Issue 10, 2023

Hexavalent chromium waste removal via bioelectrochemical systems – a life cycle assessment perspective

Abstract

Bioelectrochemical systems (BESs) such as microbial fuel cells (MFCs) present numerous benefits for the removal and recovery of heavy metals from industrial and municipal wastewater. This study evaluated the life cycle environmental impact of simultaneous hexavalent chromium (Cr(VI)) removal and bioelectricity generation in a dual chamber MFC. Results indicate a global warming potential (GWP) of −0.44 kg carbon dioxide (CO2)-eq. per kg of chromium recovered, representing a total saving of up to 97% in comparison with existing technologies for the treatment of Cr(VI) laden wastewater. The observed savings in GWP (kg CO2-eq.) reduced to 61.8% with the removal of the allocated credits from the MFC system's life cycle. Of all the various sub-systems considered within the chromium waste treatment plant, the MFC unit and the chromium metal recovery unit had the largest impact in terms of GWP (kg CO2-eq.), non-renewable energy use (NREU) (MJ primary), and mineral extraction (MJ surplus). A statistical analysis of the results showed that an increase in chemical oxygen demand (COD) was associated with a reduction in GWP (kg CO2-eq.), NREU (MJ primary), and terrestrial ecotoxicity (kg triethylene glycol equivalents into soil (TEG soil)-eq.). The life cycle assessment (LCA) output showed a high sensitivity to changes in the materials and construction processes of MFC reactors, indicating the need for further research into sustainable materials for MFC reactor construction. The observed interaction effects of process variables also suggest the need for combined optimization of these variables. Analysis with other types of metals is also important to further demonstrate the practical viability of metal removal through MFCs.

Graphical abstract: Hexavalent chromium waste removal via bioelectrochemical systems – a life cycle assessment perspective

Supplementary files

Article information

Article type
Paper
Submitted
11 5 2023
Accepted
28 7 2023
First published
31 7 2023
This article is Open Access
Creative Commons BY license

Environ. Sci.: Water Res. Technol., 2023,9, 2487-2500

Hexavalent chromium waste removal via bioelectrochemical systems – a life cycle assessment perspective

R. I. Muazu, J. Sadhukhan, S. Venkata Mohan and S. Gadkari, Environ. Sci.: Water Res. Technol., 2023, 9, 2487 DOI: 10.1039/D3EW00344B

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