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Characterization of Selenate Removal from Drainage Water Using Rice Straw
Author(s) -
Zhang Yiqiang,
Frankenberger William T.
Publication year - 2003
Publication title -
journal of environmental quality
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.888
H-Index - 171
eISSN - 1537-2537
pISSN - 0047-2425
DOI - 10.2134/jeq2003.4410
Subject(s) - selenate , straw , chemistry , selenium , drainage , oryza sativa , tile drainage , agronomy , environmental chemistry , environmental science , ecology , biology , inorganic chemistry , biochemistry , organic chemistry , gene
Removal of selenium (Se) from agricultural drainage water is very important for protecting wildlife in wetland systems. We conducted a series of experiments on selenite [Se(IV)] adsorption and selenate [Se(VI)] reduction to determine Se removal from drainage water amended with 1000 μg/L of Se(VI) or Se(IV) and 5 g of rice ( Oryza sativa L.) straw. Under sterile conditions, the added Se(IV) was not adsorbed to the rice straw within 2 d of the experiment and the added Se(VI) was not reduced within 14 d. In contrast, added Se(VI) in a nonsterile rice‐straw solution was reduced rapidly, from 930 μg/L at Day 3 to 20 μg/L at Day 5, with an increase in unprecipitated elemental Se [Se(0)] and total Se(0). In the last several days of the experiments, unprecipitated Se(0) was the major Se form in the rice‐straw solution, with a small amount of organic Se(−II). This study showed that Se removal from drainage water in the presence of rice straw involves a two‐step process. The first is the microbial reduction of Se(VI) to Se(IV) and then to colloidal Se(0). The second is flocculation and precipitation of colloidal Se(0) to the bottom of the experimental flasks and the surface of rice straw.