RESUMO
The present study showed for the first time that selenium, iron, and nitrate could be simultaneously removed in a sulfidogenic bioreactor to meet drinking water standards. A bioreactor inoculated with mixed bacterial consortium was operated for around 330 days in anoxic environment at 30⯰C under varying combination of inï¬uent selenate (200-1000⯵g/L as selenium), and iron (3-10â¯mg/L) in presence of 50â¯mg/L of nitrate. Required amount of acetic acid (as carbon source) and sulfate were supplied and the reactor was operated at different empty bed contact time (EBCT) of 45-120â¯min. Along with complete removal of nitrate, the reactor removed both selenium and iron to meet the drinking water standards. Field emission transmission electron microscopy (FETEM) and X-ray diffraction (XRD) analyses confirmed the formation of selenium sulfide (SeS), achavalite (FeSe) and pyrite (FeS2), which were the possible removal mechanisms of selenium and iron. Thus, this study exhibited that selenium, iron, and nitrate can be simultaneously removed to meet the drinking water standards in a sulfidogenic bioreactor.