Constructed Wetlands
Why wetlands?
Toxic metals can be precipitated out of solution by bacteria. These bacteria use the metals as electron acceptors in redox reactions. However, in order for this process to take place, the environment must be anaerobic since O2 is a much more preferrable electron acceptor than any metal. Thus one strategy for bioremediating metals is to create artificial wetlands which provide the necessary anaerobic conditions.
Here is a picture of a constructed wetland in Pennsylvania
How is this implemented?
Wetlands are usually constructed using limestone drains aid in neutralizing acid from acid mine drainage. Here is a possible design for a constructed wetland.
The basin is constructed and is then filled in with water, plants, and organic matter to foster the necessary conditions for microbial remediation.
Sources:
Wildeman (1994, 1998)