Self-induced bio-potential and graphite electron accepting conditions enhances petroleum sludge degradation in bio-electrochemical system with simultaneous power generation

Bio-electrochemical treatment (BET) documented effective degradation of real field petroleum sludge over the conventional anaerobic treatment (AnT). BET (41.08%) operation showed enhanced total petroleum hydrocarbons (TPH) removal over AnT (20.72%). Aromatic fraction visualized higher removal (75.54%) compared to other TPH fractions viz., aliphatics, asphaltenes and NSO (nitrogen, sulfur and oxygen) during BET operation. Higher ring aromatics (5–6) documented easy degradation in BET, while AnT was limited to lower ring (2–3) compounds. Voltammetric analysis evidenced simultaneous redox behavior during BET operation due to presence of graphite electrode as electron acceptor, while AnT showed extended reduction behavior only. Self-induced primary and secondary oxidation reactions and capacitive-deionization might have enhanced the degradation capability of BET. BET documented higher charge/capacitance (2810 mJ/1120 mF) than AnT (450 mJ/180 mF). Power output corroborated well with observed results supporting BET performance as fuel cell. Electrodes offer a potential alternative electron acceptor for promoting the degradation of organic contaminants.