Emerging technologies for selenium separation and recovery from aqueous systems: A review for sustainable management strategy

Abstract Selenium (Se) is known both as an essential micronutrient for human health as well as a toxic element when consumed in excess. This work endeavours to critically review the existing selenium literature over the period 1980–2021, following a systematic sub‐classification into the domains of occurrence, speciation, and existing conventional and advanced technologies, while directing further research towards emerging integrated sustainable recovery strategies. The review reveals that the majority of the conventional and advanced separation techniques eventually lead to secondary pollution rather than offering a complete solution, whereas resource recovery studies from water are very scant. Some of the techniques, being miserably slow, cannot be applied in the situations of the occurrence of excess selenium in drinking water, posing a serious threat to human health. Research efforts have so far been directed mainly at the removal of selenium rather than recovery through processes that have the potential of turning selenium abatement technology into a sustainable one with value addition. Emerging integrated technologies involving resource recovery from waste streams or generated sludge such as physicochemical technologies, biochemical reduction, electro‐biological reduction, and membrane‐based hybrid technologies are presently at a very early development stage. Moreover, the application of studies where Se nanoparticles (SeNPs) ormetal selenides are obtained is very limited, which may be attributed to the particle size, purity, morphology, and challenges involved in their separation. This review evaluates the challenges in separation and resource recovery from contaminated streams and points future research in a new direction.