DEVELOPMENT AND SCALE - UP OF A PROCESS FOR NEUTRALIZATION OF ALKALINE WASTEWATER WITH FLUE GASES

In this work, neutralization process of alkaline industrial wastewater using flue gases was studied. Experiments were performed using a pilot system consisting of a venturi ejector and neutralization tank; alkaline waters and flue gases used were simulated. Experiments were performed following a central composite face-centered design, where the input variables were the gas composition (CO2 v/v percentage) with 3 levels (8, 11 and 2 14% CO2 v/v) and. flows of alkaline water fed to neutralization tank (0.2, 0.3, 0.4, 0.5 and 0.6 liters/minute), which were expressed in terms of ratio of gas flow to liquid flow (G/L) in experimental design. Neutralization was obtained for flows of 0.2, 0.3 and 0.4 L/min for all CO2 concentrations. The flow rate of 0.5 l/min only neutralized with a CO2 concentration of 14%. For a basic water flow of 0.6 L/min, neutrality was not achieved with any of CO2 concentrations tested. A mode, l which was used later for scaling - up the proposed neutralization system was built. It was found that neutralization process of alkaline waters using flue gas was technically feasible, even for gases with low concentration of CO2 (8% v/v). The best pH output is achieved with a G/L ratio of 8.74 (alkaline water flow = 0.2 L/min) and a CO2 concentration of 14% v/v.