Recent advances in bioremediation of biofuel blends

Biofuels are frequently used in blends with petrofuels (i.e. biodiesel/diesel, ethanol/gasoline). The presence of biofuels changes the degradation dynamics and rates of petroleum hydrocarbons. There are several works focused on the assessment of bioremediation approaches applied to biofuel/petrofuels blend contamination. Despite all the knowledge yielded, hitherto this information has not been compiled and organized to have a global overview on the best remediation alternative(s) depending on the different blends and factors influencing the degradation processes. Therefore, we reviewed and compiled the literature information available on bioremediation strategies applied to degradation of biofuel/fossil fuel blends in different contamination contexts (i.e. matrix, time of exposure, biofuel concentration), focusing on the best performing bioremediation options. These reviewed data allowed us to construct a decision tree tool to help select the most adequate remediation technique to be applied depending on the case. This tool showed that natural attenuation is a suitable alternative when the biodiesel blend proportion is >50%, especially in short-term contamination. Also, biostimulation showed to be the most useful option in most cases. On the other hand, a gap in literature about ethanol/gasoline blend bioremediation was evident. As more studies are carried out, the decision tree will be more robust. Nonetheless, this review can be helpful as a guide to help choose the bioremediation approaches to begin with.