Production of algal bioproducts during the treatment of produced water effluent collected from the oil industry
Dunaliella salina, produced water, hypersaline, microalgae, oil and gas.
The oil industry can generate a high volume of wastewater associated with oil extraction activities. This effluent is known as produced water and is characterized by a complex composition of petroleum products and salts. This effluent must be treated before being discarded or used in other industrial processes. The objective of this study was to evaluate the treatment of produced water from the oil industry through its use for the cultivation of microalgae. The produced water has essential nutrients for the cultivation of microalgae and its reuse economically increases its value (upcycling). Dunaliella salina was grown in different concentrations of produced water supplemented with the Conway medium, and later went through an adaptation period to produced water with high salts content. The results showed that the culture medium prepared with AP can generate biomass and algal lipid with a reduction of only 2.3 times in relation to the control. However, the process of adapting or acclimating the microalgae to salted AP showed a positive gain for the cultivation of Dunaliella salina, reaching an increase in the specific growth rate of 0.28 and 0.29 d-1, biomass productivity 45 and 48 mg L d-1 and pigment accumulation at salts concentrations of 45 and 50 gSDT / L, respectively. The adaptation process also reduced the cultivation period. It is also noteworthy that during culturing showed a significant removal of inorganic nutrients (N and P), as well as organic load (COD) during the cultivation process (≥ 85%, respectively). Therefore, contributing significantly to the treatment of PA. This research also identifies that the best saline concentration for the cultivation of Dunaliella salina in AP is 50 gSDT / L. This fact facilitates the cultivation process in open and large-scale lagoons, since the selective strength of the high concentration of salts prevents contamination and growth by invasive microalgae.