Microalgae-based phycoremediation represents a sustainable approach for treating complex industrial wastewaters while simultaneously enabling the generation of high-value bioproducts. In this study, the performance of Chlorella vulgaris cultivated under mixotrophic and heterotrophic conditions was evaluated using ten binary combinations of oilfield wastewater and poultry wastewater. The direct use of these real wastewater streams is particularly relevant, as they are abundant effluents enriched in both organic and inorganic compounds, and their management poses a significant environmental challenge. All experiments were conducted at laboratory scale in reactors operated under strictly controlled conditions, allowing a robust comparison of C. vulgaris performance under the different cultivation regimes. Key parameters monitored included biomass production, removal of total petroleum hydrocarbons (TPH), uptake of nutrients (PO 4 3− and NO 3 − ), and production of extracellular polymeric substances (EPS). After 15 days of cultivation, TPH removal was consistently high, with average values of 90% under mixotrophic conditions and 93% under heterotrophic conditions, with the highest removals observed in treatments combining oilfield wastewater with sterilized seawater. Biomass production was significantly higher under mixotrophic conditions, reaching 1594 mg L⁻ 1 in the mixture of oilfield wastewater and sterilized poultry wastewater, indicating a nutrient synergy between both wastewater types. Nitrogen in the form of nitrate and phosphorus in form of phosphate removal efficiencies varied among treatments, with maximum values of 68% for nitrogen (NO 3 − ) and 99% for phosphorus (PO 4 3− ). EPS production reached its highest value (up to 1.34 mg L⁻ 1 ) in treatments with oilfield wastewater and sterilized seawater, showing an inverse relationship with biomass yield, which suggests a trade-off between cellular growth and the synthesis of protective metabolites. This work demonstrates the feasibility of using mixed industrial effluents as nutrient-balanced media for efficient hydrocarbon and nutrient removal by C. vulgaris , supporting sustainable bioproduct recovery and circular bioeconomy applications.
Ñañez et al. (Wed,) studied this question.