Removal and recovery of selenium from wastewater: current status and future prospects

Selenium exists naturally in the Earth’s crust and is distributed into different environmental compartments by natural and anthropogenic activities. Selenium (Se) is generally discharged from industrial sectors into the environment in the forms selenate [42−] and selenite [32−], which are both toxic. Selenate is particularly difficult to remove from aqueous streams containing elevated concentrations of other compounds, such as sulphate, that compete with selenium in wastewater treatment processes. While a variety of physical-chemical and biological treatment processes have been reported to exhibit good treatment efficiencies for selenium removal from aqueous streams, only a few have successfully demonstrated to achieve effluent concentrations less than 5 μg/L. Moreover, there are only a few number of studies which describe the progress in technological developments over the last decade. Therefore, this document presents an overview of the ongoing research trends for Se removal from (waste)water as well as the challenges associated with different techniques and future research directions