Bioaccumulation and biosorption of lead by poultry litter microorganisms

Microorganisms are known to interact with metals through a number of mechanisms, including binding the metals to their cells' walls and intracellular accumulation. Poultry litter has a high density of various microorganisms along with many nutrients. The objective of this research was to study the removal of Pb from an aqueous solution by the microorganisms found in poultry litter under an aerobic environment. A Pb(NO3)2 solution was treated with the aqueous extract of either the nonradiated litter or gamma-radiated litter in order to differentiate between the removal of Pb through bioaccumulation (by the living organisms) and biosorption (by the dead organisms). Lead removal was measured using anodic stripping voltammetry. Both the nonradiated and the gamma-radiated litter removed significant amounts of Pb. After 14 d, the amount of Pb removed through bioaccumulation by the nonradiated litter and through biosorption by the radiated litter was about 44 and 30%, respectively. There was no increase in Pb removal between 14 and 60 d. The biomass density of the aqueous extract of poultry litter increased significantly in the presence of 400 ppb Pb(NO3)2.