Removal of petroleum hydrocarbons and sulfates from produced water using different bioelectrochemical reactor configurations

Abstract

Produced water (PW) is a wastewater generated in large quantities from the extraction of oil and gas. PW found to have high amounts of dissolved solids (TDS) and residual petroleum hydrocarbons causing considerable damage to the environment. PW also contains sulfates in significant amounts, due to which treating this wastewater is essential prior to discharge. The present study was aimed for bioelectrochemical treatment of PW and simultaneous bioelectrogenesis in the two most studied configurations viz., single and dual chamber microbial fuel cells (MFCs). The study evidenced treatment of recalcitrant pollutants of PW. Both MFCs were operated by keeping similar operating conditions such as anode chamber volume, hydraulic retention time (HRT) for batch mode of operation, electrode materials, inlet characteristics of PW and ambient temperature. Among both configurations, dual chamber MFC showed higher efficiency with respect to bioelectrogenesis (single chamber - 789 mW/m²; dual chamber - 1089 mW/m²), sulfates removal (single chamber - 79.6%; dual chamber - 93.9%), total petroleum hydrocarbons removal (TPH, single chamber - 47.6%; dual chamber - 53.1%) and chemical oxygen demand degradation (COD, single chamber - 0.30 kg COD/m³-day (COD removal efficiency, 54.7%); dual chamber - 0.33 kg COD/m³-day (COD removal efficiency, 60.2%)). Evaluated polarization behavior of both MFCs were also evidenced the effective response of the electroactive anodic biofilm.

Keywords: Green energy; MFC configuration; Produced water; Sulfates; Total petroleum hydrocarbons.