Bioremediation of heavy metals in a synthetic wastewater using a rotating biological contactor.

Immobilised microorganisms provide a potential system for the treatment of metal-contaminated waters. This study investigates the efficiency of a rotating biological contactor (RBC) in the treatment of waters contaminated with cadmium, copper and zinc in multiple sorption-desorption cycles. Each sorption cycle extended over a period of 12 weeks at an HRT of 24h to determine the efficiency of the system over a protracted period of time. The removal pattern observed in the initial cycle, namely Cu >> Zn > Cd, was repeated in both subsequent cycles. After completion of each cycle metals were successfully desorbed by means of an acid wash. The sorption ability of the biofilm was not adversely affected by the desorption process as evidenced by the similar metal removal rates obtained in each of the three sorption cycles. These results suggest that RBCs can be used successfully in the treatment of high-strength metal-contaminated wastewaters.