Saline petroleum refinery wastewater treatment integrated with bioelectricity production using halophiles in microbial fuel cell (MFC).

Petroleum refinery wastewater (PRWW) with 4% salinity was subjected to treatment and simultaneous generation of energy in air cathode-microbial fuel cell (MFC). Substrate load (SL) such as 0.41 gCOD/L, 0.84 gCOD/L, 1.26 gCOD/L, 1.78 gCOD/L and 2.25 gCOD/L was trialed in air cathode MFC. COD (chemical oxygen demand) reduction was 88% (total COD) and 87% (soluble COD) at optimized SL of 1.78 gCOD/L. Corresponding power and current density derived at optimized SL of 1.78 gCOD/L was 879 mW/m2 and 1052 mA/m2 respectively. Degradation of low and high molecular weight petroleum hydrocarbons in the PRWW was greater than 90% to 100%  and 71% to 82% respectively. Supplementation with a mild nutritional substrate in PRWW accelerated the hydrocarbon biodegradation with time reduction in MFC operated at 1.78 gCOD/L SL. Phylogenetic analysis revealed the dominancy of exo-electrogenic halophilic strains such as Ochrobactrum, Marinobacter, Bacillus and Stenotrophomonas in the reactor. Thus the bioaugmentation of halophiles in MFC efficiently treated PRWW and harvested bioenergy under saline condition.