent uptake and the removal appeared to be irreversible. The experimental evidence suggests that the disappearance of malathion resulted from a chemical reaction, while physical adsorption appears to account for removal of the other compounds.