Arsenic in contaminated waters: biogeochemical cycle, microbial metabolism and biotreatment processes.

Arsenic is responsible for the contamination of water supplies in various parts of the world and poses a major risk to human health. Its toxicity and bioavailability depend on its speciation, which in turn, depends on microbial transformations, including reduction, oxidation and methylation. This review describes the development of bioprocesses for the treatment of arsenic-contaminated waters based on bacterial metabolism and biogeochemical cycling of arsenic.