A novel process by using chemical leaching followed by bacterial reductive precipitation was proposed for selenium recovery from kiln powder as a byproduct of cement manufacturing. The kiln powder at a slurry concentration of 10 w/v% with 0.25 M Na2CO3 at 28°C produced wastewater containing about 30 mg-Se/L selenium. The wastewater was diluted four-fold and adjusted to pH 8.0 as preconditioning for bioreduction. A bacterial strain Pseudomonas stutzeri NT-I, capable of reducing selenate and selenite into insoluble elemental selenium, could recover about 90% selenium from the preconditioned wastewater containing selenium of 5 mg-Se/L when supplemented with lactate or glycerol. The selenium concentrations in the treated wastewater were low around the regulated effluent concentration of 0.1 mg-Se/L in Japan.
Selenium recovery from kiln powder of cement manufacturing by chemical leaching and bioreduction
S. Soda, A. Hasegawa, M. Kuroda, A. Hanada, M. Yamashita, M. Ike; Selenium recovery from kiln powder of cement manufacturing by chemical leaching and bioreduction. Water Sci Technol 1 October 2015; 72 (8): 1294–1300. doi: https://doi.org/10.2166/wst.2015.339
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