Abstract
The industrial sector has adopted practices for minimize the impacts of large water use on water resources. Among these practices, the treatment of effluents is the most important because ensures that wastewater will be properly disposed and allows its reuse. The constant use of oil in industry causes a significant generation of oily effluents which leads to the need for effective treatment for this type of pollutant. Constructed wetlands (CWs) are systems created for the purpose of treating anthropogenic such as municipal or industrial wastewater. CWs are a cost-effective and technically feasible approach to treating wastewater and runoff for several reasons like low expenses (build, operation and maintenance), operation and maintenance periodic only, on-site labor and water reuse and recycling facilitation. The extremely adaptable sizing of constructed wetlands allows modifications to improve this treatment efficiency. For oily wastewater treatment, CWs filled with floating macrophytes can receive microbubbles nozzles in order to improve the system, increasing the drag of oil to the surface and the supply of oxygen to the aerobic microorganisms. In this work, the increase of the efficiency of oily wastewater treatment in constructed wetlands by addition of microbubbles was evaluated. Computational fluid dynamics (CFD) simulations in the software ANSYS to validate the fluid dynamic behavior of the system. Experimental tests in two constructed wetlands pilot prototypes, with and without addition of microbubbles were made in transparent acrylic. Initial and final concentrations of an oily wastewater in pilot prototypes were determined, as well as essential operation parameters. An oil collector was designed and installed to remove the free oil on the water surface, ensuring the maximum removal of oily waste on constructed wetland prototype. The experimental tests results showed that the final concentration on prototype without aeration was 34.3 mg/L. The final concentration of the aerated prototype was 11.6 mg/L, standing below of the limit of Brazilian Environmental Legislation (CONAMA Resolution nº 430/2011), validating the efficiency increase of the treatment through a simple adaptation.
