Bioremediation and Biofuel Production Potential of Chlorella sorokiniana Cultivated in Petroleum-Derived Produced Water

Petroleum-derived produced water (PW) contains toxic pollutants such as phenol, posing significant environmental challenges. Microalgae-based bioremediation offers a sustainable alternative for wastewater treatment with the added benefit of biomass valorization. This study investigates the dual potential of Chlorella sorokiniana (C. sorokiniana) for phenol biodegradation and bioenergy production when cultivated in synthetic PW. It was hypothesized that C. sorokiniana could not only survive but also actively degrade phenol under varying concentrations of PW while generating biomass with energy-rich properties. The main objective was to evaluate growth dynamics, phenol removal efficiency, and the bioenergy potential of the resulting biomass. The microalga was cultivated in different PW concentrations (0%, 10%, 20%, 30%, 40%, 50%, and 100%), and its performance was assessed in terms of biomass productivity, phenol degradation, lipid content, and energy value. Experimental results showed optimal growth at 10% PW loading, yielding a biomass productivity of 64.7 mg/L d. Phenol removal reached up to 96%, with biodegradation identified as the dominant removal mechanism over bioadsorption. Lipid analysis revealed a 30% lipid content in dry biomass, while the elemental composition and higher heating value (15.20 MJ/kg) confirmed its suitability for biofuel production. These findings highlight the robust bioremediation capability of C. sorokiniana under saline- and phenol-stressed conditions, alongside its potential for renewable energy generation. This research contributes to advancing circular economy approaches by integrating environmental remediation with sustainable energy production.