Microbial electrochemical bioremediation of petroleum hydrocarbons (PHCs) pollution: Recent advances and outlook

Soil contamination by petroleum hydrocarbons (PHCs) causes various acute problems such as crop growth, yield, and grain quality. Many Physico-chemical and biological approaches are employed to remove the PHCs from polluted soil. However, some of these approaches are too slow, or ineffective, and/or environmentally un-friendly. Indeed, bioelectrochemical systems (BES) combine biological methods and electrochemistry in the context of a redox reaction. BES is gaining attention from scientists and policymakers as a promising technology for the remediation of soil contaminated with PHCs. This review discusses BES working principles, mechanisms, design configuration, operational parameters, and advances in BES applications to remediate PHCs from contaminated soil efficiently. The role of biosurfactants and biochar in enhancing PHC degradation in soil using BES mediating extracellular electron transfer (EET) and biofilm formation is highlighted. Furthermore, recent innovations in this field, technical and economic challenges and limitations in scaling-up BES, and future per-spectives are discussed. This review suggests that biochar-based single-chamber air-cathode reactors are preferred because of their lower cost compared to the other classic configurations. Additional efforts are needed in the design of BES reactors, soil characteristics, and seasonal variations in BES performance over a long period of operation to improve the efficiency of soil remediation and power production as well as to apply it on a large scale.