Laboratory-scale continuous reactor for soluble selenium removal using selenate-reducing bacterium, Bacillus sp. SF-1.
A model continuous flow bioreactor (volume 0.5 L) was constructed for removing toxic soluble selenium (selenate/selenite) of high concentrations using a selenate-reducing bacterium, Bacillus sp. SF-1, which transforms selenate into elemental selenium via selenite for anaerobic respiration. Model wastewater contained 41.8 mg-Se/L selenate and excess lactate as the carbon and energy source; the bioreactor was operated as an anoxic, completely mixed chemostat with cell retention time between 2.2-95.2 h. At short cell retention times selenate was removed by the bioreactor, but accumulation of selenite was observed. At long cell retention times soluble selenium, both selenate and selenite, was successfully reduced into nontoxic elemental selenium. A simple mathematical model is proposed to evaluate Se reduction ability of strain SF-1. First-order kinetic constants for selenate and selenite reduction were estimated to be 2.9 x 10(-11) L/cells/h and 5.5 x 10(-13) L/cells/h, respectively. The yield of the bacterial cells by selenate reduction was estimated to be 2.2 x 10(9) cells/mg-Se.
Fujita
Masanori
M
Department of Environmental Engineering, Osaka University, 2-1 Yamada-oka, Japan.
Ike
Michihiko
M
Kashiwa
Masami
M
Hashimoto
Ryoko
R
Soda
Satoshi
S
D001407:Bacillus / Q000145:classification / Q000254:growth & development / Q000378:metabolism*; D001673:Biodegradation, Environmental; D019149:Bioreactors; D003198:Computer Simulation; D008954:Models, Biological; D010084:Oxidation-Reduction; D010865:Pilot Projects; D015203:Reproducibility of Results; D064586:Selenic Acid; D012643:Selenium / Q000378:metabolism*; D018036:Selenium Compounds / Q000378:metabolism*; D012680:Sensitivity and Specificity; D018038:Sodium Selenite / Q000378:metabolism*; D013045:Species Specificity; D014874:Water Pollutants, Chemical / Q000378:metabolism; D018508:Water Purification / Q000379:methods
D018036:Selenium Compounds; D014874:Water Pollutants, Chemical; D012643:Selenium; D018038:Sodium Selenite; D064586:Selenic Acid