text: Packed towers, such as shown in Figure 1, use a distributor placed at the top of the tower to evenly distribute engineered plastic, ceramic, or metal packing to maximize air-water contact. Design criteria for packed towers include surface area provided by the packing, column height and diameter, and air to water flow rates. Designers of air strippers want to obtain the largest air-water surface contact in order to reach maximum efficiency of removing contaminants Of the two types of air strippers, packed strippers tend to be more efficient at removing contaminants than sieve tray towers. Packed towers remove 99% of volatile organic compounds due to their high Henry's constant and the high air-water surface contact of the system. Packed strippers also work more efficiently in removing lower volatility organic compounds than tray strippers. Furthermore, packed tower strippers are more cost effective than tray strippers when treating larger quantities of water. Towers can be between 5 and 12 meters in height and are typically permanent installations. Though, some towers can be transported on a movable trailer to be used in different areas where water treatment is needed.