Treatment of metal-contaminated wastes: why select a biological process?

Nature has demonstrated some subtle and intricate mechanisms for selectively controlling the mobility of metal pollutants in the environment. However, the application of this science to technology has been disappointing. A small number of pilot-plant studies have been carried out to investigate the potential of microorganisms (primarily bacteria) to remove metals from liquid wastes but only one system in the past 15 years has been commercialized. In order to explain this lack of application, it is important to understand the effectiveness, robustness and reliability of biological processes involving metals and their ability to compete with proven physicochemical technologies.