A sustained approach to environmental catalysis: Reutilization of chromium from wastewater

Wastewater pollution with heavy metals is an issue of great environmental concern. The future development of clean technologies for the treatment of wastewater loaded with heavy metals entails environment friendly and sustainable processes that may allow simultaneously the recovery of the metals and their reutilization as value-added catalysts to be used in environmental applications. This is the first review regarding the biorecovery of metals and their further reutilization as heterogeneous catalysts. In this regard, metallic residues that generally would be considered as a waste at the end of the treatment process can be reutilized and transformed into value-added catalysts to be used in environmental applications. This review is focused in two broad areas: the biorecovery of chromium by a combined biosorption system consisting of bacteria supported on zeolites and the catalytic reutilization of the metal-loaded zeolites in the oxidation of organic compounds, in both gaseous and liquid phase. After an overview describing the main subjects in the field of heavy metals recovery, biosorption, zeolites, and catalytic oxidation, in the following sections special emphasis will be given to the main results and findings regarding these clean technologies of biorecovery and reuse of metals in catalytic reactions of environmental concern.