Life cycle environmental impact comparison of bioelectrochemical systems for wastewater treatment

Bioelectrochemical systems (BESs) are developed to transform the energy harvested from the biomass into electricity. Different types of BESs including microbial fuel cell (MFC), microbial electrolysis cell (MEC), and microbial desalination cell (MDC) are under intensive research and development; however, their life cycle environmental impacts have not been systematically compared to identify the most environmentally friendly BES. To understand and eventually help reduce the environmental impacts of different BESs, life cycle assessment (LCA) models were developed in this study to assess and compare their potential environmental impacts. The results indicate that the MEC has better environmental performance than the MFC and MDC due to the large hydrogen peroxide production in the operation phase. The environmental performance of the MFC and MDC can be improved by the increase of power density, but their environmental impacts, at a relatively high power density that can be achieved by current technology, are still higher than the environmental impacts of the MEC at current power density. When the environmental impacts are benchmarked with those of the traditional wastewater treatment methods, the MEC has a better environmental performance, whereas the MFC and MDC have relatively large environmental impacts.