Selenium is a naturally occurring element with known physiological roles; while it is a necessary trace metal at low concentrations, it poses a significant threat to environmental and public health at higher concentrations. Anthropogenic and industrial activities�semiconductors, fertilizers, and solar cells� mobilize selenium into the biosphere: land, soil, and water. In natural waters, selenium can exist under various oxidation states: selenite (Se4+, SeO3 2- ) and selenate (Se6+, SeO42-); these oxyanions of selenium are toxic because of increased solubility and bioavailability.Selenium contaminated water can be remediated in several different ways: a) membrane filtration; b) activated alumina; c) coagulation/filtration; and, d) bioremediation. Among these methods, bioremediation utilizes the biochemical potential of the bacteria to transform soluble and toxic selenite/selenate to insoluble, lesser-toxic elemental selenium. Recently, bioelectrochemical systems (BESs) have been studied for bioremediation applications as well as recovery of valuable metals/metalloids such as copper and chromium.Selenite reduction and removal was studied using a BES with Shewanella oneidensis MR-1 catalyzing both the anodic and cathodic reactions. MR-1-catalyzed BESs removed 4 successive feeds of 19 mg/l of selenite to below detection limit. Using electrochemical techniques, the performance (maximum power output (Pmax) and internal resistance (Rint)) of the BESs were monitored. During selenite removal, BESs produced a maximum power of 68nW (4.46 nW/cm2). Also, the system worked efficiently at lower oxygen concentrations, as oxygen hindered selenite removal. Understanding these systems could offer an economically viable strategy for selenium remediation.

Bioremedition of selenite with bioelectrochemical systems

247th National Meeting (2014)

The official archive and repository for all ACS Meetings & Expositions abstracts and select posters or presentations.