Effect of a direct electric current on the activity of a hydrocarbon-degrading microorganism culture used as the flushing liquid in soil remediation processes

• DC influences the biological activity of a diesel degrading microbial consortium.
• Such consortium is used as flushing fluid for a bioremediation–EKSR process.
• Application of low DC improves degradation of less degradable fractions of diesel.
• Endogenous decay constants are not influence by low DC.

This work aims to obtain more fundamentals for the development of novel electrokinetically enhanced bioremediation processes. It is focused on the effects of direct electric field (DC) on the microbial communities used to bioremediate soils. To evaluate this parameter, two experimental setups were used. A stirred tank reactor and a lab scale soil column. Results show that when a DC electric field (in the range 0.0–2.0 V cm−1) is applied to a diesel-degrading microbial culture, the diesel degradation rate increases. It is also demonstrated that prolonged periods of exposure to electric fields have no significant negative effects on the viability of the microorganisms. The values of the endogenous decay constant were maintained in the range 0.02–0.05 h−1. No significant differences were found between viability of microorganisms stressed under an electric field in a soil remediation process or in a single tank reactor.