Simulation of oxygen transfer in water by aeration with diffusers, applying mechanistic relationships

Abstract

The purpose of this research was to evaluate the behavior of the estimation error of a mathematical model in the prediction of the concentration of dissolved oxygen (DO) during the operation of water oxygenation at different submergence depths of a fine bubble diffuser. The model that was evaluated was generated by introducing the mechanistic relationships proposed by Lee in the equation of the double layer theory for oxygen transfer in water. The mechanistic relationships allow the calculation of the DO saturation concentration and the oxygen transfer coefficient in terms of the physical properties of the water, as well as the modification of the liquid temperature and air pressure. For the evaluation, data from deoxygenated water aeration tests in a vessel at constant volumes were used. The diffuser submergence depths tested were 35 cm, 70 cm and 105 cm. The estimation error was calculated by the difference between the results generated by the simulated model and those obtained experimentally. The simulation was carried out under the same experimental conditions and with the finite difference model. After evaluation, the maximum error was found to be 0.01 ppm at 35 cm. The relationship between submergence depth and model estimation error had no definite trend, and the effect is significant.