Biological treatment of produced water coupled with recovery of neutral lipids. (15th December 2018)

• Record Type: Journal Article
• Authors: Sudmalis, D.; Da Silva, P.; Temmink, H.; Bijmans, M.M.; Pereira, M.A.
• Is Part Of: Water research. Volume 147(2018)
• Page Start: 33
• Page End: 42
• Publication Date: 2018-12-15
• Subjects: Produced water -- Biological treatment -- Alkane biodegradation -- Neutral lipids production; Water -- Pollution -- Research -- Periodicals; 363.7394
• DOI: 10.1016/j.watres.2018.09.050
• Languages: English
• ISSNs: 0043-1354

Abstract

Abstract: 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. Graphical abstract: Highlights: Efficient removal of n-alkanes from produced water can be achieved biologically. Biodegradation of n-alkanes can be accompanied by production of neutral lipids. Treatment conditions for triggering excretion of neutral lipids can be found.