Clean Water and Sanitation (SDG 6), Climate Action (SDG 13)
Electro-bioremediation of oily wastewater: a biorefinery concept for biosurfactants, polyxydroxyalkanoates and pyocyanin production Constantina K. Varnava 1 , Ioannis Ieropoulos 2 , Epameinondas Leontidis 3 and Argyro Tsipa 1,4,* 1 Department of Civil and Environmental Engineering, University of Cyprus, Cyprus. 2 Water and Environmental Engineering Group, University of Southampton, SO16 7QF Southampton, UK. 3 Department of Chemistry, University of Cyprus, Cyprus. 4 Nireas International Water Research Centre, University of Cyprus, Cyprus. Corresponding author: tsipa.argyro@ucy.ac.cy In bioremediation, the low bioavailability of hydrocarbons, which are toxic and persistent pollutants, to microorganisms is the main reason for their relatively slow biodegradation. Microbial production of surface-active compounds, called biosurfactants (BSFs), leads to acceleration of hydrocarbons’ biodegradation and can replace chemical surfactants in several applications. Pseudomonas species, known for their adaptability to oil contaminated environments, can produce such BSFs. Hydrocarbons biodegradation by Pseudomonas has also the potential to result in polyhydroxyalkanoates (PHAs) production. PHAs can be used as bio-based building blocks of plastics replacing the current fossil-fuel based plastics. In this study, we characterized and quantified the BSFs and PHAs produced by a relatively unknown and promising Pseudomonas species, called P. citronellolis , during aerobic biodegradation of oily wastewater. Then, as electro-bioremediation enhances the biodegradation process, the electro-bioremediation of oily wastewater by P. citronellolis was assessed with simultaneous endogenous BSF production, intracellular PHAs production and pyocyanin formation which is the electron mediator of the process. Pyocyanin is recognised for its antimicrobial, antioxidant and anticancer properties as well as for the possibility to replace chemically synthesised dyes in textile industry. Therefore, the electro-bioremediation of oily wastewater can clean wastewater and be a biorefinery to produce added-value products towards sustainability. Key words: Microbial fuel cells, drill cutting fluid, hydrocarbons, electron mediator, Pseudomonas citronellolis References 1. Tsipa, A.; Stylianou, K.; Papalli, M.; Papageorgiou, E.; Kyriakou, L.; Rigopoulos, I.; Ioannou, I.; Pinakoulaki, E. Iron Stimulated Production and Antimicrobial Potential of a Novel Biosurfactant Produced by a Drilling Waste-Degrading Pseudomonas citronellolis Strain. Processes 2021, 9, 686. 2. Varnava C.K.; Persianis P.; Ieropoulos I.; Tsipa A. Electricity generation and real oily wastewater treatment by Pseudomonas citronellolis 620C in a microbial fuel cell: pyocyanin production as electron shuttle. Bioprocess Biosyst. Eng . 2024, 47, 903- 917. 3. Varnava C.K.; Grenni P.; Mariani L.; Barra Caracciolo A.; Hadjipakkou H.; Lefkaritis G.; Pinakoulaki E.; Chronakis N.; Kalogerakis N.; Tsipa A. Characterization, production optimization and ecotoxicity of a lipopeptide biosurfactant by Pseudomonas citronellolis using oily wastewater. Biochem. Eng. J . 2024, 205, 109257.
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