Biodegradation of low and high molecular weight hydrocarbons in petroleum refinery wastewater by a thermophilic bacterial consortium

ABSTRACT

Clean-up of contaminated wastewater remains to be a major challenge in petroleum refinery. Here, we describe the capacity of a bacterial consortium enriched from crude oil drilling site in Al-Khobar, Saudi Arabia, to utilize polycyclic aromatic hydrocarbons (PAHs) as sole carbon source at 60°C. The consortium reduced low molecular weight (LMW; naphthalene, phenanthrene, fluorene and anthracene) and high molecular weight (HMW; pyrene, benzo(e)pyrene and benzo(k)fluoranthene) PAH loads of up to 1.5 g/L with removal efficiencies of 90% and 80% within 10 days. PAH biodegradation was verified by the presence of PAH metabolites and evolution of carbon dioxide (90 ± 3%). Biodegradation led to a reduction of the surface tension to 34 ± 1 mN/m thus suggesting biosurfactant production by the consortium. Phylogenetic analysis of the consortium revealed the presence of the thermophilic PAH degrader Pseudomonas aeruginosa strain CEES1 (KU664514) and Bacillus thermosaudia (KU664515) strain CEES2. The consortium was further found to treat petroleum wastewater in continuous stirred tank reactor with 96 ± 2% chemical oxygen demand removal and complete PAH degradation in 24 days.

KEYWORDS:

• PAHs
• bioremediation
• thermophiles
• continuous stirred tank reactor
• pseudomonas
• bacillus

Acknowledgements

The authors acknowledge with thanks Science and Technology Unit, King Abdulaziz University for technical support. The authors thank Saudi Aramco and Petro Rabigh, Saudi Arabia for providing the wastewater samples. The authors also thank Dr Lukas Y. Wick, Department of Environmental Microbiology, Helmholtz Centre for Environmental Research – UFZ, Germany for his guidance as a consultant during the project work.

Disclosure statement

No potential conflict of interest was reported by the authors.

Additional information

Funding

This project was funded by the National Plan for Science, Technology and Innovation (MAARIFAH) – King Abdulaziz City for Science and Technology – the Kingdom of Saudi Arabia – award number (11-ENV2012-03).