LAUSR

Produced water (PW) is the largest waste stream generated by oil and gas industry. It is commonly treated by physical-chemical processes due to high salt content and poor biodegradability of water insoluble compounds, such as n-alkanes. N-alkanes can represent a major fraction of organic contaminants within PW. In this study the possibility of simultaneous n - alkane biodegradation and production of neutral lipids in a concentrated PW stream with A. borkumenis SK2 as the sole reactor inoculum was investigated. N-alkane removal efficiency up to 99.6%, with influent alkane COD of 7.4 g/L, was achieved in a continuously operated reactor system. Gas chromatography results also showed that the majority of other non-polar compounds present in the PW were biodegraded. Biodegradation of n-alkanes was accompanied by simultaneous production of neutral lipids, mostly wax ester (WE)-alike compounds. We demonstrate, that under nutrient limited conditions and 108.9 ± 3.3 mg/L residual n-alkane concentration the accumulation of extracellular WE-alike compounds can be up to 12 times higher compared to intracellular, reaching 3.08 grams per litre of reactor volume (g/Lreactor) extracellularly and 0.28 g/Lreactor intracellularly. With residual n-alkane concentration of 311.5 ± 34.2 mg/L accumulation of extracellular and intracellular WE-alike compounds can reach up to 6.15 and 0.91 g/Lreactor, respectively. To the best of our knowledge simultaneous PW treatment coupled with production of neutral lipids has never been demonstrated before.