Effect of physical and culture conditions on uptake of cadmium by Chlorella pyrenoidosa

Abstract

The effects of pH, temperature, concentrations of Cd²⁺ and P₄^3-, and density of algal suspension on the uptake of cadmium by C.pyrenoidosa were studied. Uptake occurred in at least two phases: fast (8 min) and slow (24 h). The slow uptake was dependent on pH (greater at pH 8.0 than 6.5) and temperature (faster at 25 than 4ºC) whereas the fast uptake was not. Both phases of uptake were affected by the density of the algal suspension. Dependence on the concentration of Cd²⁺, at pH 8.0, was limited by the concentration of PO₄^3- and also possibly by the concentration of CO₃^-2. Results were generally consistent with the model of initial ion-exchange uptake onto the cell wall and much slower transport across the cell membrane.