Selenium Removal from Water and Wastewater by Different Technologies: A Systematic Review

BACKGROUND: Selenium (Se) is an essential element playing a vital role in the metabolism of organisms. Se can generally be discharged in the potable water through natural and anthropogenic activities. Both excess and shortage of Se can cause significant adverse health effects in humans. Excess values of se may stimulate toxicity, leading to selenosis and alkali disease in humans and grazing animals, respectively. METHODS: A review search was systematically carried out from the databases Embase, PubMed/MEDLINE, Scopus, PubMed Central (PMC), Google Scholar, as well as medRxiv by using the following keywords: “waste water”, “bioremediation”, “selenium removal”, “adsorption”, and “drinking water”. This study provides a review of the recent literature covering the period between 2011 and 2021. After screening the full text of the articles, 27 papers were enrolled. This study reviews the reported techniques for Se removal from water and wastewater, including adsorption, biological treatment, microbial reduction, bioreactors, fungal bioreactor, algal treatment, phytoremediation, and photocatalysis. RESULTS: Biological and bioremediation techniques, such as microbial reduction, biotransformation, and fluidized bed reactor have removal efficiency about 100%. The highest Se concentration of 15–7600 μg/L was achieved in ground waters in Ethiopia and the lowest level of 0.07 μg/L in Finland. CONCLUSION: The combination of biological treatment with chemical or physical technologies is envisaged to optimize se elimination and to ensure ecological protection and human health safety.