Cleaning chromium pollution in aquatic environments by bioremediation, photocatalytic remediation, electrochemical remediation and coupled remediation systems

Industrialization such as metallurgy, papermaking, chemicals, electroplating and tanning is contributing to the pollution of ecosystems by chromium (Cr). Cr pollution has many sources and high toxicity. Indeed, Cr(VI) is a strong oxidizing agent and, as a consequence, Cr(VI) bioaccumulation may induce acute, subacute or chronic poisoning, mutagenesis, carcinogenesis and teratogenesis. Cr(VI) is usually very mobile and highly soluble in aqueous solutions, but Cr(III) is not. Cr(III) is relatively stable and less toxic than Cr(VI). Thus, some remediation techniques aim to reduce Cr(VI) to Cr(III). Herein, we review bioremediation, photocatalytic remediation, electrochemical remediation and coupled remediation systems. We found that Cr(VI) remediation using coupled systems is relatively easier and more efficient, compared with other treatment systems. This review provides a basis for the development of high-efficiency Cr(VI) removal systems suitable for industrial applications.