Petrochemical wastewater treatment: Water recovery using membrane distillation

Water is a natural resource of great economic value and its imminent scarcity has led modern industrial complexes to develop projects to save water. This work investigated the application of membrane distillation in the treatment of the concentrated effluent generated in an electrodialysis reversal pilot plant which is used to treat wastewater from a petrochemical complex in the south of Brazil. The results showed that the recovery of water is technically feasible using pretreatments to improve the operating of the membrane distillation process. Considering the composition of the electrodialysis reversal effluent, it was proposed a physical treatment (filtration) to remove the suspended solids and the pH adjustment to reduce the formation of fouling on the membrane surface. With the proposed pretreatment, the drop in permeate flow rate was minimized by 30% and the rate of water recovery increased from 56% to 75% in comparison with the test carried out without pretreatment. Due to the high rejection of pollutants, the recovered water presented a physical-chemical quality that enables its direct use in the industrial process.