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

Year: 2019

Journal: Biodegradation, Volume 30, AUG, page 335–350

Authors: Silva, Elias J.; Silva, Ivison A.; Brasileiro, Pedro P. F.; Correa, Priscilla F.; Almeida, Darne G.; Rufino, Raquel D.; Luna, Juliana M.; Santos, Valdemir A.; Sarubbo, Leonie A.

Organizations: State of Pernambuco Foundation for the Support of Science and Technology (FACEPE); Research and Development Program of the National Agency of Electrical Energy (ANEEL); Candeias Energy Company (Global Group); National Council for Scientific and Technological Development (CNPq)Conselho Nacional de Desenvolvimento Cientifico e Tecnologico (CNPQ) [PD-06961-0005/2016]; Coordination for the Advancement of Higher Level Education Personnel (CAPES)Coordenacao de Aperfeicoamento de Pessoal de Nivel Superior (CAPES)

Keywords: Biosurfactant; Pseudomonas aeruginosa; Industrial residues; Dissolved air flotation; Oily water; CCRD

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 225rpm for 120h, resulting in a surface tension of 26.5mN/m and a yield of 26g/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 600mg/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.