Microbial electrochemical biosensor for real-time in situ hydrocarbon detection in groundwater

Anthropogenic contamination with petroleum hydrocarbons is a serious environmental problem. Especially dramatic is the case of environments limited in electron acceptors because, natural attenuation is not sufficient to cope with contamination that remains persistent. Groundwater pollution by oil spills has attracted an ever-growing interest in a water scarcity scenario due to global warming. The surveillance of risk sites through monitoring tools is the most suitable strategy for prevention. In this work we have investigated the detection of contaminants derived from oil industry, BTEX and ETBE, in groundwater by means of a microbial electrochemical sensor. For this purpose, we use a biosensor (polarized at 0.6 V) immersed in artificial groundwater: i) at microcosm scale and ii) at mesocosm scale. Detection of BTEX was tested separately in biosensors at microcosm scale, showing a clear response in electrical current after exposure to contaminants. The response observed in presence of BTEX and ETBE was significant and fast (<2 h) by this biosensor. Additionally, microbial community analysis was performed on the anodic biofilm after BTEX exposure. The results show two main groups of microorganisms: electroactive and hydrocarbon-degrading bacteria. This suggests that the microbial community could play an important role in the biosensor performance.