Tratamento de água produzida utilizando a técnica combinada floculação/flotação por ar dissolvido com mistura de polieletrólitos e moringa oleífera

Abstract

The Oil Industry is one of the sectors with greatest potential for environmental degradation and the produced water is the largest waste stream generated in this industry. The complex chemical composition and the high volume generated of this effluent hold a strict control and management. In accordance with current environmental legislation the water should be treated before final disposal, reuse or recycle including underground injected vapor to increase oil production. In view of the treatment of produced water for oil and grease content removal, the combined technique flocculation/dissolved air flotation has been extensively studied. In the flocculation step has been used high cost flocculants of chemical industry which are non-biodegradable. In this context it was evaluated the removal efficiency of oil and grease content from produced water by the combined technique flocculation/dissolved air flotation using Moringa OleíiferaM.O) a natural flocculant blended with two commercial flocculants “C” and “D” (currently used in the oil industry), aiming to let the water produced in the disposal conditions. The experiments were conducted by means of statistical experimental design evaluating the influence of the total concentration of flocculants, slow mixing time and flotation time over the efficiency of oil and grease content removal. Moreover, for each mixture and their respective ratios studied, were obtained mathematical models. The effluent treatment using the mixture of Moringa oleífera and commercial “D” flocculants with mixing ratio of 50:50 (%, volume basis) achieved the environmental requirements in all conditions evaluated, while, under the same conditions it wasn’t possible using the mixture of Moringa Oleífera and commercial “C” flocculant. The oil and grease removal content efficiency using a mixing ratio of 70:30 (%, volume basis of M. O and commercial flocculant, respectively) showed to be an interesting condition to reach the environmental requirements for produced water disposal once all mixtures of Moringa Oleífera and commercial flocculants “C” and “D” achieved satisfactory experimental results for produced water disposal. Finally, we evaluated the effect of improvement of Moringa oleífera into commercial flocculant “D” on oil and grease removal content efficiency.