Estratégias de tratamentos e aplicações para a água produzida utilizando um efluente sintético

Abstract

The produced water is one of the main effluents of the petroleum industry and is characterized as an effluent of complex composition, formed by various organic and inorganic compounds. It accounts for about 70% of total wastewater generated during the life of the well and their characteristics and quantities produced are also dependent on their location and age of this one. Currently, in Brazil, millions of m³ of water effluents are disposed of in the environment, as well as a considerable amount of oils and greases. The present thesis aimed to investigate, through a synthesized effluent, potential applicabilities for untreated and treated produced water and, thus, enable the management and reuse of this effluent. Synthetic produced water was used as an additional carbon source when using coconut, cashew, carnauba and sugarcane residues, as well as moringa seeds, to synthesize rhamnolipids from Pseudomonas aeruginosa at 200 rpm, 38 ° C and 72 h. The produced water was submitted to a physicalchemical treatment, whose combined process was formed by a flocculation step, with 226 rpm and 3 minutes in the fast mixing stage and 90 rpm and 4 minutes in the slow mixing stage, followed by dissolved air flotation (DAF), carried out under the injection of 10% v/v of water saturated with air at 6 bar and with a flotation time of 28 minute, using a concentration of 64 mg/L of natural flocculant. A biological treatment was also used to evaluate the removal efficiency of the oil and grease content of the produced water, operating at 6 h in a continuous and aerobic system, with a hydraulic retention time of 2.27 days. The results showed that produced water without previous treatment was presented with a potential use for supplementation of carbon source to agroindustrial residues in the production of biosurfactant. promoting a positive emulsion stability effect when using the green coconut shells as the substrate and maintaining stable, under elevated temperatures, the emulsion formed by the broth produced by cashew residues. When undergoing a physical-chemical treatment through flocculation/DAF, demonstrated that extracts of Moringa oleifera seeds with and without oil are effective natural flocculants in their treatment, reducing the content of oils and greases (TOG) in about 82%, with the oil extraction unaffecting the coagulant effect of the seeds. The biological treatment through activated sludge was highly efficient in the removal of TOG from produced water, with efficiencies, in most cases, greater than 90% and achieving compliance with the environmental requirements for this parameter. Through the results obtained it was possible to conclude that the effluent treated by this biological process presents a promising ability to be reused in the germination and irrigation of non-food crops. These results demonstrated to be promising for the reuse of produced water as resources for higher value demands production, minimizing the impact of this effluent on the environment.