ABSTRACT
Many of the above described metal-immobilization mechanisms such as biosorption, metal sulfide precipitation, and biotransformation as well as intracellular metal accumulation operate in the processes that use either natural or artificial biotopes or microbial consortia for waste water decontamination from metal(loid)s. Waste streams are either treated directly or more often after an abiotic sewage treatment that can remove up to 40-60% of the metal (Gadd 1992b). Important issues are the input concentrations of metals with respect to their toxicity. As these processes usually do not employ extremely metal-resistant organisms, they are more or less in a sensitive (steady-state) equilibrium. Therefore, the process may breakdown when the consortium (or some of its components) is overdosed with a particular metal(loid).
