title: Microbial selenium sulfide reduction for selenium recovery from wastewater.
abstract: Microbial reduction of selenium sulfide (SeS2) is a key step in a new treatment process to recover selenium from selenate and selenite streams. In this process, selenate is first reduced to selenite, and subsequently selenite is reduced by sulfide and precipitates from the solution as SeS2. The latter is bio-reduced to elemental selenium and sulfide. Two anaerobic granular sludges (Eerbeek and Emmtec) were tested for their efficiency to reduce commercial crystalline SeS2. Emmtec sludge had the highest reducing capacity with commercial SeS2and was therefore also used for the bioreduction of laboratory synthesized amorphous SeS2. Synthesized SeS2was formed mixing a sulfide solution and effluent containing selenite. With both SeS2solids (commercial and synthesized SeS2), Emmtec sludge produced sulfide and a solid consisting of hexagonal elemental selenium. The crystalline hexagonal structure suggests the absence of biomolecules, which stabilize amorphous selenium bio-particles under comparable process conditions (T=30°C and a pH between 6 and 7). Selenium particles were not attached to the biomass, suggesting an extracellular formation. The results support the feasibility of the bio-reduction process using sulfur for recovering selenium from water.
authors.affiliation: Sub-Department of Environmental Technology, Wageningen University, P.O. Box 17, 6700 AA Wageningen, The Netherlands. Electronic address: s.p.w.hageman@saxion.nl.
authors.forename: S P W
authors.initials: SP
authors.lastname: Hageman
authors.affiliation: Sub-Department of Environmental Technology, Wageningen University, P.O. Box 17, 6700 AA Wageningen, The Netherlands.
authors.forename: R D
authors.initials: RD
authors.lastname: van der Weijden
authors.affiliation: Laboratory of Microbiology, Wageningen University, Wageningen, The Netherlands.
authors.forename: A J M
authors.initials: AJ
authors.lastname: Stams
authors.affiliation: Department of Earth & Environmental Sciences, University of Waterloo, Waterloo, Canada.
authors.forename: P
authors.initials: P
authors.lastname: van Cappellen
authors.affiliation: Sub-Department of Environmental Technology, Wageningen University, P.O. Box 17, 6700 AA Wageningen, The Netherlands.
authors.forename: C J N
authors.initials: CJ
authors.lastname: Buisman
mesh_terms: D012643:Selenium / Q000302:isolation & purification*; D018036:Selenium Compounds / Q000378:metabolism*; D062065:Wastewater
chemical_list: D012643:Selenium; D018036:Selenium Compounds; D062065:Wastewater; C025698:selenium disulfide
keywords: Biocrystallization; Microbial reduction; Selenium removal and recovery; Selenium sulfide; Wastewater