Taste and Odor Removal

Aeration has little effect on taste and odor removal. Most taste and odor-causing compounds are highly soluble in water. Therefore, except in a few cases, aeration is usually less effective in removing taste and odor than other methods such as chemical oxidation or surface adsorption.

Iron and Manganese Removal

Iron and manganese removal is usually accomplished by oxidizing these ions to insoluble oxides. The purpose of aeration in this process is to provide sufficient oxygen for the oxidation reaction to occur. This process is often used for groundwaters that are low in dissolved oxygen. Therefore, aeration of groundwater causes iron and manganese to oxidize and precipitate, as well as increase the dissolved oxygen in the water. Manganese is usually not oxidized rapidly at neutral pH values. Increasing the pH to 5.8, especially if tower aerators filled with coke briquettes are used, will improve manganese oxidation.

Removal of Volatile Organic Compounds

The 1986 amendment to the Safe Drinking Water Act established new limits for organic substances known as volatile organic compounds. Most of these chemicals can be easily removed by aeration. Particular attention should be paid to the exhaust air in the design of aeration units for the removal of volatile organic compounds, since some of these compounds are subject to maximum free air concentration limits.

Removal of Hydrogen Sulfide

Hydrogen sulfide is an important taste and odor producing compound that can be effectively removed by aeration. The primary treatment mechanism in this case is the oxidation of hydrogen sulfide, which produces elemental sulfur in the water. In some cases, the resulting free sulfur cannot interfere with other treatment processes.

In waters with high concentrations of carbon dioxide, initial aeration to remove this gas provides more effective removal of hydrogen sulfide. In this process, conditions are more favorable for the removal of hydrogen sulfide.