Corrosion control of drinking water using tray aerators

The multiple-tray aerator is an effective technology for chemical stabilization and corrosion control at small, medium, and large public drinking-water treatment facilities, because of significant savings in chemical costs. A pilot-scale tray tower was built at the University of New Orleans Urban Waste Management and Research Center to study the factors affecting carbon dioxide removal by plain aeration. Several series of tests were conducted to develop a general statistical model to predict the value of the empirical kinetic coefficient which, in turn, can be used in designing a tray tower. The model includes the effect of spacing between trays, hydraulic loading rate, temperature, wind speed, and Langelier index. A method for the optimum design of tray aerators for corrosion control in drinking-water treatment is also discussed. This method is based on a computer program developed to solve the equations needed to predict both the pH after any tray in the tower and the supplemental chemical dosage that may be needed to render the water at equilibrium with respect to calcium carbonate.