BIODEGRADATION OF TOTAL PETROLEUM HYDROCARBONS IN PRODUCED FORMATION WATER BY INDIGENOUS BACTERIAL ISOLATES FROM DELTA STATE, NIGERIA

Abstract

Produced formation water (PFW) is subsurface water brought to the surface during oil and gas production, and its improper disposal poses environmental risks, including water contamination and harm to biological indicators. This study investigated the biodegradation potential of indigenous bacteria in PFW samples from five oil sites in Delta State, Nigeria. Physicochemical analysis revealed a pH of 7.63±0.06, electrical conductivity of 940.33±0.33 µS/cm, turbidity of 1.26±0.60 NTU, total dissolved solids of 4706.66±6.66 mg/L, and total petroleum hydrocarbon (TPH) content of 0.06±0.00 mg/L. Bacterial counts ranged from 1.86±1.20×10⁵ to 2.37±2.02×10⁵ CFU/mL in nutrient agar, and from 3.66±0.66×10⁴ to 6.66±1.66×10⁴ CFU/mL in mineral salt agar. Isolated bacteria included Acinetobacter baumannii, Acetobacterium sp., Enterococcus faecalis, Bacillus arbutinivorans, and Pseudomonas stutzeri. Among them, P. stutzeri showed the highest degradation efficiency, reducing TPH to 0.048 mg/L over five weeks, followed by E. faecalis, Acetobacterium sp., and B. arbutinivorans (each to 0.05 mg/L). The findings demonstrate that indigenous bacteria present in PFW possess notable hydrocarbon-degrading capabilities and could be harnessed for bioremediation applications.