(123f) Investigation of Current Production and Metal Removal from Synthetic Desalter Effluent Using a Dual Chamber Microbial Fuel Cell (MFC) with Shewanella Oneidensis MR-1

Desalter effluent treatment has multiple challenges such as chemical processing after treatment and expensive methods. Due to these disadvantages, novel studies for heavy metal removal from desalter effluent have gained popularity. This research focused on heavy metal removal and current production from synthetic desalter effluent using a dual-chamber Microbial Fuel Cell (MFC) inoculated with Shewanella oneidensis MR-1 in the anode. S. oneidensis MR-1 was used due to its ability for heavy metal reducing in their extracellular wall without affecting the electron transport from the nutrient source to the electrode. The catholyte solution was potassium hexacyanoferrate III (K₃Fe(CN₆)) dissolved in 100 mM phosphate buffer solution and it was separated from the anode by a cation exchange membrane and connected to the anode with an external resistance of 1000 Ω using carbon felt electrodes with an area of 0.0036 m². The synthetic desalter effluent was composed by ZnSO₄7H₂O (13.5 mg/L), MgSO₄ (415 mg/L), CuSO₄5H₂O (10.5 mg/L), MnSO₄H₂O (7.5 mg/L), NaCl (2410 mg/L) and phenol (354.2 mg/L), and the total metals in solution were evaluated by ICP-OES. Synthetic desalter effluent was inoculated with 52.5 mL of inoculum at OD₆₀₀ of 0.25. The nutrient source composed of tryptic soy broth and M9 mineral solution in 18 mM was fed into the anode every 24 hours, and catholyte solution was fed into the cathode every 48 hours. The MFC was operated for 140 hours with these conditions. Additionally, biofilm formation on the electrode was evaluated by scanning electron microscopy (SEM). The maximum current density and open-circuit voltage (OCV) were 70.3 mA/m² and 252.9 mV, respectively. The heavy metal removal showed a Cu (II), Mg (II), Mn (II), and Zn (II) removal of 11%, 65%, 79%, and 60%, respectively. SEM analysis of the anode electrode showed formation of bacterial nanowires that enhanced the electron transport from the nutrient source to the cell and the electrode surface. With these results, MFCs could arise as a new method for heavy metal removal and energy production.