Comparative bioremediation of BTEX-contaminated produced water using mixed marine algae and Tetraselmis sp. QUCCCM152

Abstract Produced water (PW) derived from petroleum and natural gas extraction operations encompasses hazardous BTEX compounds (benzene, toluene, ethylbenzene, and xylenes), thereby posing significant ecological threats when released into marine ecosystems. This investigation explores the bioremediation capabilities of mixed marine algal culture in conjunction with the isolated strain Tetraselmis sp. QUCCCM152 for the degradation of BTEX in seawater environments. Typical BTEX concentrations in produced water range from 1 to 15 mg/L, depending on geological and operational factors, which justifies the selection of 2.5, 5, and 10 mg/L as representative test conditions. Both experimental systems exhibited vigorous growth and substantial removal efficiencies at BTEX concentrations of 2.5, 5, and 10 mg/L. The mixed algal culture accomplished a significant percentage removal of benzene (%η benzene ) up to 96% for benzene, whereas Tetraselmis sp. QUCCCM152 demonstrated higher percentage o-xylene removal efficiency (%η o-xylene ) of 95%. Significantly, Tetraselmis sp. adapted effectively to the stress induced by BTEX compounds, emerged as the dominant species within the mixed culture, and consistently exhibited removal capabilities across all BTEX constituents. The comparative analysis indicated that while mixed cultures facilitate broad-spectrum degradation, the isolated Tetraselmis sp. strain delivers targeted efficiency, resilience, and scalability conducive to practical applications in the field. These results highlight the promising potential of marine microalgae, especially Tetraselmis sp. QUCCCM152 as sustainable agents for the bioremediation of BTEX compounds. This study enhances the understanding of eco-friendly treatment methodologies for PW, with consequential implications for coastal conservation and the advancement of a circular bioeconomy.