Implementation of a continuous-flow stirred bioreactor system in the bioremediation of heavy metals from industrial waste water.

The industrial applicability of immobilized non-viable yeast biomass (Saccharomyces cerivisiae) in continuous-flow stirred bioreactors was tested with respect to metal removal from electroplating effluent solutions containing Cu, Cd, Cr, Ni and Zn in excess of the stipulated water quality criteria. Two systems, a dual bioreactor and triple bioreactor system in series, were tested and compared regarding their efficiency of metal removal. The system containing two bioreactors linked in series provided a more efficient solution to the problem. The introduction of a third bioreactor into the system had a marginal effect on the amount of metal removed. Subsequent to treatment within the bioreactors the levels of Cu, Cr and Ni in the effluent complied with the stipulated drinking water quality criteria and, although in excess of these criteria only 18% of the initial Zn and 17% of the Cd remained in solution.