In situ Groundwater Treatment with Bioelectrochemical Systems (BES): Critical Review and Future Perspectives

Groundwater contamination is an ever-growing environmental issue, that has attracted much and undiminished attention for the past half century. Groundwater contamination originates from anthropogenic (e.g. hydrocarbons), natural compounds (e.g. nitrate and arsenic), or both; to tackle these contaminants different technologies have been tested during the years. Recently, bioelectrochemical systems (BESs) have emerged as a potential treatment for groundwater contamination, with in situ applications reported, that showed promising results. Nitrate and hydrocarbons (toluene, phenanthrene, benzene, BTEX and light PAHs) have been successfully removed, due to the interaction of microbial metabolism with poised electrodes, other than physical migration due to the electric field generated in BES. The selection of proper BESs relies on several factors and problems such as complexity of the groundwater, scale-up and energy requirements that need to be taken into account. Modelling efforts could help predict case scenarios and choose an ideal design and approach to solve these issues. In this review, we critically analyze in situ BES applications for groundwater remediation, focusing in particular on the different setups proposed, and we identify and discuss the existing research gaps in the field.