Selenium removal with adsorption by activated alumina packed continuous-flow reactor

Selenium released from manufacture industries of glass, pigments, fossil fuel and metal alloys is toxic to both human beings and aquatic lives leading to substantial risks to the ecological environment. Two dominant inorganic species, Se(IV) and Se(VI), can be easily found in water due to their high solubility. Microbial selenium reduction is one of the most effective ways to remove selenium from water by reducing selenium oxyanions, Se(VI) and Se(IV) into insoluble elemental Se(0). Se(VI) removal was investigated using a continuous-flow bioreactor packed with activated alumina. The Se(VI) can be removed through a combined process of activated alumina adsorption and microbial reduction leading to the improvement of removal efficiency. Approximately 19.7 mg/L of Se(VI) was detected in the effluents at feeding concentrations of 50 mg/L at the end of the experiments, indicating that Se(VI) has been significantly removed. Insignificant Se(IV) concentration in the effluent was observed as Se(IV) generated from Se(VI) reduction was further absorbed by activated alumina.