Treatment of oily effluent using a low-cost biosurfactant in a flotation system.

Fuel and lubricating oil leaks produce an oily wastewater that creates an environmental problem for industries. Dissolved air flotation (DAF) has been successfully employed for the separation of oily contaminants. Collectors constitute an auxiliary tool in the DAF process that enhances the separation efficiency by facilitating the adhesion of the contaminant particles. The use of biosurfactants as collectors is a promising technology in flotation processes, as these biomolecules are biodegradable and non-toxic. In the present study, a biosurfactant was produced from the bacteria Pseudomonas aeruginosa UCP 0992 cultivated in 0.5% corn steep liquor and 4.0% vegetable oil residue in a bioreactor at 225 rpm for 120 h, resulting in a surface tension of 26.5 mN/m and a yield of 26 g/L. The biosurfactant demonstrated stability when exposed to different temperatures, heating times, pH values and salt and was characterised as a glycolipid with a critical micelle concentration of 600 mg/L. A central composite rotatable design was used to evaluate the effect of the crude biosurfactant added to a laboratory DAF prototype on the removal efficiency of motor oil. The isolated and formulated forms of the biosurfactant were also tested in the prototype after the optimisation of the operational conditions. The results demonstrated that all forms of the biosurfactant increased the oil separation efficiency of the DAF process by 65 to 95%. In conclusion, the use of biosurfactants is a promising alternative as an auxiliary tool in flotation processes for the treatment of oily waters generated by industrial activities.

Formulation of a Commercial Biosurfactant for Application as a Dispersant of Petroleum and By-Products Spilled in Oceans.

Oil spills in oceans cause irreparable damage to marine life and harm the coastal populations of affected areas. It is therefore fundamental to develop treatment strategies for such spills. Currently, chemical dispersants have been used during oil spills, although these agents have been increasingly restricted due to their toxic potential. Thus, the aim of the present study was to formulate a biodegradable commercial biosurfactant for application as a dispersant. Biosurfactants are scientifically known biomolecules produced by microorganisms capable of allowing water-oil interaction. Thus, a biosurfactant was produced by the yeast Candida bombicola URM 3718 cultivated in industrial waste and formulated with the addition of a potassium sorbate preservative for fractionated sterilization (tyndallization) and the combination of fluent vaporization with the preservative. After formulation, samples were stored for 120 days, followed by surface tension, emulsification and oil dispersant tests in sea water. The results were promising for the biosurfactant formulated with the preservative, which demonstrated stability and an absence of toxicity in experiments with a marine indicator. The commercial biosurfactant was tested at different pH values, temperatures and in the presence of salt, demonstrating potential industrial application at a cost compatible with the environmental field. The formulation process developed in this research was patented in the Brazilian National Intellectual Property Institute (patent number BR1020140179631).