Strategy for the cultivation of Chlorella vulgaris with high biomass production and biofuel potential in wastewater from the oil industry

Abstract

This work aimed to provide a biochemical characterisation of Chlorella vulgaris biomass cultivated with daily supplementation of produced water. The simultaneous phytoremediation and production of biomolecules and bioproducts of commercial interest were analysed and discussed. Cultures were grown in laboratory scale photobioreactors for 26 days in 1.5 L of BG11 medium, with daily supplementation of 50 mL of non-autoclaved produced water (TPW) or distilled water (TDW). Biomass production differed among the control (3.86 g L−1), TPW (1.69 g L−1), and TDW (1.82 g L−1). The TPW-treated culture showed a high concentration of carbohydrates (40.19 %) with a bioethanol production of 18.22 mL 100 g−1 of biomass. The content of carotenoids (2.4μg mL −1), protein (22.83 %), and lipids (21.53 %) were also determined. The lipid composition consisted mostly of palmitoleic (5.42 mg g−1), γ-linolenic (3.02 mg g−1), and linolelaidic (1.94 mg g−1) acids, which gave the oil the ideal properties for quality biodiesel. In addition, the high phytoremediation efficiency of heavy metals such as copper (70.00 %), manganese (76.89 %), and molybdenum (97.82 %), as well as total petroleum hydrocarbons (48.59 %), were also detected. Therefore, TPW can be a promising alternative for phytoremediation of chemical compounds, while utilising effluent from the oil industry to produce a high content of valuable biomass, biomolecules, and biofuels.