Fate of colloidal-particulate elemental selenium in aquatic systems

• Published in: Journal of environmental quality Vol. 33; no. 2; pp. 559 - 564
• Main Authors: Zhang, Y, Zahir, Z.A, Frankenberger, W.T. Jr
• Format: Journal Article
• Language: English
• Published: Madison, WI Crop Science Society of America 01-03-2004; American Society of Agronomy
• Subjects: Adsorption; Agricultural pollution; Agricultural practices; Agronomy; Agronomy. Soil science and plant productions; Applied sciences; Aquatic ecosystems; Aquatic environment; Bacteria; bioavailability; Biodegradation, Environmental; Biological and medical sciences; Bioremediation; Bottom sediments; Chemical Precipitation; Colloids; Copyrights; Documents; Drainage; Drainage systems; Drainage water; Earth sciences; Earth, ocean, space; Engineering and environment geology. Geothermics; environmental fate; Environmental quality; Exact sciences and technology; Flocculating; Flocculation; Fundamental and applied biological sciences. Psychology; Geologic Sediments; Organisms; Oxidation; Oxidation-Reduction; Particle Size; Pathways; Pollution; pollution control; Pollution, environment geology; redox potential; Reduction; remediation; Sediments; Selenic Acid; Selenites; Selenium; Selenium - analysis; Selenium - pharmacokinetics; Selenium Compounds - metabolism; Water column; Water Pollutants - analysis; Water Pollutants - pharmacokinetics; water pollution; Utah; California; Removal; Laboratory study; Pollutant behavior; Pollution control; Sediments; Sedimentation; Reduction; Adsorption; Decontamination; Flocculation; Selenates; Physicochemical purification; Oxidation; Bioremediation; Selenium; Technique; Selenites; Drainage water
• ISSN: 0047-2425; 1537-2537; 1537-2537
• DOI: 10.2134/jeq2004.0559

Bacterial reduction of selenate [Se(VI)] to elemental Se [Se(0)] is considered an effective bioremediation technique to remove selenium (Se) from agricultural drainage water. However, the fate of the newly formed Se(0) in aquatic systems is not known when it flows out of the treatment system. A set of laboratory experiments was conducted to determine the fate of the colloidal-particulate Se(0) in a water column and in a water-sediment system. Results showed that the newly formed colloidal-particulate Se(0) followed two removal pathways in aquatic systems: (i) flocculation-sedimentation to the bottom of the water and (ii) oxidation to selenite [Se(IV)] and Se(VI). During 58 d of the experiments, 51% of the added Se(0) was precipitated to the bottom of the water and 47% was oxidized to Se(IV) in the water column. In the water-sediment system, Se(IV) in the water accounted for 21 to 25% of the added Se(0). Adsorption of Se(IV) to the bottom sediment resulted in a relatively low amount of Se(IV) in the water. This study indicates that the newly formed Se(0) may be an available form of Se for uptake by organisms if it flows to aquatic systems from a treatment site. Therefore, an effective bioremediation system for removing Se from drainage water must reduce Se(VI) to Se(0) and remove Se(0) directly from the drainage water.