Uso da cavitação hidrodinâmica para o tratamento de águas residuárias

Abstract

The treatment of industrial effluents has been a challenge for modern technologies that combine high efficiency of pollutant degradation with low process costs. The present study aimed to evaluate the potential of hydrodynamic cavitation in degrading organic compounds from wastewater. The degradation experiments were performed in a venturi tube and orifice plate. A synthetic effluent was used from an aqueous sucrose solution (C12H22O11), with pH 2.5 at different pressure values (2, 4, 6 and 7,3 bar), both in the Venturi tube and in the orifice plate. The sample collection intervals were 0 ', 3', 6 ', 9', 12 'and 15' and throughout the process there were temperature variations, reaching 47 ° C. Hydrogen peroxide (H2O2) at 30% (m / m) was used as the oxidizing agent in the approximate ratio of 1 mole C12H22O11 to 20 moles of H2O2. The efficiency of the cavitation process was determined by reducing the Chemical Oxygen Demand (COD) of the treated effluent. The results showed that the removal efficiency of the orifice plate showed considerable degradation (mean of 82.5%), however the methodology chosen as the best performance and also applied in the effluent of the refrigerant industry was the methodology using the tube Venturi. This option demonstrated that, in addition to the final efficiency (mean of 94%), the behavior in the intervals until reaching the 15 minutes was relevant, especially in the pressure of 4.0 bar, where with the same 48mL of peroxide used in all the tests , an efficiency peak was obtained at 3 '(90% efficiency) until reaching 94% efficiency at 15', and this methodology and test was chosen for testing the effluent of the refrigerant industry (Venturi tube at 4.0 Pub). By replicating the assay in an actual effluent from the refrigerant industry, an efficiency greater than 70% was obtained, even with the difference in stoichiometric ratio calculated in the assays using water and sucrose, as explained in the present study. Thus, the proposed objectives were met, ratifying the hydrodynamic cavitation as an important method to be inserted in the industries as an impact mitigation process.