Microbial-electrochemical bioremediation and detoxification of dibenzothiophene-polluted soil

• Microbial Electroremediating Cells (MERCs) enhance DBT removal from polluted soils.
• Detoxification of soil via MERC was demonstrated by ecotoxicological assays.
• MERCs are a low cost technology to stimulate natural populations for bioremediation.
• MERCs overcome low availability of electron acceptor in soil promoting biodegradation.

Bioremediation is a relatively efficient and cost-effective technology for treating polluted soils. However, the availability of suitable electron acceptors to sustain microbial respiration can reduce the microbial activity. This work aims to evaluate the impact of burying electrically conductive electron acceptors in soil for enhancing the removal of dibenzothiophene (DBT) by native electrogenic microbes. Although this novel approach is based on the use of a microbial electrochemical technology as microbial fuel cells, our goal is not to harvest energy but to maximize bioremediation, so we concluded to name the device as Microbial Electroremediating Cell (MERC). Our results proved that stimulating the microbial electrogenic metabolism, DBT removal was enhanced by more than 3-fold compared to the natural attenuation. On top of that, ecotoxicological test using green algae confirms a decrease of 50% in the toxicity of the treated soil during incubation in MERC, in contrast to the unaltered values detected under natural conditions.