Page 85 -

CHAPTER 5

AERATION AND

AIR STRIPPING

John E. Dyksen
Black & Veatch
Oradell, New Jersey

Aeration processes have been used to improve water quality since the earliest days of
water treatment. In this process, air and water are brought into intimate contact with each
other to transfer volatile substances to or from the water. Aeration processes generally
are used in two types of water treatment applications. The first is the removal of a gas
from water and is classified as desorption, or air stripping. The second is the transfer of
a gas to water and is called gas absorption, or aeration. The U.S. Environmental Pro-
tection Agency (USEPA) has identified air stripping as one of the best-available tech-
nologies for the removal of volatile organic chemicals (VOCs) and radon from contam-
inated groundwater.

USES OF AERA TION/AIR STRIPPING

Principal uses for aeration in water treatment include

• To reduce the concentration of taste- and odor-causing substances and, to a limited ex-
tent, for oxidation of organic matter.
• To remove substances that may in some way interfere with or add to the cost of sub-
sequent water treatment. A prime example is removal of carbon dioxide from water for
corrosion control and before lime softening.
• To add oxygen to water, primarily for oxidation of iron and manganese so that they
may be removed by further treatment.
• To add ozone or chlorine gas to the water for oxidation and/or disinfection purposes.
• To remove gases such as radon, hydrogen sulfide, and methane.
• To remove ammonia from the water.
• To remove VOCs considered hazardous to public health.

5.1