OVERVIEW

Several different types of air stripping and aeration systems are widely used for a variety of water treatment applications. The most common types are diffused-air, surface aerator, spray, and packed-tower systems. Water treatment applications for these systems include the absorption of reactive gases for water stabilization and disinfection, precipitation of inorganic contaminants, and air stripping of volatile organic compounds (VOCs) and nuisance-causing dissolved gases. The diffused-aeration (or bubble) systems are primarily used for the absorption of reactive gases, such as oxygen (O ₂), ozone (O ₃), and chlorine (Cl ₂). Oxygen is frequently used for the oxidation/precipitation of iron and manganese. Ozone is used for disinfection, color removal, and oxidation of total organic carbon (TOC). Chlorine is primarily used for disinfection and sometimes as a preoxidant for the oxidation of iron and manganese or for other purposes. Diffused-aeration systems have also been used for the stripping of odor-causing compounds and VOCs. Surface-aeration systems are primarily used for removal of VOCs. The packed-tower and spray nozzle systems are primarily used for the removal of NH ₃, CO ₂, H ₂S, and VOCs. The packed-tower systems include countercurrent flow, cocurrent flow, and cross-flow configurations. Spray nozzle systems can include tower and fountain-type configurations.

A fundamental understanding of the theory of gas transfer is first discussed, followed by a description of the various unit...